Tissue Eng GPT

Question 1

Q: How is tissue engineering formally defined?

Answer 1

Answer: It is the application of engineering and life-science principles to develop biological substitutes that restore maintain or improve tissue function.

Question 2

Q: Why is tissue engineering important in healthcare?

Answer 2

A: It addresses limitations in organ and tissue transplantation reduces donor shortages and aims to create functional living substitutes to replace or repair damaged tissues.

Question 3

Q: Name the four key components typically involved in tissue engineering.

Answer 3

A: (1) Cells (2) Scaffolds (3) Growth/signaling factors (4) Bioreactors.

Question 4

Q: What are the three main strategies to create or repair tissues using TE approaches?

Answer 4

A: (1) In vitro culture of cells on scaffolds before implantation (2) Implantation of a scaffold to recruit host cells (3) Direct cell therapy by transplanting specific cells.

Question 5

Q: What is the difference between autologous and allogeneic cell sources?

Answer 5

A: Autologous cells come from the patient’s own body minimizing immune rejection; allogeneic cells come from a donor of the same species and can be “off-the-shelf” but may pose immunogenic risks.

Question 6

Q: What characterizes a stem cell?

Answer 6

A: Stem cells are undifferentiated cells capable of both self-renewal and differentiation into specialized cell types.

Question 7

Q: Name three main types of stem cells often referenced in tissue engineering.

Answer 7

A: (1) Embryonic Stem Cells (ESCs) (2) Adult (somatic) stem cells (e.g.

Question 8

Q: Why are induced pluripotent stem cells (iPSCs) significant for regenerative medicine?

Answer 8

A: They avoid ethical issues of embryonic cells can be patient-specific to reduce rejection and have pluripotent differentiation potential.

Question 9

Q: List two ways to isolate cells from tissue.

Answer 9

A: (1) Enzymatic digestion (e.g.

Question 10

Q: What is one common lab method used to isolate and count specific cell populations based on their markers?

Answer 10

A: Flow cytometry / FACS (Fluorescence-Activated Cell Sorting).

Question 11

Q: What is a scaffold in the context of tissue engineering?

Answer 11

A: A 3D biomaterial that provides support and structure for cells to adhere proliferate and form new tissue.

Question 12

Q: What are the essential properties a scaffold should have?

Answer 12

A: Biocompatibility adequate porosity interconnectivity of pores biodegradability suitable mechanical strength and surface chemistry for cell adhesion.

Question 13

Q: Give one advantage and one disadvantage of natural scaffold materials.

Answer 13

A: Advantage: Good bioactivity and compatibility. Disadvantage: Often weaker mechanical properties and batch variability.

Question 14

Q: Name three natural polymers commonly used for scaffolds.

Answer 14

A: Collagen chitosan and alginate.

Question 15

Q: List three synthetic polymers frequently used in tissue engineering.

Answer 15

A: Poly(glycolic acid) (PGA) Poly(lactic acid) (PLA) and their copolymer PLGA.

Question 16

Q: What is a bioceramic

Answer 16

and in which tissue engineering application are bioceramics especially used?

Question 17

Q: How does the solvent-casting/particulate-leaching method create pores in a scaffold?

Answer 17

A: A polymer solution is cast with salt (or sugar) particles which are then leached out in water leaving behind a porous structure.

Question 18

Q: What happens during freeze-drying to form pores?

Answer 18

A: The polymer solution is frozen to form ice crystals and upon sublimation of the ice interconnected pores remain.

Question 19

Q: Why is electrospinning attractive for tissue scaffold fabrication?

Answer 19

A: It can produce nanofibrous meshes that closely mimic the fibrous architecture of the native extracellular matrix with high surface area.

Question 20

Q: What advantage does 3D printing have over traditional scaffold fabrication methods?

Answer 20

A: Precise control of geometry pore size and distribution allowing for highly tailored reproducible scaffold architectures.

Question 21

Q: Why add growth factors to a scaffold?

Answer 21

A: They guide cell proliferation migration and differentiation enhancing the functional development of the engineered tissue.

Question 22

Q: What is a bioreactor in tissue engineering?

Answer 22

A: A device providing a controlled environment (e.g.

Question 23

Q: How do spinner flasks improve scaffold seeding compared to static cultures?

Answer 23

A: Convection generated by stirring helps distribute cells uniformly onto and into porous scaffolds improving seeding efficiency.

Question 24

Q: Why is shear stress in bioreactors a concern for TE?

Answer 24

A: Excessive shear can damage delicate cells especially stem cells reducing viability and functionality.

Question 25

Q: How does a rotating-wall vessel minimize shear stress?

Answer 25

A: The entire medium rotates at the same angular velocity as the cylinder creating laminar flow and “free-fall” conditions for cells/scaffolds.

Question 26

Q: Why are hollow fibre membrane bioreactors (HFMBs) beneficial for highly metabolic cells?

Answer 26

A: They allow efficient nutrient and oxygen diffusion through semi-permeable fibers mimicking capillary networks for large cell densities.

Question 27

Q: What is the main advantage of perfusion bioreactors for 3D constructs?

Answer 27

A: Forced flow through the porous scaffold ensures uniform nutrient delivery and waste removal deep inside thick constructs.

Question 28

Q: Which tissues particularly benefit from mechanical loading in vitro

Answer 28

and why?

Question 29

Q: What parameters are commonly monitored in a tissue-engineering bioreactor?

Answer 29

A: pH temperature dissolved oxygen (DO) possibly glucose lactate and other metabolites.

Question 30

Q: In convective mass transfer

Answer 30

how is the mass flux at a surface often modeled (film theory)?

Question 31

Q: How does Henry’s Law relate gas partial pressure to dissolved gas concentration?

Answer 31

A: 𝑝𝑖=𝐻×𝐶𝑖; the partial pressure is equal to the Henry’s constant times the dissolved concentration

Question 32

Q: Why is oxygen often the limiting nutrient in engineered tissues?

Answer 32

A: It has relatively low solubility in aqueous media and cells rapidly consume it; without proper supply central regions of constructs can become hypoxic.

Question 33

Q: How can effective diffusivity in a hydrogel bead be experimentally determined (transient uptake method)?

Answer 33

A: By measuring solute concentration changes over time and plotting ln(𝐶𝑡−𝐶∞/𝐶0−𝐶∞) vs. 𝑡. The slope yields 𝐷e/𝑟2

Question 34

Q: Why do we need to cryopreserve cells and TE products?

Answer 34

A: To ensure long-term storage off-the-shelf availability and stable inventory of engineered tissues or cell stocks without rapid degradation.

Question 35

Q: Contrast the risks of slow vs. rapid freezing rates for cells.

Answer 35

A: Slow: Excessive cell dehydration and high intracellular solute concentration. Fast: Intracellular ice formation that can rupture cells.

Question 36

Q: How do cryoprotectants like DMSO help in freezing cells or tissues?

Answer 36

A: CPAs reduce ice crystal formation and moderate osmotic gradients improving cell viability after thawing.

Question 37

Q: Why is cryopreserving thick engineered tissue more complex than cryopreserving cell suspensions?

Answer 37

A: Non-uniform cooling rates CPA distribution and ice formation can vary across larger denser scaffolds risking differential cell damage.

Question 38

Q: Name one major challenge when scaling up tissue-engineered constructs from lab scale to clinical size.

Answer 38

A: Oxygen and nutrient delivery become harder to maintain evenly risking necrosis in thick or large tissues.

Question 39

Q: How can shear damage be reduced in a stirred bioreactor design?

Answer 39

A: Using axial-flow impellers moderate agitation speeds baffles that reduce vortexing or bubble-free oxygenation membranes.

Question 40

Q: What is one crucial piece of advice for tissue engineering exam questions?

Answer 40

A: Integrate both the engineering (mixing shear mass transfer) and biological (cell type ECM growth factors) perspectives to present a well-rounded justified solution or design rationale.