Effect of phototherapy on growth factor levels in neonatal rat skin

Neonates undergoing surgery may receive phototherapy (PT) for the treatment of hyperbilirubinemia. Although the effects of PT on neonatal structures are well documented, the effect of PT on wound healing has not been previously evaluated. An experimental study was performed to evaluate the effect of PT on growth factor levels responsible for wound healing in neonatal rat skin.

Eighteen Wistar newborn rats (7 ± 2 g) were included in the study. Rats were randomized into 3 groups: control (CG), PT, and sham (SG) (n = 6). Both groups had 1-cm median dorsal skin incision. In CG, 1 × 1 cm of dorsal skin was sampled including the incised skin. The PT group received 5 banks of blue light (wave density, 30-40 μw/cm(2) per nanometer; exposure distance, 45 cm). Phototherapy was started 24 hours after birth and exposed during light period (mean duration, 21 hours to 15 minutes ± 2 hour to 1.5 minutes). Sham group consisted of animals that received a bank of white light with same exposure distance and a total duration of 26 hours to 18 minutes ± 3 hours to 9.1 minutes. After exposure, 1 × 1 cm dorsal skin samples were obtained from both PT and SG groups, including the median incision. The effect of PT was evaluated with the expressions of vascular endothelial growth factor (VEGF), its receptor (VEGF receptor), and transforming growth factor β (TGF-β) in endothelial vessels and fibroblasts of neonatal skin samples.

There was no significant difference between groups in VEGF receptor and transforming growth factor β expressions. The VEGF levels in endothelial vessels were significantly decreased in PT and SG when compared with CG (P < .05).

Vascular endothelial growth factor is a mediator of angiogenesis and may decrease in neonatal rat skin after light exposure. It can be suggested that decreased levels of VEGF after PT application may alter angiogenesis and also may adversely affect the healing features of neonatal skin.