Stem Cell Therapy: Healing or Hype?
Why Stem Cell Delivery Doesn’t Work
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During the last 2 decades, there has been a surge in the development of stem cell therapies to treat numerous debilitating diseases. Cardiovascular disease is a leading target of this research because of the minimal proliferative and regenerative capabilities of the heart. These studies have quickly progressed to clinical trials; however, the initial enthusiasm has faded because outcomes from these studies have led to disappointing and inconsistent results.1 This viewpoint offers an explanation as to why stem cells have yet to demonstrate a significant benefit in patients having cardiovascular disease and how these challenges should be addressed.
Cell Type Does Not Seem to Matter
It is currently unknown which cell lineage provides the greatest potential in regenerative effects. While most cardiac clinical trials have delivered mesenchymal stem cells or bone marrow–derived stem cells (BMSCs), others have used adipose-derived stem cells (ASCs) and cardiac stem cells (CSCs).1,2 Yet, regardless of the cell type used, stem cell trials for cardiovascular diseases have not yielded clinically meaningful outcomes, though most have only been statistically powered to demonstrate feasibility and safety.
Mesenchymal stem cells are advantageous because they can be delivered to patients without the need for immunosuppression and secrete numerous antiapoptotic and angiogenic growth factors.3 In 2014, 30 patients were enrolled in a multicenter, double-blind trial and randomized to receive an intramyocardial injection of 25 million mesenchymal stem cells or cell medium concurrent with left ventricular assist device implantation. The authors concluded that administration of mesenchymal stem cells was feasible and safe, with a trend toward functional efficacy.3
BMSCs are commonly administered in cardiac trials and are attractive because of their proven safety and paracrine effects.4 A BMSC trial published in 2013 randomized 200 patients with acute myocardial infarction to an open-labeled, controlled trial with 2 BMSC groups. These cells were administered via …