Outline 1. Irreversible injury 2. Regenerative and nonregenerative tissues 3. Antagonistic relation between contraction and regeneration 4. Present theory: Selective inhibition of contraction necessary but not sufficient for regeneration 5. Mechanism

BIOMATERIALS-TISSUE INTERACTIONS BIOMATERIAL TISSUE Strength ize scale IOnm 100nm lum 10 um 100 um Imm Modulus of Elasticity Fracture mechanics

C. Cell-Matrix Interactions A. How cells pull onto and deform the matrix to which they attach themselves. B. Cell-matrix interactions control the spontaneous closure of wounds in organs. C. What happens when regeneration is induced?

UNIT CELL PROCESSES Concept of a \Control Volume\ around a Cell Soluble Regulator Cell Matrix

TISSUE ENGINEERING What is tissue engineering Production of tissue in vitro by growing cells in porous, absorbable scaffolds (matrices). Why is tissue engineering necessary? Most tissues cannot regenerate when injured or diseased

C. Synthesis of biologically active scaffolds (regeneration templates) 1. History of biologically active scaffolds (regeneration templates). 2. Physical chemistry of collagen: Melting of collagen quaternary structure (thromboresistance). Melting of collagen tertiary structure (gelatinization). 3. Synthesis of ECM analogs: lonic complexation

RESPONSE TO IMPLANTS: WOUND HEALING Surgical Implantation Inc. time Vascular Response Acute Clotting Inflammation Phagocytosis Granulation Neovascularization New Collagen Synthesis Tissue

RESPONSE TO IMPLANTS WOUND HEALING flury Vascular Response Inflammation Tissue of labile Tissue of and stable cells Permanent cells Framework framework Scar Intact Destroyed

UNIT CELL PROCESSES Regulator UCP Cell Matrix Product Regulator Connect. ECM Mitosis Tiss. Adhesion Sy Synthesis Epithelia |Protein Migration Muscle Collagen

BIOMATERIALS-TISSUE INTERACTIONS: \Tools\ for Understanding the Molecular, Cellular, and Physiological, Bases of the Tissue Response to Implants M. Spector, Ph. D. and I. V. Yannas, Ph.D. BIOMATERIALS-TISSUE INTERACTIONS