YAG laser treatment causes rapid degeneration and regeneration of collagen fibres in pig skin and facilitates fibroblast growth

Abstract

The non-ablative laser therapies have been speculated to cause microinjury in the dermal collagen fibres and increase collagen synthesis in the fibroblasts, leading to remodelling of the extracellular matrix. This study investigated the effects of neodymium YAG laser treatment on pig skin, especially focusing on its extracellular matrix molecules. The dorsal areas of a minipig were subjected to laser treatment, and samples were obtained by punch biopsies, and histological, immunohistochemical, and biochemical analyses were performed. The laser treatment caused degeneration of collagen fibres and fibrils, which were reconstituted within 24 hours, whereas there was no inflammation and no apparent damage on elastic fibres. Small blood vessels disappeared by the laser treatment, which re-appeared in 3 days. Biochemically, the amounts of collagen decreased up to day 3 after the treatment and then increased at day 7. When fibroblasts in dermal tissue at day 28 were counted, more fibroblasts in the treated tissue were observed than non-treated control. These results suggest that, although the laser treatment transiently degenerates collagen fibres and fibrils, it restores and increases them, mainly by an increase in dermal fibroblasts, assuring its minimal complication of skin.

Keywords::

• YAG laser
• collagen fibres
• dermis

Acknowledgement

We thank Dr H. Takama and Dr T. Hasegawa for helpful discussion, Dr J. Sano, Y. Nakagomi, T. Miyake, and members of Animal Care Center, Aichi Medical University, for technical assistance, and M. Suzuki and A. Miyoshi at Niic, Co. for the laser machine. The work was partly supported by Grants-in-aid for Scientific Research (B) (KAKENHI) (to HW) and Grants-in-aid for Priority Areas (to HW). We thank Mr C. O. Villanueva for critical proofreading of the manuscript.