Rab37 Promotes Endothelial Differentiation and Accelerates ADSC-Mediated Diabetic Wound Healing through Regulating Secretion of Hsp90α and TIMP1

Accumulating evidence indicates that adipose tissue-derived mesenchymal stem cells (ADSCs) are an effective treatment for diabetic refractory wounds. However, the application of ADSCs to diabetic wounds is still limited, indicating that we still lack sufficient knowledge regarding regulators/mediators of ADSCs during wound healing. Rab37, a member of RabGTPase, may function as regulator of vesicle trafficking, which is a crucial event for the secretion of cytokines by ADSCs. Our previous study indicated that Rab37 promotes the adiopogenic differentiation of ADSCs. In this study, we explored the role of Rab37 in ADSC-mediated diabetic wound healing. An in vivo study in db/db diabetic mice showed that Rab37-expressing ADSCs shortened the wound closure time, improved re-epithelialization and collagen deposition, and promoted angiogenesis during wound healing. An in vitro study showed that Rab37 promoted the proliferation, migration and endothelial differentiation of ADSCs. LC-MS/MS analysis identified Hsp90α and TIMP1 as up-regulated cytokines in conditioned media of Rab37-ADSCs. The up-regulation of Rab37 enhanced the secretion of Hsp90α and TIMP1 during endothelial differentiation and under high-glucose exposure. Interestingly, Rab37 promoted the expression of TIMP1, but not Hsp90α, during endothelial differentiation. PLA showed that Rab37 can directly bind to Hsp90α orTIMP1 in ADSCs. Moreover, Hsp90α and TIMP1 knockdown compromised the promoting effects of Rab37 on the proliferation, migration and endothelial differentiation of ADSCs. In conclusion, Rab37 promotes the proliferation, migration and endothelial differentiation of ADSCs and accelerates ADSC-mediated diabetic wound healing through regulating the secretion of Hsp90α and TIMP1.

[One patient with chronic refractory wound caused by bamboo sticks in lower leg]

One patient with chronic refractory wound in right lower leg was admitted to our department in June 2017, which experienced repeated ulceration for 4 years. On 4 days post admission, two bamboo sticks were taken out from the deep muscle of the right lower leg. The wound was repaired by perforator flap of posterior tibial artery in the right lower leg. The donor site was covered with split-thickness skin in the upper leg of the same side. On 7 days post operation, the flap and skin graft survived. During follow-up of 12 months, the flap had good appearance. This case suggests that the first thing for the treatment of chronic refractory wound is to find out the cause of wound.

[Lay further emphasis on cause analysis and non-surgical treatment of chronic refractory wound]

There are many pathogenic correlation factors of chronic refractory wound. Due to the complexity and particularity of the causes of wounds and lack of a standard diagnosis guide, it is hard to treat this kind of wound. Based on our recent scientific research data and the relative research at home and abroad in the present, we systematically analyze and summarize the causes and non-surgical treatment of chronic refractory wound in this article.