Mesenchymal Stem Cells and Their Derivatives: Old Problems and New Possibilities in Regenerative Medicine for Neurological Diseases

Mesenchymal stem cells are multipotent stromal cells with immunomodulatory, anti-inflammatory, and trophic properties that support tissue repair and regeneration. Increasing evidence suggests that their therapeutic effects are primarily mediated by paracrine signaling, especially through extracellular vesicles, which can cross the blood–brain barrier and act as cell-free therapeutic agents. Preclinical and clinical studies in stroke, multiple sclerosis, spinal cord injury, and neurodegenerative diseases report encouraging outcomes but also reveal major challenges, including limited engraftment, donor-related heterogeneity, incomplete understanding of mechanisms, and potential oncogenic risks. Recent advances in biotechnology—such as mesenchymal stem cell-derived extracellular vesicles, genetic engineering using CRISPR/Cas9 or viral vectors, 3D culture systems, and bioengineered delivery platforms—offer new opportunities to overcome these limitations. Early clinical trials demonstrate promising safety and functional improvements, yet results remain inconsistent, highlighting the need for standardized protocols and large-scale controlled studies. This review outlines current knowledge, key challenges, and emerging strategies aimed at optimizing mesenchymal stem cell-based approaches for regenerative neurology.