The DanCell clinical trial was conducted about seven years ago at the Odense University Hospital, Odense, Denmark by a clinical research team led by Axel Diederichsen. The DanCell study examined 32 patients with severe ischemic heart failure who had received two rounds of bone marrow stem cell treatments.
The DanCell study was small and uncontrolled. However, because the vast majority of stem cell-based clinical trials have examined the efficacy of stem cell treatments in patients who have recently experienced a heart attack, this study was one of the few that examined patients with chronic heart failure.
In this study, patients had an average ejection fraction of 33 ± 9%, which is in the cellar – normal ejection fractions in healthy patients are in the 50s-60s. Therefore, these are patients with distinctly “bad tickers.” All 32 patients received two repeated infusions (4 months apart) of their own bone marrow stem cells, but these stem cell infusions were quantitated to determine the number of “CD34+” cells and the number of “CD133+” cells. CD34 is a cell surface protein found on bone marrow hematopoietic stem cells, but it by no means exclusive to HSCs. CD133 is also a cell surface protein found, although not exclusively, on the surfaces of cells that form blood vessels and blood vessels cells as well.
Initially, patients showed no improvements in heart function after 12 months. However, when patients were classified according to those who received the most or the least number of CD34+ cells, a curious thing emerged: those who received more CD34+ cells had a better chance of surviving than those who received fewer CD34+ cells.
Is this a fluke? To determine if it was, Diederichsen and his colleagues followed these patients for 7 years after the bone marrow infusion. When Diederichsen and his colleague recorded the number of deaths and compared them with the number of CD34+ cells infused, the pattern once again held true. The CD34+ cell count and CD133+ cell count did not significantly correlate with survival, but the CD34+ cell count alone was significantly associated with survival. In the authors own words: “decreasing the injected CD34 cell count by 10 increases the mortality risk by 10%.”
The conclusions of this small and admittedly uncontrolled study: “patients might benefit from intracoronary stem cell injections in terms of long-term clinical outcome.”
Three things to consider: Patients with heart conditions have poorer quality bone marrow stem cell numbers. Therefore, allogeneic stem cells might be a better way to go with this patient group. Secondly, the Danish group used Lymphoprep to prepare their bone marrow stem cells, which has been used in other failed studies, and the stem cell quality was almost certainly an issue in these cases (see the heart chapter in my book The Stem Cell Epistles for more information). Therefore, independent tests of the bone marrow quality are probably necessary as well or a different isolation technique in general. Also, a controlled trial must be run in order to confirm the efficacy of bone marrow stem cell infusions for patients with chronic ischemic heart disease. Until them, all we can conclude is that intracoronary injections of a high number of CD34+ cells may have a beneficial effect on chronic ischemic heart failure in terms of long-term survival.