17 Jul Study Uses Dental Stem Cells To Promote Retinal Regeneration After Eye Injury
Medical Research: What are the main findings of the study?
Answer: Traumatic and neurodegenerative disease of the retina lead to an irreversible loss of retinal ganglion cells (RGC) which are the neuronal cells located in the inner retina that transmit visual signals to the brain. Thus RGC injury results in visual defects which can ultimately progress into permanent blindness. One promising therapeutic approach is the use of stem cells as a source of replacement for lost retinal cells. However a theory has emerged suggesting that stem cells can act through the secretion of signalling molecules (growth factors). One stem cell that has recently shown great promise for neuronal repair are dental pulp stem cells (DPSC), which are multipotent stem cells easily isolated from adult teeth, including third molars (Mead et al 2013, 2014).
In our research, we transplanted either dental pulp stem cells or the more widely studied bone marrow-derived mesenchymal stem cell (BMSC) into the vitreous chamber of the eye after optic nerve crush (Mead et al 2013). The main finding of this study was that DPSC, to a significantly greater degree than BMSC, promoted the survival of injured RGC and the regeneration of their axons. We also showed that the mechanism of action was not through differentiation and replacement of cells but was actually paracrine mediated, i.e. through DPSC-derived growth factors (Mead et al, 2013, 2014).
Answer: Transplantation of mesenchymal stem cells (such as BMSC and DPSC) into other sites of the body is short lived and the cells are cleared very quickly. The eye is an immunoprivileged environment and migration of cells is limited. We found that the cells survived for 21 days in the eye and did not engraft or migrate into any tissues. We also found that, due to the neural crest origin of the DPSC, their neurotrophic secretory profile was more pronounced than BMSC, explaining why DPSC were more neuroprotective and axogenic for injured RGC in vitro and in vivo.
Medical Research: What should clinicians and patients take away from your report?
Answer: Stem cells show great promise in treating a variety of neurological conditions, including traumatic and neurodegenerative diseases of the eye. However, their mechanism of action is not restricted to cell replacement and could be used therapeutically as a paracrine-mediated therapy (Mead et al., 2014). Finally, stem cell therapy using ethically unhindered cells such as the easily isolated BMSC and DPSC is showing promise as a future treatment for the retina.
Medical Research: What recommendations do you have for future research as a result of this study?
Answer: The study warrants further investigation into the mechanisms of how different stem cells work to promote neuroprotection and axogenesis. It also highlights how stem cells from different sources in the body can have differing efficacy and highlights the need to test different stem cells to ensure the most appropriate cell is taken forward to clinical trials.
Mead B, Logan A, Berry M, Leadbeater W, Scheven BA (2013) Intravitreally transplanted dental pulp stem cells promote neuroprotection and axon regeneration of retinal ganglion cells after optic nerve injury. Invest Ophthalmol Vis Sci 54:7544-7556.
Mead B, Logan A, Berry M, Leadbeater W, Scheven BA (2014) Dental pulp stem cells, a paracrine-mediated therapy for the retina. Neural Regeneration Research 9: 577-578.