The adipogenesis in infantile hemangioma and the expression of adipogenic-related genes

Infantile hemangioma, a common benign tumor of infancy, grows quickly in six months to one year after birth, then slowly involutes into fibrofatty tissue childhood. In this study, we observed the adipogenesis in hemangioma and investigated the expression of adipogenic differentiation-related genes. 33 fresh resected hemangioma samples were collected, including 18 proliferating cases (less than one year old), 9 involuting cases (from one to five years old), and 6 involuted cases (more than five years old). The pathological evolution of hemangioma was observed by H-E staining. The expression of Perilipin A was showed by immunohistochemistry staining. The expression and location of PPAR-γ (a key transcription factor in adipogenesis) was displayed by Immunofluorescence staining, with the co-staining of α-SMA and CD31. The expression of adipose differentiation-related genes including PPAR-γ2, LPL, CEBPA, and Perilipin A was detected by Quantitative real time PCR. The results of H-E and Immunohistochemical staining showed the increase of adipose cells as hemangioma developed from the proliferative phase to involuting phase and later to involuted phase. Immunofluorescence staining showed that PPAR-γ wa expressed in the perivascular cells in hemangioma. Quantitative PCR analysis showed a significant increase of PPAR-γ2, LPL, CEBPA and Perilipin A genes' expression in the involuting and involuted heangioma. In conclusion, the PPAR-γ(+) perivascular cells (specific mesenchymal stem cells or pericytes) contribute to the adipogenesis in hemangioma. The siginificantly increased expression of adipogenic differentiation-related genes in the involuting and involuted phase suggested that they played a role in the adipogenesis in hemangioma.