Abstract
Purpose :
Endothelial colony forming cells (ECFCs) are well characterised progenitors that have been shown to have vasoreparative potential in the ischaemic retina. How ECFCs interact with the choroidal vasculature remains unknown and this study aims to investigate their interaction with choroidal vessels in an ex vivo system.
Methods :
ECFCs were obtained from human umbilical cord blood and were characterised based on morphology, function and via the presence or absence of multiple surface markers such as CD34 and CD105. To create choroidal explants, C57/Bl6 mice were sacrificed at different ages (Postnatal day (P) 8,10,11 or 13; N=4 mice per group). N=6 choroids per eye were placed in Matrigel and allowed to grow for 5 days. Images were taken daily to determine the angiogenic sprouting distance per age group. In further explants taken from P8 Mice (N=8), ECFCs, which had been fluorescently labelled, with PKH67 were added in suspension and the angiogenesis quantified. Explants were fixed and the nature of ECFC interaction assessed.
Results :
Mice taken at p8 sprouted faster and had a larger mean sprouting distance on day 5 (464.4±31.52 Pixels) than mice at P11 (351.5±38.33 Pixels) and P13 (141.7±30.39 Pixels). Furthermore, p8 explants in the presence of ECFCs showed significantly increased sprouting distance when compared to control explants (P=0.0001) whereas conditioned media from ECFCs failed to induce any difference to choroidal explants. ECFCs integrated with the murine choroidal vasculature, especially in relation to formation of tip cells. Integrated ECFCs displayed marked tip-cell characteristics such as filopodia. ECFCs integrating into choroidal vessels induced a greater number of branching points compared to explants with no ECFCs present.
Conclusions :
ECFCs lead to an enhanced angiogenic response in choroidal tissue by directly integrating into the murine vessels. Further studies are analysing the role of these progenitor cells and their potential for vascular repair and/or role in pathological angiogenesis.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.