Stem cells are indeed useful for gene treatment, particularly because they can self-renew and provide a long-term source of corrected cells. When a patient's own stem cells are harvested, genetically modified in the laboratory to correct a genetic defect, and then reinfused, the body can produce healthy cells for years or even a lifetime. This approach minimizes immune rejection risk since the cells are autologous (from the patient themselves).

The most mature and clinically validated application is in blood and immune system disorders. Casgevy, an FDA-approved CRISPR-based therapy, exemplifies this success: it edits a patient's blood stem cells to treat sickle cell disease and beta-thalassemia [1][2]. Blood-forming stem cells are particularly well-suited because they are accessible via bone marrow harvest and naturally repopulate the blood system after reinfusion. Gene therapies using stem cells can also address primary immunodeficiencies and other hematological conditions where no suitable donor is available for transplantation [2].

Beyond blood and immune disorders, stem cell gene therapy remains largely experimental. Researchers are exploring neural stem cells for neurodegenerative diseases like Parkinson's and ALS, and investigating applications in skin, eye, liver, and muscle tissues. However, these applications have not yet achieved the same level of clinical validation as blood-based therapies. Most are in preclinical research or early-phase trials, and long-term safety and efficacy data remain limited.

Safety concerns exist across all applications, including risks from viral vectors used in gene editing, potential off-target edits, and the possibility of tumorigenicity if stem cells are not carefully controlled. Despite these challenges, stem cell gene therapy represents a powerful platform for durable genetic correction, particularly in disorders where affected cells originate from accessible stem cell populations.