Increase aq. solubility, biocompatibility, biorecognition
Nanotube properties (size, mechanical properties, hollow?)
diameter in nanometer range, HIGH mechanical properties - Can be filled, because they are hollow
Targeted delivery of nanoparticles (pH)
Cancer cells lower pH - specificity of solubility allows for targeted release
Mimicking ECM - What is an advantage?
Matrices of nanotech can be used to mimic the ECM and guide cell differentiation/proliferation
Nanofibers - How formed?
Formed w/ electric charge - formed w self assembling peptides - NOT HOLLOW
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
Pros of regenerating Heart tissue - Increased what?
Initial results positive - increase ventricular output, contractile strength, cardiac output
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
Specific issues w/ regenerated Heart tissue - What can go wrong?
cell survival - cells must survive the trip, can be damaged, can leak
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,
Hepatocyte delivery - What polymer, what advantage, minimizes what?
PLGA used - pre-vasculatization of scaffold, minimize FIBROUS TISSUE ENCAPSULATION
Tissue Engineered bladder successful properties - Made of what? How successful?
Collagen-based matrices -- Large acellular structures, good epithelial lining, decent performance after 3 years
Challenge of T.E. bladders
Challenging to grow bladder cells in vitro (epithelial and smooth muscle cells) REGULATORY PROCESS
Does presence of biomaterial matrix improve functionality
Typical life span of valve replacement
10-15 years, shorter in younger individuals (valves do not grow with patient)
Treating aneurysms - what material, coated with what
Platinum coil deployed into aneurism, prevents bloodflow, induces clotting when DACRON is applied (dacron induces clotting)
Treating atherosclerosis (buildup of fat in arteries) - what implant
STENT deployment, widens closed arteries,
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
Tg above and below brittleness
above Tg is flexible below Tg is brittle
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!
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 :(
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
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)
Genzyme - what happens
Patient's chondrocytes are harvest and cultured outside of the body - implanted to damaged site after culture
Formation of cartilage replacement - polymer used, method used, where implanted?
PLGA web knitted - Freeze dried, sheets either stacked or rolled, then implanted in vivo
Osteoconductive vs osteoinductive
Osteoconductive - Osteoblasts attach - Bone cells can attach and grow Osteoinductive - Osteoclasts attach - Undifferentiated cell can attach and become bone
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
1st gen Ligament tissue engineering
Natural replacements (auto/allografts) - lose 20% tensile strength and 46% max load after 1 year :(
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,
Fibers bundled to larger fibers then braided - synthetic ligaments resemble native ligaments
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
Surface charge can be induced by bending a piezoelectric material
Cell response can depend on...
Both physical and electrical forces!
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?
Traction Force microscopy
Measure force of contraction of muscle cells
Cell remember previous surfaces, why is that a problem
Problem if you culture on a hard surface and implant on a soft surface