Immunomagnetic isolation of canine circulating endothelial and endothelial progenitor cells

Abstract

Increased concentrations of circulating endothelial cells (CECs) are thought to be a biomarker of vascular injury in human patients with cardiovascular disease, neoplasia, vasculitis, sickle cell anemia, shock, and sepsis. Immunomagnetic isolation is a technique currently used to enumerate human CECs and can detect low numbers of cells. The purpose of this study was to determine whether a standard protocol for immunomagnetic isolation could be used to obtain and enumerate CECs and a subpopulation of endothelial progenitor cells (EPCs) from canine whole blood. Cultured canine aortic endothelial cells were stained immunohistochemically with von Willebrand factor to verify morphology and number. Using magnetic beads conjugated with anti-CD146, CECs/EPCs were isolated in culture and in canine whole blood. CD146-positive cells were stained with fluorescein-conjugated Ulex europaeus agglutinin 1 (UEA-1) to confirm endothelial origin and cells were counted manually using a fluorescent microscope. The method was then applied to EDTA-anticoagulated whole blood samples from 10 healthy client-owned dogs. The anti-CD146-coated magnetic beads (>5/cell) bound the cultured canine aortic endothelial cells. Only rare UEA-1-positive cells were obtained from whole blood, while >85-90% of cultured canine aortic endothelial cells were UEA-1 positive. The percentage recovery of cultured canine aortic endothelial cells was >86%. CECs in canine whole blood had >8 beads attached to the surface and were 10-40 microm in size. Using immunomagnetic isolation, 43.4 +/- 15.6 CECs/mL (range 24-70/mL) were isolated from canine whole blood samples. Immunomagnetic isolation is an acceptable method for enumerating canine CECs/EPCs in whole blood. Further studies are warranted to evaluate the clinical significance of CEC/EPC concentration in different canine diseases.