# 660–808 nm simultaneous irradiation enhance keratinocyte migration and change the keratin expression: An in vitro study

## TL;DR

Combining 660 and 808 nm light improves skin cell movement and changes keratin patterns, which could help wound healing.

## Contribution

Simultaneous 660–808 nm irradiation enhances keratinocyte migration and alters keratin expression in vitro.

## Key findings

- Dual irradiation increased cell viability compared to single-wavelength treatments.
- Simultaneous irradiation reduced scratch area, indicating better cell migration.
- Dual irradiation shifted keratin expression toward less-differentiated keratinocytes.

## Abstract

This in vitro study aimed to determine if simultaneous irradiation with 660 and 808 nm wavelengths enhances keratinocyte migration and alters keratin expression. Keratinocytes were exposed to either 660 nm or 808 nm irradiation alone, as well as to both wavelengths simultaneously using a laser device with the same energy parameters (2 J, 22.22 J/cm2). Cell viability, migration, and keratin expression (K1, K10, K5, and K14) were assessed in a scratch model assay. After 24 h of PBM, the simultaneous group showed higher cell viability compared with the control and the irradiated groups with one wavelength (660 and 808 nm groups). Simultaneous irradiation also resulted in a smaller scratch area compared with the control and 660 nm groups. The frequency of cells positive for K1/K10 at the wound border was lower after dual irradiation, while cells positive for K5/K14 at the wound periphery were more frequent after simultaneous irradiation. These results suggest a potential increase in the population of less‐differentiated keratinocytes following 660–808 nm dual emission. In conclusion, combined irradiation improved cell viability and migration, potentially leading to a shift in keratinocyte differentiation. This dual‐wavelength effect may help stimulate the reepithelization process in the tissue repair.

Exposure to both 660 and 808 nm wavelengths at the same time induced intense keratinocyte migration and altered keratin expression, indicating a potential enhancement of a subset of less‐differentiated keratinocytes.