Biomodulative effects of polarized light on the healing of cutaneous wounds on nourished and undernourished Wistar rats

Objective: This study aimed to evaluate, by light microcopy, the differences in healing process of cutaneous wounds on nourished or undernourished rats following illumination by polarized light (lambda 400-2000 nm) with 20 or 40 J/cm(2). Background Data: There are some reports in the literature on different effects of polarized light on wound healing. Amongst the factors that interfere with wound healing one is the nutritional status of the subject. Methods: Thirty nourished or undernourished Wistar rats had one standardized surgical wound created on the dorsum and were divided into six groups: group 1, control (standard diet); group 2, control (Northeastern Brazilian Basic Diet [DBR]); group 3, standard diet + polarized light (20 J/cm(2)); group 4, standard diet + polarized light (40 J/cm(2)); group 5, DBR + polarized light (20 J/cm(2)); group 6, DBR + polarized light (40 J/cm(2)). The first application of treatment was carried out immediately after wounding and repeated every 24 h during 7 days. The animals were sacrificed, and specimens were taken and routinely processed to wax, cut, and stain with hematoxylin and eosin (H&E) and Sirius Red. These were then analyzed under light microscopy. The analysis included re-epitheliialization, inflammatory infiltrate, and fibroblastic proliferation. Sirius Red-stained slides were used to perform descriptive analysis of collagen. Results: The analysis of the results showed better results in these groups illuminated with 20 J/cm(2). Conclusion: It is concluded that nutritional status influenced the progression of the healing process as well as the quality of the healed tissue, and that the use of polarized light resulted in a positive biomodulatory effect.