Routinely collected data: a path to assess safety of human mesenchymal stromal cell transplantation in randomized controlled trials

Human mesenchymal stromal cells (hMSCs) are currently at the center of interest in many randomized and non-randomized clinical trials. According to the data, the number of trials on hMSCs has increased rapidly over time. However, the safety of this treatment, despite some available evidence, remains questionable. Routinely collected data (RCD) has become a helpful approach for gathering clinical data, especially in clinical trials. This method of data collection has helped investigators overcome the limitations of randomized controlled trials (RCTs), such as ensuring long-term follow-ups. Herein, the potential role of RCD in investigating the safety of hMSCs in RCTs, particularly concerns about their possible pro-tumorigenic potential, is discussed. The patterns of recent trials in this field suggest high feasibility and the potential for using RCD for this purpose.