Blood interaction with grafts

W. Norde and R. A. Gage, Interaction of bovine serum albumin and human blood plasma with PEO-tethered surfaces influence of PEO-chain length, grafting density and temperature, Langmuir 20, 4162-4167 (2004). 

Calcium chaimel blockers traditionally have been the first-line agents to treat hypertension after transplantation. In addition to their ability to control blood pressure, calcium channel blockers may ameliorate the nephrotoxic effects of CSA, improve renal hemodynamics, decrease the incidence of delayed graft function and development of allograft atherosclerosis, and provide some immunosuppression. Calcium channel blockers, however, also may contribute to gingival hyperplasia that is often associated with CSA-based immunosuppression. CYP 3A4 interactions with CSA and TAC are of concern with this class of medications, particularly with dil-tiazem, verapamil, and nicardipine, and CSA or TAC concentrations must be monitored to ensure proper dosage adjustments. 

The attachment of proteins and other biomolecules to PEG-grafted surfaces is also of interest for a number of applications. In solid-phase immunoassay and extracorporeal therapy, antibodies or other bioactive molecules are immobilized to a support that interacts with cells, blood, or plasma. Biocompatibility of implants and artificial organs can be improved by the attachment of growth factors to the surface via PEG spacers. These applications are all based on the regulating function of PEG in the interaction between a biomolecule, usually a protein, and another biomolecule or cell. More specifically, immobilization of the biologically active molecules to the free end of grafted PEG chains offers a way to minimize the interactions (deformation and nonspecific adsorption) of attached biomolecules with underlying surface, thus maximize the functions of immobilized biomolecules. 

The studies referred to have been immensely helpful in analyzing tiie progress of vascular diseases, which are often associated with tiie migration of proteins to the vessel wall followed by an interaction with wall cells, leading, for example, to blood coagulation. Mass transfer is also important in the performance of vascular grafts and of controlled release devices (see Practice Problems 1.7 and 1.10). 

A series of polyamine-graft copolymers (See Sect. 4.3) were found to form microdomain structure and to exhibit unique biomedical behavior at the interface with living cells, e.g. blood platelets or lymphocytes. Although a number of postulates were proposed to explain the unique behavior of microdomain-structured surface, mechanisms for the mode of interaction of living cells with any of the domain-structured materials have not been adequately explained. In Sect. 4, the author will review results on the biomedical behavior of SPUs, HEMA-STY, and polyamine-graft copolymers, and discuss their interfacial properties in terms of the random network concept of water molecules on the material s surface. 

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