Thermal injury effects on intestinal crypt cell proliferation and death are cell position dependent

We examined the effects of thermal injury on intestinal epithelial cell pro liferation and death. We recorded histologically identifiable mitotic and a poptotic crypt cells in relation to cell position after a 60% full thicknes s cutaneous thermal injury in the rat. The injury significantly reduced mit osis (0.53 +/- 0.11 vs. 1.50 +/- 0.70, P< 0.05) at cell positions 4-6, stem cells, 6 h after injury. A similar reduction in mitosis (1.13 +/- 0.59 vs. 3.50 +/- 0.80, P< 0.05) was observed at higher cell positions 7-9 12 h aft er injury, indicating a positional cell shift. In addition, a significant i ncrease in the number of apoptotic bodies occurred at cell positions 7-9 (2 .32 +/- 0.87 vs. 0.13 +/- 0.22, P< 0.05) and 10-12 (2.2 +/- 0.12 vs. 0.00, P< 0.05) 6 h after injury. Thermal injury-induced alterations in mitotic an d apoptotic activities were transient since crypts recovered with a moderat e increase in mitotic activity 24 h after injury. In control and thermal-in jury rats 24 h after injury, crypt cell mitosis and apoptosis did not diffe r significantly. This demonstrates that cutaneous thermal injury causes a t ransient suppression of mitosis as well as induction of apoptosis in a cell position-dependent manner in the small intestinal crypt.