Stem Cell Therapy for Patients with Ischemic Cardiomyopathy


A medical research group from Miami Miller School of Medicine has examined the safety of transendocardial stem cell injections with a patient’s own bone marrow stem cells in patients with ischemic cardiomyopathy.

Ischemic cardiomyopathy is the most common type of “dilated cardiomyopathy,” which is a fancy way of saying that the heart enlarges in its failing struggle to supply the body with blood. The enlarged heart has more heart muscle to feed with oxygen, but because the heart enlarges faster than the blood vessels remodel, large portions of the enlarged heart are left without adequate blood supply, and the result is and oxygen deficit, also known as “ischemia.” In patients with ischemic cardiomyopathy, the heart’s ability to pump blood is decreased because the heart’s main pumping chamber, the left ventricle, is enlarged, dilated and weak. Usually, heart ischemia also results from coronary artery disease and heart attacks.

The symptoms of ischemic CM include shortness of breath, swelling of the legs and feet (edema), Fatigue (feeling overly tired), inability to exercise, or carry out activities as usual, angina (chest pain or pressure that occurs with exercise or physical activity and can also occur with rest or after meals), weight gain, cough and congestion related to fluid retention, palpitations or fluttering in the chest due to abnormal heart rhythms (arrhythmia), dizziness or light-headedness, and fainting (caused by irregular heart rhythms, abnormal responses of the blood vessels during exercise, without apparent cause).

Clearly an effective regenerative treatment of ischemic cardiomyopathy (ICM) would address of the needs of some of these patients. Bone marrow transplants into the heart have been tested as treatments and the stem cells were directly injected into the heart muscle (see Williams AR, et al., Circ Res. 2011;108(7):792-796; and Losordo DW, et al., Circ Res. 2011;109(4):428-436). Both of these studies, however used mononuclear cells from bone marrow. Mononuclear cells refer to white blood cells from bone marrow and it includes a wide variety of stem cells, progenitor cells, and other mature white blood cells, but excludes red blood cells or platelets, which have no nuclei.

In order to determine if mesenchymal stem cells were also safe for this type of treatment, Alan W. Haldman and his colleagues from the laboratory of Joshua M. Hare tested 65 patients who suffered from ICM and compared injection of mesenchymal stem cells (n = 19) with placebo (n = 11) and bone marrow mononuclear cells (n = 19). Patients were followed up to one year after their procedures.

To measure serious adverse effects of the procedure, all patients were evaluated at 30 days post-procedure. Severe adverse effects includes death, heart attack, stroke, hospitalization for worsening heart failure, perforation of rupture of the heart, tamponade (compression of the heart due to a collection of fluid around it), or sustained ventricular arrhythmias.

None of the patients in this study showed any severe adverse events up to day 30, and up to 1 year after the procedure, 31.6% of the bone marrow mononuclear and mesenchymal stem cell groups had some sort of serious adverse event, and 38.1% of the placebo group had serious adverse events.

Over one year, the Minnesota Living with Heart Failure score, which is a measure of the quality of life of a heart patient, improved with the mesenchymal stem cell and bone marrow cells but not with the placebo. Also, the 6-minute walk distance increased in the mesenchymal stem cell group, but none of the other groups when the baseline time was compared with the six-month and 12-month trials.

Patients in the mesenchymal stem cell group exhibited a significant increase in 6-minute walk distance when 6-month and 12-month time points were compared to baseline in a repeated measures model (P = .03). No significant difference was observed for patients in the bone marrow cell group (P = .73) or in the placebo group (P = .25). Data markers represent means; error bars, 95% CIs. Analysis of variance (ANOVA) was conducted with repeated measures.aWithin group, P<.05.bWithin group, P<.01.
Patients in the mesenchymal stem cell group exhibited a significant increase in 6-minute walk distance when 6-month and 12-month time points were compared to baseline in a repeated measures model (P = .03). No significant difference was observed for patients in the bone marrow cell group (P = .73) or in the placebo group (P = .25). Data markers represent means; error bars, 95% CIs. Analysis of variance (ANOVA) was conducted with repeated measures.aWithin group, P

Also, the size of the heart scar showed greater shrinkage in the mesenchymal stem cell group than in the other groups.

Significant reduction in scar size as the percentage of left ventricular mass for patients treated with mesenchymal stem cells (MSCs) and those in the placebo group who underwent serial magnetic resonance imaging. Repeated measures of analysis of variance model P values: treatment group, P=.99; time, P=.007; treatment group × time, P=.22. Data markers represent means; error bars, 95% CIs. Analysis of variance (ANOVA) was conducted with repeated measures.aWithin group, P<.05 vs baseline.bWithin group, P<.01 vs baseline.
Significant reduction in scar size as the percentage of left ventricular mass for patients treated with mesenchymal stem cells (MSCs) and those in the placebo group who underwent serial magnetic resonance imaging. Repeated measures of analysis of variance model P values: treatment group, P=.99; time, P=.007; treatment group × time, P=.22. Data markers represent means; error bars, 95% CIs. Analysis of variance (ANOVA) was conducted with repeated measures.aWithin group, P

And if a more visual way to view this would help, here is the heart of one particular patient.  Notice the shrinkage in the red area, which represents the scarred area, after one year.

A, Short-axis views of the basal area of a patient’s heart, with delayed tissue enhancement delineated at the septal wall. Delayed tissue enhancement corresponds to scarred tissue and is depicted brighter than the nonscarred tissue (automatically detected and delineated with red using the full width at half maximum technique). The red, green, and white lines demarcating the endocardial, epicardial contours, and borders of the segments, respectively, were drawn manually. Twelve months after injection of mesenchymal stem cells, scar mass was reduced from 30.85 g at baseline to 21.17 g at 12 months. B, Long-axis 2-chamber views of the same heart with delayed tissue enhancement delineated at the anterior and inferior wall, as well as the entire apex. At baseline and at 12 months after injection of mesenchymal stem cells, the delayed tissue enhancement receded in the midinferior and basal anterior walls (see Interactive of representative cardiac MRI cine sequences).
A, Short-axis views of the basal area of a patient’s heart, with delayed tissue enhancement delineated at the septal wall. Delayed tissue enhancement corresponds to scarred tissue and is depicted brighter than the nonscarred tissue (automatically detected and delineated with red using the full width at half maximum technique). The red, green, and white lines demarcating the endocardial, epicardial contours, and borders of the segments, respectively, were drawn manually. Twelve months after injection of mesenchymal stem cells, scar mass was reduced from 30.85 g at baseline to 21.17 g at 12 months. B, Long-axis 2-chamber views of the same heart with delayed tissue enhancement delineated at the anterior and inferior wall, as well as the entire apex. At baseline and at 12 months after injection of mesenchymal stem cells, the delayed tissue enhancement receded in the midinferior and basal anterior walls (see Interactive of representative cardiac MRI cine sequences).

The authors concluded from this study that these “results provide the basis for larger studies to provide definitive assessment of safety and to assess efficacy of this new therapeutic approach.”  Mesenchymal stem cells might certainly provide a way to treat ICM patients.  Also, if the patient’s bone marrow is of poor quality as a result of their poor health, then mesenchymal stem cells from a donor might provide healing for these patients.  For now, I say, “bring on the larger trials!!”

The Benefits of Repeated Mesenchymal Stem Cell Treatments to the Heart


Mesenchymal stem cells have the ability to improve the heart after a heart attack. However can repeated administrations of mesenchymal stem cells cause an increased benefit to the heart after a heart attack?

A collaborative research project between the Royal Adelaide Hospital, the University of Adelaide in South Australia, and the Mayo Clinic in Rochester, Minnesota has administered mesenchymal stem cells multiple times to rodents after a heart attack to determine if administering these stem cells multiple times after a heart attack increases the performance of the heart.

The experimental procedure was relatively straight-forward. Three groups of mice were evaluated by means of cardiac magnetic resonance imaging (MRI). Then all three were given heart attacks by tying off the left anterior descending artery. Immediately after the heart attack, two groups were injected with one million mesenchymal stem cells into the heart. The third group was injected with ProFreeze (a cryopreservation solution). One week later, a second set of heart MRIs were taken, and the first and third group of mice received injections of ProFreeze and the third group received another one million mesenchymal stem cells. All animals were given two more heart MRIs one week later and two weeks after that. One month after the initial heart attacks, the mice were euthanized and their hearts were sectioned and examined.

Those mice that did not receive injections of mesenchymal stem cells showed a precipitous drop in their heart performance. The ejection fraction (average percent of blood pumped from the heart) dropped from around 60% to about 20% and then stayed there. Those mice treated with one round of mesenchymal stem cells (MSCs) after their ejection fractions drop from 60% to about 35% after one week, and then stayed there. Those animals that received two shots of MSCs have their ejection fractions drop from around 60% to about 41%. Thus the administration of a second round of MSCs did significantly increase the performance of the heart.

The heart also shows tremendous structural improvements as a result of MSC transplantation. These improvements are even more dramatic in those mice that received two doses of MSCs. The mass of the heart and the thickness of the walls of the heart are greater in those animals that received two MSC doses, than those that received only one dose. Secondly, the size of the heart scar is smallest in those animals that received two doses of MSCs. Third, the density of blood vessels was MUCH higher in the animals that received two MSC doses. Also, the tissue far from the infarction in those animals that had received two doses of MSCs showed twice the density of blood vessels per cubic millimeter of heart tissue than those animals that had only received one injection of MSCs. Therefore, additional transplantations of MSCs increase blood vessel density, decrease the size of the heart scar and increase the thickness of the walls of the heart.

MSCs have the capacity to heal the heart after a heart attack. The degree to which they heal the heart differs from patient to patient, but additional treatments have the capacity to augment the healing capacities of these cells.  Also, in this experiment, the mice received someone else’s MSCs.  This is known as “allogeneic” transplantation, and it is an important concept, since older patients, diabetic patients, or those who have had a heart attack typically have MSCs that do not perform well.  Therefore to receive MSCs from a donor is a way around this problem.

The problem with this experiment is that it was done in mice, and they were injected directly into the heart tissue. Such a procedure is almost certainly impractical for human patients. Instead, intracoronary delivery is probably more practical, but here again, repeated releasing cells into the coronary arteries increases the risk of clogging them. Therefore, it is probably necessary to administer the second dose of MSCs some time after the first dose. To calibrate when to administer the second dose, large animal experiments will be required.

Thus, while this experiment looks interesting and hopeful, more work is required to make this usable in humans.  It does, however, establish the efficacy of repeated allogeneic MSC transplantations, which is an important feature of these experiments.

The Use of Synthetic Messenger RNAs Augment Heart Regeneration and Healing After a Heart Attack


A collaborative effect between researchers at Harvard University and Karolinska Institutet has shown that the application of particular factors to the heart after a heart attack can heal the heart and induce the production of new heart muscle.

Kenneth Chien, who has a dual appointment at the medical university Karolinska Institutet and Harvard University, led this research teams said this about this work: “This is the beginning of using the heart as a factory to produce growth factors for specific families of cardiovascular stem cells, and suggests that it may be possible to generate new heart parts without delivering any new cells to the heart itself.”

This study builds upon previous work by Chien and his colleagues in which the growth factor VEGFA, which is known to activate the growth of endothelial cells in the adult heart (endothelial cells line blood vessels), also serves as a switch that converts heart stem cells away from making heart muscle to forming coronary vessels in the fetal heart.

To drive the expression of VEGFA in the heart, Chien and others made synthetic messenger RNAs that encoded VEGFA and injected them into the heart cells. Injections of these synthetic VEGFA messenger RNAs produced a short burst of VEGFA.

Chien induced a heart attack in mice and then administered the synthetic VEGFA messenger RNAs to some mice and buffer to others 48 hours after the heart attacks. Chien and his crew was sure to inject the synthetic VEGFA mRNAs into the regions of the heart known to harbor the resident cardiac stem cell populations.

Not only did the VEGFA-mRNA-injected mice survive better than the other mice, but their hearts had smaller heart scars, and had clear signs of the growth of new heart muscle that had been made by the resident cardiac stem cell populations. One pulse of VEGFA had long-term benefits and those cells that would have normally made the heart scar ended up making heart muscle instead as a result of one pulse of VEGFA.

Chien said of this experiment, “This moves us very close to clinical studies to regenerate cardiovascular tissue with a single chemical agent without the need for injecting any additional cells into the heart.”

At the same time, Chien also noted that this technology is in the early stages of development. Even though these mice had their chests cracked open and their hearts injected, for human patients, the challenge is to adapt heart catheter technologies to the delivery of synthetic messenger RNAs. Also, to demonstrate the safety and efficacy of this technology to humans, Chien and others will need to repeat these experiments in larger animals that serve as a better model system for the human heart than rodents. Chien’s laboratory is presently in the process of doing that.

To adapt catheter technology to deliver these reagents, Chien had co-founded a company called Moderna Therapeutics to research this problem and develop the proper platform technology for clinical use. Chien is also collaborating with the biotechnology company AstraZeneca to help expedite moving the synthetic RNA technology into a clinical setting.