Final Exam

Question 1

Why nanoparticles

Answer 1

Increase aq. solubility, biocompatibility, biorecognition

Question 2

Nanotube properties (size, mechanical properties, hollow?)

Answer 2

diameter in nanometer range, HIGH mechanical properties - Can be filled, because they are hollow

Question 3

Targeted delivery of nanoparticles (pH)

Answer 3

Cancer cells lower pH - specificity of solubility allows for targeted release

Question 4

Mimicking ECM - What is an advantage?

Answer 4

Matrices of nanotech can be used to mimic the ECM and guide cell differentiation/proliferation

Question 5

Nanofibers - How formed?

Answer 5

Formed w/ electric charge - formed w self assembling peptides - NOT HOLLOW

Question 6

Replacing heart tissue - What cells are delivered, what is fixed

Answer 6

Delivering cardiac muscle cells to site of tissue damage, restores contractility to damaged/scarred tissue

Question 7

Pros of regenerating Heart tissue - Increased what?

Answer 7

Initial results positive - increase ventricular output, contractile strength, cardiac output

Question 8

Cons of regenerated heart tissue - What symptom? Do cells proliferate?

Answer 8

Ventricular arrhythmias in weeks after treatment Poor migration of implanted cells, not enough extracellular structure

Question 9

Specific issues w/ regenerated Heart tissue - What can go wrong?

Answer 9

cell survival - cells must survive the trip, can be damaged, can leak

Question 10

Hepatocyte transplantation - What is harvested, what is success dependent on? How can it be made more successful?

Answer 10

Cells harvested from liver and isolated, transplanted so they migrate to liver – DEPENDS ON SURVIVAL AND FUNCTION OF TRANSPLANTED CELLS – These cells can be incorporated in biomaterials to increase longevity, protect from rejection,

Question 11

Hepatocyte delivery - What polymer, what advantage, minimizes what?

Answer 11

PLGA used - pre-vasculatization of scaffold, minimize FIBROUS TISSUE ENCAPSULATION

Question 12

Tissue Engineered bladder successful properties - Made of what? How successful?

Answer 12

Collagen-based matrices – Large acellular structures, good epithelial lining, decent performance after 3 years

Question 13

Challenge of T.E. bladders

Answer 13

Challenging to grow bladder cells in vitro (epithelial and smooth muscle cells) REGULATORY PROCESS

Question 14

Does presence of biomaterial matrix improve functionality

Answer 14

yes

Question 15

Typical life span of valve replacement

Answer 15

10-15 years, shorter in younger individuals (valves do not grow with patient)

Question 16

Treating aneurysms - what material, coated with what

Answer 16

Platinum coil deployed into aneurism, prevents bloodflow, induces clotting when DACRON is applied (dacron induces clotting)

Question 17

Treating atherosclerosis (buildup of fat in arteries) - what implant

Answer 17

STENT deployment, widens closed arteries,

Question 18

Synthetic polymer vascular graft design - what polymers, describe it

Answer 18

2 degradable polymers combined - inner PGA layer is 95% porous, outer layer nonporous, allows for cell ingrowth – Outer PHA layer degrades quickly, inner layer degrades slowly, mechanical integrity during cell infiltration — EVENTUALLY THE WHOLE IMPLANT IS REPLACED BY NATIVE TISSUE

Question 19

Tg above and below brittleness

Answer 19

above Tg is flexible below Tg is brittle

Question 20

Natural polymer graft design - what cells, what extra things to stimulate growth?

Answer 20

Type I Collagen fibers, mixed w/ smooth muscle cells, Vitamin C and Vitamin A stimulate SMCs to produce collagen and elastic to MATCH THE MECH PROPs of native vessel!

Question 21

Hybrid natural polymer graft - Adding what increases what

Answer 21

Collagen+Elastin Hybrid - Adding elastin increases the tensile strength and modulus of the artery graft, but still lower than native tissue :(

Question 22

Purely cellular graft - How created and cultured,

Answer 22

Series of cellular sheets, grown separately, compiled - forms completely cellular vascular graft - Each layer applied separately – SMC layer is adhered to a fibroblast layer, which goes on top of teflon mandrel- MANDREL is removed after cell culture BEFORE implantation - Final implant is cells only

Question 23

Cartilage replacement - 3 generations, what’s special about third

Answer 23

1st gen - injure the bone to release marrow to repair 2nd gen - Replace broken cartilage w/ other cartilage that is not used as much 3rd gen - cell based regeneration, add GROWTH FACTORS also 3rd gen - matrix based regen – scaffolds to provide structure and cell attachment (porous, 3D, mesh)

Question 24

Genzyme - what happens

Answer 24

Patient’s chondrocytes are harvest and cultured outside of the body - implanted to damaged site after culture

Question 25

Formation of cartilage replacement - polymer used, method used, where implanted?

Answer 25

PLGA web knitted - Freeze dried, sheets either stacked or rolled, then implanted in vivo

Question 26

Osteoconductive vs osteoinductive

Answer 26

Osteoconductive - Osteoblasts attach - Bone cells can attach and grow Osteoinductive - Osteoclasts attach - Undifferentiated cell can attach and become bone

Question 27

Composite Bone substitute - what materials? Advantages and disadvantages of each individually?

Answer 27

Combining Polymer and ceramic to make composite material - Ceramic - bioactive, osteoconductive, but brittle and poor formability Polymer - Biodegradable, easily formed, low bioactivity Combine = best of both worlds

Question 28

1st gen Ligament tissue engineering

Answer 28

Natural replacements (auto/allografts) - lose 20% tensile strength and 46% max load after 1 year :(

Question 29

2nd gen Ligament tissue engineering

Answer 29

(-) Synthetic replacements - fail due to fragmentation, stress shielding, fatigue, creep, wear debris - Not same mechanical properties - (+) similar mech strength as native, supports cell growth,

Question 30

Hierarchal design

Answer 30

Fibers bundled to larger fibers then braided - synthetic ligaments resemble native ligaments

Question 31

3rd gen ligament engineering - what polymers, advantages, how to evaluate in vitro

Answer 31

Tissue engineered ligament replacement -Biodegradable, biocompatible, supports cell attachment, PLLA and PLGA In vitro evaluation - ACL removed from rabbits and replaced with tissue engineered segment and tested - There is EVIDENCE OF HEALING and INTEGRATION of implant

Question 32

Piezoelectric effect

Answer 32

Surface charge can be induced by bending a piezoelectric material

Question 33

Cell response can depend on...

Answer 33

Both physical and electrical forces!

Question 34

PDMS photolithography - how are pillars modified, what is detected?

Answer 34

Pillars can be modified (diameter, modulus, etc.) Can detect how much force used in bending pillars (detecting the forces of cell movement) Do the conditions dictate migratory behavior?

Question 35

Traction Force microscopy

Answer 35

Measure force of contraction of muscle cells

Question 36

Cell remember previous surfaces, why is that a problem

Answer 36

Problem if you culture on a hard surface and implant on a soft surface