MIT 20 441J - UNIT CELL PROCESSES ASSOCIATED WITH WOUND HEALING (34 pages)

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UNIT CELL PROCESSES ASSOCIATED WITH WOUND HEALING



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Massachusetts Institute of Technology Harvard Medical School Brigham and Women s Hospital VA Boston Healthcare System 2 79J 3 96J 20 441 HST522J UNIT CELL PROCESSES ASSOCIATED WITH WOUND HEALING M Spector Ph D Acute Chronic Photos and diagrams of skin wound healing removed due to copyright restrictions WOUND HEALING Roots of the Tissue Response Resolution Slight Nonvascularized tissue No Healing Injury Inflammation Vascularized tissue 4 Tissue Categories Connective Tissue Epithelium Nerve Muscle Healing Process Regeneration CT bone Ep epidermis Muscle smooth spontaneous Repair Scar CT cartilage Nerve Muscle cardiac skel RESPONSE TO IMPLANTS WOUND HEALING Injury Vascular Response Inflammation Tissue of Labile and Stable Cells Framework Framework Intact Destroyed Regeneration Scar Tissue of Permanent Cells Scar RESPONSE TO IMPLANTS WOUND HEALING Surgical Implantation Acute Inflammation Vascular Response Clotting Phagocytosis Neovascularization New Collagen Synthesis Tissue of Labile and Stable Cells Inc time Granulation Tissue Tissue of Permanent Cells Implant Movement Framework Framework Intact Destroyed Regen Scarring incorp fibrous encapsulation of implant synovium Chronic Inflammation Scarring fibrous encapsulation synovium Chronic Inflammation Acute Inflammation Local Gross Changes The cardinal signs of acute inflammation are Redness Heat Swelling Pain Loss of function Granulation Tissue Photo removed due to copyright restrictions UNIT CELL PROCESSES Regulator UCP Cell Matrix Connective ECM Tissue Adhesion Epithelia Protein Muscle Collagen Nerve Biomaterial Integrin Product Regulator Mitosis Synthesis Migration Contraction Endocytosis Exocytosis UNIT CELL PROCESSES VASCULAR RESPONSE Diagrams removed due to copyright restrictions Contraction Endothelial Cell Basal Lamina Leakage Reg UNIT CELL PROCESSES VASCULAR RESPONSE circulation Exocytosis Platelet serum Seratonin PAF circulation Exocytosis Basophil serum tissue Reg Reg Exocytosis Mast Cell ECM Reg Seratonin Histamine Contraction Endothelial Cell Basal Lamina Leakage Reg PAF platelet activating factor Mast cells can be identified by their darkly staining granules which contain histamine and heparin They are involved in the inflammatory response and are very common near blood vessels Photo of mast cell removed due to copyright restrictions See Figure 10 45 in Berg J M et al Biochemistry 5th edition W H Freeman 2002 http www ncbi nlm nih gov bookshelf br fcgi book stryer part A1378 rendertype figure id A1413 UNIT CELL PROCESSES VASCULAR RESPONSE Exocytosis Platelet serum Seratonin PAF Reg Exocytosis Basophil serum Reg Exocytosis Mast Cell ECM Seratonin Histamine Reg Contraction Endothelial Cell Basal Lamina Leakage Reg Histamine Contraction Smooth Muscle Basal Lamina Vasoconstrict Cell UNIT CELL PROCESSES CLOTTING Exocytosis Platelet Collagen Coagulation factors Fibrin polymerization Image removed due to copyright restrictions See Fig 10 2 The role of platelets in thrombosis In Rubin E and H M Reisner editors Essentials of Rubin s Pathology Lippincott Williams Wilkins 2008 http books google com books id 7HdzBBhtxycC pg PA197 Scanning electron micrograph shows the fine structure of a fibrin clot that has entangled 2 red blood cells Platelets released from the circulation and exposed to the air use fibrinogen from the blood plasma to spin a mesh of fibrin Photo removed due to copyright restrictions See http www cellsalive com cover7 htm UNIT CELL PROCESSES CLOTTING Exocytosis Platelet Collagen Coaguation factors Fibrin polymerization PAF In Circulation Exocytosis Basophil serum PAF In Tissue Reg Exocytosis Mast Cell ECM Reg UNIT CELL PROCESSES PHAGOCYTOSIS Endocytosis Macrophage Part Sol Part Reg Cell debris and degraded ECM Alveolar macrophage phagocytosis of E coli lung pleural cavity The macrophage is the large yellowish cell with projections the bacterial cells are small rod like blue cells Microscope image removed due to copyright restrictions See http www visualsunlimited com c visualsunlimited image I0000pCnNefPj tE Dennis Kunkel Microscopy Scanning electron micrograph shows a human macrophage gray approaching a chain of Streptococcus pyogenes yellow Riding atop the macrophage is a spherical lymphocyte Macrophages and lymphocytes can be found near an infection and the interaction between these cells is important in eliminating infection Photo removed due to copyright restrictions See http www cellsalive com cover5 htm This scanning electron micrograph courtesy of Drs Jan M Orenstein and Emma Shelton shows a single macrophage surrounded by several lymphocytes Courtesy of Jan M Orenstein Used with permission http users rcn com jkimball ma ultranet BiologyPages B Blood html Macrophage phagocytosing 2 erythrocytes red blood cells Photo removed due to copyright restrictions Transmission electron micrograph showing a macrophage Photo removed due to copyright restrictions Macrophage containing engulfed bacteria The bacteria are colored red for easy identification The large purple structure at the bottom of the cell is the cell nucleus Image removed due to copyright restrictions http hei org research aemi mac htm Light Microscopy Polyethylene Particles in Peri prosthetic Tissues Nucleus Transmission Electron Microscopy TEM See Benz E Spector M et al Biomat 2001 22 2835 1 mm UNIT CELL PROCESSES PHAGOCYTOSIS Endocytosis Macrophage Part Sol Part Reg Fibroblast ECM Reg Endothelial Cell ECM Reg Cell debris and degraded ECM Neovascularization Angiogenesis New Blood Vessel Formation Parent vessel 4 Differentiation 3 Mitosis 2 Migration 1 Basement membrane degradation Figure by MIT OpenCourseWare UNIT CELL PROCESSES NEOVASCULARIZATION Synthesis enzymes Endothelial Cell Basal Lamina Reg Migration Endothelial Cell ECM Reg Mitosis Endothelial Cell ECM Reg UNIT CELL PROCESSES NEW COLLAGEN SYNTHESIS Fibroblast ECM Reg Fibroblasts are the most common cell type in connective tissue They are large long branching cells that produce and secrete the collagen fibers and proteoglycans Photo removed due to copyright restrictions Once the connective tissue has been formed the immature fibroblast will become a mature and largely inactive fibrocyte If the tissue becomes damaged however this fibrocyte can revert to an active fibrocyte Photo removed due to copyright restrictions UNIT CELL PROCESSES NEW COLLAGEN SYNTHESIS Migration Fibroblast ECM Reg Mitosis Fibroblast ECM Reg Synthesis Fibroblast ECM Reg UNIT CELL PROCESSES NEW COLLAGEN SYNTHESIS


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