Photodynamic therapy suppresses tumor growth in an animal model of human infantile hemangioma

Abstract

Purpose: The author investigated the efficacy of photodynamic therapy against infantile hemangiomas using the hemangioma animal model.

Materials and Methods: Eighty-three hemangioma specimens from 5 children were implanted into nude mice. The gross and volume changes of the implants were evaluated for up to 13 weeks. The histological change of the implant was evaluated at 5 weeks after transplantation. Photodynamic therapy was performed between 6 and 10 weeks after transplantation. The photosensitizer uptake of the implant was evaluated at 24 hours after photosensitizer administration. The implant response was evaluated at 0, 12, and 24 hours after light delivery. The change in ATF3 levels, a transcription factor induced under severe hypoxic conditions, were investigated immediately after treatment.

Results: The implants volume increased slowly during the first 4 weeks and then became involuted. At 5 weeks after transplantation, plump endothelial cells formed tightly packed sinusoidal channels, and the endothelial cells were positive for CD31 and GLUT1 expression. At 24 hours after photosensitizer administration, confocal analysis showed that photosensitizer was present within CD31-positive cells. The implant volume was significantly decreased in the treated implants compared with the untreated implants (p< .0001). At 24 hours after light delivery, most cells had collapsed. ATF3 expression increased gradually and then reached a maximum level at 4 hours after treatment.

Conclusion: Photodynamic therapy was effective in the treatment for infantile hemangiomas. Apoptosis, a major mechanism of hemangioma destruction in the early phase, might be caused by ischemic injury as well as direct effects of photodynamic therapy.