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July 2011

How Safe Could Intrathecal Transplantation of Mesenchymal Stem Cells Be Considered in Multiple Sclerosis?—Reply

Author Affiliations

Author Affiliations: The Center for Multiple Sclerosis and the Agnes Ginges Center for Human Neurogenetics, the Department of Neurology, Hadassah University Medical Center, Jerusalem, Israel.

Arch Neurol. 2011;68(7):955-956. doi:10.1001/archneurol.2011.162

In reply

Karacostas and colleagues express their concerns about safety issues arising from our trial with MSCs in MS and ALS.1 Our detailed responses to each question raised follow.

Concerning general safety issues, in our phase I/II study, our main goal was to investigate the feasibility and short-term safety of the treatment modality. We were able to rule out any short-term toxicity, as shown by the 6-month follow-up. Additionally, as mentioned in the manuscript, we followed up the patients for up to 3 years and were not confronted with any exceptional clinical change. We performed yearly MRI scans in all patients that did not reveal any unexpected pathology (up to at least 3 years) and continued to show stabilization and suppression of the disease (follow-up data not yet published). We definitely share the concerns regarding unknown long-term toxicities, especially because previous experience with other treatments of MS (natalizumab, linomide) has shown that small-scale trials are not sensitive enough to rule out all possible adverse effects. This is clearly underlined in our conclusions that “ . . . larger studies are warranted to establish the long term safety and efficacy of this modality. . . . ”