Stem cell therapy is an emerging alternative therapeutic or disease-modifying strategy for amyotrophic lateral sclerosis (ALS). The aim of this open-label phase I clinical trial was to evaluate the safety of two repeated intrathecal injections of autologous bone marrow (BM)-derived mesenchymal stromal cells (MSCs) in ALS patients. Eight patients with definite or probable ALS were enrolled. After a 3-month lead-in period, autologous MSCs were isolated two times from the BM at an interval of 26 days and were then expanded in vitro for 28 days and suspended in autologous cerebrospinal fluid. Of the 8 patients, 7 received 2 intrathecal injections of autologous MSCs (1 × 106 cells per kg) 26 days apart. Clinical or laboratory measurements were recorded to evaluate the safety 12 months after the first MSC injection. The ALS Functional Rating Scale-Revised (ALSFRS-R), the Appel ALS score, and forced vital capacity were used to evaluate the patients' disease status. One patient died before treatment and was withdrawn from the study. With the exception of that patient, no serious adverse events were observed during the 12-month follow-up period. Most of the adverse events were self-limited or subsided after supportive treatment within 4 days. Decline in the ALSFRS-R score was not accelerated during the 6-month follow-up period. Two repeated intrathecal injections of autologous MSCs were safe and feasible throughout the duration of the 12-month follow-up period. Significance: Stem cell therapy is an emerging alternative therapeutic or disease-modifying strategy for amyotrophic lateral sclerosis (ALS). To the authors' best knowledge, there are no clinical trials to evaluate the safety of repeated intrathecal injections of autologous bone marrow mesenchymal stromal cells in ALS. After the clinical trial (phase I/II) was conducted, the stem cell (HYNR-CS, NEURONATA-R) was included in the revision of the regulations on orphan drug designation (number 160; December 31, 2013) and approved as a New Drug Application (Department of Cell and Gene Therapy 233; July 30, 2014) by the Korean Food and Drug Administration. The phase II trial is expected to be reported later.

Objective: To assess the safety and efficacy of 2 repeated intrathecal injections of autologous bone marrow–derived mesenchymal stem cells (BM‐MSCs) in amyotrophic lateral sclerosis (ALS).Methods: In a phase 2 randomized controlled trial (NCT01363401), 64 participants with ALS were randomly assigned treatments (1:1) of riluzole alone (control group, n = 31) or combined with 2 BM‐MSC injections (MSC group, n = 33). Safety was assessed based on the occurrence of adverse events. The primary efficacy outcome was changes in Amyotrophic Lateral Sclerosis Functional Rating Scale–Revised (ALSFRS‐R) score from baseline to 4 and 6 months postinjection. Post hoc analysis includes investigation of cerebrospinal fluid biomarkers and long‐term survival analysis.Results: Safety rating showed no groupwise difference with absence of serious treatment‐related adverse events. Mean changes in ALSFRS‐R scores from baseline to 4 and 6 months postinjection were reduced in the MSC group compared with the control group (4 months: 2.98, 95% confidence interval [CI] = 1.48–4.47, p < 0.001; 6 months: 3.38, 95% CI = 1.23–5.54, p = 0.003). The MSC group showed decreased proinflammatory and increased anti‐inflammatory cytokines. In good responders, transforming growth factor β1 significantly showed inverse correlation with monocyte chemoattractant protein‐1. There was no significant difference in long‐term survival between groups.Interpretation: Repeated intrathecal injections of BM‐MSCs demonstrated a possible clinical benefit lasting at least 6 months, with safety, in ALS patients. A plausible action mechanism is that BM‐MSCs mediate switching from pro‐ to anti‐inflammatory conditions. A future randomized, double‐blind, large‐scale phase 3 clinical trial with additional BM‐MSC treatments is required to evaluate long‐term efficacy and safety. Ann Neurol 2018;84:361–373