Evaluation of the use of low level laser and photosensitizer drugs in healing

Background and Objectives In the last decade, many different kinds of therapies have emerged as a consequence of advances in the field of applied technology. It is known that low level laser therapy contributes to tissue healing; however, the use of photodynamic therapy (PDT) in healing and the scar formation processes has not been fully explored. The present study analyses the effect of low level laser InGaAIP (685 nm), radiation, either alone or combined with a phthalocyanine‐derived photosensitizer (PS) in a gel base delivery (GB) system, on the healing process of cutaneous wounds in rats. Study Design/Materials and Methods The rats were divided into six groups: control (untreated) (CG), gel base (GB), photosensitizer (PS), laser (LG), laser+photosensitizer (LPS), and laser+photosensitizer in a GB (LPSG). Standardized circular wounds were made on the dorsum of each rat with a skin punch biopsy instrument. After wounding, treatment was performed once daily and the animals were killed at day 8. Tissue specimens containing the whole wound area were removed and processed for histological analysis using conventional techniques. Serial cross‐sections were analyzed to evaluate the organization of the dermis and epidermis as well as collagen deposition. Results The animals of groups LG, PS, LPS, and LPSG presented higher collagen content and enhanced re‐epithelialization as compared to CG (control) and GB rats. Connective tissue remodeling was more evident in groups LPS and LPSG. Conclusions The results clearly indicated a synergetic effect of light+photosensitizer+delivery drug on tissue healing. PDT did not cause any healing inhibition or tissue damage during the healing process. Lasers Surg. Med. 34:451–457, 2004. © 2004 Wiley‐Liss, Inc.