K. E. Leibl1, A. Martin1, T. W. King1 1University Of Wisconsin,Plastic Surgery,Madison, WI, USA
Introduction:
Decreased rates of wound healing affect millions of diabetic patients annually. We are interested in discovering novel strategies to enhance the wound healing process in diabetic patients. We have previously shown that inhibiting Notch inhibits wound healing. Based upon our previous work, we propose that upregulation of Notch would increase rates of wound healing. JAG1 is a known activator of Notch. Therefore, we hypothesized that applying topical JAG1 to stented excisional wounds on the backs of diabetic and wild-type mice would result in increased Notch activity, and thus an increased wound healing rate as compared to untreated wounds.
Methods:
8-week old, healthy male diabetic mice (db/db, n=44), or heterozygous mice exhibiting wild-type phenotype (WT/db, n=44) were anesthetized & after depilation, two 1cm2 full-thickness wounds were placed on their backs extending through the panniculus carnosus. A 12 mm diameter silicone stent was secured around each wound with cyanoacrylate glue & interrupted 5-0 nylon suture to prevent healing by contraction. Wounds were dressed with sterile N-terface & Tegaderm, then the mice were wrapped with Coban, which was secured with Transpore tape. Dressings were changed every day after topical application onto the open wound bed of JAG1 (10 nM) or vehicle (PBS) for 14 days. Digital photographs were taken at every dressing change. At the end of the experiment, the mice were sacrificed & wounds were harvested for histological and protein analysis. Wounds were analyzed using ImageJ software & expressed as a ratio of wound area to stent area, with scaling normalized to the inner circumference of the splint as a standard. Wound area was calculated as a percent area of the original wound size. Statistical significance was defined as p<0.05 using the students’ t-test.
Results:
Partial to complete re-epithelialization was seen in the wounded tissues over the experimental period in both the control & JAG1 treated groups. Both diabetic and wild-type mice treated with topical JAG1 had an increased rate of wound closure when compared to wounds treated with PBS. As expected, the control wounds on diabetic mice demonstrated a slower rate of healing than control wounds on wild-type mice. No significant local side effects such as increased edema or allergic reaction were noted in the JAG1-treated mice.
Conclusions:
JAG1 increases the rate of re-epithelialization of cutaneous wounds in the in vivo diabetic murine stented wound-healing model, indicating that Notch signaling plays a crucial role in wound healing in mice. Based upon our findings, further study of Notch in diabetic wound healing should be conducted which may then lead to better therapeutics for the wound healing process in patients.