The purpose of this study was to determine the proliferative activity of tissue repair fibroblasts recovered directly from injured peritoneum at various times after surgery and to test the mitogenic response of tissue repair cells (TRC) to growth factors. Rabbits underwent bilateral peritoneal abrasion (5 × 5 cm) with sterile gauze until punctate bleeding developed. Postsurgical (Days 2, 5, 7, and 10) tissue repair cells were recovered from the injured peritoneum by scraping with a scalpel blade. Although tissue repair cells consisted of a mixed cell type after 4 days in culture, recovered cells were essentially fibroblasts. These TRC were then pulsed with [3H]thymidine after 4 days in culture. The incorporation of thymidine into Postsurgical Day 5 TRC increased significantly compared to that of Day 2 TRC (P < 0.05). Incorporation then decreased with time following surgery. Fibroblast growth factor (FGF) and epidermal growth factor (EGF) stimulated the incorporation of thymidine into TRC. However, the response of Postsurgical Day 7 and 10 TRCs to 1 μg/ml EGF was significantly greater than those of Postsurgical Day 2 and 5 TRCs (Day 2 TRC, 166 ± 7.4; Day 10 TRC, 420 ± 96% of control cells without EGF, P < 0.05). Platelet-derived growth factor (PDGF, 10 ng/ml) also stimulated the incorporation of thymidine into Day 10 TRCs, but this stimulatory activity (129.9 ± 8.5% of control) was less than EGF or FGF. IL-1α and IL-2 did not stimulate the incorporation of thymidine into TRC at a concentration of 100 pg/ml, but these cytokines did stimulate protein synthesis by TRC. Our data suggest that, following surgery, fibroblasts migrate into injured tissue, proliferate, and differentiate in vivo in a time-related manner and that growth factors may function as modulators of the proliferation and function of these cells. The effects of these factors on TRC may be dependent upon the stage of tissue repair.
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