Mononuclear cells of UCB paracrine action and vascular reactivity in right ventricle. Immunofluorescence analysis for the angiogenesis marker CD31 was performed on paraffin embedded cell-treated and PAB only heart tissue. (A-F) Vascularity in RV and LV was assessed, and resulted in an increase in the number of blood vessels in RV after four weeks of cells delivery (P = 0.01 versus PAB, scale bars = 100 μm). (G, H) CD31 positive vessels (endothelial-red) were analyzed through CellSens Dimension software (n = 4) and non-specific/background was filtered out for final calculation. A representative image (LV, RV) of immunofluorescence staining is illustrated. LV, left ventricle; PAB, pulmonary artery banding; RV, right ventricle; UCB, unbilical cord blood.