Safety and preliminary efficacy of allogeneic bone marrow-derived mesenchymal stromal cells (BMSC) for painful lumbar facet arthropathy: study protocol for a randomised, double-blinded, placebo-controlled, crossover phase II clinical trial.

backgroundLumbar facet arthropathy (LFA) is a degenerative, arthritic joint disorder and a common specific cause of axial low back pain and functional impairment. Currently, no disease-modifying therapies are available for symptomatic LFA. Mesenchymal stem/stromal cell (MSC)-based therapy represents an emerging regenerative treatment modality with the promise to target the underlying pathophysiology of LFA. Despite encouraging clinical evidence supporting the safety and efficacy of MSC therapy in other osteoarthritis, its therapeutic utility in LFA remains largely unexplored. We recently completed a prospective, single-arm, open-label phase I clinical trial that demonstrated a favourable safety profile and preliminary clinical benefit following intra-articular administration of bone marrow-derived MSCs (BMSCs) in patients with symptomatic LFA. Building on these findings, we present the protocol for METHODS AND ANALYSIS: This study is a single-centre, randomised, double-blind, placebo-controlled, cross-over phase II trial with a target accrual of 40 patients. Eligible patients will be randomly assigned in a 1:1 ratio to receive a single intra-articular injection of either Arm A: BMSC or Arm B: Placebo (dimethyl sulfoxide). At the 6-month follow-up, all patients will be unblinded. Patients initially randomised to Arm A will continue follow-up for up to 12 months. Patients initially randomised to Arm B may cross over to receive the BMSC treatment, followed by an additional 12 months of post-BMSC treatment follow-up, or they may continue observation for another 6 months without BMSC treatment. Overall, each patient will be followed up to 12 months after BMSC treatment. The primary endpoints are back pain, functional outcomes and adverse events at 6 months post-randomisation. ETHICS AND DISSEMINATION: This study will be conducted in compliance with U.S. federal regulations and Mayo Clinic institutional research policies and procedures. The protocol has been approved by the Mayo Clinic Institutional Review Board (IRB) and the Data Safety Monitoring Board (IRB No. 21-013278). The results of this trial will be disseminated through publication in peer-reviewed journals and on ClinicalTrials.gov. TRIAL REGISTRATION NUMBER: NCT06001853.