# Modulating the Behavior of Schwann Cells with NGF Exposure Combined with Different Energy Densities of Photobiomodulation Cultured on Polyhydroxybutyrate (PHB) Scaffolds

## TL;DR

This study explores how laser therapy and nerve growth factor affect Schwann cells on a specific scaffold material.

## Contribution

The study introduces a novel combination of photobiomodulation and NGF exposure to modulate Schwann cell behavior on PHB scaffolds.

## Key findings

- LLLT at 4 J/cm2 reduced Schwann cell viability on day 3.
- NGF exposure consistently reduced cell viability and proliferation across all time points.
- NGF exposure promoted morphological changes and cell intertwining with PHB scaffold fibers.

## Abstract

This study evaluated the effect of irradiation of different energy densities in low-level laser therapy (LLLT) and exogenous nerve growth factor (NGF) on Schwann cells (SCs). SCs (SCL 4.1/F7) exposed to LLLT (4 or 80 J/cm2) and NGF (25 ng/mL) were evaluated on days 1, 3, and 7. Cell viability (MTT), proliferation (crystal violet) and morphology (SEM—Scanning Electron Microscopy) on the polyhydroxybutyrate (PHB) scaffold were compared among five study groups: Control; L4. 4 J/cm2 LLLT; L80. 80 J/cm2 LLLT; L4N. 4 J/cm2 LLLT + NGF; and L80N. 80 J/cm2 LLLT + NGF. Viability and proliferation increased over time in groups treated exclusively with LLLT, with 4 J/cm2 reduced cell viability on the third day. The NGF exposition showed a reduction in cell viability and proliferation. The SCs remained attached to the PHB scaffold during the 7 days analyzed. The LLLT energy densities did not modify SC behavior, except for a reduction in cell viability after irradiation of 4 J/cm2 on the third day. Consistently, SC exposure to exogenous NGF significantly reduced proliferation and viability in all periods analyzed. Morphological changes were observed, and NGF exposure appears to have helped cells intertwine with PHB scaffold fibers.