Tissue-material interactions

Blood coagulation resulting in the formation of a stable fibrin clot involves a cascade of proteolytic reactions involving the interaction of clotting factors, platelets, and tissue materials. Clotting factors (see table) exist in the blood in inactive form and must be converted to an enzymatic or activated form before the next step in the clotting mechanism can be stimulated. Each factor is stimulated in turn until an insoluble fibrin clot is formed. 

Using the above multimicroprocessed surfaces, which are manufactured by semiautomatic manipulations, early events of tissue-material interactions possibly predicting the tissue compatibility of implant materials have been... 

The placement procedure initiates a response to injury by the tissue, organ, or body and mechanisms are activated to maintain homeostasis. The degrees to which the homeostatic mechanisms are perturbed and the extent to which pathophysiologic conditions are created and tmdergo resolution are a measure of the host reactions to the biomaterial and may ultimately determine its biocompatibility. Although it is convenient to separate homeostatic mechanisms into blood-material or tissue-material interactions, it must be remembered that the various components or mechanisms involved in homeostasis are present in both blood and tissue and are a part of the physiologic continuum. Furthermore, it must be noted that host reactions may be tissue dependent, organ dependent, and species dependent. Obviously, the extent of injury varies with the implantation procedure. 

The interaction of materials at the interface is integral to composite performance, and this can be affected by the tissue response in various ways, such as filling and swelling of interfacial voids with fluid and fibrous tissue, altering the interfacial adhesion strength between matrix and reinforcement, and delamination of laminate composites. Such effects can lead to failure of a composite, particularly in structural applications. 

While it is convenient to consider blood-material interactions separately from tissue-material interactions, it must be emphasized that blood-material interactions and the inflammatory response are intimately linked and, in fact, early responses to injury involve mainly blood and blood vessels. Therefore, both cellular and humoral elements, i.e., plasma proteins, etc., are considered as cells and components of vascularized connective tissue. 

Marker, L.A., Ratner, B.D. and Didisheim, P. (eds) (1993) Cardiovascular Biomaterials and Biocompatibility A Guide to the Study of Blood-Tissue-Material Interactions, Cardiovascular Pathology, 2 (3 Suppl), 1S-224S. 

An important further development of the retrieval study would be the simulation and modeling of in vivo performance of the biotextile implant. By simulating the various parameters such as blood flow and tissue-material interactions it may in the future be possible to predict such biological response variables as thrombosis, aneurysm formation and the rate of healing. 

Some poly [(organo)phosphazene] materials are of interest as biomedical polymers as non-interacting tissue replacement materials. Allcock examined the possibility of poly [(organo) phosphazenes] to be used as coating materials for artificial implants (Allcock et al, 1992). This coating materials should be able to enhance the antibacterial actiwty of the surface of implanted materials. 

William, D.F., 1987a. Tissue-biomaterial interactions. J. Material Sci. 21, 3421. 

Extensive studies of blood-material and tissue-material interactions ate not available in the literature, but Mason el aL (7] repotted PVDF to have inletmcdiale characteristics of blood compatibility as determined through an in vitro lest system. Irreversible loss of remanent polarization occurs above 7IPC. with a quasi linear decrease in residual pyro- and piezoelectric response approximating 1%TC (8]. This must be taken into account in device sterilization, which can be achieved by exposure to ethylene oxide, or by irradiation with an electron beam from a radiouctive source, with a dose of the order of US Mrad. PVDF films retain their polarization fully below 23-Mrad irradialioa from a °Co source (9). According to data provided by Dynamit Nobel. PVDF shows no appreciable chemical attack from ethylene oxide up to a temperature of lOtTC... 

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