Genetically Modified MSCs for Targeted Regeneration: Balancing Efficacy, Biosafety, and GMP Standardization.

Mesenchymal stromal cells (MSCs) are a versatile platform for regenerative medicine and gene delivery because they combine multipotency, immunoregulatory activity, and injury-directed trafficking. Translation is nevertheless limited by donor- and tissue-dependent heterogeneity, variable biodistribution, and engineering-related risks. This review evaluates genetically modified MSCs as medicinal products rather than as a general MSC class. We compare self-inactivating lentiviral (SIN-LV) transduction, which provides efficient and durable expression and has limited early clinical experience, with targeted genome editing, which can define the integration locus and copy number but remains constrained by variable precise knock-in efficiency, off-target and double-strand-break-associated effects, manufacturing cost, and the absence of long-term clinical safety data. We integrate preclinical and clinical evidence with GMP-compatible manufacturing, potency testing, genomic surveillance, and release criteria. Particular attention is given to safe-harbor integration and B2M/CIITA-based hypoimmunogenic designs as strategies to reduce engineering-related batch variability and HLA-dependent donor variability. Together, these developments support a transition from empirically optimized MSC preparations toward molecularly defined cellular medicines with predefined genotype, expression, potency, and safety attributes.