Support of B19V infection of CD36⁺ EPCs under hypoxia vs. normoxia.

(A) Status of CD36⁺ EPCs cultured under hypoxia vs. normoxia. Day 4 HSCs were ex vivo expanded under either hypoxia or normoxia to produce CD36⁺ EPCs. At day 8, the cells were profiled by flow cytometry analysis for surface antigens indicated. Numbers shown in each plot are percentage of positive cells. (B&C) B19V infection under hypoxia vs. normoxia. Day 8 CD36⁺ EPCs were infected with B19V at an MOI of 5,000 gc/cell. (B) At 48 hrs p.i., immunofluorescence staining was performed using anti-NS1 or anti-11 kDa antiserum. DAPI was used to stain the nucleus. Confocal images were taken at a magnification of 40×(objective lens) using an Eclipse C1 Plus confocal microscope controlled by EZ-C1 software (Nikon). (C) At 48 hrs p.i., mRNA was extracted from infected cells, and the levels of B19V VP2-encoding mRNA per β-actin mRNA were quantified.