MODULATION OF THE TISSUE REACTION TO BIOMATERIALS .1. BIOCOMPATIBILITY OF CROSS-LINKED DERMAL SHEEP COLLAGENS AFTER MACROPHAGE DEPLETION

Although in the last few years in general the biocompatibility of biom aterials has significantly improved, unwanted tissue reactions are oft en observed resulting in early resorption of the biomaterial, loosenin g of the implant or in a chronic (immunologic) response. From immunolo gic studies it is known that inflammatory reactions can be modulated b y use of (anti) growth factors or anti-inflammatory drugs. Before this can be employed the role of individual factors (humoral and cellular) involved in the inflammatory reaction against biomaterials has to be studied. In this part of the study the role of macrophages is studied with and without depletion by use of the liposomes-mediated macrophage suicide technique. Crosslinked dermal sheep collagens were used as bi odegradable test materials. The results showed that macrophage depleti on increases vascularization, and decreases the infiltration of granul ocytess into the collagens. The foreign body reaction, i.e. the infilt ration of macrophages and giant cells was significantly inhibited, res ulting in a strongly delayed degradation time of the biomaterials. How ever, macrophage depletion did not inhibit attraction of fibroblasts a nd even resulted in increased formation of autologous rat-collagen, wh ich improved the biocompatibility and the function of the biomaterials as a tempory scaffold.