Objective: To study effects of P311 on the migration of epidermal stem cells (ESCs) in mice with superficial partial-thickness burn and injured cell model in vitro and to explore the mechanism.
Methods: (1) Eighteen male C(57) BL/6 mice were used. Fifteen of them were inflicted with superficial partial-thickness burn on the back. In three injured mice wound tissue and skin of wound edge were obtained at post burn hour (PBH) 6, 12, 24, 48, 72 respectively. The rest three mice were used as normal control, and samples were harvested with the same method as above. The expressions of P311 in harvested samples were assessed with biotin-streptavidin-peroxidase (SP) staining. (2) Six newly born C(57) BL/6 mice were intraperitoneally injected with 50 µg/g BrdU (two times a day) for three days for ESCs-labelling. Seven weeks later, the mice were inflicted with superficial partial-thickness burn on the back. Serial slices of burn wound tissue were prepared at PBH 72 and immunohistochemically stained with SP for observation of the co-localization of BrdU-positive ESCs and P311-positive cells. (3) The empty vector pAdEasy-enhanced green fluorescence protein (EGFP) and the adenovirus P311-expressing vector named pAdEasy-EGFP-P311 were constructed and packed. Human ESCs were isolated by the method of rapid adhesion to collagen IV. After being divided into P311 high-expressing group (n = 3) and EGFP control group (n = 3), the ESCs in two groups were respectively infected by pAdEasy-EGFP-P311 and pAdEasy-EGFP. Scratching assay was performed on ESCs in both groups after they were treated by mitomycin C for 2 hours. The remaining area within the fixed range was measured at post scratching hour (PSH) 0, 24, 48, and 72, and the wound-area healing rate was calculated. Data were processed with independent samples t test.
Results: (1) Expression amount of P311 was different in different parts of wound at different time points after burn. Expression amount of P311 in the newly formed epidermis and hair follicle of wound increased along with prolongation of time. Expression amount of P311 in the epidermis and hair follicle of wound edge peaked at PBH 12 and then decreased to normal levels at PBH 72. (2) Co-localization of BrdU-positive ESCs and P311-positive cells was observed in the new epidermal layer of wound tissue of mice, where ESCs were labeled by BrdU. (3) At PSH 48 and 72, wound-area healing rate was obviously higher in P311 high-expressing group [(69 ± 31)%, (89 ± 26)%] than in EGFP control group [(35 ± 12)%, (46 ± 31)%, with t values respectively -2.336, -2.611, P values all below 0.05].
Conclusions: P311 may promote the migration of ESCs both in rats with superficial partial-thickness burns and in injured cell model in vitro, and it may play an important role in wound healing.