<i>In vitro</i> properties of crosslinked, reconstituted collagen sheets

Abstract

Reconstituted, 100-microns-thick collagen sheets were crosslinked with either UV light, chromium, or cysteine for use as a burn covering. The sheets were also exposed to a "surface agent" (hydroxyproline, fibronectin, or soluble basement membrane matrix containing Type IV collagen) as a preliminary step in planned adherence studies. Since some chemicals render the collagen toxic, the modified sheets were tested for cytotoxicity using human keratinocytes and fibroblasts. Autoradiography and 3H-thymidine incorporation were used to quantitate the proliferative rate of these cells in vitro. There was a universal depression of keratinocyte incorporation of 3H-thymidine following a 1-day exposure to any collagen sheet when compared to cells not exposed to any collagen. This effect had lessened by 5 days' exposure to the collagen. Conversely, the fibroblasts the collagen. Conversely, the fibroblasts showed an enhancement in rate of incorporation after 1-day exposure, especially for cells exposed to collagen sheets cross-linked by UV light. This effect had also lessened by 5 days' exposure. Autoradiography showed few significant variations for any of the cells exposed for either time period. Chromium leaching was determined, with no values greater than 30% of the allowable maximum set by both the British and American Pharmacopeia.