LAUSR

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.