Molecular Comparison of Macrophage Foreign Body Response

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DESCRIPTION (provided by applicant): Current use of human- or animal-derived phagocytic cell sources required for biomaterials inflammation and foreign body assay is inconvenient, costly, and potentially unnecessary. Equivalence of secondary macrophage-lineage cell lines in these in vitro assays is largely unproven, although many unpublished anecdotes exist regarding their utility in biomaterials toxicity or inflammatory assays. This proposal's overall objective is to establish, using quantitative modem molecular and cell biological methods, the validity of certain macrophage-derived cell line cultures in accurately duplicating phenotypic behavior of human- and animal-derived phagocytes commonly used to model aspects of the biomaterial implant-generated foreign body response. Our working hypothesis is that phenotypic response and foreign body giant cell formation on several model biomaterials using select secondary macrophage-derived cell lines in cultures designed to monitor cell-mediated inflammatory responses on biomaterials will be measurably similar to that observed using host-derived primary macrophages. Studies seek answers to important, long-standing questions surrounding the appropriate use and limitations of macrophage culture systems to analyze the foreign-body response ubiquitous for all implanted biomaterials. New data will be compared against well-developed primary monocyte/macrophage culture assays now common for biomaterials inflammatory assessments with foreign body giant cells. The following Specific Aims are proposed: (1) Determine selected cell-produced cytokines representing the Th1 and Th2 phenotypic responses in cultured secondary macrophage-derived cell lines on several model biomaterials of controlled surface chemistry; (2) Identify short and long term phenotypic stability in culture through changes in cytokine production and responses in macrophage derived cell cultures as a function of surface chemistry; (3) Quantify several distinct known phenotypic features of foreign body giant cell formation as a function of surface chemistry for macrophage-derived cell lines and primary macrophages over time in culture; (4) Establish reliable, quantitative microarray-based gene analysis to accelerate profiling of specific known markers of macrophage activation and inflammatory behavior, specifically for cytokine expression and apoptosis markers; and (5) Exploit an in vitro co culture system containing cultured macrophages and fibroblasts to study affects of macrophage-derived cytokine production on fibroblast production of collagen and fibrous precursors relevant to encapsulation reactions common to foreign bodies in vivo.