Dopaminergic induction of human dental pulp stem cells by photobiomodulation: comparison of 660nm laser light and polychromatic light in the nir.

Human dental pulp stem cells (hDPSCs) are able to differentiate into dopaminergic neurons and help the maintenance of partially degenerated neurons, which makes them as an alternative cell source for treatment of Parkinsons' disease (PD) patients. Here, the effect of photobiomodulation with polychromatic light source in the near infrared (NIR) range (600-1200 nm) or low level 660 nm diode laser light on hDPSCs during dopaminergic induction was investigated. Real time RT-qPCR analysis indicated that expressions of brain derived neurotrophic factor (BDNF), glial cell line derived neurotropic factor (GNDF), matrix associated protein 2 (MAP2), nuclear receptor related 1 protein (NURR1) and dopamine transporter (DAT) were increased, especially in the first 7 days of dopaminergic induction when 660 nm laser light was applied with a total energy density of 1.6 J/cm. The activity of polychromatic light on hDPSCs depended on the differentiation media and protein type. BDNF, GDNF, NURR-1 and MAP2 expressions were increased in the presence of pre-induction factors, and decreased when the post-induction factors were added into the culture medium. In contrast with all these promising results, the dopaminergically induced hDPSCs did not show any functional characteristics of dopaminergic neurons and died after they were transferred to a new laminin coated culture plates. In conclusion, the expression of dopaminergic neuron protective protein mRNAs in hDPSCs was increased by photobiomodulation in defined conditions. However, the cells were not able to differentiate into functional dopaminergic neurons either in control or in photobiomodulated groups that are prone to cell death and exhibit immature dopaminergic neuron characteristics.