To investigate the effects and mechanism of allogeneic platelet rich plasma (PRP) on collagen in wound surface at different time.

A total of 50 clean 7-week rats were selected for this study, including 10 rats for platelet-rich blood plasma preparation, 20 rats for PRP group and 20 rats for control group, 0.1 ml allogenic PRP and 0.1 ml saline were smeared respectively on wound surfaces of PRP and control group, wound regeneration and healing were examined. Cellular and histological morphology alteration was observed via Masson staining, type Ⅰ and type Ⅲ collagen protein and mRNA expression level were detected by Western blot and real-time PCR. T test was applied for comparison between two samples and one-way ANOVA was utilized for comparison between two groups.

The wound healing rate of PRP group was higher than that of control group on 3^rd, 6^th, 10^th and 15^th day (30.33±3.35 vs.18.35±2.04, 55.51±2.74 vs.36.83±2.34, 79.64±1.40 vs.56.92±1.44, 86.88±2.12 vs.65.80±1.76) after wound surface formation, there were statistic differences (t=13.66-50.48, all P<0.05). The wound collagen of PRP group form faster and coarser, and the fibers arrayed more densely in Masson staining. The protein expression of type Ⅰ collagen(1.92±0.09 vs.1.18±0.11) and type Ⅲ collagen(1.16±0.05 vs.0.74±0.11) of PRP group were higher than that of control group (t=22.99, P<0.01; t=17.62, P<0.05); the mRNA expression of type Ⅰ collagen(5.17±0.11 vs.1.79±0.18, 6.97±0.09 vs.1.96±0.08, 6.00±0.26 vs.2.10±0.05, 4.95±0.11 vs.3.58±0.09)and type Ⅲ collagen(2.35±0.08 vs.1.44±0.05, 3.08±0.05 vs.1.84±0.06, 3.48±0.07 vs.2.36±0.09, 4.42±0.07 vs.2.77±0.10) were higher than that of control group on 3^rd, 6^th, 10^th and 15^th day after wound surface formation, there were significant differences (t=43.37-188.37, all P<0.05).

The allogeneic platelet rich plasma may promote fibroblasts secreted collagen by activated and releasing all kinds of growth factors, especially type Ⅰ and type Ⅲ collagen to accelerate the wound healing.

Platelet rich plasma; Wound healing; Collagen; Synthesis mechanism