Abstract
Purpose :
Our group has shown that corneal plasmacytoid dendritic cells (pDCs) play a role in preserving corneal heme-angiogenic privilege during both steady state and inflammation. The aim of this study is to analyze the functional effect of pDCs on vascular endothelial cell proliferation and differentiation in vitro.
Methods :
Six-8 week old male C57BL/6 mice were injected subcutaneously with B16 Flt3-L melanoma tumor cells. After 10 days, splenic pDCs were isolated by sorting on CD45+, B220+ and PDCA-1+ pDC markers. pDCs were cultured in either transwell inserts (TW) with human umbilical vein endothelial cells (HUVECs) in the underlying well or directly co-cultured with HUVECs. Proliferation of HUVECs was assessed in two ways by counting cell numbers with a hemocytometer and metabolic activity by MTT assay. In addition, HUVECs were plated on Matrigel with direct co-culture. Differentiation of endothelial cells and the formation of tube-like structures were evaluated. Real-time (RT) qPCR of pDCs for endostatin and thrombospondin-1 were performed.
Results :
HUVEC proliferation was inhibited in both methods observed. Incubation with 20,000 pDCs per TW resulted in decreased cell number of HUVECs at day 2 (1.64 fold) and day 4 (1.78 fold), significantly lower compared to HUVECs alone (p<0.005). Further, the MTT assay showed a significant decrease in HUVECs with 10, 000 (1.44 fold) and 20,0000 (1.40 fold) pDCs per TW at day 5 as well as when 20,000 pDCs were co-cultured with HUVECs at day 1 (1.55 fold) and day 6 (1.16 fold) compared when HUVECs were grown alone (p<0.05 and p=0.01; respectively). HUVECs on Matrigel with the addition of pDCs did not form complete tube-like structures as the controls without pDCs. Finally, RT-qPCR of pDCs in TW showed mRNA expression for endostatin and thrombospondin-1, peaking at Day 3.
Conclusions :
This is the first study demonstrating the direct effect of plasmacytoid dendritic cells in reducing vascular endothelial cell proliferation and differentiation in vitro. pDCs may thus serve as a new cell-based therapy for the treatment of angiogenesis.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.