Biological Constraints in Using Biomaterials- Inflammation Readings for September 2, 4 & 9:

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 INTERACTIONSHemostasis/Thrombosis

Acute InflammationChronic InflammationHealing, FibrosisGranulation Tissue, GranulomasCell Injury and NecrosisSEQUENCE of EVENTS of BIOMATERIAL RESPONSESSurgery, Material Implanted

CAUSES of CELL INJURYMaterials (biomaterials)SurgeryHypoxiaPhysical AgentsChemicals and DrugsMicrobiologic AgentsImmunologic ReactionsGenetic DefectsNutritional Imbalances

CELL/TISSUE INJURY CELL INJURYreversible vs. irreversiblepoint of no return

CELL DEATHNecrosis- the summation of the morphologic changes following cell death in living tissueApoptosis- programmed cell death

ADAPTATION- cells responses to stress

Materials & Biomaterials

CELL INJURY CAUSES NECROSISNormal Heart Tissue

CELLS ADAPT to INJURY/STRESS

REGENERATIVE CAPACITY of CELLS The growth response depends on the cell type:

LabileStable Permanent

ATROPHY

HYPERTROPHYWheres the beef?

HYPERTROPHYCor bovinum

Hyperplasia (Fibrosis around Biomaterials) Fibroblast Proliferation Increased ECM (collagen)+Fibrosis

HYPERPLASIAFIBROSIS & FIBROUS ENCAPSULATIONPolymerCellsCollagen and other ECMs

Acute InflammationChronic InflammationHealingGranulation tissueCell Injury and NecrosisSEQUENCE of EVENTS of BIOMATERIAL RESPONSE to INJURYSurgery, Material Implanted

INFLAMMATION, HEALING & BIOMATERIALSLocal reaction of vascular (or vascularized) tissue to injuryOccurs in both acute and chronic inflammation!!

TWO MAIN THEMES:Destruction of tissue- or walling off of biomaterial Repair- by normal parenchyma or by scar (fibrosis)

TEMPORAL PATTERNACUTE- short duration, exudative- cells + proteins, PMNsCHRONIC- long duration, macrophages/lymphocytes, proliferative cells-fibroblasts and blood vessels

CELLS of INFLAMMATION

Erythrocytic Granulocytic MononuclearMegakaryocyticBone Marrow stem cells + Growth factorsWhite Blood cellsPlateletsPMNs=neutrophils Eosinophils BasophilsMonocytes T & B Lymphocytes

WHERE DO THESE CELLS COME FROM?

Bone MarrowBoneFat

EosPMN-segBasoMonoLymphoPlateletPMN-band

INFLAMMATION and BIOMATERIALSSequence of EventsInjuryAcute inflammationChronic inflammationGranulation tissueForeign body reactionFibrosis

ACUTE INFLAMMATIONShort duration

Hours to a few days

Hemodynamics, Vascular permeability, Leukocyte migration

Exudative or exudatesAre protein and cells which bind to biomaterials, pus is an exudate

CalorRuborTumorDolor

HEMODYNAMICS and INFLAMMATIONQ or Jv = ([Pc Pi] [c i])

Q or Jv = ([Pc Pi] [c i]) Pc-Pic i

TRANSUDATES vs. EXUDATES

CHARACTERISTICTRANSUDATEEXUDATEDefinition & EtiologyHemodynamic, an ultrafiltrate of plasmaInflammatoryInflammatory cellsNoneYesBacteriaNoneOftenProteinLow (4%)Specific Gravity1.020ExamplesCongestive heart failure, blisterPneumonia, abscesses, pus

TRANSUDATEThis 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 effusionsAscitesPericardial effusion

from Webpath 7.0

EXUDATEPUS!!!!

LEUKOCYTES in INFLAMMATIONAlso known as White Blood Cells (WBCs)Granulocytes- PMNs, Eosinophils, BasophilsMonocytesLymphocytes

Mast cells- are tissue cells, not in circulating blood

Normal value (blood) is 10,000 cells/cubic mmLeukocytosis (or philia)- >10,800/cubic mm, increased numbersLeukopenia-

INFLAMMATION & BIOMATERIALSHEALINGCell & Tissue Response

Leukocytes in InflammationAcuteChronic

PMNsMononuclearcellS

Other Cells/Components of Inflammation

LEUKOCYTES in INFLAMMATIONfrom Webpath 7.0Capillary(Blood) SideMaterial with Bacteria

Leukocytes in InflammationPhagocytosisClick on the link above, need to be in full slide mode

Chemical Mediators of Inflammation

Plasma-derived Circulating precursors Have to be activated

Cell-derivedsequestered 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

COMPLEMENT SYSTEMand biomaterial surfacesComplement binds to biomaterials and is activated by biomaterialsBiomaterials

FEVER, IL-6

Acute InflammationChronic InflammationHealing, FibrosisGranulation Tissue, GranulomasCell Injury and NecrosisSEQUENCE of EVENTS of BIOMATERIAL RESPONSE to INJURYSurgery, Material Implanted

CHRONIC INFLAMMATION

Long duration

Few days, weeks, months

Proliferative- fibroblasts and blood vessel divideBut also- macrophages & lymphocytesNote- macrophages do not divide

Leukocytes in InflammationAcuteChronic

MACROPHAGES and FBGCs(Biomaterials)

MACROPHAGES, FBCGs and BIOMATERIALS

Foreign Body Giant CellsSuture

IN VIVO BIOCOMPATIBILITY TESTINGCage Implant SystemMaterialCageImplantationDays 7, 14 and 21Exudates Analyzed for Cell CountsSurfaces Explanted and Adherent Cells Analyzed

Insertsyringe

MACROPHAGES and FOREIGN BODY GIANT CELLSFusion

MACROPHAGES and BIOMATERIALSThe Big Mac Attack--- DegradationBIOMATERIAL DEGRADATION-OHH202-O2Enzymes+HPits, holes etc.

FREE RADICALS

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 & AntioxidantsAntioxidants

PACEMAKER LEAD DEGRADATIONMacrophage adhesionForeign body giant cells (FBGC)Surface pittingSurface crackingFull thickness crackingDEVICE FAILUREExplanted pacemaker leadAdherent macrophages & FBGC release degradative enzymes and radicals.

FBGC - Mediated Surface Degradation

ACUTE INFLAMMATION & ROS

Acute InflammationChronic InflammationHealingGranulation Tissue, GranulomasCell Injury and NecrosisSEQUENCE of EVENTS of BIOMATERIAL RESPONSE to INJURYSurgery, Material Implanted

INFLAMMATION & BIOMATERIALSHEALINGCell & Tissue Response

GRANULATION TISSUEA 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 tissueGlycosaminoglycans (GAGS)Glycoproteins- fibronectin, lamininCollagens

HEALING RESPONSE to BIOMATERIALSBiomaterialFibrosis:Collagen-richGranulation Tissue:GAG-richInfection following Implantation

GRANULATION TISSUEGAGSBlood Vessels

ANGIOGENESIS in GRANULATION TISSUE

TISSUE RESPONSE to BIOMATERIALSGRANULATION TISSUE-H&EGranulation tissue:Blood vesselsGAGsSome MacsSome fibroblasts

GLYCOSAMINOGLYCANSHighly Sulfated-binds to water

GLYCOSAMINOGLYCANS

Acute InflammationChronic InflammationHealing, FibrosisGranulation TissueCell Injury and NecrosisSEQUENCE of EVENTS of BIOMATERIAL RESPONSESSurgery, Material Implanted

INFLAMMATION & BIOMATERIALSHEALINGCell & Tissue Response

HEALING RESPONSE to BIOMATERIALSBiomaterialFibrosisGranulation Tissue

FIBROUS TISSUEor Scar TissueA complex of macromolecules and cells, macrophages, blood vessels, fibroblasts

Biomolecules are produced by cells that results in a hard, tough, connective tissueGlycoproteins- fibronectin, lamininElastinCollagens- type III than type I, type I collagen makes up the final scar tissue

FIBROSIS & FIBROUS ENCAPSULATIONPolymerCellsCollagen and other ECMs

EXTRACELLULAR MATRIX- COLLAGENType III collagen is produced first thancells (fibroblasts) produce Type I collagen

7 days14 days21 days28 daysFIBROUS ENCAPSULATION

GROWTH FACTOR FAMILIES

GROWTH FACTORSCELLCell responses:growth, migration, shape etc.

FIBROBLAST RESPONSES Growth Factors and Cytokines FIBROBLAST RESPONSES

CYTOKINES and LYMPHOKINESImportant in Biomaterials ApplicationsCYTOKINES- from cells, Cell derived products- Soluble or membrane bound INTERLEUKINS- 1-37Key Interleukins for Biomaterials (IL-1, IL-4, IL-6, IL-13)

TUMOR NECROSIS FACTOR- TNF-a

COLONY STIMULATING FACTORS- GM-CSF

Cytokines and Lymphokines

SUMMARY of the INFLAMMATORY RESPONSE to BIOMATERIALSHEALINGCell & Tissue Response

SUMMARYCellular Injury and adaptations Acute vs. chronic inflammation- fluids, cells, timeTransudates vs. exudatesMacrophages and Foreign body giant cell response to biomaterialsFree radicals and material degradationGranulation tissue vs. scar (fibrous encapsulation) tissueFibroblast responses and healing phase- cell types, growth factors, cytokines

Resize of Shoulder_abscess_liquefactive_necrosis_gross.JPGREMEMBER THIS DIAGRAM

Granulation tissue fibrotic tissue

What cell types make proteoglycans? FibroblastsWhat about Collagen? Osteofibroblasts

How do they do this? How many collagens in human body? 28Chains in type 3 is lose, whereas type 1 is very distinct (every 64 nm), providing strong tensile tissue reticular collagenWhy is the thickness decreasing? Inflammation is decreasing, less collagen, cells are contracting down, less proliferate Molecular weights : 20,000 kDa

Except peptidesBind to growth factor receptor, then signal transduction, activation of pathway, and cell responses occurRemember whatever is in red