Tissue Engineering - Biomaterials II

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  1. What is the average size of cells?
    5-100 um
  2. What is the approximate size of viruses?
    10-100 nm
  3. What is the approximate size of proteins?
    1 - 10 nm
  4. What is the approximate size of bacteria?
    1 - 5 um
  5. (T/F) There are about 10 to 100 times the number of bacteria cells than the number of human cells.
    True. They are primarily located in the gut.
  6. What are 3 roles of the immune system?
    • Defense against infection/immune surveillance
    • Distinguish self from non-self (otherwise would be autoimmune)
    • Proliferation and differentiation of responsive cells such as B cells.
    • Generation of a protective response
    • Humoral response
    • Cell-mediated response
  7. What would an overactive immunological response be?
    Autoimmunity allergy
  8. What would an underactive immunological response?
    Disease prone, drug treatment required, infection common, mutations common
  9. What is an antigen?
    A molecule that is recognized by the immune system's antibodies. It has specific bonding between antigen-antibody.

    • Any molecule recognized by specific antibodies or T cells such as
    • proteins
    • carbohydrates
    • lipids
    • self or nonself
    • infectious or non-infectious
  10. What are cytokines?
    Small cell-signaling molecules that are released by immune cells as signaling molecules that are used extensively in intercellular communication.

    They are signaling molecules that are released by cells such as dendritic cells and T cells that bind to their target cells such as macrophages or epithelial cells and activate them.

    • Proteins that regulate immune responses and inflammation
    • Generally short during of prudction
    • Multiple effects and redundant
    • Work in cytokine cascades
    • Potent and stimulus-independent
    • Positive and negative aspects
    • -Positive - Pain, fever, effector function
    • -Negative - cytokine storm
  11. What is the innate immune system?
    Innate immunity is an antigen-nonspecific defense mechanism that a host uses immediately or within several hours after exposure to almost any microbe. This is the immunity one is born with and is the initial response by the body to eliminate microbes and prevent infection.

    In the case that a pathogen breaches the physical barriers of an organism, the innate immune response provides an immediate, but non-specific response.

    • Reponse is non-specific
    • Exposure leads to immediate maximal response
    • Cell-mediated and humoral components
    • Non immunological memory
    • Found in nearly all forms of life
  12. (T/F) The innate immune system is non-specific.

    Unlike the adaptive immune system, it does not recognize every possible antigen. Instead it is designed to recognize molecules shared by groups of related microbes that are essential for the survival of those organisms and are not found associated with mammalian cells.
  13. (T/F) The innate immune responses do not improve with repeated exposure to a given infection.

    There is no immunological memory.
  14. What is the adaptive immune system?
    Adaptive (acquired) immunity refers to antigen-specific defense mechanisms that take several days to become protective and are designed to react with and remove a specific antigen. This is the immunity one develops throughout life.

    If pathogens successfully evade the innate response, vertebrates possess a second layer of protection which is activated by the innate response. The immune system adapts its response during an infection to improve its recognition of the pathogen. The improved response is then retained after the pathogen has been eliminated, in the form of an immunological memory, and allows the adaptive immune system to mount faster and stronger attacks each time this pathogen is encountered.

    • Pathogen and antigen specific response
    • Lag time between exposure and maximal response
    • Cell-mediated and humoral components
    • Exposure leads to immunological memory
    • Only found in jawed vertebrates
  15. What is a cell-mediated immunity?
    An immune response that does not involve antibodies but rather involves the activation of macrophates, natural killer cells (NK), antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines.

    Cell-mediated immunity deals with cells killing the pathogen or other infected cells, that involves cells that are part of the innate and the adaptive immune system.
  16. What is humoral immunity?
    The aspect of immunity that is mediated by secreted antibodies produced in the cells of the B lymphocyte lineage.

    It involves the interaction of B cells with antigen and their subsequent proliferation and differentation into antibody-secreting plasma cells. The antibody functions as an effector molecule of the humoral response by binding to antigen and neutralizing it or facilitating its elimination.

    Humoral immunty is based on antibody secretion which is a part of adaptive immune response only. However, the complement system from innate immunity can be activated by antibodies so the antibodies can be used by phagocytes of the innate immune system to grab onto the pathogen.
  17. What are germinal centers?
    Located in lymph nodes.

    Where B cells differentiate into plasma cells once they have become activated. Every cell type (B cell, T cell) have what's called effector cell types, once they become activated, they differentiate into their effector cell types that actually provide the immune response in the case of B cells, they become the plasma cells that secrete antibodies that are specific for whatever antigen triggered them to be activated
  18. What are the roles of the immune system (6)?
    • Defense against infection/immune surveillance
    • Distinguish self from non-self
    • Proliferation and differentation of responding cells
    • Generation of a protective response
    • Humoral response
    • Cell-mediated response
  19. What is inflammation?
    The reaction of vascularized living tissue to local injury. It serves to contain, neutralize, dilute, or wall off injurious agent or processes.
  20. (T/F) Humoral-mediate responses may allow for antibodies to block viral adsorption by binding to the receptors.

    The process works for many diseases including influenze, yellow fever, smallpox, tetanus, hepatitis B etc..
  21. What are two methods for measuring the B cell response to a vaccine?
    • Magnitude of an in vitro B-cell response.
    • -quantitative measurement of the antibody ressponse
    • -Serological titer

    • Quality of the in vitro B-cell response.
    • -Neutralizing antibody responses
    • -Affinity/avidity indices
  22. Are T cells used in cell-mediated immune responses or humoral immune responses?
    Cell-mediate immune responses.
  23. Are B cells used in cell-mediated immune responses or humoral immune responses?
    Humoral immune responses
  24. What is the function of the T helper cell?
    CD4+ releases cytokines and activate other cells (B cells mature) by direct interaction with the target.
  25. What is the function of the T cytotoxic cell?
    CD8+ cells kill targets.
  26. What is a measure of of T-Cell response to a vaccine?
    • Magniture od an in vitroT-cell response
    • -Quantitative measurement of the T-cell response (frequency of CD4+ or CD8+ T cells that are antigen specific) (Total cytokine secretion, cytolytic activity or proliferation) (Measures number of T cells)

    • Quality of the in vitro T-cell response
    • -Combination of T cell functions
    • (Proliferation organization of immune cells, effector cells)
    • (Multifunctional T cells have been shown to correlate with disease non-progression and protection)
  27. (T/F) Humoral-mediate responses includes the use of antibodies to block viral adsorption by blocking the receptors.
  28. What is a cytokine storm?
    A postive feedback group involving cytokines and immune cells, with potentially fatal results, resulting in elevated levels of various cytokines.
  29. What is the regulatory switch for cytokine control?
    Neurotransmitters are anti-inflammatory's control.
  30. What are interferons? Are they in the innate or the adaptive immune system?
    Interferons are proteins produced by host cells in the presence of a pathogen. They are non-specific and in the innate immune system.
  31. What is the sequence of local events following implanation in soft tissue (5)?
    • Injury
    • Acute inflammation
    • Granulation tissue
    • Foreign body reaction
    • Fibrosis
  32. What is fibrosis?
    The formation or development of excess fibrous connective tissue in an organ or tissue as a reactive process.

    This is compared to the formation of fibrous tissue as a normal constituent of an organ or tissue.
  33. What are 5 important design criterias for skin?
    • Adhere to substrate
    • Mechanically durable and resistant
    • Regulate water evaporation
    • Provide a microbial barrier
    • Permit remodeling
    • Do not invoke adverse immune reaction
  34. What was the function of Integra?
    • Dermal replacement layer that serves as a matrix for infiltration of fibroblasts and capillaries
    • Endogenous collagen matrix is deposited by fibroblasts simultaneously the dermal layer is degraded
    • Upon vascularization of the neodermis, the silicone layer is removed and a thin, meshed epidermal autograft is placed over the neodermis
    • Cells from the epidermal autograft grow and form a confluent epidermis with a stratum corneum
  35. What are important design criteria for the ideal biomaterial (material's properties)?
    • Structurally strong - fit for the function.
    • Porosity - High porosity for high surface area to volume ratio and the desired vascularization/angiogenesis.
    • Uniformally distribued and interconnected pore structure.
    • Ability to be processed into desired shape.
    • Biostability (desired biodegradability)
  36. What are important design criteria for the ideal biomaterial (Cell to material interaction)?
    • Biocompatibility
    • Promotion of cell adhesion
    • enhancement of cell growth
    • retention of differentiated cell function.
  37. What are some of the production aspects of tissue engineering?
    • Production issues (scale up, production etc)
    • Cell source for tissue engineering
    • Scaffold design - Natural or synthetic materials
  38. What are the pros and cons between natural and synthetic materials for scaffold selection?
    Natural: biodegradable, desirable biological properties; but limited availablity and disease transmission concerns

    Synthetic: Consistency and ease of manufacture; controlled chemical and physical properties but lack specific biological properties
  39. What are four concerns for tissue engineering and manufactoring?
    • Scalable - generate numbers of constructs required to meet the projected clinical need
    • Reproducible - high % of successful products made
    • Safe - Safe for host and for use
    • Economical - Affordable
Card Set
Tissue Engineering - Biomaterials II
Tissue Engineering - Biomaterials II
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