Ulceration and delayed healing following pressure loading in hyperglycemic rats with an immature dermal collagen fiber network

The collagen fiber network plays a key role regarding mechanical properties that maintain tissue shape, absorb stress, and recover from tissue deformation. The purpose of this study was to reveal the effects of hyperglycemia on the process of ulceration and wound healing, and on the structure of dermal collagen network. Methods. A spontaneous type 2 diabetic, non-obese rat without hyperlipidemia (GK rat) was used. On the right abdominal flank region, 8 kg/3 cm² of pressure was loaded, and then the morphological change in wound area was macroscopically observed. The tissue of wounded area and healthy area on opposite side of the abdomen was collected and histologically analyzed on days 3, 5, 7, and 14 after wounding. Results. The hyperglycemic animals showed severer ulceration and delayed wound healing after pressure loading compared to control rats. The diabetic rat had an immature collagen fiber network with poor cross-linkage in the dermis. In the wounded area, collagen fibrils were packed more densely and reconstruction of the fiber network was delayed. Conclusion. These results suggest that the disrupted structure of the collagen network lowers the tolerance of diabetic skin to external pressure loading, and that this delayed reconstruction increases time to healing.