Exosome-derived microRNAs from stem cells from human exfoliated deciduous teeth (SHED): Emerging therapeutics for neurodegenerative disorders

Neurodegenerative diseases (NDDs) cause progressive damage of brain structures, resulting in a loss of function and, eventually, the patient's death. Current therapeutic strategies are limited to late stages of the disease, culminating in palliative care, while tackling the underlying causes of neurodegeneration could halt or at least slow down the disease at an early stage. In this vein, stem cell transplantation therapies are emerging as a promising alternative, as such as cells can penetrate the central nervous system, engraft, differentiate, and secrete neurotrophic, neuro-regenerative, and neuroprotective factors. Stem cells derived from human exfoliated deciduous teeth (SHED) have demonstrated significant regenerative potential in various biological systems and pathological conditions, showing high proliferative capacity and multipotency to differentiate into neuronal cells both in vivo and in vitro, apparently functioning through exosome-derived microRNAs (exos-miRs). Here, we summarize recent reports on specific miRs from SHED's exosomes, which exert diverse regulatory functions counteracting oxidative stress, and provide immunomodulatory and neurotrophic benefits contributing to the treatment of neurodegeneration in NDDs. We discuss clinical and preclinical evidence supporting the potential of SHED cells in the treatment of NDDs, including Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), spinal cord injury, focal cerebral ischemia, and peripheral nerve damage. We also highlight that the use of SHED in NDDs treatment remains largely underexplored, opening a wide field for further research. We suggest deeper studies on the role of SHED-exos-miRs in NDDs, including their proneurotrophic activity, reduction of genotoxic neuronal stress, and disruption of proinflammatory signaling pathways.