Abstract
The use of laser therapy for the treatment of particular wounds is reported in exotic animals,1,2 and treatments with laser therapy on marine mammal skin, such as bottlenose dolphins and beluga whales, have recently been reported3. Skin wounds are common in captive cetaceans. They can be caused by the interaction between animals, or with objects like gates or walls in the pool. Skin lesions can also be caused by atmospheric conditions (i.e., very cold temperatures). Due to the aquatic environment in which cetaceans live, the application of topical treatments can reside on the lesions for only short periods, without improving healing process.
This study aims to determine the efficiency of laser therapy in promoting the wound healing process in Risso's dolphin skin lesions and to determine if there is a correlation between the speed of cetacean wound healing and the mechanism responsible for lightening the pigmentation of the skin once injured.
Here we used a low level laser therapy on both a traumatic lesion and chronic lesions caused by cold temperature during winter season. Several protocols of laser treatment (Portable laser BTL-2000, low level laser therapy device, diode semiconductor laser, frequency 0.1–5000 Hz, Red probe of 685 nm wavelength and 50 mW power output, Infrared probe of 830 nm wavelength and 200 mW power output) were performed. The evolution of healing was evaluated daily.
Preliminary results suggest that the wounds treated with laser heal faster and are less affected by secondary infections.
Risso's dolphin presents the peculiarity of permanently changing the color of injured and healed skin. As the mechanism responsible for this color modification is not completely understood, we decided to perform histological analysis of Risso's dolphin skin collecting samples from both dark (never injured) and white (post-injured/healed) skin. For this purpose, histological sections of 8 mm biopsies taken in both sites were routinely stained by haematoxylin & eosin for morphological evaluations, and with a panel of antibodies (PCNA, Melan-A, S100, Collagen I and III, and alpha-MSH) to evidence fibroblast activity, dermal matrix collagen remodeling, melanocyte modifications (level of alpha-MSH and POMC expression in unpigmented post-injured and healed skin). The number of melanocytes in the basal layer was counted in the epidermis overlying the scar and in the adjacent epidermis, since in other species, as in human, the melanocyte/basal epidermal cells ratio normally matched with the chronological age of the scars.
Furthermore, samples of pigmented and unpigmented skin were collected in RNA stabilizing solution from a stranded Risso's dolphin. RNA was successfully extracted and the expression of genes involved in the healing process, as well as the pigment formation is currently being investigated.
The wound healing process is a significant challenge for regenerative medicine researchers because the body's typical response to a wound is to create scar tissue, which does not look or function as normal, healthy tissue. A better understanding of these mechanisms in Risso's dolphin may give rise to therapies for non-healing chronic wounds (due to factors like diabetes, old age, and infection) in human regenerative medicine.
Acknowledgments
The authors wish to thank Dr. Sandro Mazzariol of the University of Padova - College of Veterinary Medicine and Dr. Laura Abbriano of the Aeolian Dolphin Research (Messina-Italy) for the skin samples provided.
References
1. Nardini G, Bielli M. Low level laser therapy (LLLT) in reptile medicine. ARAV 18nd Annual Association of Reptilian and Amphibian Veterinarians Conference. Seattle, Washington; 2011:171.
2. Nardini G, Bielli M., Partata V. Laser therapy in sea turtles. 4th Mediterranean Conference on Marine Turtles Proceedings. Naples, Italy; 2011:51.
3. García-Párraga D, Alvaro T, Valls M. The effect of LLLT (Low Level Laser Therapy) treatment on wound healing in bottle nose dolphins (Tursiops truncatus). IAAAM 37th Annual Conference Proceedings, Nassau, Bahamas; 2006:171.