Cell-based therapies for COVID-19: A living, systematic review

Objective This living, systematic review aims to provide a timely, rigorous, and continuously updated summary of the available evidence on the role of cell-based therapies in the treatment of patients with COVID-19. Data sources We conducted searches in PubMed/Medline, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), grey literature, and in a centralized repository in L.OVE (Living OVerview of Evidence). L.OVE is a platform that maps PICO questions to evidence from the Epistemonikos database. In response to the COVID-19 emergency, L.OVE was adapted to expand the range of evidence it covers and customized to group all COVID-19 evidence in one place. All the searches covered the period until 23 April 2020 (one day before submission). Eligibility criteria for selecting studies and methods We adapted an already published standard protocol for multiple parallel systematic reviews to the specificities of this question. We searched for randomized trials evaluating the effectiveness and safety of cell-based therapies versus placebo or no treatment in patients with COVID-19. Anticipating the lack of randomized trials directly addressing this question, we also searched for trials evaluating other coronavirus infections, such as MERS-CoV and SARS-CoV, and nonrandomized studies in COVID-19. Two reviewers independently screened each study for eligibility. A living, web-based version of this review will be openly available during the COVID-19 pandemic. We will resubmit this review to a peer-reviewed journal every time the conclusions change or whenever there are substantial updates. Results We screened 1 043 records, but no study was considered eligible. We identified 61 ongoing studies, including 39 randomized trials evaluating different types of cell-based therapies in COVID-19. Conclusions We did not find any studies that met our inclusion criteria, and hence there is no evidence to support or refute the use of cell-based therapies for treating patients with COVID-19. A substantial number of ongoing studies should provide valuable evidence to inform researchers and decision-makers in the near future.