J. Van Eps2,3, X. Wang2, S. Minardi2, E. Tasciotti2, J. Fernandez-Moure1,2 1Hospital Of The University Of Pennsylvania,Traumatology, Surgical Critical Care, And Emergency Surgery,Philadelphia, PA, USA 2Houston Methodist Research Institute,Houston, TX, USA 3Houston Methodist Hospital,Surgery,Houston, TX, USA
Introduction: Platelet rich plasma (PRP), a growth factor rich form of superconcentrated platelets, has been shown to improve metrics of incorporation (MOI), improve acellular dermal matrix (ADM) strength, and reduce recurrence in ventral hernia repair (VHR) with ADM. Macrophage phenotypic differentiation to the M2 phenotype has been shown to promote ADM incorporation. We hypothesized that PRP would induce a differential pattern of macrophage polarization towards a regenerative phenotype and improve early MOI.
Methods: Lewis rats underwent chronic hernia creation and subsequent repair with non- crosslinked porcine ADM after 30 days(d). A standardized dose (200μl) of PRP with a concentration of 1×106 platelets/μl was applied prior to skin closure. The abdominal wall including mesh was harvested at 3d and 10d. To determine macrophage phenotype, the excised mesh and 2 mm of surrounding tissue was decellularized and flow cytometry performed at 3d using CD3, CD45, CD206, and antimacrophage marker. Expression of genes associated with an inflammatory (M1) phenotype (IL-1b, iNOS, TNFα) and a regenerative (M2) phenotype (ARG-1, IL-10) were then quantified with RT-PCR. To assess MOI, tissues were fluorescently stained for αSMA and CD31 and the expression of Col1, Col3, VEGF, and vWF at 10d quantified by RTPCR .
Results: PRP treated ADMs had increased percentage of M2 (antimacrophage+CD206+) macrophages at 3d (p<0.05) (Figure 1a). This correlated with a significant increase in expression of M2 associated genes (Figure 1 b-c) and decreased expression of M1 associated genes at 3d (Figure 1d-f). PRP treated ADMs showed increased αSMA and CD31 intensity in histology. This finding correlated with increased Col1, Col3, VEGF, and vWF expression at 10d.
Conclusion: PRP, a growth factor rich blood product, improves metrics of wound healing. We demonstrate that M2 polarization is a responsible mechanism for the clinically relevant findings of improved ADM performance seen in our previous studies. PRP induced a differential pattern of macrophage polarization to the M2 phenotype and was associated with improved MOI. These findings suggest that PRP is a useful adjunct with ADM and may have a putative role in other wound healing scenarios, especially those in which graft incorporation is essential.
