G. Garg1,2, B. C. Carney1,3, B. J. Browne1, L. T. Moffatt1,3, J. W. Shupp1,2,3,4 1MedStar Health Research Institute,Firefighters’ Burn & Surgical Research Laboratory,Washington, DC, USA 2MedStar Washington Hospital Center,The Burn Center,Washington, DC, USA 3Georgetown University School of Medicine,Department Of Biochemistry,Washington, DC, USA 4Georgetown University School of Medicine,Department Of Surgery,Washington, DC, USA
Introduction: Rapid wound closure to maintain a barrier against environmental insult is critical, and is especially relevant to the surgical field. Platelet-Rich Plasma (PRP) is an autologous suspension that acts as a “biobandage” to contribute to positive healing. The mechanism is thought to be the release of concentrated growth factors, including VEGF, TGFβ1, and FGF2, upon platelet activation. Platelets also contain polyP, a phosphate polymer which has been shown to have effects on wound healing, coagulation, and bone remodeling. In this experiment, PRP was studied as a means for accelerating wound healing in acute excisional wounds. Furthermore, the effects of individual growth factors on wounds treated with PRP were measured.
Methods: PRP was created by multiple rounds of centrifugation of citrated whole blood, and platelet concentration was confirmed via Wright-Giemsa staining. 6 mm punch biopsies were used to create two wounds on the dorsum of C57BL/6 mice. Splints were placed on the wounds to allow healing by re-epithelialization instead of contraction. Mice were divided into PRP-treated and untreated groups. PRP was activated by CaCl2 and recombinant thrombin to form a gel for application. Photos of wounds were taken prior to necropsy on post-injury days 3, 5, and 7, and whole wounds were fixed in formalin. Open wound areas were quantified using Image J to assess healing rate. Fixed wounds were stained with H&E and Cytokeratin 16 and were examined histomorphometrically for re-epithelialization. Immunofluorescent staining was used to quantify the expression of VEGF, TGFβ1, and FGF2 in the wounds collected on post-injury day 3. 5 images were obtained from tissues adjacent to the edge of the healing epithelium from each wound and the Cy3 fluorescence intensity was quantified using Zen Imaging Software.
Results: PRP-treated wounds re-epithelialized faster compared to untreated wounds when wound photos were analyzed at days 3 and 5 (n = 6 wounds, p < 0.05). Open wound areas were smaller in treated wounds when H&E and Cytokeratin 16 sections were analyzed. None of the growth factors investigated showed significantly different fluorescence intensity between treated and untreated groups (VEGF: 867.0 ± 292.1 vs. 518.9 ± 5.48, p = 0.1750; TGFβ1: 1453 ± 222.3 vs. 1491 ± 192.7, p = 0.8534; FGF2: 663.5 ± 182.7 vs. 503.6 ± 218.0, p = 0.4484).
Conclusion: Due to its autologous nature, PRP is a safe and efficacious option for accelerating wound healing. Previous work has demonstrated that polyP can accelerate healing in an in vitro keratinocyte scratch model. Our data shows that concentrated growth factors found in PRP do not exert a significant effect early in wound healing, suggesting that polyP may be primarily responsible for the accelerated healing seen here. Future work will analyze the effect that spiking PRP with an excess amount of polyP has on wound healing.