Principles of Tissue Engineering

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Principles of Tissue Engineering
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Contents
	Part One The basis of growth and differentiation63
	Part Two In vitro control of tissue development155
	Part Three In Vivo Synthesis of Tissues and Organs257
	Part Four Biomaterials in tissue engineering273
	Part Five Transplantation of engineered cells and tissues361
	Part Six Stem cells419
	Part Seven Gene therapy491
	Part Eight Breast555
	Part Nine Cardiovascular system577
	Part Ten Endocrinology and metabolism655
	Part Eleven Gastrointestinal system707
	Part Twelve Hematopoietic system755
	Part Thirteen Kidney and genitourinary system803
	Part fourteen Musculoskeletal system881
	Part Fifteen Nervous system1023
	Part Sixteen Ophthalmic1113
	Part Seventeen Oral/Dental applications1185
	Part Eighteen Respiratory system1251
	Part Nineteen Skin1287
	Part Twenty Tissue-engineered food1353
	Part Twentyone Emerging technologies1389
	Part Twentytwo Clinical experience1481
	Part Twenty three Regulation, commercialization and ethics1551
List of contributors
Preface
1 Tissue engineering: current status and future perspectives
	Clinical need
	Current state of the field
		Smart biomaterials
		Cell sources
			Embryonic stem cells
			Induced pluripotent stem cells
			Adult stem cells
	Whole organ engineering
	Biofabrication technologies
		Electrospinning
		Inkjet three-dimensional bioprinting
		Extrusion three-dimensional bioprinting
	Spheroids and organoids
		Imaging technologies
		Tissue neovascularization
		Bioreactors
		Organ-on-a-chip and body-on-a-chip
		Integration of nanotechnology
	Current challenges
	Future directions
		Smart biomaterials
		Cell sources
			Embryonic stem cells
			Induced pluripotent stem cells
			Adult stem cells
		Whole organ engineering
		Biofabrication technologies
		Tissue neovasculatization
		Bioreactors
		Integration of nanotechnology
	Conclusions and future challenges
	References
	Further reading
2 From mathematical modeling and machine learning to clinical reality
	Introduction
	Modeling stem cell dynamics
		Positive feedback–based molecular switches
		Variability in stem cell populations
	Modeling tissue growth and development
		Monolayer tissue growth in vitro
		Tissue growth on complex surfaces in vitro
		Three-dimensional tissue growth in vitro
		Pattern formation
	Machine learning in tissue engineering
		Supervised methods
		Unsupervised methods
		Machine learning of cellular dynamics
		Regulatory network inference
	From mathematical models to clinical reality
	References
3 Moving into the clinic
	Introduction
	Current state of tissue engineering
	Pathway for clinical translation
	Regulatory considerations for tissue engineering
	Conclusion
	Acknowledgment
	References
	Further reading
Part One: The basis of growth and differentiation
4 Molecular biology of the cell
	The cell nucleus
		Control of gene expression
		Transcription factors
		Other controls of gene activity
	The cytoplasm
		The cytoskeleton
			Microtubules
			Microfilaments
			Small GTPases
		The cell surface
		Cell adhesion molecules
	Extracellular matrix
	Signal transduction
	Growth and death
	Culture media
	Cells in tissues and organs
		Cell types
		Tissues
		Organs
	Reference
	Further reading
		General
		Chromatin
		Signaling, general
		Cytoskeleton, adhesion molecules and extracellular matrix
5 Molecular organization of cells
	Introduction
	Molecules that organize cells
		Changes in cell–cell adhesion
		Changes in celleextracellular matrix adhesion
		Changes in cell polarity and stimulation of cell motility
		Invasion of the basal lamina
	The epithelial–mesenchymal transition transcriptional program
		Transcription factors that regulate epithelial–mesenchymal transition
		Regulation at the promoter level
		Posttranscriptional regulation of epithelial–mesenchymal transition transcription factors
	Molecular control of the epithelial–mesenchymal transition
		Ligand-receptor signaling
			Growth factor-β pathway
			Wnt pathway
			Signaling by receptor tyrosine kinase ligands
			Notch pathway
			Hedgehog pathway
		Additional signaling pathways
		A model for epithelial–mesenchymal transition induction
	Conclusion
	List of acronyms and abbreviations
	Glossary
	References
6 The dynamics of cell–extracellular matrix interactions, with implications for tissue engineering
	Introduction
		Historical background
		Extracellular matrix composition
		Receptors for extracellular matrix molecules
	Cell–extracellular matrix interactions
		Development
			Adhesion and migration
			Proliferation
			Differentiation
			Apoptosis
		Wound healing
			Adhesion and migration
			Proliferation
			Differentiation
			Apoptosis
	Signal transduction events during cell–extracellular matrix interactions
	Relevance for tissue engineering
		Avoiding a strong immune response that can cause chronic inflammation and/or rejection
		Creating the proper substrate for cell survival and differentiation
		Providing the appropriate environmental conditions for tissue maintenance
	References
7 Matrix molecules and their ligands
	Introduction
	Collagens
		Fibrillar collagens
		Fibril-associated collagens with interrupted triple helices (FACIT)
		Basement membrane–associated collagens
		Other collagens
	Major adhesive glycoproteins
		Fibronectin
		Laminin
		Elastic fibers and microfibrils
	Other adhesive glycoproteins and multifunctional matricellular proteins
		Vitronectin
		Thrombospondins
		Tenascins
	Proteoglycans
		Hyaluronan and lecticans
		Perlecan
		Small leucine-rich repeat proteoglycans and syndecans
	Conclusion
	References
8 Morphogenesis and tissue engineering
	Introduction to tissue morphogenesis
	Biology of tissue morphogenesis
		Morphogens as bioactive signaling molecules during morphogenesis
		The extracellular matrix as a key regulator of tissue morphogenesis
		Cell–cell interactions during tissue morphogenesis
		Tissues as integrated systems in the body
	Engineering tissue morphogenesis
		Cells as building units in tissue engineering
		Biomaterial scaffolds as artificial extracellular matrices
		Morphogens as signaling cues in tissue engineering
		Tissue remodeling in healthy and diseased environments
	Current focuses and future challenges
	References
9 Gene expression, cell determination, differentiation, and regeneration
	Introduction
	Determination and differentiation
	MyoD and the myogenic regulatory factors
	Negative regulators of development
		MicroRNAs—regulators of differentiation
	Pax in development
	Satellite cells in skeletal muscle differentiation and repair
	Tissue engineering—repairing muscle and fostering regeneration by controlling determination and differentiation
	Conclusion
	References
Part Two: In vitro control of tissue development
10 Engineering functional tissues: in vitro culture parameters
	Introduction
	Key concepts for engineering functional tissues
		Fundamental parameters for engineering functional tissues
		Fundamental criteria for engineering functional tissues
	Importance of in vitro studies for engineering functional tissues
		In vitro studies relevant to tissue engineering and regenerative medicine
		In vitro platforms relevant for high throughput screening of drugs and other agents
	Influence of selected in vitro culture parameters on the development and performance of engineered tissues
		Culture duration
			Cartilage tissue engineering
			Cardiac tissue engineering
		Biomaterials
			Cartilage tissue-engineering biomaterials
				Fiber-reinforced constructs for cartilage repair
				Stratified and osteochondral constructs for cartilage repair
				Bioinductive and bioactive scaffolds
			Cardiac tissue–engineering biomaterials
		Bioreactors and growth factors
			Cell seeding
			Construct cultivation
			Cartilage tissue-engineering bioreactors
			Cardiac tissue-engineering bioreactors
		Bioreactors and mechanical forces
			Effects of hydrodynamic forces
			Effects of mechanical tension, compression, and shear loading
			Mechanical effects on engineered cartilage tissue
			Electromechanical effects on engineered myocardium
	Conclusion
	Acknowledgments
	References
	Further reading
11 Principles of bioreactor design for tissue engineering
	Introduction
	Macrobioreactors
		Design principles
			Mass transport
			Physiological biomimicry cues
			Cell environment
		Sustainable bioreactors
		Cell manufacturing quality attributes and process analytics technology
		Future outlook
			Microgravity bioreactor
			Real-time assessment in the bioreactor
	Microbioreactors
		Design principles
			Flow rheology
			Cell microenvironment
			Integration of multiple compartments
		Types of microreactors
		Components and integration into microreactors
		Applications
			Drug testing and screening
			Experimental models of disease
			Prognostic/diagnostic tools
	Summary
	Acknowledgments
	References
12 Regulation of cell behavior by extracellular proteins
	Introduction
	Thrombospondin-1
	Thrombospondin-2
	Tenascin-C
	Osteopontin
	Secreted protein acidic and rich in cysteine
	Conclusion
	References
13 Cell and matrix dynamics in branching morphogenesis
	Introduction
	The basis of branching morphogenesis
	Branching morphogenesis in the lung
	Branching morphogenesis in the salivary gland
	Branching morphogenesis in the kidney
	Contributions of other cell types
	MicroRNAs in branching morphogenesis
	Extracellular matrix components in branching morphogenesis
		Laminin
		Collagen
		Heparan sulfate proteoglycan
		Fibronectin and integrins
	Basement membrane microperforations
	Mathematical and computational models
		Geometry
		Mechanical forces
		Signaling mechanisms
	Conclusion
	Acknowledgments
	References
14 Mechanobiology, tissue development, and tissue engineering
	Introduction
	Mechanical forces in biological systems
		Tension
		Compression
		Fluid shear
	Cellular mechanosensing
		The cytoskeleton
		Stretch-activated ion channels
		Cell–cell adhesions
		Cell–substrate adhesions
		The extracellular matrix
	Cellular effects of mechanotransduction
		Substrate adhesion, spreading, and migration
		Cell–cell interactions in collectives
		Proliferation and differentiation
	Mechanotransduction in biological phenomena
		Wound healing
		Tissue morphogenesis
		Cancer metastasis
	Mechanobiology in tissue engineering
		Bone-implant design
		Organs-on-a-chip
	References
Part Three: In Vivo Synthesis of Tissues and Organs
15 In vivo engineering of organs
	Introduction
	Historical context
	Nature’s approach to cellular differentiation and organization
	Conceptual framework of the in vivo bioreactor
	In vivo bone engineering—the bone bioreactor
	In vivo cartilage engineering
	Induction of angiogenesis using biophysical cues—organotypic vasculature engineering
	De novo liver engineering
	Repairing brain tissue through controlled induction of reactive astrocytes
	Conclusions and outlook
	References
Part Four: Biomaterials in tissue engineering
16 Cell interactions with polymers
	Methods for characterizing cell interactions with polymers
		In vitro cell culture methods
			Adhesion and spreading
			Migration
			Aggregation
			Cell phenotype
			High-throughput methods for the characterization of cell–polymer interactions
		In vivo methods
	Cell interactions with polymers
		Protein adsorption to polymers
		Effect of polymer chemistry on cell behavior
			Synthetic polymers
			Surface modification
			Biodegradable polymers
			Synthetic polymers with adsorbed proteins
			Hybrid polymers with immobilized functional groups
		Electrically charged or electrically conducting polymers
		Influence of surface morphology on cell behavior
		Use of patterned surfaces to control cell behavior
	Cell interactions with polymers in suspension
	Cell interactions with three-dimensional polymer scaffolds and gels
	Cell interactions unique to the in vivo setting
		Inflammation
		Fibrosis and angiogenesis
	References
17 Polymer scaffold fabrication
	Introduction
	Design inputs: materials, processing, and cell types
		Materials and inks
		Processing and cell viability
		Cell types and biological interactions
		Assessment of cell viability and activity
	3D printing systems and printer types
		Inkjet printing
		Extrusion printing
		Laser-assisted bioprinting
		Stereolithography
		Open source and commercial 3D printing systems
	Print outputs: patterning, resolution, and porous architecture
		Printing/patterning of multiple inks
		Print resolution
		Porous architecture
		Assessment of scaffold fidelity
	Printing applications: vascularized and complex, heterogeneous tissues
	Conclusion
	Acknowledgments
	Abbreviations
	References
18 Biodegradable polymers
	Introduction
	Biodegradable polymer selection criteria
	Biologically derived polymers
		Peptides and proteins
			Collagen
			Gelatin
			Elastin
			Keratin
			Silk
			Proteoglycans
		Biomimetic materials
		Polysaccharides
			Cellulose
			Starch
			Alginate
			Gellan gum
			Glycosaminoglycans
			Chitosan
		Polyhydroxyalkanoates
		Polynucleotides
	Synthetic polymers
		Aliphatic polyesters
			Polyglycolide, polylactide, and their copolymers
			Poly(ɛ-caprolactone)
			Poly(p-dioxanone)
			Poly(ortho esters)
		Aliphatic polycarbonates
		Biodegradable polyurethanes
		Polyanhydrides
		Polyphosphazenes
		Poly(amino acids) and pseudo-poly(amino acids)
	Combinations (hybrids) of synthetic and biologically derived polymers
	Using polymers to create tissue-engineered products
		Barriers: membranes and tubes
		Gels
		Matrices
	Conclusion
	References
19 Three-dimensional scaffolds
	Introduction
	Three-dimensional scaffold design and engineering
		Mass transport and pore architectures
		Mechanics
		Electrical conductivity
		Surface properties
			Surface chemistry
			Surface topography
		Temporal control
			Scaffold degradation
			Delivery of soluble bioactive factors
		Spatial control
	Conclusion
	References
Part Five: Transplantation of engineered cells and tissues
20 Targeting the host immune response for tissue engineering and regenerative medicine applications
	Introduction
	Immune cells and their roles in building tissues after injury
		Neutrophils
		Eosinophils
		Macrophages
		Dendritic cells
		T and B cells
	Specialized immune cell functions beyond host defense
	Tissue engineering/regenerative medicine strategies as immunotherapy
	Future considerations for immune cell targeting tissue engineering/regenerative medicine therapies
	References
	Further reading
21 Tissue engineering and transplantation in the fetus
	Introduction
	Rationale for in utero therapies
	In utero transplantation
		Early murine experiments with in utero transplantation
		In utero transplantation experiments in large preclinical animal models
		Barriers to in utero transplantation success
		Clinical experience with in utero transplantation
	Rationale for in utero gene therapy
		Hemophilia A as a model genetic disease for correction by in utero gene therapy
	The need for better hemophilia A treatments
		Preclinical animal models for hemophilia A and recent clinical successes
		Sheep as a preclinical model of hemophilia A
		Feasibility and justification for treating hemophilia A prior to birth
	Mesenchymal stromal cells as hemophilia A therapeutics
		Preclinical success with mesenchymal stromal cell–based hemophilia A treatment
	Risks of in utero gene therapy
	Genomic integration–associated insertional mutagenesis
	Potential risk to fetal germline
	Conclusion and future directions
	References
22 Challenges in the development of immunoisolation devices
	Introduction
	Rejection and protection of transplanted cells and materials
		Rejection pathways
	Cellular nutrition
	Therapeutic cells
		Primary cells
		Immortalized cell lines
		Stem cells
	Device architecture and mass transport
	Transplantation site
	Improving oxygenation of immunoprotected cells
	Controlling immune responses to implanted materials
		Steps in the foreign body reaction
		The role of geometry in the foreign body reaction
		Tuning chemical composition to prevent attachment
		Directing immune cell behavior in the transplant niche
	References
Part Six: Stem cells
23 Embryonic stem cells
	Introduction
	Approaches to human embryonic stem cell derivation
	Maintenance of human embryonic stem cell
	Subculture of human embryonic stem cell
	Nuances of human embryonic stem cell culture
	Directed differentiation
	Safety concerns
	Conclusion
	Acknowledgment
	References
24 Induced pluripotent stem cell technology: venturing into the second decade
	Disease modeling
	Drug discovery
	Stem cell–based therapeutic development
	Concluding remarks
	Acknowledgements
	References
25 Applications for stem cells
	Introduction
	Reprogramming of somatic cells into induced pluripotent stem cells
	Epigenetic remodeling
	Reprogramming techniques
	Induced transdifferentiation
	Genomic stability
	Applications of induced pluripotent stem cells
	Disease modeling
	Challenges and future possibilities in disease modeling
	Disease-modifying potential of induced pluripotent stem cells
	Other applications for induced pluripotent stem cells
	Conclusion
	List of acronyms and abbreviations
	References
26 Neonatal stem cells in tissue engineering
	Introduction
	Stem cells
		Embryonic stem cells
		Induced pluripotent stem cells
		Perinatal stem cells
			Cells from the umbilical cord, amniotic membrane, and placenta
			Umbilical cord blood–derived cells
			Amniotic fluid stem cells
	Scaffolding specifics in fetal and neonatal tissue engineering
		Synthetic materials
		Natural materials
	Relevance to prenatal therapy
		Immunology
		Physiology
	Conditions of interest
		Spina bifida
		Gastroschisis
		Congenital diaphragmatic hernia
		Esophageal atresia
		Congenital heart disease
		Congenital airway anomalies
		Bladder
		Bone and bone marrow
	Conclusion
	References
27 Embryonic stem cells as a cell source for tissue engineering
	Introduction
	Maintenance of embryonic stem cells
	Directed differentiation
	Genetic reprogramming
	Microenvironmental cues
	Three-dimensional versus two-dimensional cell culture systems
	High-throughput assays for directing stem cell differentiation
	Physical signals
	Isolation of specific progenitor cells from embryonic stem cells
	Transplantation
	Transplantation and immune response
	Future prospects
	Conclusion
	Acknowledgments
	Conflicts of interest
	References
	Further reading
Part Seven: Gene therapy
28 Gene therapy
	Strategies of gene therapy
		Ex vivo versus in vivo gene therapy
		Ex vivo
		In vivo
	Chromosomal versus extrachromosomal placement of the transferred gene
	Gene transfer vectors
		Nonviral vectors
		Adenovirus
		Adeno-associated virus
		Retrovirus
		Lentivirus
	Cell-specific targeting strategies
		Targeting of Ad vectors
		Targeting of adeno-associated virus vectors
		Targeting of retroviral and lentiviral vectors
	Regulated expression of the transferred gene
	Using gene transfer vectors for gene editing
	Combining gene transfer with stem-cell strategies
		Gene transfer to stem cells
		Gene transfer to control uncontrolled stem-cell growth
		Gene transfer to instruct stem-cell differentiation
		Gene transfer to regulate gene expression
	Challenges to gene therapy for tissue engineering
	Acknowledgments
	References
29 Gene delivery into cells and tissues
	Introduction
	Fundamentals of gene delivery
	Biodistribution, targeting, uptake, and trafficking
		Tissue biodistribution/targeting
		Cellular uptake and intracellular trafficking
	Viral nucleic acid delivery
		Introduction to viral gene therapy
		Types of viral vectors
		Engineering viral vectors
	Nonviral nucleic acid delivery
		Introduction to nonviral nucleic acid delivery
		Oligonucleotide modifications
		Conjugates
		Synthetic polymers
		Polymers derived from natural sources or monomers
		Lipid-based delivery systems
		Inorganic nanoparticles
		High-throughput screening
	Engineering tissues with gene delivery
		Introduction to engineering tissue with gene delivery
		Viral delivery to engineer tissues
		Nonviral delivery from scaffolds
		Nucleic acid delivery for tissue engineering advances into the clinic
		Future challenges
	Outlook
	Acknowledgments
	References
Part Eight: Breast
30 Breast tissue engineering: implantation and three-dimensional tissue test system applications
	Introduction
	Breast anatomy and development
	Breast cancer diagnosis and treatments
	Breast reconstruction
		Synthetic implants
		Tissue flaps
		Cell transplants
		Cellular scaffolds
			Cell types and related challenges
			Scaffolds
				Synthetic materials
				Naturally derived materials
				Therapeutic scaffolds
				Injectable scaffolds
				Combination scaffolds
			Strategies to enhance the vascularization of engineered tissue
		Special considerations
	Breast cancer modeling
		Animal models
		Breast tissue test systems
	In silico breast cancer models
	Concluding remarks
	Acknowledgement
	References
Part Nine: Cardiovascular system
31 Cardiac progenitor cells, tissue homeostasis, and regeneration
	Origin of cardiac stem/progenitor cells
	Modeling cardiac development with pluripotent stem cells
	In vivo fate mapping of cardiac progenitors
	Neonatal cardiac repair
	Reprogramming cardiac fibroblasts
		Cardiac resident mesenchymal stem cells
	Cardiomyocytes and cardiac repair/regeneration
	Cell-based therapy
		Cardiac progenitor/stem cell therapy
		Combination stem cell therapy
		Pluripotent stem cells
	Future directions
	References
32 Cardiac tissue engineering
	Introduction
	Clinical problem
	Engineering cardiac tissue: design principles and key components
		Cell source
		Scaffold
		Biophysical stimulation
	Directed cardiac differentiation of human stem cells
		Derivation of cardiomyocytes from human pluripotent stem cells
		Purification and scalable production of stem cell–derived cardiomyocytes
	Scaffolds
		Decellularization approach
		Artificial scaffolds
	Biophysical cues
		Electrical stimulation
		Mechanical stimulation
		Perfusion
	In vivo applications of cardiac tissue engineering
		Engineered heart issue
		Vascularized cardiac patches
		Electrical coupling of cardiomyocytes on the heart
	Modeling of disease
		Generation of patient-specific cardiomyocytes
		Engineered heart tissue models
		Cardiac fibrosis
		Titin mutation–related dilated cardiomyopathy
		Diabetes-related cardiomyopathy
		Chronic hypertension induced left ventricle hypertrophy
		Barth syndrome
		Tissue engineering as a platform for pharmacologic studies
	Summary and challenges
	Acknowledgments
	References
33 Blood vessels
	Introduction
	Normal and pathologic composition of the vessel wall
		Developmental biology cues important in vascular tissue engineering
	Conduits
		Arteries
		Veins
	Current status of grafts in patients
		Conduit patency and failure
		Venous reconstruction
		Hemodialysis vascular access
		Inflammation and the host response to interventions and grafts
		Host environment and the critical role of the endothelium
		Prevalent grafts in clinical use
			Cryovessels
			Synthetic grafts
				Dacron
				Expanded polytetrafluoroethylene
	Vascular tissue engineering
		Early efforts—in vitro tissue-engineered vascular grafts
		Endothelial cell seeding
		In vitro approaches to tissue-engineered vascular grafts
		In vivo tissue-engineered vascular grafts
		Bioresorbable grafts
		The living bioreactor
		Cellular and molecular mediators of graft outcome
			Cellular recruitment
			Physical or chemical modification of current grafts to improve durability
				Surface characteristics
				Surface modifications
				Thromboresistance
				Protein adsorption
				Porosity
				Compliance
				Resistance to infection
				Biological modification through exogenous sources
				Protein therapy
				Gene therapy
				Cell therapy
	Conclusion and predictions for the future
	References
34 Heart valve tissue engineering
	Introduction
		Heart valve function and structure
		Cellular biology of the heart valve
			Valvular endothelial cells
			Valvular interstitial cells
			Innervation and vasculature
		Heart valve dysfunction and valvular repair and remodeling
			Heart valve dysfunction
			Valvular repair and remodeling
		Heart valve replacement
	The application of tissue engineering toward the construction of a replacement heart valve
		Tissue engineering theory
		Biomaterials and scaffolds
		The search for appropriate cell sources
		Cell seeding techniques
		Bioreactors
		Neotissue development in tissue engineered heart valves
		Clinical applications of the tissue engineered heart valve
	Conclusion and future directions
	References
Part Ten: Endocrinology and metabolism
35 Generation of pancreatic islets from stem cells
	Introduction
	State-of-the-art
	The challenge of making a β-cell
	Recent achievements (first generation of pancreatic progenitors used in the clinic)
	Need of late maturation: cabimer protocol
	Strategies to maintain cell viability
	Encapsulation and tolerogenic strategies
	The concept of cellular medicament
	Conclusion
	Acknowledgments
	References
36 Bioartificial pancreas: challenges and progress
	Introduction
	History of the bioartificial pancreas
	Replenishable cell sources and encapsulation
	Macro- or microedevices
	Factors contributing to biocompatibility of encapsulation systems
	Avoiding pathogen-associated molecular patterns in polymers
	Natural and synthetic polymers
	Multilayer capsule approaches
	Antibiofouling approaches
	Formation of polymer brushes
	Immunomodulatory materials
	Intracapsular environment and longevity of the encapsulated islet graft
	Concluding remarks and future considerations
	Acknowledgments
	References
37 Thymus and parathyroid organogenesis
	Structure and morphology of the thymus
	Thymic epithelial cells
		Complexity of the thymic epithelium compartment
		Functional diversity
		In vitro T cell differentiation
	Thymus organogenesis
		Cellular regulation of early thymus organogenesis
		Origin of thymic epithelial cells
		Thymic epithelial progenitor cells
		Human thymus development
		Cervical thymus in mouse and human
	Molecular regulation of thymus and parathyroid organogenesis
		Molecular control of early organogenesis
		Transcription factors and regulation of third pharyngeal pouch outgrowth
		Specification of the thymus and parathyroid
		Foxn1 and regulation of thymic epithelial cell differentiation
		Medullary development and expansion
	Maintenance and regeneration of thymic epithelial cells: Progenitor/stem cells in the adult thymus
	Strategies for thymus reconstitution
	Summary
	Acknowledgments
	References
Part Eleven: Gastrointestinal system
38 Stem and progenitor cells of the gastrointestinal tract: applications for tissue engineering the intestine
	Introduction
	Stem cells of the intestine
		Cell types of the epithelial layer
		Stem and progenitor cell types
		Signaling pathways in the intestinal epithelium
		The Wnt pathway
		The Notch pathway
		Epidermal growth factor receptor/ErbB signaling
		The Hedgehog pathway
		The BMP pathway
	Tissue engineering the intestine with stem/progenitor cells
		Organ-specific stem cell progenitors versus pluripotent stem cells
		Synthetic and biological scaffolds
		Primary intestinal-derived organoid units
		Pluripotent stem cell approaches—human intestinal organoids
	Remaining barriers to the generation of tissue-engineered intestine
	Conclusion
	Acknowledgment
	References
39 Liver stem cells
	Introduction
	Liver architecture and function
	Liver development
	Fetal liver stem cells
	Hepatocytes and liver progenitors in organ regeneration
		Molecular signaling and processes involved in liver regeneration
		Hepatocytes’ role in liver regeneration
		Cholangiocytes and liver stem cells in liver regeneration
	Pluripotent stem cell–derived hepatoblasts and hepatocytes
	3D liver organoids and expansion
		Pluripotent stem cell–derived liver organoids
		Bile duct–derived organoids
		Hepatocyte-derived organoids
		Novel scaffolds for liver organoids
		Organoids as a model to study liver cancer disease
	Reprogramming of human hepatocytes to liver progenitors using different culture conditions
	Conclusion
	References
	Further reading
40 Hepatic tissue engineering
	Liver disease burden
	Current state of liver therapies
		Extracorporeal liver support devices
		Biopharmaceuticals
		Liver transplantation
		Hepatocyte transplantation
		Current clinical trials
	In vitro models
		Two-dimensional liver culture
		Three-dimensional liver constructs
		Physiological microfluidic models of liver
		Controlling three-dimensional architecture and cellular organization
	In vivo models
	Cell sourcing
		Cell number requirements
		Immortalized cell lines
		Primary cells
		Fetal and adult progenitors
		Reprogrammed hepatocytes
	Extracellular matrix for cell therapies
		Natural scaffold chemistry and modifications
		Synthetic scaffold chemistry
		Modifications in scaffold chemistry
		Porosity
	Vascular and biliary tissue engineering
		Vascular engineering
		Host integration
		Biliary network engineering
	Conclusion and outlook
	References
Part Twelve: Hematopoietic system
41 Hematopoietic stem cells
	Introduction
	Hematopoietic stem cells and hematopoietic stem cells niche
	Effects of biomaterials on hematopoietic stem cells
	Applications
		Engineering hematopoietic stem cells niche for in vitro expansion
		Manipulation of the multilineage differentiation of hematopoietic stem cells
		In vivo tracking hematopoietic stem cells
	Future perspectives
	Acknowledgments
	References
42 Blood components from pluripotent stem cells
	Introduction and history of modern hematology
	Red blood cells
	Megakaryocytes/platelets
	White blood cells
		Lymphocytes—T cells
		Lymphocytes—NK cells
		Lymphocytes—NKT cells
		Monocyte-derived dendritic cells
		Monocyte-derived macrophages
		Granulocytes—neutrophils
	Perspectives
	References
43 Red blood cell substitutes
	Introduction
	Replicating red blood cell functions
	Hemoglobin-based oxygen carriers
	Hemoglobin toxicity
	Oxygen delivery
	Viscosity and colloid osmotic pressure
	Cross-linked and polymeric hemoglobin
	Surface conjugated hemoglobin
	Encapsulated hemoglobin
	Sources of hemoglobin
	Recombinant hemoglobin
	Erythrocruorins
	Perfluorocarbons
	Perspectives
	Organ transplant preservation
	Cancer treatment
	Tissue-engineered construct oxygenation
	References
Part Thirteen: Kidney and genitourinary system
44 Stem cells in kidney development and regeneration
	Kidney development
		Early embryonic origins of nephrogenic tissues
		Development of the nephric duct and ureteric bud
		Maintenance and differentiation of the nephron progenitor cell
		Role of stromal lineages in kidney organogenesis
		Nephron endowment
	Kidney repair and regeneration
		Stem cells in kidney repair
		Sources of nephrogenic cells
		Differentiation of renal tissue from pluripotent stem cells (organoids)
	Conclusion
	Disclosures
	Acknowledgements
	References
45 Tissue engineering of the kidney
	Introduction
	Cell-based tissue engineering of the kidney
		Cell sources
			Kidney tissue–derived primary or stem/progenitor cells
				Primary renal cells
				Stem/progenitor cells derived from kidneys
					Renal stem cells in Bowman’s capsule
					Renal stem cells in the papilla
					Renal stem cells in tubules
			Adult and fetal stem cells
				Mesenchymal stem cells
				Amniotic fluid stem cells
			Pluripotent stem cells
				Embryonic stem cells
				Induced pluripotent stem cells
		Tissue-engineered cellular three-dimensional renal constructs
			Engineering three-dimensional kidney constructs using natural and synthetic polymers
			Decellularization/recellularization strategy
	Cell-free tissue engineering of the kidney
		In situ kidney regeneration
		Granulocyte-colony stimulating factor
		Stromal cell–derived factor-1
	Conclusion and future perspectives
	Acknowledgment
	References
46 Tissue engineering: bladder and urethra
	Introduction
	Cell sources
		Bladder and ureter cells
		Stem cell sources
		Mechanism of cell therapy
			Cell expansion
			Multipotentiality
			Paracrine effects and immunomodulatory properties
	Biodegradable biomaterials
		Synthetic scaffolds
			Biodegradable properties
			Porosity
		Natural collagen matrix
			Acellular tissue matrices
			Collagen
			Silk
			Matrix binding with growth factors
	Preclinical models
		Tissue regeneration models
		Fibrotic bladder model
	Clinical trials
		Clinical translation
		Clinical studies
	Conclusion
	References
47 Tissue engineering for female reproductive organs
	Introduction
	Uterus
	Acellular tissue engineering approaches for uterine tissue repair
	Cell-seeded scaffolds for partial uterine repair
	Scaffold-free approaches for partial uterine repair
	Uterine cervix tissue engineering
	Ovary
	Tissue engineering ovarian follicles
	Vagina
	Tissue engineering approaches for neovagina reconstruction
	Conclusion and future perspectives
	References
48 Male reproductive organs
	Introduction
	Testes
		Spermatogonial stem cell technology
		Androgen-replacement therapy
	Ejaculatory system
		Engineering vas deferens
		Spinal ejaculation generator
	Penis
		Penile reconstruction
		Penile transplantation
		Stem cell therapy for erectile dysfunction
	Conclusion
	References
Part Fourteen: Musculoskeletal system
49 Mesenchymal stem cells in musculoskeletal tissue engineering
	Introduction
	Mesenchymal stem cell biology relevant to musculoskeletal tissue engineering
	Mesenchymal stem cell identification
	Tissue sources of mesenchymal stem cells
	Mesenchymal stem cell isolation and in vitro culture
	Mesenchymal stem cell self-renewal and proliferation capacity
	Skeletogenic differentiation of mesenchymal stem cells
	Plasticity of mesenchymal stem cells
	Mesenchymal stem cell heterogeneity
	Mesenchymal stem cell effect on host immunobiology
	Safety of using mesenchymal stem cells for transplantation
	Mesenchymal stem cells in musculoskeletal tissue engineering
	Cartilage tissue engineering
		General properties of articular cartilage
		Cells for cartilage tissue engineering
			Mesenchymal stem cell chondrogenesis
				Mesenchymal stem cell chondrogenic potential
				Signaling in mesenchymal stem cell chondrogenesis
			Scaffolds for cartilage tissue engineering
			Factors influencing outcomes of tissue-engineered cartilage
	Bone tissue engineering
	Osteochondral tissue engineering
	Engineering other skeletal tissues with mesenchymal stem cells
		Tendon/ligament
		Meniscus
	Gene therapy in musculoskeletal tissue engineering
	Conclusion and future perspectives
	Acknowledgments
	References
50 Bone tissue engineering and bone regeneration
	Introduction
	Skeletal stem cells
	Fracture repair—the (limited) self-reparative capacity of bone
	A framework for bone repair: biomaterial-driven strategies for bone regeneration
	Growth factors: biomimetic-driven strategies for bone regeneration
	Bone biofabrication
	Development of vascular bone
	Preclinical development—ex vivo/in vivo small and large animal preclinical models
	Clinical translation
	Summary and future perspectives
	Acknowledgments
	References
51 Tissue engineering for regeneration and replacement of the intervertebral disk
	Introduction
	Intervertebral disk structure and function
	Cell-biomaterial constructs for intervertebral disk regeneration
		Nucleus pulposus cell-biomaterial implants
		Annulus fibrosus repair and regeneration
		Composite cell-biomaterial intervertebral disk implants
	Cellular engineering for intervertebral disk regeneration
		Cell therapy preclinical studies
		Cell therapy clinical studies
	Growth factors and other biologics for intervertebral disk regeneration
		In vitro studies
		In vivo studies: growth factors
		In vivo studies: other biologics
	Gene therapy for intervertebral disk regeneration
		Gene transfer studies: viral
		Gene transfer studies: nonviral
		Endogenous gene regulation
		Gene therapy in summary
	In vivo preclinical models for intervertebral disk regeneration and replacement
	Concluding remarks
	Acknowledgment
	References
52 Articular cartilage injury
	Introduction
	Articular cartilage injury and joint degeneration
	Mechanisms of articular cartilage injuries
	Response of articular cartilage to injury
	Matrix and cell injuries
	Chondral injuries
	Osteochondral injuries
	Preventing joint degeneration following injury
	Promoting articular surface repair
	Penetration of subchondral bone
	Periosteal and perichondrial grafts
	Cell transplantation
	Artificial matrices
	Growth factors
	Antiinflammatories
	Conclusion
	Acknowledgments
	References
	Further reading
53 Engineering cartilage and other structural tissues: principals of bone and cartilage reconstruction
	Introduction
	Biomaterials for cartilage tissue engineering
	Cell sources for cartilage tissue engineering
	Biofabrication of cartilage tissue
		Magnetic resonance imaging and computerized tomography scans
		Scaffolds for cartilage tissue engineering
		Bioprinting techniques for fabrication of cartilage constructs
		Bioinks for cartilage tissue printing
	Osteochondral tissue engineering
	References
54 Tendon and ligament tissue engineering
	Introduction
	Tendon and ligament composition, structure, and function
		Composition
		Structure
		Function
	Requirements for a tissue-engineered tendon/ligament
		Scaffold
		Cell
		Bioactive factors
	Three-dimensional bioprinting and bioink
	Bioink inspired from ligament and tendon structures
	Tissue engineering tendon and ligament in clinical application
	Summary
	References
55 Skeletal tissue engineering
	Introduction
	Distraction osteogenesis
	Critical-sized defects
	Cellular therapy
	Cytokines
	Scaffolds
	Tissue engineering in practice
	Conclusion
	References
Part Fifteen: Nervous system
56 Brain implants
	Introduction
	Cell replacement implants
		Primary tissue implants
		Cell line implants
	Cell protection and regeneration implants
		Cell implants secreting endogenous factors
		Cell implants secreting engineered factors (ex vivo gene therapy)
		Encapsulated cell brain implants
		Controlled-release implants
	Combined replacement and regeneration implants
	Disease targets for brain implants
	Surgical considerations
	Conclusion
	References
57 Brain–machine interfaces
	Introduction
	Brain–machine interface signals
	Voluntary activity versus evoked potentials
	Mutual learning
	Context-aware brain–machine interface
	Future directions
	References
58 Spinal cord injury
	Introduction
	Epidemiology
	Spinal cord organization
	Spinal cord injury
	Available clinical interventions
	The continuum of physical, cellular, and molecular barriers to spinal cord regeneration
	The role of tissue engineering in spinal cord injury repair
	Bioengineering for integrated spinal cord biocompatibility
	Animal models of spinal cord injury
	Principles of biomaterial fabrication for spinal cord injury repair
	Biomaterials for spinal cord tissue engineering: natural polymers
		Extracellular matrix polymers
		Polymers from marine or insect life
		Polymers derived from the blood
	Biomaterials for spinal cord tissue engineering: synthetic polymers
		Poly α-hydroxy acid polymers
		Nonbiodegradable hydrogels
	Conclusion and future directions: the promise of clinical translation
	References
59 Protection and repair of hearing
	Introduction
	Protection from “acquired” sensory hair cell loss
	Oxidative stress and stress-related mitochondrial pathways
	Calcium influx
	Endoplasmic reticulum stress
	Prevention of ototoxicity
	Prevention of acoustic trauma
	Antiinflammatory agents
	Heat shock proteins
	Neurotrophic factors
	Protection from excitotoxicity: “acquired” loss of auditory nerve connections to hair cells
	Gene transfer for the prevention and treatment of genetic deafness
	Interventions for hair cell repair: gene therapy for transdifferentiation
	Interventions for repair: hair cell and auditory nerve replacement—exogenous stem cells
	Interventions for repair/replacement: cochlear prostheses
	Fully implantable cochlear prostheses
	Interventions for repair/replacement: central auditory prostheses
	Local delivery to cochlear fluids
	Conclusion
	Acknowledgments
	References
	Further reading
Part Sixteen: Ophthalmic
60 Stem cells in the eye
	Introduction
	Endogenous ocular stem cells
		Corneal stem cells
			Epithelial stem cells
			The limbal stem cell niche
			Regulation of limbal epithelial stem cells and transient amplifying cells
			Evidence of corneal epithelial cell plasticity
			The pursuit of corneal epithelial stem cell markers
			The potential for tissue engineering of limbal epithelial stem cells in ocular surface disease
			Tissue-engineered stem cells from noncorneal sources as an alternative to limbal epithelial cells
		Stromal stem cells
		Endothelial stem cells
		Conjunctival epithelial stem cells
		The bioengineered cornea
		Retinal progenitor cells
		Müller stem cells
		Retinal pigment epithelium stem cells
	Nonocular stem cells
		Induced pluripotent stem cells (iPSCs)
		Embryonic stem cells/iPSCs in retinal regeneration
			Generating retinal pigment epithelial from embryonic stem cells/iPSCs
			Generating photoreceptors from embryonic stem cells/iPSCs
			Generating retinal ganglion cells from embryonic stem cell/iPSCs
			Generating hematopoietic/vascular progenitors (CD34/endothelial colony-forming cells) from iPSC
		Bone marrow stem cells
			Mesenchymal stem cells
			Mesenchymal stem cells for cell therapy in the eye
			Hematopoietic stem cells/CD34+ cells
			Hematopoietic stem cells/CD34+ and retinal disease
			Endothelial colony-forming cells
			The potential for stem cells in ocular repair and tissue engineering
	References
61 Corneal replacement tissue
	Introduction
	Corneal anatomy and structure
	Epithelium
	Stroma
	Endothelium
	Conclusion
	References
62 Retinal degeneration
	Epidemiology of visual impairment and blindness
	Structure/function of the retina and cell types affected in retinal degenerative diseases
	Age-related macular degeneration
	History of retinal pigment epithelium as a cellular therapy for age-related macular degeneration
	Retinal pigment epithelium from pluripotent stem cells
	Retinitis pigmentosa
	Photoreceptors from pluripotent stem cells
	Glaucoma
	Stem cell–based therapies to treat glaucoma
	Diabetic retinopathy
	Stem cell–based therapies to treat diabetic retinopathy
	Future directions and competing therapies
	References
63 Vision enhancement systems
	Introduction
	Visual system, architecture, and (dys)function
	Current- and near-term approaches to vision restoration
		Enhancing the stimulus through optoelectronic and optical means
		Visual prostheses based on electrical tissue stimulation
		Retinal cell transplantation
		Optic nerve protection and regeneration
		Drug delivery
		Genetic interventions
	Emerging application areas for engineered cells and tissues
		Photosensitive structures
		Optogenetics
		Outer retinal cell transplantation
		Cell matrices supporting axonal regrowth
		Repopulating ischemic or diabetic retina
		Assessing the functional outcomes of novel retinal therapies
	Conclusion: toward 2020 vision
	Acknowledgment
	References
	Further reading
Part Seventeen: Oral/Dental applications
64 Biological tooth replacement and repair
	Introduction
	Tooth development
	Whole tooth-tissue engineering
		Stem cell-based tissue engineering of teeth
		Bioteeth from cell-seeded scaffolds
		Root formation
		Cell sources
	Dental-tissue regeneration
		Natural tissue regeneration
		Importance of the injury-regeneration balance
		Signaling events in dental regeneration
		Control of specificity of dental-tissue regeneration
		Dental postnatal stem cells
		Directed tissue regeneration
		Signaling-based strategies
		Cell- and gene-based strategies
	Conclusion
	References
65 Tissue engineering in oral and maxillofacial surgery
	Introduction
	Special challenges in oral and maxillofacial reconstruction
	Current methods of oral and maxillofacial reconstruction
		Mandibular defects
		Maxillary defects
	Relevant strategies in oral and maxillofacial tissue engineering
		Bone applications
		Cartilage applications
		Oral mucosa applications
		Composite tissue applications
		Animal models
	The future of oral and maxillofacial tissue engineering
	References
66 Periodontal tissue engineering and regeneration
	Introduction
	Stem cells for periodontal bioengineering
		Intraoral mysenchymal stem cells
		Periodontal tissue–derived stem cells
		Stem cells from apical papilla
		Dental follicle stem cells
		Hertwig’s epithelial root sheath
		Stem cells from dental pulp or exfoliated deciduous teeth
		Extraoral mysenchymal stem cells
		Bone marrow–derived mysenchymal stem cells
		Adipose-derived stem cells
		Selection of cell types
	Signaling molecules
		Types of signals
			Bone morphogenetic proteins
			Platelet-derived growth factors
			Fibroblast growth factor-2
			Growth/differentiation factor-5
			Platelet-rich plasma
			Enamel matrix derivative
			Stem cell–derived exosomes
		Crucial delivery barriers to progress
		Gene delivery as an alternative to growth factor delivery
	Scaffolding and biomaterials science
		Requirements of cell scaffolds
		Biomaterial-based immune modulation
		Classes of biomaterials
			Naturally derived polymers
			Synthetic polymers
			Ceramic-based materials
		Biomaterial redesign for periodontal application
	Periodontal bioengineering strategies
		Cell-free approaches
		Cell-based approaches
			Scaffold-free cell delivery
			Scaffold-based cell delivery
	Challenges and future directions
	Closing remarks
	Acknowledgments
	References
Part Eighteen: Respiratory system
67 Cell- and tissue-based therapies for lung disease
	Introduction: challenges facing cell and tissue-based therapy for the treatment of lung disease
	Lung morphogenesis informs the process of regeneration
		Integration and refinement of signaling and transcriptional pathways during lung formation
		The mature lung consists of diverse epithelial and mesenchymal cell types
		Structure and function of pulmonary vasculature
		Embryonic development of alveolar capillaries
		Evidence supporting lung regeneration
		A diversity of lung epithelial progenitor/stem cells is active during regeneration
		Role of lung microvasculature in lung repair
		Endothelial progenitor cells in lung repair
	Pulmonary cell-replacement strategies for lung regeneration
		Induced pluripotent stem cells for study of treatment of pulmonary disease
		Differentiation of induced pluripotent stem and embryonic stem cells to pulmonary epithelial cell lineages
	Bioengineering of lung tissues
		Mesenchymal stromal cells and mesenchymal stromal cell products for the treatment of lung disease
		Important role of the extracellular matrix in lung structure and repair
		Tissue engineering for conducting airways
		Pulmonary macrophage transplantation for the treatment of interstitial lung disease
	Conclusion
	Acknowledgments
	References
68 Lung tissue engineering
	Introduction
	Design criteria for pulmonary engineering
	Decellularized scaffolds and biofabrication approaches
	Pulmonary epithelial engineering
		Proximal airway engineering
		Distal airway engineering
		Mesenchymal support of pulmonary epithelium
	Pulmonary endothelial engineering
		Endothelial cell sources for lung tissue engineering
			Pulmonary endothelial cells
			Induced pluripotent stem cell derived endothelial cells
		Endothelial seeding into lung scaffolds
		Organomimetic endothelial culture
		Mesenchymal support of pulmonary microvasculature
	Bioreactor technologies for pulmonary engineering
	Conclusion
	References
Part Nineteen: Skin
69 Cutaneous epithelial stem cells
	Introduction
	Interfollicular epidermal stem cells
		Models for skin renewal: epidermal proliferative unit versus committed progenitor
	Hair follicle stem cells
		The bulge as stem cell source
		Defining characteristics of the bulge as a stem cell source
			Quiescence
			Molecular signature
			Multipotency
		Multiple hair follicle stem cell subpopulations by marker expression
			Bulge
			Upper hair follicle
	Stem cells of other ectodermal appendages
		Sebaceous glands
		Sweat glands
		Nails
	Hair follicle stem cells in skin homeostasis, wound healing, and hair regeneration
		Homeostasis
		Wound healing
		Wound-induced hair follicle neogenesis and regeneration
	Epithelial stem cells in aging
	Role of stem cells in alopecia
	Skin as an active immune organ
		Cross talk between hair follicles and the immune system
		The inflammatory memory of skin cells
	Tissue engineering with epidermal stem cells
	Epidermal stem cells as a therapy: the future
	Conclusion
	References
70 Wound repair: basic biology to tissue engineering
	Introduction
	Basic biology of wound repair
		Inflammation
		Transition from inflammation to repair
		Reepithelialization
		Granulation tissue
			Fibroplasia
			Neovascularization
		Wound contraction and extracellular matrix organization
	Chronic wounds
	Scarring
		Pathological scars
		Scarless healing
	Tissue engineered therapy with skin cells
		Engineered epidermal constructs
		Engineered dermal constructs
		Engineered skin substitutes
		Skin autograft harvesting without scarring
	Tissue-engineered therapy with stem cells, bioactives, and biomaterials
	References
71 Bioengineered skin constructs
	Introduction
	Skin structure and function
	The epidermis
	The dermis
	The process of wound healing
	Impaired healing and its mechanisms
		Acute versus chronic wound healing
		Bacterial colonization
		Growth factor imbalances
		Matrix metalloproteinase activity
		Moist wound healing in chronic wounds
		Ischemia
		Abnormalities at the cellular level
	Engineering skin tissue
	Design considerations
	Commercial considerations
	Process considerations
	Regulatory considerations
	Immunological considerations
	Summary: engineering skin tissue
	Epidermal regeneration
	Dermal replacement
	Bioengineered living skin equivalents
	Bioengineered skin: FDA-approved indications
		Cutaneous indications
		Oral indications
	Apligraf and Dermagraft: off-label uses
	The importance of wound bed preparation
	Proposed mechanisms of action of bioengineered skin
	Construct priming and a new didactic paradigm for constructs
	Other considerations
	Conclusion
	References
	Further reading
Part Twenty: Tissue-engineered food
72 Principles of tissue engineering for food
	Introduction
	Why tissue engineering of food?
	Specifics of tissue engineering for medical application
		Uniqueness
		Function
	Skeletal muscle and fat tissue engineering
		Tissue engineering of skeletal muscle
			Cells
			Gel and seeding
		Tissue engineering of fat
			Cells
			Biochemistry of adipocyte differentiation
			Scaffold and cell seeding
	Specifics of food tissue engineering
		Scale
		Efficiency
		Taste, texture, juiciness
	Enhanced meat
	Other foods
	Consumer acceptance
	Regulatory pathway
	Conclusion
	References
73 Cultured meat—a humane meat production system
	Introduction
	Need and advantages of cultured meat
	Cultured meat
		Scaffolding techniques
		Self-organizing tissue culture
		Organ printing
		Biophotonics
		Nanotechnology
	Challenges and requirements for industrial production
		Generation of suitable stem cell lines from farm-animal species
		Safe media for culturing of stem cells
		Safe differentiation media to produce muscle cells
		Tissue engineering of muscle fibers
		Scaffolds
		Industrial bioreactors
		Fields
		Atrophy and exercise
		Senescence
		Meat processing technology
		Associated dangers and risks
		Regulatory issues
		Consumer acceptance and perception
	Role of media in publicity of cultured meat
	Market for cultured meat
	Conclusion
	References
Part Twenty one: Emerging technologies
74 Three-dimensional bioprinting for tissue engineering
	Introduction
	3D Bioprinting strategy: from medical image to printed bioengineered tissue
	Three-dimensional bioprinting techniques
		Jetting-based bioprinting
		Extrusion-based bioprinting
		Laser-assisted bioprinting
		Laser-based stereolithography
		Digital light processing
		Hybrid and other techniques
	Biomaterials as bioinks for three-dimensional bioprinting
		Hydrogel-based bioinks for cell-based three-dimensional bioprinting
			The required properties of hydrogel-based bioinks
			Synthetic hydrogels
			Naturally derived hydrogels
			Tissue-specific extracellular matrix–based hydrogels
		Biodegradable synthetic polymers for structure-based three-dimensional bioprinting
		Scaffold-free cell printing
	Three-dimensional bioprinting in tissue engineering applications
		Three-dimensional bioprinted vascular structures
		In vitro tissue models
			Tumor models
			Tissue-specific models
		Three-dimensional bioprinted implantable tissue constructs
			Bone
			Cartilage
			Skeletal muscle and tendon
			Cardiac tissue and heart valves
			Skin
			Other tissue types
	Conclusion and future perspectives
	Abbreviations
	Glossary
	References
75 Biofabricated three-dimensional tissue models
	Introduction
		Current methods of three-dimensional biofabrication
			Inkjet printing
			Extrusion printing
			Light-assisted bioprinting
				Digital light processing–based bioprinting
				Two-photon polymerization–based bioprinting
		Biomaterials for three-dimensional fabrication
			Naturally derived biomaterials
			Synthetically derived biomaterials
			Cell selection
	Three-dimensional tissue models for drug screening, disease modeling, therapeutics, and toxicology
		WARNING!!! DUMMY ENTRY
			Brain and nerve tissue models
			Cancer models
				Heart tissue models
				Liver tissue models
				Vascular tissue models
	Conclusion and future directions
	Acknowledgments
	References
76 Body-on-a-chip: three-dimensional engineered tissue models*
	Introduction
	Advanced in vitro modeling systems—progression from two-dimensional to three-dimensional models
	Organ-on-a-chip technologies and their applications
		Microengineering and biofabrication
		Liver-on-a-chip
		Vessel-on-a-chip
		Lung-on-a-chip
		Heart-on-a-chip
		Cancer-on-a-chip
	Body-on-a-chip: integrated multiorgan systems and future applications
		The importance of multiorganoid integration
			Cancer
			Drug testing/toxicology
			Additional disease modeling
		Cutting edge body-on-a-chip: the first highly functional multiorganoid systems
			The Ex vivo Console of Human Organoids platform
			Other body-on-a-chip programs
			Organ-on-a-chip systems for personalized precision medicine
	Conclusion and perspectives
	References
77 Monitoring and real-time control of tissue engineering systems
	Introduction
	Current state-of-the-art
		General environmental monitoring and real-time control
		Tissue-level monitoring
			Extracellular matrix structure
			Extracellular matrix amount/levels
		Mechanical properties
			Ultrasound
			Optical coherence tomography
	Cell-level monitoring
		Reporter-based gene expression imaging
	Tissue-specific
		Cartilage monitoring and real-time control
		Skin
	Concluding remarks
	Acknowledgments
	References
78 Biomanufacturing for regenerative medicine
	Current landscape of biomanufacturing
	Highlighting current workflows for biomanufacturing
	Current challenges in biomanufacturing for regenerative medicine
	Current platform technologies enabling biomanufacturing
	Regulatory challenges for biomanufacturing
		Food and Drug Administration guidance documents
		Creating standards
	The future: envisioned advanced biomanufacturing
		Closed-modular biomanufacturing systems
		Off-the-shelf products
		Preservation advances
		Synthetic biology advances
		Cell banking advances
		Medical applications for biomanufacturing in regenerative medicine
		Space exploration
	References
Part Twenty two: Clinical experience
79 Tissue-engineered skin products
	Introduction
	Types of therapeutic tissue-engineered skin products
	Components of tissue-engineered skin grafts as related to function
		Scaffold
		Keratinocytes
		Fibroblasts
		Extracellular matrix
		Subcutaneous fat
		Components of the immune system
		Melanocytes
		Adnexal structures
		Commercial production of tissue-engineered skin products
		Regulation
		Product development
		Overall concept
		Allogeneic cell source
		Viability of product and avoidance of a final sterile fill
		Shelf life
		Size, user convenience
	The manufacture of Dermagraft and TransCyte
		Cells
		Medium
		Bioreactor design
	The Dermagraft and TransCyte production processes
		Release specifications
		Distribution and cryopreservation
		Problems with commercial culture for tissue engineering
	Clinical trials
	Immunological properties of tissue-engineered skin
	Commercial success
		Mechanism of action
	Future developments
	Conclusion
	References
80 Tissue-engineered cartilage products
	Introduction
	Cartilage defects, osteoarthritis, and reconstructive surgical options
		Cartilage defects pathophysiology
		Surgical treatment options for articular cartilage defects
	Tissue-engineered cartilage products for orthopedic reconstruction
	Cells for tissue-engineered cartilage repair
	Scaffolds for clinical tissue-engineered cartilage repair
		Collagen scaffolds
		Hyaluronan
		Synthetic polymers
		Agarose and alginate
		Scaffold-free three-dimensional systems
	Bioreactors for tissue-engineered cartilage repair
	Clinical nomenclature of scaffold-based techniques
		Clinical generations of autologous chondrocyte implantation
		Acellular, scaffold-based products
		Particulated autologous or allogenic articular cartilage
	Commercial autologous chondrocyte implantation products
		MACI (Vericel, Cambridge, MA, United States)
		ChondroCelect (TiGenix, Leuven, Belgium)
		Spherox (Co.don, Berlin, Germany)
		Novocart 3D (Tetec, Reutlingen, Germany)
		BioSeed C (Biotissue, Geneva, Switzerland)
		Novocart Inject (Tetec, Reutlingen, Germany)
		Chondron (Sewon Cellontech, Seoul, Korea)
		Cartipatch (Tissue Bank of France, Génie Tissulaire, Lyon, France)
		CARTISTEM (Medipost, Seongnam, Korea)
	Clinical application of autologous chondrocyte implantation in reconstructive articular cartilage surgery
		Indications for autologous chondrocyte implantation
		Contraindications
		Surgical steps
	Clinical results of autologous chondrocyte implantation
		Overview
		Data from prospective randomized clinical trials
		Long-term results of autologous chondrocyte implantation
		Clinical factors affecting the clinical outcomes of autologous chondrocyte implantation
	Conflict of interest
	References
81 Bone tissue engineering
	Introduction
		Conventional bone tissue engineering strategies: cells, scaffolds, and biofactors
		Delivery of molecules and/or scaffolds to augment endogenous bone regeneration
		Biomaterials development and three-dimensional printing
			Clinical successes and opportunities in regenerative repair of diaphyseal defects
		Clinical successes and opportunities in regenerative repair of craniofacial defects
	Conclusion
	Acknowledgments
	References
82 Tissue-engineered cardiovascular products
	Clinical situation/reality
	Considerations for tissue-engineered cardiovascular constructs
	Components for tissue-engineered cardiovascular constructs
		Cell sources
		Scaffolds
			Synthetic scaffolds
			Extracellular matrix as scaffold
				Decellularized extracellular matrix as an ideal scaffold
				Perfusion decellularization
	Tissue-engineered cardiovascular constructs
		Vascular grafts
			Scaffold-free grafts
			Scaffold-based tissue-engineered vascular grafts
		Valves
			Current valve prostheses
			Tissue-engineered valves
		Cardiac patches
			Noncontractile cardiac patches
			Bioprinted patches
			Contractile patches
				Hurdles for using cardiac patches
					Achieving vascularization—a must for a beating patch
					Achieving electromechanical integration
		Building the next level of complexity: whole heart
	Pathway to approval and commercialization
	Future perspectives
	References
83 Tissue organoid models and applications
	Introduction
	Cell sources
	Types of organoid models
	Cardiac organoid
	Liver organoid
	Brain organoid
	Lung organoid
	Gastrointestinal tract organoid
	Other organoid models
	Applications
		Tumor and disease models
		Drug analysis
		Organ-on-a-chip
		Developmental biology
	Conclusion
	References
Part Twenty three: Regulation, commercialization and ethics
84 The regulatory process from concept to market
	Introduction
	Regulatory background
	Overview of development and approval process
	Early-stage development
		Chemistry, manufacturing, and controls
		Pharmacology and toxicology
		Clinical
	US Food and Drug Administration/sponsor meetings
	Submitting an investigational new drug application
		Required US Food and Drug Administration forms
		Investigational new drug application contents
			Previous human experience/electronic common technical document Module 2.5: clinical overview
			Chemistry, manufacturing, and controls information/electronic common technical document Module 3: quality
			Pharmacology and toxicology data/electronic common technical document Module 4: nonclinical
			Clinical protocol/electronic common technical document Module 5: clinical
			Additional information
		US Food and Drug Administration review of an original investigational new drug application submission
	Later-stage development topics
		Compliance with current good manufacturing practice
		Product readiness for Phase 3
		Potency assay
		Pharmacology and toxicology
		Phase 3 clinical development
	Combination products
	Tissue-engineered and regenerative medicine products
		3D bio-printed tissue-engineered/regenerative-medicine products
	Medical devices
		Least burdensome principles
		Breakthrough device program
		Evaluation of devices used with regenerative medicine advanced therapy
	Expedited review programs
	Other regulatory topics
		Minimal manipulation and homologous use of human cells, tissues, and cellular and tissue-based products
			Minimal manipulation
			Homologous use
		Clinical research involving children
		Expanded access to investigational drugs for treatment use
		Charging for investigational drugs under an investigational new drug application
		Responsibilities of sponsors and investigators
			Sponsor responsibilities (21 CFR 312.50–59)
			Clinical investigator responsibilities (21 CFR 312.60–69)
			Sponsor–investigator responsibilities
		Clinical research conducted outside of the United States
		Use of standards
		US Food and Drug Administration international regulatory activities
		The role of cell-based products in medical product testing
	Conclusion
	Acknowledgments
	Appendix I Code of Federal Regulations citations relevant to cellular product development4
	Appendix II The list of acronyms
	References
85 Business issues
	Introduction
	The aging population
	Rise of regenerative medicine
	Product development
		Embryonic stem cells
		Induced pluripotent stem cells
		Direct reprogramming of differentiated cells
		Small molecule-induced differentiation
	Reimbursement
	Conclusion
	References
86 Ethical issues
	Introduction
	Duty and healing: natural makers in a broken world
	To make is to know: notes on an old problem about knowledge
	What is a thing? The perils of deconstruction
	What contextual factors should be taken into account, and do any of these prevent the development and use of the technology?
	What purposes, techniques, or applications would be permissible and under what circumstances?
	On what procedures and structures, involving what policies, should decisions on appropriate techniques and uses be based?
	Conclusion
	References
Index