Experimental Study Of Negative Pressure Wound Therapy Combined With Platelet-Rich Fibrin In Repairing Bone Exposed Wounds

Objective The aim of this study was to explore the efficacy of negative pressure wound therapy(NPWT)combined with platelet-rich fibrin(PRF)in the treatment of bone exposed wounds.Methods Thirty-two Sprague-Dawley(SD)rats aged 10-12 weeks and weighted 250-300 g were randomly divided into four groups of A?B?C?D.A circular fullthickness skin of 1.5 cm in diameter of the anterior cranial region of all SD rats was excised and the periosteum on the surface of the skull was removed.The wounds in group A were covered with normal saline;the wounds in group B were directly installed with VAC device;the wounds in group C were covered with the same amount of PRF;the wounds of group D were covered with equal of PRF then VAC device was installed.The wound dressings were changed and photographed on day 4,day 7 and day10 respectively.Quantitative assessment of bone exposure area?skin contraction rate and coverage of granulation was performed using Image J software;vascularization of granulation tissue and concentration of growth factors in granulation tissue were measured.The statistics involved in the experiment were analyzed using Two-Way ANOVA.Results On day 10,the bone-exposed wounds in group D were completely covered by granulation tissue while other groups still remained different proportion of boneexposure.The bone-exposed area in group D was significantly lower than the other three groups at each time point(P<0.001).The skin contraction rates of group B and group D were significantly higher than of group A and group C at each time point(P < 0.001).On day 4,the coverage of granulation tissue in group C and group D were significantly higher than those in the other two groups(P<0.001).On day 7 and day 10,the coverage of granulation tissue in group C was still higher than those in other groups,while the coverage of granulation tissue in group D decreased.On day 10,HE staining sections showed neovascularization in the granulation tissue in the center and the edge of each group,and red blood cells were observed in the vessels;the microvessel density(MVD)in the center of group D was 22.60±1.23%,and the other three groups were 5.92±2.00%,14.69±1.86%,and 17.00±1.81%,respectively.The difference between group D and the other three groups was statistically significant(P <0.001);Masson staining results showed that the group D had more abundant collagen fibers and arranged more ordered than the other three groups.(P<0.001).The results of Masson staining showed that the collagen of group D was more homogeneous and richer than the other three groups;simutaneously,the cells in group B and group D were more ordered.The Enzyme-Linked ImmunoSorbent Assay(ELISA)results showed that the angiogenic factors(VEGF and bFGF)and profibrotic factors(PDGF-BB and TGF-?)in group D were significantly higher than those in the group A(p<0.001).Conclusion NPWT contracts the wound through macro-deformation,and PRF contains rich growth factors to stimulate the growth of granulation tissue and to promote collagen formation.The combination of NPWT and PRF can repair bone exposed wounds effectively and accelerate the process of bone exposed wounds healing.