In the context of this course, what is meant by the term “Biomaterial”.
Any material of natural or of synthetic origin that comes in contact with tissue, blood or biological fluids, and is intended for use in medicine.
List the different classes of biomaterials.
Two Schemes:
1: metals, ceramics, polymers, composites
2: synthetic materials, natural materials
Compare and contrast the molecular make-up, microstructure, and properties of metals, ceramics and polymers
- Metals: packed crystals, high electrical conductivity, crystalline structure, strong, ductile, high melting pt and density, reflective, malleable
- Ceramics: ionic and covalent bonds, crystal pack but smaller than metals, low elec and heat conductivity, high stiffness and melting pt, low ductility, lustrous, lubriciuos, polishable
- Polymer: intrachain covalent bonds, interchain weak forces, cross-linked polymer chain, elastic, flexible, elongatable.
On a stress/strain curve draw the curves of an ideal ceramic, metal, polymer
- Ceramics highest stress, shortest strain.
- Metals 2nd highest stress, more strain than ceramics
- Polymers: low stress but far on strain %
Define what is meant by the term “Biocompatibility.”
- ability of biomaterial/device to perform with an appropriate host response in a specific application.
- Risk vs. Benefit ratio of device
Describe how blood clots (make sure to describe the three primary arms and the makeup of the final clot)
- Vasoconstriction: upon injury endothelial cells release endothelin, angiotensin II and serotonin. smooth muscle cells contract. pinch off blood vessel slow flow through injured vessl.
- Platelet Adhesion: release platelet factors, promote coagulation. Thrombocytes.
- Coagulation Cascade: self amplifying cascade of proteins, intrinsic arm by collagen, extrinsic arm by tissue factor
- Final clot: platelets, fibrin matrix, and anything caught in matrix
Describe three consequences of blood coagulation on biomaterial surfaces
- occlusion of blood vessels: stents, catheters, shunts
- heart attack, stroke, pulmonary embolism
- emboli can move down stream and occlude
Explain is meant the term “foreign body response.”
-the bodies reception to any foreign manipulation or material that is placed within it.
What is meant by the term “wound healing?”
- normal process of tissue repair.
- interaction of various cellular and molecular components. kill bacteria
- orderly process to form new tissue at injury and effect wound closure.
Describe the major events that occur in wound healing in the absence of an implant.
- Blood vessel damage
- Restoration of hemostasis
- acute inflammation
- granulation tissue: fibroblast migration, new blood vessels, ECM maturation
- wound remodeling
How does the Foreign Body Response to an implanted material/device differ from normal wound healing?
- persistent inflammation: continual macrophage recruitment and activation, foreign body giant cell formation
- fibrous encapuslation
List three types of regenerative medicine approaches
cell therapy, smart biomaterials, tissue engineering
What is meant by the term “tissue engineering”?
- idea of combining cells with scaffold, have cells grow on scaffold, then implant filled scaffold into patient.
- ECM best because not foreign body response.
Describe the three components of the tissue engineering triad
- cells: harvest and develop cells from a source, then implant. Sources: Autologous, allogeneic, xenogeneic.
- scaffolding: synthetic (plastics) or biologic (ECM).
- conditioning: grow cells and nurture under similar conditions as body, ex vocal fold tissues.
What is a primary advantage of ECM materials over traditional synthetic scaffolds for regenerative medicine?
-avoids foreign body response, so little to no persistent macrophage activation, little to no scar tissue formation
