The effects of low-level laser irradiation on cellular viability and proliferation of human skin fibroblasts cultured in high glucose mediums

Delayed wound healing is one of the most challenging complications of diabetes mellitus (DM) in clinical medicine. This study has aimed to evaluate the effects of low-level laser therapy (LLLT) on human skin fibroblasts (HSFs) cultured in a high glucose concentration. HSFs were cultured either in a concentration of physiologic glucose (5.5 mM/l) or high glucose media (11.1 and15 mM/l) for either 1 or 2 weeks after which they were subsequently cultured in either the physiologic glucose or high concentration glucose media during laser irradiation. LLLT was carried out with a helium–neon (He–Ne) laser unit at energy densities of 0.5, 1, and 2 J/cm², and power density of 0.66 mW/cm² on 3 consecutive days. HSFs’ viability and proliferation rate were evaluated with the dimethylthiazol-diphenyltetrazolium bromide (MTT) assay. The LLLT at densities of 0.5 and 1 J/cm² had stimulatory effects on the viability and proliferation rate of HSFs cultured in physiologic glucose (5.5 mM/l) medium compared to their control cultures (p = 0.002 and p = 0.046, respectively). All three doses of 0.5, 1, and 2 J/cm² had stimulatory effects on the proliferation rate of HSFs cultured in high glucose concentrations when compared to their control cultures (p = 0.042, p = 0.000, and p = 0.000, respectively). This study showed that HSFs originally cultured for 2 weeks in high glucose concentration followed by culture in physiologic glucose during laser irradiation showed enhanced cell viability and proliferation. Thus, LLLT had a stimulatory effect on these HSFs.