Assessment of monocyte derived dendritic cell phenotype upon biomaterial contact in vitro

Immune response remains a concern associated with the successful integration of tissue engineered device into living systems. Upon implantation, both living and non-living device components elicit a specific immune and a nonspecific inflammatory response, respectively. We hypothesize that biomaterial contact is a maturation stimulus for dendritic cells (DC), the antigen presenting cells that activate T cells and initiate adaptive immunity. Maturation of DC was reconstituted by culturing human blood monocytes with GM-CSF and IL-4 to induce differentiation into immature DC (iDC). iDC were then treated with 4 μm poly(lactic-co-glycolic) acid microparticles (PLGA MP), or with LPS to yield mature DC (mDC) as positive control. Cell morphology and surface phenotype were monitored as a function of time. On day 10, biomaterial- treated cells morphologically most closely resembled mDC with dendritic processes. In contrast and as expected, monocytes/macrophages did not exhibit processes and expressed high levels of CD14. mDC expressed high levels of costimulatory and MHC molecules compared to iDC. Our preliminary results show that biomaterial microparticles were phagocytosed, and the level of costimulatory and MHC molecules expression by biomaterial- treated cells was between that expressed by iDC and mDC.