Keratin Based Biomaterial (KeraStat™ Burn Gel) for Thermal Burns and Cutaneous Radiation Injury Luke Burnett1, J. Daniel Bourland2, Mike Robbins2, Ryan Best3, Stephen Dozier4, Carmen Gaines5, Deepika Poranki5, Mark Van Dyke6, Michael Tytell7 1KeraNetics LLC; 2Dept Radiation Oncology, Wake Forest School of Medicine; 3Dept of Physics, Wake Forest University; 4North Carolina State University; 5Wake Forest Institute of Regenerative Medicine; 6Dept Orthopaedic Surgery, Wake Forest School of Medicine; 7Dept of Neurobiology & Anatomy, Wake Forest School of Medicine Introduction There is a significant need to develop new treatments for thermal and radiation burns that produce wound healing and tissue salvage for thermal and radiation-induced skin injuries. These new treatments should be field deployable and easy to use as medical care delivery will be compromised in the event of a catastrophic nuclear disaster. Here we describe data from animal efficacy studies testing a novel keratin-biomaterial called KeraStat Burn Gel. This biomaterial is in the process of receiving an Investigative Device Exemption from the FDA to begin a safety and efficacy study in partial thickness thermal burn patients. Methods Swine Thermal Burn Study Yorkshire Swine (n=14) received 12 partial thickness burns using a heated burn block and were treated with KeraStat, SSD, or Coloplast. Treatment was topically applied after 1 hour and reapplied every 72 hrs for 15 days. Animals were euthanized at day 30 and tissue examined histologically. Digital photographs of thermal burns in swine. KeraStat Burn Gel treated wounds show progression of eschar formation (days 6 and 9), granulation (day 12), re-epithelialization (day 15), and total wound closure (day 30). This process was more rapid in the KeraStat Burn Gel treatment group compared to the SSD and Coloplast treatment groups. Mouse Radiation Injury Study Three groups of CD-1 male mice (n=45) had the fur removed from their backs and were irradiated with 300 kV x-rays at a dose of 37-40 Gy. The x-ray beam was collimated to a 1 cm2 square field by a lead shield so as to produce a sharply defined radiation skin wound slightly caudal to the shoulder blades. This dose was shown in prior test animals to produce skin lesions restricted to the irradiated area. KeraStat or saline was topically applied at 1 or 24 hours post-exposure and repeated every 48 or 72 hrs for 5 -15 days. Results Swine Thermal Burn Study Healing Rates for Thermal Burns In Swine Group Rate (% reepithelialization/ day) R squared of linear regression % Difference SSD 2.9 ± 2.0 0.42 -72.4% Coloplast 4.0 ± 1.3 0.77 -25.0% KeraStat 5.0 ± 1.6 0.77 -- Healing Rates The mean percent reepithelialization was calculated at each day across all treatment groups (n=6). Linear regression was performed on percent re-epithelialization vs. time data to calculate the healing rate (i.e. % reepithelialization/day) for each treatment. The difference in healing rate was assigned a negative value if it was slower than KeraStat Burn Gel. KeraStat vs. Control 24 hour delay treatment. Representative sections stained with Mason’s trichrome from mice that received 40 Gy x rays and treatment 24 hours after radiation exposure. KeraStat treated animals are shown on the right, saline controls on left. (A) and (B) were euthanized at 15 days post radiation, (C) and (D) at 30 days. Normal non-irradiated mouse skin tissue is shown in the inset (bottom left). KeraStat treated animals showed a striking difference in hair follicle and dermal fat cell salvage and greater preservation of normal skin morphology. Conclusions Histology of thermal burns in swine. Representative histologic images at day 30. KeraStat Burn Gel condition shows more advanced collagen remodeling and thicker epithelium. Rete pegs appear to be re-forming, and collagen is more organized and densely packed. SSD and Coloplast treated wounds show more defects in the collagen layer and less demarcation between dermis and epidermis. Mouse Radiation Injury Study KeraHeal vs. Control 1 hour delay treatment. Two example animals treated with 37 Gy of 300 kV x-rays allowed to survive for 15 days. (A) KeraHeal treated animal shows no skin lesions or desquamation; (B) shows an untreated animal with skin lesions • In a swine model of thermal burn, KeraStat treated animals showed faster healing rates with histological differences of improved collagen remodeling, thicker epithelium and reformation of rete pegs • In a mouse model of CRI, KeraStat treated animals showed greater subdermal vasculature, a difference in hair follicle number, dermal fat cell salvage and greater preservation of normal skin morphology. • The keratin biomaterial (KeraStat™) is a potential treatment for thermal burns and CRI that could be used by first responders at point of injury and further studies are underway Acknowledgements Special thanks to Cathy Mathis, Wake Forest Institute for Regenerative Medicine for assistance with histology. CRI work funded by KeraNetics, swine thermal burn work funded by AFIRM.W81XWH-08-0032 Additional work being conducted with funding from BARDA (HHSO100201200007C) Disclosure: Co-Author Mark Van Dyke holds stock and is an officer in the company, KeraNetics LLC, who has provided partial funding for this research. Wake Forest University Health Sciences has a potential financial interest in KeraNetics LLC through licensing agreements.
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