Quiz 2 Flashcards
In Vitro
in a test tube, culture dish, or elsewhere outside a living organism
In Silico
by means of computer modeling or computer simulation
In Vivo
In a living Organism
Ex Vivo
In an artificial environment outside a living organism
Biocompatibility
the ability of a material or substance to perform its intended function within a specific biological system without causing harm or adverse effects to living tissues or organisms
classes of Biomaterials
Metals, ceramics, polymers, composites, natural materials
ISO 10993
standards for evaluating the biocompatibility of medical devices to manage biological risk
Toxicology
the scientific study of adverse effects of substances on living organisms
In Vitro accessing of Biocompatibility
materials compatibility with specific cell lines and does not involve immunological components similar to the body
cytotoxicity
to cause toxic effects on the cellular level
Leachability
analysis of extracts
Hemocompatibility
Blood-materials/leachates interactions
-Clotting
-absorption
platelet assay
Agar Diffusion Test Assay
test the cytotoxicity of biomaterial-generated leachable chemicals to diffuse from biomaterials. cells then are evaluated to determine the toxicity of the material: the zone of cell destruction is measured and scored 0-4
MEM Elution
material is extracted from mammalian cell culture media and placed in contact with a monolayer of cells and then allowed to grow in extraction fluid and then evaluated for qualitative or quantitative methods
MTT Assay
colorimetric assay for assessing cell metabolic activity based on reducing MTT by dehydrogenase to form water-insoluble formazan
Sensitization, Irritation, Intradermal Reactivity
reversible=irritant
irreversible=corrosive
systemic Toxicity
Adverse effects occurring from single or multiple doses
Genotoxicity
only performed if DNA mutations have been observed during in vitro testing
Implantation
Investigation into how the local tissue/organ responds to the biomaterial
Hemocompatibility
Blood compatibility testing
Carcinogenicity
chemical-induced cancer
Reproductive and Developmental Toxicity
chemically induced adverse effects on sexual function, fertility, and/or normal offspring development
Biodegradation
how does the material degrade in vivo, where do those pieces go, and how does the body respond
Immune response
Does the body recognize as “not self”? = We will discuss this further later this semester
Histology and histochemistry
relative numbers of various cell types and the amount of ECM components around the implant
Immunohistochemistry
Membrane, intracellular and extracellular molecules
Transmission and scanning electron microscopy
analysis of cells at the interface and morphology
biochemistry
inflammatory mediators
mechanical testing
mechanical strength
overview of Immunology
-Innate Immune System
-Complement System
-Specific Immune System
First Line of Defence
-Physical
-Chemical
-Biological
Physical Barrier
-skin
-nasal hair
-Eyelashes & eyelids
-mucous membranes
-Mucociliary Clearance
-Urination
Chemical Barrier
-Low pH
-Antimicrobial molecules
Ex. Sebum in skin, mucous, beta-defensins in epithelial cell, pepsin in gastric mucosal defence
Biological Barrier
Microbiome
Initial immune response-macrophage
recognize pathogen and then activate the innate system
Initial immune response dendritic cells
Pick up antigens, track down T & B cells, and activate specific system
Initial immune response activates the complement system
lectin pathway and alternative pathway
Phagocytosis
1.) entrapment
2.) Formation of a phagosome
3.) Degradation
4.) Exocytosis
Inflammation
vasodilation, increased vascular permeability, mast cell degranulation, clotting system, kinin system
Acute Phase Response-Interleukin 1
-fever
-decrease appetite
-lethargy
Acute Phase Response-Interleukin 6
acute phase proteins(opsonins)
Acute Phase Response-Interleukin 8
recruits and activates neutrophils
Acute Phase Response-Interleukin 2 and 12
activates natural killer cells
Opsonins
any substance that enhances phagocytosis
-attaches to pathogens, help neutrophils and macrophages
C-reactive protein-opsonin(inflammation marker)
-produced by liver
-response to IL-6
-measure serum level
-Marker of inflammation/infection severity
Complement System
results in: opsonins, inflammation, destroys pathogens
triggers: lectin pathway, alternative pathway(directly by pathogens) and classical pathway(antibody-antigen complexes)
lymph node
“army barracks”
“waiting for enemy”
Plasma cells
B cells differentiated to antibody-producing cells
antibodies structure
-fixed region stem recognized by cells of the immune system, and variable region y matches different antigens
antibodies function
-attach to toxins(neutralise them)
-attach to receptors(preventing viral infection)
-agglutination
-opsonins
hemocompatibility
the ability to come into contact with blood without causing adverse reactions
ISO 10993-4
Hemocompatibility in vitro analysis for clinical application
blood components
55% plasma, 44% erythrocytes, and 1% leukocytes
Erythrocytes
the most rigid cells in the blood, they are sensitive to rupture and hemolysis due to shear stress and changes in osmotic pressure
Blood Platelets
are the smallest and the second most abundant cell type in the blood with 1.5-3.5 x10^5 cells/microliters, which can rapidly recognize foreign surfaces and initiate blood coagulation
immune cells
(abundant neutrophils, monocytes) belonging to the innate immune system can be rapidly activated upon recognition of a foreign invade such as a pathogen or foreign material
categories of devices contacting blood
-Externally communicating devices with indirect blood contact
-externally communicating devices with direct blood contact
-implant devices
hemocompatibility test components
-static and dynamic models
-hemolysis, cell counts, platelets activation, leukocytes, coagulation, complement system
-attachment, absorption of proteins, and generation of thrombus and fibrin
evaluation steps for hemocompatibility
- blood collection and anticoagulation
- analysis of blood before incubation with the test material
- transfer of blood into a static, agitated or dynamic test model
- incubation at 37 dC
- analysis of blood and the surface of the material
analysis of hemocompatibility
-changes of platelets, erythrocytes, and leukocytes
-generation of activation products in plasma
-deposition of proteins and cells on the material surface
-blood and the surface of biomaterials are analyzed before and after the incubation
hemocompatibility tests
-determination of blood cell numbers and hemolysis
-coagulation activation
-activation of the complement system
-activation of leukocytes
-analysis of biomaterial surfaces
determination of blood cell numbers and hemolysis
the number of erythrocytes, leukocytes, and platelets is measured before and after the incubation of blood with biomaterial using a hematology analyzer(electrical impedance, coulter principle). decrease of platelet count ->thrombogenic material
hemolysis
the rupture of erythrocytes, accompanied by the release of hemoglobin
-detected by using a photometric colorimetric test
Coagulation Activation
the interaction of plasma proteins with artificial surfaces triggers the intrinsic coagulation pathway by contact activation
Activation of Complement system
-classical, alternative, and mannose binding lectin
-plasma proteins can bind to material surfaces. Binding of IgG and C3 lead to activation, which promotes inflammation
platelet activation
plasma proteins absorb to the biomaterial surface. Fibrinogen, VWF, fibronectin, and vitonectin induce adhesion of the platelets which releases substances and activates other platelets
platelet activation detection
determined according to ISO 10993-4 by measuring
-released contents from alpha granules
-detection of P-selectin
-activated GPIIb/IIIa platelet receptor using flow cytometry
Activation of Leukocytes
evaluates the induced inflammatory response
-neutrophil extracellular traps release the nuclear material in the form of a meshwork of chromatin by activated neutrophils
CD11b
marker of leukocyte activation
high regenerative capacity
epithelial, lymphoid, hematopoietic, mesenchymal tissues, high vascularization
Low regenerative capacity
Nerve, muscle, cartilage
Necrosis
death by extrinsic means
apoptosis
death by suicide
Atrophy
decrease in cell size and/or function
Hypertrophy
increase in cell size
Hyperplasia
increase in cell number
metaplasia
change in cell type
tissue injury responses
-necrosis, apoptosis, atrophy, hypertrophy, hyperplasia, metaplasia, change in phenotype
wound healing model
-Homeostasis(hours)
- inflammation(days)
-Proliferation(weeks)
-Remodeling(months/years)
CHronic wound
elevated repsonse: matrix mettaloprotease production, infection/biofilm, fibroblast senescence, inflammation
Inhibition: ecm & fibroblast production, collagen fibres production
stalled: epithelialization, angiogensis
Immune cells after injury
Neutrophils(hours)
Mononscytes and macrophages(1-3 days)
T cells(1-2 weeks)
after device implantation
injury(BV damage), acute inflammation(leukocytes), chronic inflammation(moncytes and macrophages), granulation tissue(fibroblasts and cap), foreign body reaction(macrophages and FBGC), fibrous encapsulation(Fibrous capsule)
Acute Inflammation
immediate response to injury
-deposition of fluids and plasma, inflitration of neutrophils and moncytes
chronic inflammation
-monmuclear cells, BV proliferation
diapedesis
transendothelial migration
“squeezing through endothelium”
neutrophils roles
-protein absorption
-release enzymes
-phagocytosis
-respiratory burst
-cytokine secretion
Mast Cells
similar to basophils
communication Immune repsonse to inflammatory response
-release histamine
reduce acute inflamation
-surface modification
-Nano-patterning
-modification of surface charge
-use of hydrogels and hydrogel coating
-controlled release of agonists
Macrophages produce
proteases, chemotaxis factors, reactive oxygen metabolites, complement components, coagulation factors, growth-promoting factors, cytokines
