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Flashcards in Final Exam Deck (36):
1

Why nanoparticles

Increase aq. solubility, biocompatibility, biorecognition

2

Nanotube properties (size, mechanical properties, hollow?)

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

3

Targeted delivery of nanoparticles (pH)

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

4

Mimicking ECM - What is an advantage?

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

5

Nanofibers - How formed?

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

6

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

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

7

Pros of regenerating Heart tissue - Increased what?

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

8

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

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

9

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

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

10

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

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,

11

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

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

12

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

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

13

Challenge of T.E. bladders

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

14

Does presence of biomaterial matrix improve functionality

yes

15

Typical life span of valve replacement

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

16

Treating aneurysms - what material, coated with what

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

17

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

STENT deployment, widens closed arteries,

18

Synthetic polymer vascular graft design - what polymers, describe it

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

19

Tg above and below brittleness

above Tg is flexible below Tg is brittle

20

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

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!

21

Hybrid natural polymer graft - Adding what increases what

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

22

Purely cellular graft - How created and cultured,

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

23

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

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)

24

Genzyme - what happens

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

25

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

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

26

Osteoconductive vs osteoinductive

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

27

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

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

28

1st gen Ligament tissue engineering

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

29

2nd gen Ligament tissue engineering

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

30

Hierarchal design

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

31

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

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

32

Piezoelectric effect

Surface charge can be induced by bending a piezoelectric material

33

Cell response can depend on...

Both physical and electrical forces!

34

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

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?

35

Traction Force microscopy

Measure force of contraction of muscle cells

36

Cell remember previous surfaces, why is that a problem

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