[Effects of platelet-rich plasma combined with polylactic acid/polycaprolactone on healing of pig deep soft tissue defect caused by fragment injury].

To investigate the effects of platelet-rich plasma (PRP) combined with polylactic acid/polycaprolactone (PLA/PCL) on healing of mininature pig deep soft tissue defect caused by fragment injury. Two male Bama miniature pigs with 11 to 12 months (the same below) were selected by lottery to prepare PRP. The other twenty-seven male Bama miniature pigs were used to reproduce deep soft tissue defect caused by high-explosive ammunition fragment injury on bilateral posterior femoral region. According to the random number table, 27 pigs were divided into control group, material group, and PRP+material group, with 9 pigs in each group. After debridement, wounds of pigs in material group and PRP+material group were filled with PLA/PCL and PLA/PCL+2 mL activated PRP, respectively. Pigs in each group received suture of full-thickness skin to close the wounds. The operative duration was recorded. The length and volume of wounds of pigs in the above groups were measured immediately after surgery. In 1, 2, and 4 weeks after surgery, 3 pigs in each group were sacrificed to collect femoral wounds tissue on two sides, and PLA/PCL were collected from wounds of pigs in material group and PRP+material group for general observation of wounds tissue and degradation of the material. In 2 and 4 weeks after surgery, wounds tissue was obtained to observe the histological changes by hematoxylin-eosin staining, and expressions of transforming growth factor β (TGF-β) and vascular endothelial growth factor (VEGF), and angiogenesis were determined by immunohistochemical method. In 1, 2, and 4 weeks after surgery, wounds tissue was collected to determine mRNA expressions of TGF-β and VEGF by real-time quantitative reverse transcription polymerase chain reaction. Data were processed with analysis of variance of factorial design, one-way analysis of variance, and least significant difference- test. (1) There were no significantly statistical differences in length and volume of the wounds of pigs among the three groups (=0.336, 0.282, >0.05). The operative duration in control group [(30.9±2.1)min] was significantly shorter than that of material group [(39.7±2.2)min] and PRP+material group[(40.0±2.6)min], =-11.45, -11.88, <0.01. (2) There were respectively 10, 7, and 5 wounds tissue with infection in pigs of control group, material group, and PRP+material group. In 1, 2, 4 weeks after surgery, all of the wounds tissue of pigs was infected in control group, while none of wounds tissue of pigs was infected in material group and PRP+material group. In pigs of material group and PRP+material group, materials and tissue were easily separated in 1 week after surgery; some materials were integrated with tissue and showed a tendency of degradation in 2 weeks after surgery; materials were completely embedded with tissue in 4 weeks after surgery. (3) In pigs of control group, erythrocytes and inflammatory cells infiltration in wounds tissue were observed in 2 weeks after surgery, and necrotic tissue and inflammatory cells infiltration in wounds tissue were still observed in 4 weeks after surgery. In pigs of material group and PRP+material group, a large number of erythrocytes and inflammatory cells infiltration were observed in 2 weeks after surgery. Compared with that of material group, wounds tissue of pigs in PRP+material group had no inflammatory cells infiltration in 4 weeks after surgery. (4) Protein expressions of TGF-β in fibroblasts and multinuclear macrophagocytes, VEGF in fibroblasts and vascular endothelial cells, and blood vessel formation in wounds tissue of pigs in PRP+material group were significantly more than those of pigs in control group and material group in 2 and 4 weeks after surgery. (5) The mRNA expression of TGF-β in wounds tissue of pigs in material group was significantly higher than that in control group in 4 weeks after surgery (=-3.93, <0.01). Compared with those of pigs in control group and material group, the mRNA expression of TGF-β in wounds tissue of pigs in PRP+material group was significantly increased at each time point (=9.23, 13.81, 11.73, -7.51, -12.04, -7.80, <0.01). The mRNA expression of VEGF in wounds tissue of pigs increased significantly in material group compared with that of pigs in control group in 4 weeks after surgery (=-3.94, <0.01). Compared with those of pigs in control group and material group, the mRNA expression of VEGF in wounds tissue increased significantly in wound tissue of pigs in PRP+material group at each time point (=12.33, 3.95, 7.97, -11.36, -2.97, -4.04, <0.01). PRP combined with PLA/PCL can accelerate wound healing of deep soft tissue defect of mininature pigs caused by fragment injury by providing physical scaffold for newborn tissue growth, promoting mRNA and protein expressions of TGF-β and VEGF.