Apoptosis and p53 protein expression increase in the process of burn wound healing in guinea-pig skin

Apoptosis and the expression of p53 protein, an apoptosis-related protein, in the process of healing of a full-thickness burn wound in guinea-pig skin were studied with the terminal deoxynucleotide transferase nick-end labelling method, electron microscopy, and immunohistochemistry, respectively. Apoptosis was detected in the peripheral zone of heat-injured skin from 12 h until day 10 after the burn, with the peak occurring on day 2. The peripheral zone of heat-injured skin showed p53 protein from 12 h through day 2, with the peak occurring on day 2. Apoptosis was also detected in tissues regenerated for covering skin defects. The peak of apoptosis in the regenerated epidermis occurred at days 7-10, when the epidermis was most acanthotic. p53 protein reactivity was also detected in the acanthotic regenerated epidermis, with a peak on day 7. The peak of apoptosis in the granulation and scar tissue took place from day 10 to 14, when the granulation tissue started diminishing, but p53 protein reactivity was not detected there. These findings suggest that apoptosis plays an important part in the elimination of dying and/or dead cells resulting from heat stress, the terminal differentiation of the regenerated epidermis, and the decrease in cellularity during remodelling. The apoptotic process during remodelling may be mediated by some p53-independent pathway.