BACKGROUND: Study on epidermal stem cells (ESCs) is satisfying. However, the amount and the distribution dynamic changing rule in each skin layer of ESCs during survival of skin graft need to be investigated.OBJECTIVE: To observe the changing rule of ESCs in the microenvironment during the survival of full-thickness skin graft.DESIGN: Prospective animal experiment based on controlled observation.SETTTNG: Department of Burn and Plastic Surgery, First Hospital Affiliated to Nanhua University.MATERIALS: Forty-two Wistar rats of clean grade and either gender, aged 2 to 3 months, weighing about 200 to 250 g,were provided by the Experimental Animal Center of South China University. After being raised for 1 week, the rats were divided into 7 groups according to observation time: post-operation 24 hours, 3 days, 5 days, 7 days, 14 days, 21 days and 30 days groups, with 6 rats in each group. Primary antibody: rabbit anti-rat integrinβ1 polyclonal antibody (Boster Biological Company, Wuhan); mouse anti-rat p63 monoclonal antibody (Santa cruz Company); Second antibody: goat anti-rabbit lgG (Zhongshan Biological Company, Beijing), goat anti-mouse lgG (Zhongshan Biological Company, Beijing);S-P immunohistochemical kit and DAB kit (Zhongshan Biological Company, Beijing).METHODS: This experiment was carried out in the Animal Laboratory of Nanhua University in May 2006. ①An area of (1.5×1.5) cm2 autologous full thickness skin graft model was made on the back of the all the rats. The color change of skin graft was observed at different time points. Meanwhile, whether hematocele and fluidify as well as binding to wound appeared under the skin graft were investigated. ②During the operation, a few skin graft was taken from each rat and immediately fixed with 100 g/L neutral formaldehyde solution and labeled, serving as blank control group. ③Skin graft packages of rats in the post-operation 24 hours, 3 days, 5 days, 7 days and 14 days were open at corresponding time points. Skin tissues were cut from the center of each wound and labeled; Skin graft packages of rats in post-operation 21 days and 30 days groups were open at postoperative 14 days. Rats in the two groups were raised till post-operation 21 days and 30 days, respectively, and skin tissue was cut from the center of skin graft. ④Pathological sections were made for haematoxylin and eosin (HE) staining and immunohistochemical staining.MAIN OUTCOME MEASURES: ①The amount of inflammatory cells, epithelization degree and the level of fibrocytes in the section. ② Integrin β1 and gene p 63 positive cell rate.RESULTS: Forty-two Wistar rats were involved in the final analysis. ①Gross observation of wound: At postoperative 1 to 2 days, the skin graft was pale and edematous; At postoperative 3 days, the color of skin graft did not turn better, but skin graft closely attached to the wound; At postoperative 7 days, the color of skin graft obviously turned better,epidermal color was close to normal, skin graft more closely attached to the wound, and some hair roots grew out of the wound; At postoperative 14 days, wound border and wound had healed completely; At postoperative 30 days, the color of skin graft became darker than normal, and the hair grew in the wound as in the normal skin. ②Observation results of HE stained pathological sections: Cellular edema and small quantity of inflammatory cell infiltration were found in the skin graft of the former 4 groups; Partial keratinocytes were necrotic and fell off at postoperative 5 days. ③Changing rule of distribution and amount of positive cells: Before operation, β1 integrin and gene p63 positive cells were mainly distributed in the epidermal basal membrane and eminence of hair follicle. Positive cells appeared in each epidermal layer from postoperative 24 hours and gradually increased. At postoperative 14 days and 21 days, many positive cells appeared in each epidermal layer. At postoperative 30 days, positive cells were distributed mainly in the basal layer of epidermis, and slightly in the other layers. Among the immunohistochemical sections, genic substance p63 positive cells were more thanβ1integrin positive cells at the same time point. p63 positive cells began to decrease from postoperative 24 hours,reached the lowest level at postoperative 3 days, then were gradually increased, reached or were close to the preoperative level at postoperative 7 days, reached the highest level at postoperative 21 days, subsequently were gradually decreased, and were still higher than preoperative level at postoperative 30 days.CONCLUSION: ①During the survival of full-thickness skin graft, ESCs are firstly decreased, then gradually increased, and even over the level in the normal skin. ②During the survival of full-thickness skin graft, firstly, ESCs arrange disorderly in the skin, and then they gradually gather in the epidermal basal membrane and eminence of hair follicle.

Objective To investigate the effect of repairing soft tissue defects in the middle and distal phalanx with the reverse dorsal metacarpal and digital fasciocutaneous flap based on the dorsal cutaneous branches of the proper digital artery. Methods Twenty-five fingers with soft tissue defects in the middle and distal phalanx were repaired by the reverse dorsal metacarpal and digital fasciocutaneous flaps based on the dorsal cutaneous branches of the proper digital artery from June 2007 to June 2009. Their pivot points were located at the midpoint or distal segment of proximal phalanx. Results Among 25 flaps, 24 survived completely, but cuticular layer in the distal part of one flap was partially necrotic. Twenty flaps were followed up from 12 to 18 months after operation. All flaps were characterized by rich blood supply, cold-resistance, suitable thickness, soft texture and good colour, except that 6 flaps required a secondary operation because of their fat and clumsy pedicel. There was no adhesion of extensor tendon and contraction of interdigital web in the donor sites. Two-point discriminations of anastomosing cutaneous nerve ranged from 6 mm to 10 mm in 5 of the 20 flaps, and 8 mm to 14 mm in the other 15 flaps. Conclusion The dorsal metacarpal and digital fasciocutaneous flap based on the dorsal cutaneous branches of the proper digital artery is an ideal option for repairing soft tissue defects of middle and distal phalanx because of its advantages of easy and secure dissection, reliable blood supply, longer arch of rotation, being closer to the raw surface of finger, less injury to the donor site, good appearance, avoidance of sacrificing major arteries ,and high probability of reconstructing flap sensation by anastomosing cutaneous nerve.