Tissue Eng Midterm Flashcards
1
Q
What is TE?
A
Application of engineering and life science methods and principles toward the development of biological substitutes that restore, maintain, or improve tissue function
2
Q
What is RM?
A
Any therapy that induced regeneration of tissue or organs following disease or injury.
3
Q
How can RM be achieved?
A
Through gene/cell therapy or pharmaceuticals.
4
Q
Name the factors in the TE triad.
A
Cells
Scaffolds
Regulators
5
Q
What is the criteria for TE designs?
6
A
- Disease/Stage-specific
- Clinically applicable
- Achieve function
- Mimic native tissue
- Host response
- Shelf life/storage
6
Q
What are the goals of TE?
4
A
- Decrease patient symptoms
- Decrease disease progression
- Increase function
- Mimic native tissue
7
Q
Name the 3 critical steps in TE.
A
- Define your problem
- Develop design criteria
- Test appropriate models to mimic the clinical situation
8
Q
Name the different cell sources.
3
A
Autologous
Allogenic
Xenogenic
9
Q
What are autologous cells?
A
Patient’s own cells
10
Q
What are allogenic cells?
A
Human cells. Another person’s cells
11
Q
What are xenogenic cells?
A
Cells taken from different species
12
Q
What are the 3 characteristics of autogenic cells?
A
Not rejected
Require isolations + expansion
Limits in cell type
13
Q
What are the 3 characteristics of allogeneic cells?
A
Can be off-the-shelf
Often require immune suppression
Concerns about disease transmission
14
Q
What are the 3 characteristics of xenogenic cells?
A
Require immune suppression
Concerns about animal-human viral transmission
15
Q
What are stem cells?
A
Cells that can divide indefinitely in culture and can give rise to specialized cells
16
Q
Why are stem cells important in TE?
A
They can regenerate and repair tissues.
Can secrete proliferative and anti-inflammatory growth factors
17
Q
What are the 3 types of stem cells?
Describe each one.
A
Totipotent: can give rise to any cell type + embryonic tissue
Pluripotent: capable of giving rise to most tissue
Multipotent: gives rise to many cell types
18
Q
What are the 4 different stem cell sources?
A
Adult - multipotent
Fetal - pluripotent/multipotent
Embryonic - pluripotent
IPSCs - pluripotent
19
Q
Name the 3 characteristics of adult stem cells.
A
- Small numbers
- Isolation and expansion isn’t well-defined
- Limited ability to expand in culture
20
Q
Name the 3 characteristics of embryonic cells.
A
- Highest degree of pluripotency
- Isolated from embryos
- Ethical concerns
21
Q
Name a characteristic of IPSCs.
A
Converted from fully differentiated somatic cells into ESC-like cells
22
Q
How do we induce differentiation?
6
A
Soluble factors
Cell-cell interactions
Matrix interactions
Cell shape and polarity
Dynamic stress
Oxygen tension
23
Q
What are the 2 types of cell-cell interactions?
A
Homotypic: contact-mediated adhesion molecules
Heterotypic: soluble paracrine factors
24
Q
Why are scaffolds important in TE?
4
A
- Serve as a matrix for cell adhesion to facilitate/regulate cell processes
- Maintain shape + structure
- Cell delivery vehicles
- Serve as barrier
25
What is the ECM composed of?
| 6
1. Insoluble macromolecules
2. Collagens
3. Elastin
4. Proteoglycans and glycosaminoglycans
5. Cell adhesion molecules
6. Water (67%)
26
Name the 4 ECM characteristics.
1. Determine shape and maintain homeostasis
2. Maintain structure and chemical makeup
3. Not static
4. Changes during development
27
What are polymers?
Long-chained insoluble macromolecules made of repetitive units
28
What are hydrogels?
Water-swollen, crosslinked, insoluble polymers
29
Name 3 natural polymers.
Agarose
Collagen
Hyaluronic acid
30
Name 3 synthetic polymers
PEG
PMMA
PGA
31
How do cells adhere?
| 3
1. Protein absorption
2. Modifications to cell adhesion ligands
3. Results from bioactive surfaces that mediate cell attachments
32
What should be taken into consideration when designing a scaffold?
| 4
1. Chemical composition
2. Structure
3. Degradation rate
4. Mechanical properties
33
Where is integrin binding involved?
| 6
1. Cell adhesion
2. Migration
3. Survival
4. Growth
5. Differentiation
6. Gene expressions
34
Why is chemical composition important in scaffolds?
They can regulate cell function through chemical makeup
35
What 2 scaffold design characteristics are dependent on chemical makeup?
Degradation rate and mechanical properties
36
What changes can occur in the degradation rate?
Too rapid = no proper regeneration
Too slow = interferes with remodeling
37
What are the steps in 3D bioprinting?
1. Imaging
2. Design
3. Material
4. Cell type
5. Bioprinting
6. Application
38
Name the 3 types of bioprinting.
1. Inkjet - droplets
2. Microextrusion - continuous
3. Laser-assisted - drop-cell
39
What is electrospinning?
An electric field draws a polymer stream out of the solution.
40
What is phase separation?
Separation of polymer solution into polymer-rich/poor layers
41
Name 3 pros of phase separation.
Similar to setting gel
Control macroporous architecture
Consistent
42
Name 2 cons of phase separation.
Limited to several polymers
Small production scale.
43
What are nanofibers?
Spontaneous organization into stable structure without covalent bonds
44
Name 2 pros of nanofibers
Injectable
Can achieve a small diameter
45
Name 2 cons of nanofibers.
Limited to several polymers and hydrophobic/philic interactions
Small size
46
What are 2 types of design modifications?
Chemical and Biological
47
Describe the two types of biological modifications.
1. Noncovalent: Adherance through hydrophobic and electrostatic interactions
2. Covalent: Presence of reactive group on the surface (OH, NH2, SH, etc.)
48
What are the 2 degradation factors in biomaterials?
Enzymatic degradation and hydrolysis
49
Name the 2 enzymatic degradation characteristics.
1. Amount and types of enzymes at implantation sites
2. # of cleavable moieties in the polymer
50
Name 4 characteristics of hydrolysis.
1. Chemical reactivity
2. Presence of primary and secondary bonds
3. Media amount
4. Surface area
51
Through what can scaffolds be sterilized?
Type of sterilization and time taken
52
Why is time important while sterilizing?
| 2
It reduced infection
Removes/kills microorganisms
53
What are the 3 types of sterilization methods?
Steam
Ethylene oxide
Radiation
54
What are the characteristics of steam sterilization?
| 3
- Autoclaving
- Denatures proteins and lipids
- Effective, quick, simple, no toxicity
55
What are the characteristics of ethylene oxide sterilization?
| 3
- Toxic, flammable
- Chemical alteration of nucleic acids
- Need to purge to allow aeration
56
What are the characteristics of radiation sterilization?
| 2
- Done through Gamma rays or electron beam
- Ionizes important cellular elements, including nucleic acids
57
What are cytokines?
Polypeptides (proteins) that regulate cell function
58
What are growth factors?
They stimulate or inhibit several different cell functions.
59
What do growth factors inhibit?
| 6
- Cell proliferation
- Differentiation
- Migration
- Adhesion
- Gene expression
- Secretion
60
Name 3 characteristics of protein delivery.
Expensive
Short half-life
Diffuse from the target site
61
Name the 3 factors needed for gene delivery.
1. Expression casette
2. Non-viral vectors
3. Viral vectors
62
What are the three types of controlled release?
- In scaffold
- Linked to scaffold
- Transport transfected cells
63
What cells are mostly used for GFs?
Fibroblasts
64
What are the three types of mechanical regulators?
Flow - endothelial
Mechanical - muscle
Electrical - neurons
65
Name 6 characteristics of innate immunity.
- Non-specific
- From birth
- Anatomic barriers (skin / mucous)
- Physiological barriers (body temp)
- Phagocytic cells
- Inflammation
66
Name 3 characteristics of acquired immunity.
- Specific
- Lymphocyte activation
- Vaccines
67
What is inflammation?
Non-specific response to damaged tissue
68
Signs of acute inflammation
- Redness
- Swelling
- Pain
- Heat
69
What are the first cells in the site of inflammation?
Neutrophils
70
What are 4 characteristics of neutrophils at the site of inflammation?
- Stick to capillary
- Penetrate between endothelial cells
- Move to surrounding tissue
- Emigrate in min/hrs
- Activate when engaged with foreign particles
71
What cells substitute neutrophils at the injury site?
Monocytes
72
Why do monocytes replace neutrophils?
Neutrophils are short-lived (24-48 hrs)
Chemotactic factors for neutrophil emigration are deactivated in later stages.
73
Why are macrophages important?
They are phagocytic
They release cytokines
They produce a large # of biologically active products
74
What are the characteristics of chronic inflammation?
- Persistence of macrophages, monocytes, and lymphocytes.
- Proliferation of blood vessels and connective tissue
- No exudates
75
What GFs are present in inflammation?
PDF
FGF
TGFB
IL-1
TNF
76
What is the end stage of healing called?
Fibrosis
77
When does resolution happen?
When no biological changes occur
78
What are the steps of resolution?
1. Extrusion
2. Resorption
3. Integration
4. Encapsulation
79
What is histology?
The study of tissue's structure and arrangement
80
What does hematoxylin and eosin (H&E) staining represent?
Hematoxylin: basophilic structures, blue-purple staining, nucleic acids
Eosin: eosinophilic structures, bright pink staining, cytoplasm
81
Name 5 pros of natural materials for scaffolds.
- Lower risk of immune rejection
- Promotes structure remodeling
- Biodegradable
- Inherit structural resemblance
- Interaction with surrounding env.
82
Name 5 cons for natural materials for scaffolds.
- Hard to control degradation properties
- Storage --> expensive
- Cross-contamination
- Hard to manufacture in bulk
- Less acceptable to structural and mechanical properties
83
Name 5 pros for synthetic materials for scaffolds.
- Uniform composition
- Controllable and reproducible
- Can be optimized
- Ethical
- Engineered with desired properties
84
Name 5 cons for synthetic materials for scaffolds.
- Binding sites must be incorporated
- Poor biocompatibility
- Higher in cost production
- Risk of rejection
- Toxic byproducts
85
Name 5 pros of ESCs
- Longterm expansion
- Disease modeling
- IVF Increased
- Reprogrammable
- Low genetic manipulation
86
Name 5 cons for ESCs
- Ethical concerns
- Unclear history and characteristics
- Heterogeneity
- Genome editing is slow
- High risk of tumorigenesis
87
Name 5 pros of ASCs
- Less prone to genetic modification
- High regenerative ability
- No immune response (autologous)
- Easy to culture
- Low process costs
88
Name 5 cons of ASCs
- Limited differentiation potential
- Age donors can affect
- In vivo/In vitro differences
- Reprogram takes several weeks
- Poorly characterized
89
Name 5 pros of IPSCs
- Low immunogenicity
- Disease modeling
- Low ethical concerns
- Easy to harvest
- Has reached clinical trials
90
Name 5 cons of IPSCs
- Can form teratomas
- Immune response
- Epigenetic memory
- Genomic instability
- Expensive
91
What is the consumption rate of oxygen?
0.05 - 0.5 umol
10^6 cells/hr
92
What is the consumption rate of glucose?
0.2 umol
10^6 cells/hr
93
What is the consumption rate of amino acids?
0.1 - 0.5 umol
10^9 cells/hr
94
What is the equation to determine supply?
S = kpx^2 / DCo
95
Give 3 characteristics of a rapid regulatory pathway.
1. $0.2-2 million in costs
2. Quality, steriability
3. 1-2 years
96
Give 3 characteristics of the short-term regulatory pathway.
1. $2-20 million in costs
2. Safety, 501K
3. 1-3 years
97
Give 4 characteristics of medium-term regulatory pathways.
1. $30-200 million in costs
2. Animal/safety studies, IDE, PMA
3. Clinical trials
4. 1-6 years
98
Give 4 characteristics of long-term regulatory pathways.
1. $50- >300 million dollars
2. Animal/safety studies, IND, NDA
3. Clinical trials
4. 1-8 years
