| The objective of this research was to understand the response of dendritic cells (DCs) to different biomaterials upon contact and identify biomaterials suitable for use in tissue engineering constructs for RA applications. It was hypothesized that DCs respond with differential levels of maturation upon contact with different biomaterials and, further, these DCs treated with different biomaterials induce differential phenotype and polarization of autologous T cells upon co-culture of DCs and T cells, with elucidation of the differential integration effects of biomaterials in the RA knee joint of rabbits, wherein DCs and T cells are seriously involved in its pathophysiology.;Following initial characterization of five different biomaterials including four natural biomaterials [alginate, hyaluronic acid (HA), chitosan, and agarose] and one synthetic biomaterials [Poly(lactic-co-glycolic acid) (PLGA, 75:25)], treatment of immature DCs (iDCs) with these different biomaterials was performed to observe the effects of inherently different features of biomaterials on human monocyte-derived DC maturation in vitro. Differential levels of functional DC maturation were observed depending on the type of biomaterial in 2-dimensional (2-D) films used to treat iDCs using the variety of immunobiological functional assessment which includes DC morphologies in cytospin, surface marker (MHC class II or costimulatory molecules) expression, allostimulatory ability in a mixed lymphocyte reaction, and pro-inflammatory cytokine release.;In addition to biomaterials in 2-D film form, biomaterial scaffolds in 3-dimensional (3-D) porous form have also been assessed for their effect on changes of DC phenotypes. Extended from the previous result of opposite effects of their 2-D film form on phenotypical changes in DC maturation, PLGA or agarose 3-D scaffold has been used to treat DCs, and effects of DC treatment with these biomaterial scaffolds were assessed with phenotypical changes of DCs. Similarly to the results observed in the previous study using different 2-D biomaterial films, DC phenotypes were differentially modulated by PLGA or agarose scaffolds in porous 3-D form. In the assessments of DC morphologies in confocal microscopy, surface marker (MHC class II or co-stimulatory molecules) expression, and allostimulatory ability in a mixed lymphocyte reaction, PLGA scaffold induced DC maturation in significantly higher levels of phenotypical changes of DCs, as compared to iDCs, while DCs treated with agarose scaffolds had similar phenotypes to iDCs.;Extended from the biomaterial effects on phenotypical changes of DC maturation, DCs treated with different biomaterial films were assessed for their functional impacts in regulating autologous T cell phenotype and polarization. Dendritic cells treated with agarose films induced CD4+CD25+FoxP3+ (T regulatory cells) expression on autologous T cells at level similar to iDCs and interleukin (IL)-10 release at higher levels whereas PLGA film treatment induced release of IFN-gamma at higher levels, as compared to DC treatment with other biomaterial films, in the DC-T co-culture system. Interestingly, when DCs were treated with the different biomaterial films, profiles of released cytokines were influenced by the presence of antigen or autologous T cells.;Based on these in vitro results, to further understand the influence of RA environment to different biomaterials and to identify biomaterial useful for tissue engineering in the RA situation, integration of inherently different biomaterials (PLGA and agarose) was assessed upon implantation of them into the knee joint of antigen-induced arthritis (AIA) rabbit. Upon RA induction combined with biomaterial implantation or sham operation into the right knee joint, the knee swelling size and total leukocyte concentration in the right knee remarkably increased, compared to the untreated left knees, and these increased levels in the right knee consistently went through the end point of Day 36. However, total leukocyte concentrations in the peripheral blood or in the joint lavage of the left knees (untreated control) were observed in differential levels depending on the biomaterial implant, possibly due to the systemic circulation of the peripheral blood. Furthermore, cartilage and bone healing progression was differentially observed in the osteochondral defect of the knee joint of RA-induced rabbit, depending on type of biomaterial scaffold implanted into the defect. (Abstract shortened by UMI.). |
