Effect of Notch signaling on differentiation of hemangioma-derived pericytes

Objective To explore the dynamic expression of major Notch components in infantile hemangioma (IH) and determine whether or not Notch pathway is involved in the regulation of hemangioma-derived pericyte (Hem-pericyte) differentiation. Methods Immunofluorescence staining was performed for evaluating the expression of Jagged1, Notch3 and Hes1 in proliferating and involuting IH tissues. The gene expressions of Notch components in Hem-pericytes were assayed by real-time polymerase chain reaction (PCR). The roles of Notch pathway in modulating Hem-pericytes were also examined. Results The lumens of proliferating specimens were less well-formed as compared to involuting counterparts. Both proliferating and involuting IH expressed Jagged1, Notch3 and Hes1. Notch3 and Hes1 co-localized predominantly with pericyte marker α-SMA. In contrast, Jagegd1 co-localized with endothelial cell marker CD31. As compared with proliferating Hem-pericytes, involuting Hem-pericytes showed higher expressions of Notch3 and Hes1 (3.10±0.32 vs 1.41±0.37, 1.89±0.35 vs 0.78±0.41). Furthermore the expressions of genes associated with differentiated/contractile phenotype, including smooth muscle myosin heavy chain (smMHC) and smooth muscle-specific isoform of actin (αSMA) in involuting Hem-pericytes increased as compared to proliferating Hem-pericytes (4.27±0.28 vs 0.48±0.19, 1.43±0.21 vs 0.39±0.20). An inhibition of Notch signaling restored involuting Hem-pericyte phenotype from differentiated to dedifferentiated states through a negative effect on the expressions of smMHC and αSMA (4.31±0.34 vs 2.1±0.32, 1.40±0.31 vs 0.56±0.27). Conclusions Consistent activation of Notch signaling occurs in Hem-pericytes. And Notch may play a role in in vitro differentiation of Hem-pericytes.