Recovery course of full-thickness skin defects with exposed bone: an evaluation by a quantitative examination of new blood vessels.

Background: Full-thickness skin defects with exposed bone are often hard to heal. The lack or delayed re-vascularization is considered one of the major causes, and the periosteum is also suggested to have an important role in tissue regeneration.
Materials and Methods: Full-thickness skin defect wounds with exposed bone were made in the parietal region of Wister rats. The periosteum of the exposed parietal bone was removed in the periosteum-lacking group, but maintained in the control group (periosteum-intact group). The wound was covered by an artificial dermis made of collagen. The wound healing process was histologically compared. Double immunostaining of alpha-smooth muscle actin (SMA) and von Willebrand factor (vWF) was used for re-vascularization examination, and the blood vessel density in the artificial dermis was quantified.
Results: The density of the blood vessels in the uninjured parietal tissue was approximately 80 vessels/mm(2). To reach this density, 7 and 21 days were required for the control (periosteum-intact) and the periosteum-lacking groups, respectively. This coincided with complete revascularization, fibroblast migration and the reentry of blood vessels to the upper layer of the wound were observed.
Conclusion: The described results support the importance of the periosteum in the full-thickness skin defect healing process.