Mesenchymal stem cells in neurological disorders: Insights from clinical trials

Mesenchymal stem cells (MSCs) exhibit unique properties that make them promising candidates for cell therapy, particularly in neurological disorders. They can be derived from various tissues, with bone marrow, adipose tissue, umbilical cord, and placenta being the most common sources. Evidence suggests that the tissue of origin significantly influences MSC characteristics, including secretome composition, proliferation rate, and adhesion capacity. Clinical trials have demonstrated the safety and therapeutic potential of MSCs in conditions such as spinal cord injury, multiple sclerosis, and stroke. MSC therapy has been associated with improvements in motor, sensory, and cognitive functions, as well as enhanced quality of life. Mechanistically, MSCs promote neuroprotection, reduce inflammation, and modulate immune responses. In spinal cord injury, intrathecal administration of adipose- and bone marrow-derived MSCs has led to significant functional recovery, with single high-dose treatments often yielding better outcomes than multiple lower doses. In amyotrophic lateral sclerosis, bone marrow-derived MSCs have shown potential in slowing disease progression, though higher doses do not always result in greater benefits. In multiple sclerosis, high doses of umbilical cord-derived MSCs improved quality of life and prevented disease progression, whereas lower doses of bone marrow-derived MSCs provided limited functional benefits. While MSC therapy is considered safe, patient responses vary, and a definitive correlation between administered dose and therapeutic effects remains elusive. The small number of studies using comparable protocols impedes comparison of other relevant factor, limits the drawing of conclusions and underscore the importance of developing standardized protocols to optimize MSC-based treatments and maximize their clinical efficacy.