The Importance of Recruiting a Diverse Population for Stem Cell Clinical Trials

The development of stem cell therapies is evolving rapidly in parallel with advances in stem cell biology. However, many important issues remain to be addressed, ranging from the detailed molecular dissection of the therapeutic capabilities of stem cells in situ, through to the selection of both patients and sources of cells for clinical trials. Particularly pertinent to patient selection is the importance of enrolling sufficient numbers of patients in clinical trials, especially for comparative studies. Unfortunately, conducting comparative studies is often complicated by limitations on cell processing or the relative rarity of target diseases, so it is difficult to enroll sufficient numbers of patients with diverse backgrounds. Indeed, the number of patients enrolled in comparative stem cell studies is generally small, and few randomized trials have been conducted. In Japan, a new regulatory framework involving conditional and time-limited approval of regenerative products and mandatory post-marketing surveillance after early approval may help resolve the problem, because the enrollment qualification data for many patients will be collected. The translation of stem cell therapies to the clinic is still in its infancy, and stringent efforts to identify and establish suitable patient and control cohorts from diverse genetic, ethnic, and demographic backgrounds remain a high priority for the optimization of clinical trial design.