[Effect of extracorporeal shock wave therapy on diabetic chronic wound healing and its histological features]

Extracorporeal shock wave (ESW) can promote angiogenesis and tissue repair. To investigate the influence of ESW therapy on the histological features of diabetic chronic wounds and wound healing.

Ninety-six male Sprague Dawley rats with weight (220 +/- 20) g were divided into 3 groups (n = 32): diabetic control group, ESW treatment group, and normal control group. The diabetic rats were prepared in diabetic control group and ESW treatment group by intraperitoneal injection of Streptozotocin (60 mg/kg). Then a circular full-thickness skin wound of 1.8 cm in diameter was made at the back of diabetic rats to establish the diabetic chronic wound model, and the same wound was made in normal control group. In ESW treatment group, ESW (0.11 mJ/mm2, 1.5 Hz energy, and 500 pulses) was applied to treat the wound at 1 day after wounding; in two control groups, no ESW treatment was given. The wound healing and histological changes were observed by HE and Masson staining at 3, 7, and 14 days after treatment; and the cell proliferation, angiogenesis, and collagen deposition were observed by CD31 and proliferating cell nuclear antigen (PCNA) immunohistochemical staining.

The wound closure rate in diabetic control group was lower, and the healing time was significantly longer than those in normal control group (P < 0.05); at 3, 7, and 14 days after treatment, the inflammatory cell infiltration in wound tissue was obvious, and the relative area density of collagen fibers, wound microvessel density (MVD), and the relative density of PCNA-positive cells were significantly lower than those in normal control group (P < 0.05). The wound healing time was significantly shorter and the wound closure rate was significantly higher in ESW treatment group than those in the diabetic control group (P < 0.05). At different time points in ESW treatment group, the inflammatory cells signficantly reduced, while the relative area density of collagen fibers, MVD, and relative density of PCNA-positive cells significantly increased when compared with those in diabetic control group (P < 0.05). No significant difference in MVD and relative density of PCNA-positive cells was found between ESW treatment group and normal control group (P > 0.05).

Low-energy ESW treatment can inhibit the local inflammatory response, promote cell proliferation, increase angiogenesis and collagen deposition, and enhance granulation tissue formation, and so it can promote chronic wound healing in diabetic rats.