Horse serum or equine platelet lysate increases total vascular endothelial growth factor A concentrations and correlates with vascular growth in an equine facial arterial ring assay

Abstract

OBJECTIVE To evaluate ex vivo angiogenesis of equine arterial rings in response to various growth media. ANIMALS Facial arteries were dissected from 11 horses post-euthanasia. Equine platelet lysate (ePL) was harvested from 6 horses. PROCEDURES Arteries were exposed to endothelial growth media (EGM) + horse serum (HS) for first sprout (FS), vascular regression (VR), and (basement membrane matrix [Matrigel]) lysis (ML) evaluation. Additional rings supplemented with (1) EGM, (2) EGM + EDTA, (3) endothelial basal media (EBM), (4) EBM + HS, or (5) EBM + human VEGF were compared for vascular network area (VNA) and maximum network growth (MNG). Additional rings exposed to EGM + ePL at 10-(10xePL), 5-(5xePL), or 2-fold (2xePL) increases from baseline platelet concentration, EGM + HS, EGM + platelet-poor plasma (PPP), EBM + PPP and EBM were analyzed for branch number, density, VNA, and VEGF-A concentration from days 0–3. RESULTS Arteries demonstrated sprouting in Matrigel supplemented with EBM alone. EGM + HS exposure resulted in no differences in FS (P = .3934), VR (P = .0607), or ML (P = .2364) between horses. VNA in EGM + HS was greater than EBM (P = .0015). MNG was greater in EGM + HS, EBM + HS, and EBM + hVEGF compared with EBM (P = .0001). ePL treatment did not have an overall significant angiogenic effect compared with supplementation with HS, PPP, or EBM alone; however, VEGF-A concentrations were higher for EGM + 10xePL, EGM + 5xePL, and EGM-HS compared with EBM and positively correlated with VNA (P = .0243). CLINICAL RELEVANCE Equine arterial rings serve as an ex vivo model for angiogenesis but have a high degree of variability. HS, PPP, or ePL support vascular growth, and HS and ePL may stimulate the secretion and be sources of VEGF-A.