Biostimulative effect of laser on growth of mesenchymal stem/stromal cells in vitro

Introduction
Human adipose tissue-derived mesenchymal stem/stromal cells (hAT-MSCs) are multipotent stromal cells with a high potential application in tissue engineering and regenerative medicine. Laser irradiation of the place where the cells were implanted can stimulate their proliferation, increase the secretion of growth factors and thus increase the therapeutic effect.

Aim
To evaluate the influence of two lasers: Er:YAG and diode on the growth of hAT-MSCs in vitro.

Material and methods
hAT-MSCs were isolated from human subcutaneous adipose tissue. Immunophenotype of hAT-MSCs was confirmed by flow cytometry. Multipotency of hAT-MSCs was confirmed by differentiation into adipogenic, osteogenic and chondrogenic lineages. hAT-MSCs were irradiated with Er:YAG laser (wavelength 2940 nm, frequency 5, 10 Hz, doses: 0.1–1.2 J/cm2) for 2 s and 4 s and diode laser (wavelength 635 nm and doses: 1–8 J/cm2) for 5, 10, 20, 30 and 40 s. Cell viability was analysed 24 h after the exposure using MTT assay.

Results
Growth stimulation of hAT-MSCs after 5 Hz Er:YAG laser exposure, 0.1 J/cm2 dose for 4 s and 0.3 J/cm2 dose for 4 s was shown in comparison with the control group. Significant growth stimulation of hAT-MSCs after diode laser irradiation in doses of 1–4 J/cm2 was demonstrated compared to the control group.

Conclusions
The presented results indicate that both lasers, Er:YAG and diode can be used to stimulate stem/stromal cell growth in vitro. The biostimulative effect of laser therapy on stromal cells may be used in the future in aesthetic dermatology in combined laser and cell therapy.