Most of the studies that have examined the effects of stem cell transplantation into the heart after a heart attack have only examined the effects of these cells for 4-6 weeks. There are very few long-term studies on the effects of implanted cells.
Fortunately, Timothy Nelson at the Mayo Clinic has published a long-term study of the effects of transplantation of umbilical cord mononuclear cells into the hearts of pigs. In this study, Nelson and his coworkers aimed to evaluate the feasibility and long-term safety of autologous umbilical cord blood mononuclear cells (UCB-MNCs) that were transplanted into the right ventricle (RV) of juvenile porcine hearts. The results are very encouraging.
In this study, piglets were born by means of Caesarean section in order to enable the collection of umbilical cord blood. 12 animals were assigned to either the placebo or test group, which half of them in one group and the other half in the other. 3 × 106 cells per kilogram were injected into the hearts of the test group and 10% DMSO were injected into the hearts of the placebo animals. These animals were monitored for 3 months after implantations, and the performance of their hearts was assessed in addition to biochemical markers, followed by terminal necropsy. None of the animals died as a result of these treatments.
The worse side effect of the surgeries was that two animals from the placebo group developed local skin infection after surgery that successfully responded to antibiotic treatment. Electrocardiograms (EKGs) of the treated animals showed no abnormalities in either group throughout the 3-month study. Two animals in the cell-therapy group had some issue right after surgery, but this is almost certainly a response to the anesthesia. Overall, this study demonstrated that autologous umbilical cord blood mononuclear cells can be safely collected and surgically delivered in a pediatric setting. The safety profile of these cells shows that they can be used to safely treat juvenile hearts. These studies should accelerate cell-based therapies to clinical trials for chronic heart disease.