EBME 306 LECTURES 4-7 FALL-2023-ZIATS.pptx

Biological Constraints in Using Biomaterials- Inflammation Readings for September 20, 22, 25 and 27 Biomaterials: The Intersection of Biology and Materials Science, J.S. Temenoff and A.G. Mikos, Pearson/Prentice Hall, 2008, pp. 327-335, 369-384, 385-393 BIOMATERIALS-TISSUE INTERACTIONS Hemostasis...

Biological Constraints in Using Biomaterials- Inflammation Readings for September 20, 22, 25 and 27 Biomaterials: The Intersection of Biology and Materials Science, J.S. Temenoff and A.G. Mikos, Pearson/Prentice Hall, 2008, pp. 327-335, 369-384, 385-393 BIOMATERIALS-TISSUE INTERACTIONS Hemostasis/Thrombosis SEQUENCE of EVENTS of BIOMATERIAL RESPONSES Surgery, Material Implanted Cell Injury and Necrosis Acute Inflammation Chronic Inflammation Healing, Fibrosis Granulation Tissue, Granulomas CAUSES of CELL INJURY          Materials (biomaterials) Surgery Hypoxia Physical Agents Chemicals and Drugs Microbiologic Agents Immunologic Reactions Genetic Defects Nutritional Imbalances CELL/TISSUE INJURY CELL INJURY reversible vs. irreversible  “point of no return”  CELL DEATH Necrosis- the summation of the morphologic changes following cell death in living tissue  Apoptosis- ”programmed cell death”  ADAPTATION- cell’s responses to stress Materials & Biomaterials Cell Injury Causes Necrosis Normal Heart Tissue Cells Adapt to Injury/Stress Regenerative Capabilities of Cells The growth response depends on the cell type:    Labile Stable Permanent Atrophy Hypertrophy Where’s the beef? Hypertrophy Cor bovinum Hyperplasia (Fibrosis around Biomaterials) Fibroblast Proliferation + Increased ECM (collagen) Fibrosis Hyperplasia, Fibrosis and Fibrous Encapsulation Polymer Collagen and other ECMs Cells Sequence of Events and Biomaterial Responses to Injury Surgery, Material Implanted Cell Injury and Necrosis Acute Inflammation Chronic Inflammation Granulation tissue Healing Inflammation, Healing & Biomaterials  Local reaction of vascular (or vascularized) tissue to injury   Occurs in both acute and chronic inflammation!! Two Main Themes: Destruction of tissue- or walling off of the biomaterial  Repair- by normal parenchyma or by scar (fibrosis)   Temporal Pattern ACUTE- short duration, exudative- cells + proteins, PMNs  CHRONIC- long duration, macrophages/lymphocytes, proliferative cells-fibroblasts and blood vessels  Cells of Inflammation Bone Marrow stem cells + Growth factors White Blood cells Megakaryocytic Erythrocytic Platelets Granulocytic PMNs=neutrophils Eosinophils Basophils Mononuclear Monocytes T & B Lymphocytes Where Do These Cells Come From? EPO TPO PMN CSF CSF INTERLEUKINS INTERLEUKINS Bone Marrow Fat Bone Eos PMN-band Platelet PMNseg Lympho Baso Mono Inflammation and Biomaterials Sequence of Events       Injury Acute inflammation Chronic inflammation Granulation tissue Foreign body reaction Fibrosis Acute Inflammation  Short duration  Hours to a few days  Hemodynamics, Vascular permeability, Leukocyte migration  Exudative or exudates  Are protein and cells which bind to biomaterials, “pus” is an exudate Calor Rubor Tumor Dolor Hemodynamics and Inflammation Q or Jv = ([Pc − Pi] − σ[πc − πi]) Pc-Pi πc − πi Q or Jv = ([Pc − Pi] − σ[πc − πi]) Transudates vs. Exudates Characteristic Transudate Exudate Definition & Etiology Hemodynamic, an Inflammatory Inflammatory cells None Yes Bacteria None Often Protein Low (<2%) High (>4%) Specific Gravity <1.012 >1.020 Examples Congestive heart failure, blister Pneumonia, abscesses, pus ultrafiltrate of plasma Transudate This is a right pleural effusion (in a baby). Note the clear, pale yellow, appearance of the fluid. This is a serous effusion. Fluid appears grossly clear. Effusions into body cavities can be further described as follows:  Pleural effusions  Ascites  Pericardial effusion Exudate PUS!!!! Leukocytes in Inflammation Also known as White Blood Cells (WBCs, myeloidwhite) Granulocytes- PMNs, Eosinophils, Basophils  Monocytes  Lymphocytes    Mast cells- are tissue cells, not in circulating blood Normal value (blood) is 10,000 cells/cubic mm   Leukocytosis (or –philia)- >10,800/cubic mm, increased numbers Leukopenia- <4,500/cubic mm, decreased Inflammation & Biomaterials Cell & Tissue Response HEALING Leukocytes in Inflammation Acute Chronic PMNs Mononuclear cellS TRANSLATIONAL QUESTION: Why is it important to know whether the inflammation is acute or chronic? Think of a situation where one could use this information. Other Cells/Components of Inflammation Leukocytes in Inflammation Capillary (Blood) Side Material with Bacteria from Webpath 7.0 Leukocytes in Inflammation Phagocytosis Click on the link above, need to be in full slide mode Chemical Mediators of Inflammation  Plasma-derived ► Circulating precursors ► Have to be “activated”  Cell-derived ► sequestered intracellularly ► synthesized de novo  Most mediators bind to receptors on cell surfaces, but some have direct enzymatic or toxic activity  Mediators are tightly regulated Inflammation- Mediators Arachidonic Acid Pathway TRANSLATIONAL QUESTION: Think of a situation where one could use this information in this pathway to target a drug delivery approach. Complement System Complement binds to biomaterials and is activated by biomaterials Biomaterials and biomaterial surfaces Fever , IL-6 Sequence of Events of Biomaterial Response to Injury Surgery, Material Implanted Cell Injury and Necrosis Acute Inflammation Chronic Inflammation Healing, Fibrosis Granulation Tissue, Granulomas Chronic Inflammation  Long duration  Few days, weeks, months  Proliferative- fibroblasts and blood vessel divide But also- macrophages & lymphocytes  Note- macrophages do not divide  Leukocytes in Inflammation Acute Chronic Macrophages and FBGCs (Biomaterials) M1 and M2 Macrophages Macrophages, FBGCs And Biomaterials Foreign Body Giant Cells Suture Lymphocytes Are Important in Inflammation  T and B lymphocytes, Natural killer cells  Plasma cells are derived from B cells Macrophages and Lymphocytes Interact In Vivo Biocompatibility Testing Cage Implant System Days 7, 14 and 21 Material Exudates Analyzed for Cell Counts Insert Cage Surfaces Explanted and Adherent Cells Analyzed syringe Implantation Macrophages and Foreign Body Giant Cells Fusion Macrophages and Biomaterials “The Big Mac Attack”--- Degradation H + OH - H202 -O2 BIOMATERIAL DEGRADATION Enzymes Pits, holes etc. Free Radicals and Reactive Oxygen Species  Free Radicals- any atom or molecule with an unpaired electron in its outer orbit, that can exist independently for a period of time Reactive Oxygen Species, Free Radicals & Antioxidants Antioxidants Pacemaker Lead Degradation Adherent macrophages & FBGC release degradative enzymes and radicals. Macrophage adhesion Foreign body giant cells (FBGC) DEVICE FAILURE Explanted pacemaker lead Full thickness cracking Surface cracking Surface pitting FBGC - Mediated Surface Degradation The red circle is where a FBGC was found TRANSLATIONAL QUESTION: What is the importance of a MNGC near a biomaterial in vivo, since they are usually found there? Is it good or is it bad to find them? Acute Inflammation & ROS SEQUENCE of EVENTS of BIOMATERIAL RESPONSE to INJURY Surgery, Material Implanted Cell Injury and Necrosis Acute Inflammation Chronic Inflammation Healing Granulation Tissue, Granulomas Inflammation & Biomaterials Cell & Tissue Response HEALING Granulation Tissue    A complex of macromolecules and cells, macrophages, blood vessels, fibroblasts Blood vessels formation is referred to as neovascularization or angiogenesis Biomolecules are produced by cells that results in a soft, watery, connective tissue    Glycosaminoglycans (GAGS) Glycoproteins- fibronectin, laminin Collagens Healing Response to Biomaterials Biomaterial Infection following Implantation Granulation Tissue: GAG-rich Fibrosis: Collagen-rich Granulation Tissue GAGS Blood Vessels Angiogenesis and Wound Healing Tissue Response to Biomaterials Granulation Tissue-Trichrome stain Granulation tissue: Blood vessels GAGs Some Macs Some fibroblasts Glycoproteins are globular proteins with bound carbohydrates. They contain more protein than carbohydrate. Proteoglycans consist of a protein core with bound glycosaminoglycans (polysaccharides). They contain more carbohydrate than protein. Glycosaminoglycans Highly Sulfated-binds to water Glycosaminoglycans Sequence of Events of Biomaterial Responses Surgery, Material Implanted Cell Injury and Necrosis Acute Inflammation Chronic Inflammation Healing, Fibrosis Granulation Tissue Inflammation & Biomaterials Cell & Tissue Response HEALING Healing Response to Biomaterials Biomaterial Granulation Tissue Fibrosis Fibrous Tissue “or Scar Tissue”  A complex of macromolecules and cells, macrophages, blood vessels, fibroblasts  Biomolecules are produced by cells that results in a hard, tough, connective tissue Glycoproteins- fibronectin, laminin  Elastin  Collagens- type III than type I, type I collagen makes up the final scar tissue  Extracellular Matrix Extracellular Matrix Molecules Fibrosis and Repair After sutures are removed at one week, wound strength is only 10% of unwounded skin (Walker’s law). By 3-4 months, wound strength is about 80% of unwounded skin Collagen Identification Use of Masson’sTrichrome Stain Collagen Identification Use of picrosirius red and polarizing light red=type I collagen green= type III collagen Collagen Type Confirmation Use of antibodies to collagen types I Use of antibodies to collagen types, Western blotting III IV Fibroblasts and Fibrous Tissue Fibroblasts are mesenchymal-derived cells found in virtually all organs. Identified by various immunochemical markers. Produce collagens, elastins, proteoglycans and MMPs Myofibroblasts  Myofibroblasts are modified (differentiated) fibroblastic cells   Mechanical stress induced or via ECM signals Presence of actins Fibrosis & Fibrous Encapsulation Polymer Collagen and other ECMs Cells Implant was here Fibrous Encapsulation 7 days Implant was here 14 days Implant was here 21 days Implant was here 28 days TRANSLATIONAL QUESTION: How does the fibrous encapsulation correlate to material function? Is it good or is it bad? Growth Factor Families Growth Factors Cell responses: growth, migration, shape etc. CELL Fibroblast Responses to Cells/Growth Factors Growth Factors and Cytokines FIBROBLAST RESPONSES Cytokines and Lymphokines Important in Biomaterials Applications  Cytokines- “from cells”, Cell derived products- Soluble or membrane bound  Interleukins- 1-37  Key Interleukins for Biomaterials (IL-1, IL-4, IL-6, IL-13)  Tumor Necrosis Factor- TNF-a  Colony Stimulating Factors- GM-CSF Cytokines and Lymphokines TRANSLATIONAL QUESTION: How could you incorporate a growth factor in a biomaterial to enhance or inhibit wound healing? Summary of the Inflammatory Response(s) to Biomaterial Implantation Cell & Tissue Response HEALING Summary  Cellular Injury and adaptations  Acute vs. chronic inflammation- fluids, cells, time  Transudates vs. exudates  Macrophages and Foreign body giant cell response to biomaterials  Free radicals and material degradation  Granulation tissue vs. scar (fibrous encapsulation) tissue  Fibroblast responses and healing phase- cell types, growth factors, cytokines TRANSLATIONAL QUESTION: A material called Material X (a derivative of polygalactic acid/polylactic acid or PGA/PLA) was implanted subcutaneously into the back of a rat, and subsequent retrieval of the explant occurred. 1) describe the sequence of events, as related to inflammation which may have occurred at 3, 7, 14 and 28 days at the implant surface. 2) Describe what cells and fluids are involved at each time point and 3) the types of tissue reactions next to the implant. Also describe what tissue stain or stains you could use to determine 1-3 and whether other techniques would be helpful.