1. Figure 1. Number clinical trials with each stem cell type in a given year
Types of Stem Cells Used in US-Based Clinical Trials Between 1999 and 2004
Erin K. Luciano, Emma M Elliott, Monica J. Mosimann, Lucas A. Mitzel, Isaac J. Sanford, Derek M. Doroski
Franciscan Institute for Regenerative Medicine, Franciscan University of Steubenville, Steubenville, OH, USA
Introduction: Stem cells are a promising avenue for regenerative therapies. While research with many different
types of stem cells is being conducted, the relative contribution of different stem cell types to clinical trials is
unclear. This study examines the number of clinical trials involving different stem cell types from 1999 to 2014.
Materials and Methods: A search using the term “stem cells” was done of the clinical trials from the website
<www.clinacaltrials.gov>. 4588 clinical trials were found between the years 1999 and 2014 inclusive. 688 trials
were excluded because they did not specify the type of stem cell used or no stem cells were used in the study. A
total of 3900 trials involving stem cells remained. Each clinical trials was examined and classified by a) the year
that the clinical trial was received into the database and b) the stem cell type used, and c) whether the study was
done at a US site. Stem cells were categorized as adult stem cells (ASCs) if they were taken from someone after
birth, embryonic stem cells (ESCs) if they came from the inner cell mass of a blastocyst, extrafetal stem cells
(eFSCs) if they came from extrafetal membranes (plancenta, umbilical cord, etc.), fetal proper stem cells (FpSCs)
if they came from the fetus proper, induced pluripotent stem cells (iPSCs) if they were give this name in the
clinical trial description, and cancer stem cells (CSCs) if they came from a cancerous origin. Studies using more
than one type of stem cell were counted for both types.
Results and Discussion: Of the 3900 trials, 2269 were conducted at a US site (58%). Within these US-based
trials 89.7% used ASCs making ASCs more prevalent than all other stem cells types combined (Fig 1). 7.1% of
clinical trials used eFSCs making eFSCs more prevalent in clinical trials than all non-adult stem cells types
combined. Cancer stem cells were used in 2.2% of clinical trials, iPSCs in 0.7%, ESCs in 0.1%, and FpSCs in
0.04%. ASC clinical trials were the most prevalent in every single individual year by a wide margin (at least 6x
greater than all other combined). Excluding ASCs, eFSCs were most prevalent every year except 2010 where
CSCs were more prevalent than eFSCs. CSC clinical trials appeared to have a modest increase after 2010 with 7.2
trials/year when no previous year had more than 4 trials. iPSCs appear to be on the rise since 2012 with 3.3
trials/year when no previous year had more than 2 trials. ESCs and FpSCs never had more than 1 trial in a year.
Conclusions: These data suggest that thus far ASCs have had the most success in translating basic research into
clinical trials with eFSCs a distant second. The apparent recent rise in CSC and iPSC clinical trials may represent
promising new avenues for medical treatment. ESCs and FpSCs have not had much success translating into
clinical trials and there is no apparent trend to suggest that they will translate into more clinical trials in the near
future although the reason is not clear from this data. Further work examining trials at non-US locations may be
useful for understanding worldwide trends in stem cell clinical trials.