Mayo Clinic Uses Reprogrammed Stem Cells to Heal the Heart

A Serbian heart patient named Miroslav Dlacic suffered from a heart attack, and this event thoroughly changed his life. His heart was so damaged that he was too tired to work in his garden or work at his leather-accessories workshop in the city of Belgrade. Like other heart attack suffers, Dlacic, at the age of 71, was sure that the rest of his life would be short, and spent without energy.

However, after prompting from the Serbian hospital where he was treated, he participated in a clinical trial at the Mayo Clinic trial that used stem cells to repair his damaged heart tissue, and the results completely changed his life for the better. Two years after his experimental treatment, Dlacic can walk without it wearing him out. “I am more active, more peppy,” he says. “I feel quite well.”

“It’s a paradigm shift,” says Andre Terzic, M.D., Ph.D., director of Mayo Clinic’s Center for Regenerative Medicine and senior investigator of the stem cell trial. “We are moving from traditional medicine, which addresses the symptoms of disease, to being legitimately able to cure disease.”

The treatment of heart patients has usually involved a series of medications that try to manage the decline a of weak heart. However, a collaboration between European and Mayo Clinic researchers have discovered a new way to repair a damaged heart that actually fixes the damaged tissue.

The procedure pioneered by the Mayo Clinic harvests stem cells from the patient’s bone marrow, and then cultures these cells in the laboratory so that they can become cardiac cells. These cultured cells are then injected into the patient’s heart so that they can regenerate healthy heart tissue.

According to Terzic, this Mayo Clinic study is the first successful demonstration in people of the feasibility and safety of transforming adult stem cells into heart cells.

This study could provide new life for millions of heart patients. According to the World Health Organization, cardiovascular disease is the leading cause of death worldwide. About 5.8 million people in the US alone have heart failure, and this number is growing, according to the National Institutes of Health.

Leukemia and lymphoma (cancers of the blood) have been successfully treated with stem cell transplants. However, using stem cells from another organ to treat the heart is a sizeable challenge.

“In leukemia and lymphoma, the transplanted bone marrow is repairing bone marrow,” Dr. Terzic says. “Here, we are asking something unique of the stem cells — to repair another organ. It’s an anatomical mismatch.”

The inspiration for this experiment can from an observation made in the early 2000s. When stem cells from 11 patients undergoing heart bypass surgery were examined and analyzed, cells from two of the patients had an unusually high expression of particular transcription factors. Transcription factors are proteins that control the flow of genetic information between cells, and these cells expressed transcription factors that are important in the formation of heart muscle cells. From a clinical perspective, these two patients did not appear any different from other patients, but their stem cells seemed to show unique capacity for heart repair.

“That gave us the idea to convert nonreparative stem cells to become reparative,” Dr. Terzic says.

Converting nonreparative stem cells into reparative stem cells that can successfully repair the heart requires a deep understanding of how precisely the human heart develops. This detailed, painstaking work was led by Atta Behfar, M.D., Ph.D., a cardiovascular researcher at Mayo Clinic in Rochester, Minn.

In collaboration with other members of the Terzic research team, Dr. Behfar identified hundreds of proteins involved in the process of heart development (cardiogenesis). This team then identified the proteins that are essential in driving a stem cell to become a cardiac cell.

By using computer models, they simulated the effects of eliminating specific proteins one by one from the process of heart development. That method yielded about 25 proteins, but the team was able to reduce this number down to 8 proteins that their data indicated were essential for heart development.

The research team was able to use these proteins to reprogram stem cells to become heart cells. The treated stem cells were dubbed cardiopoietic, or heart creative cells.

This team then used their cardiopoietic cells in a proof-of-principle study that was published in the Journal of the American College of Cardiology in 2010 and demonstrated in laboratory animal models with heart disease that the injection of cardiopoietic cells had improved heart function compared with animals injected with untreated stem cells.  This work was proclaimed as a “landmark work,” by the journal’s editorial writer, since this study demonstrated that it was indeed possible to reprogram stem cells to become cardiac cells.

ransformation: The cardiopoietic cells on the left react to the cardiac environment, cluster together with like cells and form tissue.
Transformation: The cardiopoietic cells on the left react to the cardiac environment, cluster together with like cells and form tissue.

However, the step between laboratory tests and clinical trials is a huge one.  The first hurdle is expanding stem cells in the laboratory so that there are enough cells for patient treatments.  To solve this problem, the Mayo Clinch team needed collaborators with expertise in expanding stem cells in the laboratory for clinical purposes.  To this end, they contacted Cardio3 Biosciences, a bioscience company in Mont-Saint-Guibert, Belgium.  Dr. Behfar went to Belgium and spent several months working with scientists at Cardio3.

“The interaction with Cardio3 was crucial to driving Mayo Clinic’s technology forward,” he says.

With these record of laboratory successes, Mayo Clinic applied to European regulatory agencies to conduct a clinical trial to test their cardiopoietic cells in human heart patients.  Why did they choose Europe as the setting for their first clinical trials?  Practically speaking, it is easier to acquire approval for clinical studies in Europe compared with the United States.  However, clinical trials will be held in the U.S. eventually, but Terzic has many previous collaborators at European medical centers who are ready to collaborate with him in this study.  Additionally, Cardio3 has a long history of coordinating trials in multiple countries.

The clinical trials involved 45 patients from Belgium, Switzerland and Serbia. All of the patients, including Miroslav Dlacic, experienced heart failure as a result of heart attacks.

Each of these patients were randomly assigned to a group that received cardiopoietic cells or to a control group that received standard care for heart failure.  This study examined the safety and feasibility of their procedure, but it should also lead to larger, multiple-site trials.

The results from this initial trial were significant. Stem cells from each patient in the cardiopoiesis group were successfully guided to become cardiac cells. The treated cells were injected into the heart wall of each of those patients without apparent complications.

“It’s critical that this new process of cardiopoiesis was achieved in 100 percent of cases, with a very good safety profile,” Dr. Terzic says. “We have demonstrated the feasibility and safety of this procedure.”

This initial clinical trial wasn’t designed to assess the procedure’s effectiveness, but the early indications are hopeful.  If you consider that a failing heart pumps less blood and eventually enlarge, then improvements six months after the cardiopoietic treatment are potentially indicative of increased heart regeneration.

In this study, when examined six months after stem cell therapy, every patient in the cardiopoiesis group had increased blood flow from the heart to the rest of the body, and showed decreased heart volume, all indicators of improved heart health.  Patients from the cardiopoietic group were also able to walk longer distances than they could before treatment — on average. By comparison, the 10 patients in the control group showed no change or even deterioration in these measures.

“This preliminary study was not designed to be definitive. But already at six months, there was a significant benefit for patients,” Dr. Terzic says.

Although such data is far from definitive, anecdotal evidence of improvement over the study’s two-year follow-up period came from one patient who was unable to summon sufficient breath to play his trumpet before the experimental treatment but now can do so, and from another who has resumed riding a bicycle.

“We are enabling the heart to regain its initial structure and function,” Dr. Terzic says, “and we will not stop here.”

The clinical trial findings were published in the Journal of the American College of Cardiology in 2013.

Meanwhile, research to improve the injection process and cell effectiveness is underway.

“We are working on novel delivery tools that dramatically increase the cardiopoiresis cells retained by the heart,” Dr. Behfar says. “We have technology and know-how about these stem cells that we couldn’t even have dreamed of 10 years ago when this work began.”

Multicenter, phase III clinical trials are being planned for larger groups in European centers, which will hopefully be followed by trials in the U.S.  Unfortunately, much more information is needed before this technique can be validated and approved for regular clinical use.

Mayo Clinic is uniquely positioned to pursue this complex therapy. In addition to its global reach, its Center for Regenerative Medicine is at the forefront of efforts to develop reparative solutions for a range of conditions besides heart disease.

“With the cardiopoiesis research, we have shown that regenerative medicine can really work,” Dr. Terzic says. “We are now actively working on regenerative medicine in the areas of diabetes, liver and lung disease, neurologic disorders, and orthopedic surgery.”

The interdisciplinary collaboration that provides the foundation for the Center for Regenerative Medicine epitomizes Mayo Clinic’s approach to research and treatment. So, too, does a commitment to using talent and technology to enhance patient care.

“The Mayo history of being an unbelievable medical and scientific center is the reason I am here,” Dr. Terzic says. “We have extremely creative people here as well as the environment that allows them to develop definitive solutions to problems.”

New Tool for Stem Cell Transplantation into the Heart

Researchers from the famed Mayo Clinic, in collaboration with scientists at a biopharmaceutical biotechnology company in Belgium have invented a specialized catheter for transplanting stem cells into a beating heart.

This new device contains a curved needle with graded openings along the shaft of the needle. The cells are released into the needle and out through the openings in the side of the needle shaft. This results in maximum retention of implanted stem cells to repair the heart.

“Although biotherapies are increasingly more sophisticated, the tools for delivering regenerative therapies demonstrate a limited capacity in achieving high cell retention in the heart,” said Atta Behfar, the lead author of this study and a cardiologist. “Retention of cells is, of course, crucial to an effective, practical therapy.”

Researchers from the Mayo Clinic Center for Regenerative Medicine in Rochester, MN and Cardio3 Biosciences in Mont-Saint-Guibert, Belgium, collaborated to develop the device. Development of this technology began by modeling the dynamic motions of the heart in a computer model. Once the Belgium group had refined this computer model, the model was tested in North America for safety and retention efficiency.

These experiments showed that the new, curved design of the catheter eliminates backflow and minimizes cell loss. The graded holes that go from small to large diameters decrease the pressures in the heart and this helps properly target the cells. This new design works well in healthy and damaged hearts.

Clinical trials are already testing this new catheter. In Europe, the CHART-1 clinical trial is presently underway, and this is the first phase 3 trial to examine the regeneration of heart muscle in heart attack patients.

These particular studies are the culmination of years of basic science research at Mayo Clinic and earlier clinical studies with Cardio3 BioSciences and Cardiovascular Centre in Aalst, Belgium, which were conducted between 2009 and 2010.  This study, the C-CURE or Cardiopoietic stem Cell therapy in heart failURE study examined 47 patients, (15 control and 32 experimental) who received injections of bone marrow-derived mesenchymal stem cells from their own bone marrow into their heart muscle.  Control patients only received standard care.  After six months, those patients who received the stem cell treatment showed an increase in heart function and the distance they could walk in six minutes.   No adverse effects were observed in the stem cell recipients.

This study established the efficacy of mesenchymal stem cell treatments in heart attack patients.  However, other animal and computer studies established the efficacy of this new catheter for injecting heart muscle with stem cells.  Hopefully, the results of the CHART-1 study will be available soon.

Postscript:  The CHART-2 clinical trial is also starting.  See this video about it.

Treating Heart Patients with “Smart” Stem Cells

By aggressively treating heart attack patients soon after their episodes, clinicians have been able to reduce early mortality from heart attacks. However, the survival of these patients tends to create a whole new set of issues for them and their hearts. Chronic heart failure is a common aftermath of a heart attack for heart attack survivors. (see Kovacic JC and Fuster V., Clin Pharmacol Ther 2011;90:509-18).

Since the heart muscle (myocardium) has only a limited capacity to regenerate after a heart attack, multifaceted treatments have emerged that are designed to relieve symptoms and improve the patient’s clinical status. In particular, therapies target impaired contractility of the heart and the ability of the heart to handle the workload without enlarging. However, these treatments do not address the loss of heart muscle that underlies all heart attacks (see McMurray JJ. Systolic heart failure. N Engl J Med 2010;362:228-38). To address the loss of contracting heart tissue, stem cells, traditionally isolated from bone marrow, have been used in several clinical trials. However, the results of these studies have been highly variable, since most bone marrow stem cells placed in a heart after a heart attack, die soon after implantation.

To improve the ability of bone marrow stem cells to repair the heart, Andre Terzic from the Mayo Clinic Center for Regenerative Medicine has designed a special cocktail to induce mesenchymal stem cells from bone marrow to become more heart-friendly. This cocktail consisted of the following growth factors: TGFβ1, BMP-4, Activin-A, retinoic acid, IGF-1, FGF-2, α-thrombin and IL-6. Mesenchymal stem cells were cultured for 10 days in this cocktail and then tested for heart-specific genes.

Terzic calls this procedure “cardiopoiesis,” and when he subjected bone marrow mesenchymal stem cells (BM-MSCs) to this procedure, they expressed a cadre of genes that is normally found in developing heart cells (Nkx2-5, MEF2C, GATA4, TBX5, etc.). In an earlier publication, Terzic and his colleagues transplanted BM-MSCs from heart patients into the hearts of mice that had suffered a heart attack and compared the effects of these cells on the heart, with BM-MSCs that had undergone this guided cardiopoiesis protocol. The results were astounding. Not only did the function of the hearts that had received the guided cardiopoiesis M-MSCs much more normal than those had had received the untreated BM-MSCs, but post-mortem examination of the hearts showed that the hearts that had received guided cardiopoiesis BM-MSCs contained human heart muscle cells integrated into the heart muscle tissue (Atta Behfar, et al., J Am Coll Cardiol. 2010 August 24; 56(9): 721–734). Therefore, this procedure, cried out for a clinical trial, and data from such a trial has already been reported.

A, Human-specific troponin-I (green) in the anterior wall of naive- versus CP-treated hearts, respectively, co-localized with ventricular myosin light chain (MLC2v, red). Bar, 100 μm. B, Human troponin-I staining of naïve versus CP hMSC treated hearts, counterstained with α-Actinin (red), demonstrated engraftment of human cells. Cell cycle activation, documented by Ki-67 expression (yellow, arrows), noted in human troponin positive and endogenous cardiomyocytes. C, Confocal evaluation of collateral vessels from CP hMSC treated hearts demonstrated human-specific CD-31 (PECAM-1) staining. D, Human lamin staining (arrows) co-localized with nuclei of smooth muscle in vessels from CP hMSC treated but not saline or naïve treated hearts. Bar, 20 μm for B-D.
A, Human-specific troponin-I (green) in the anterior wall of naive- versus CP-treated hearts,
respectively, co-localized with ventricular myosin light chain (MLC2v, red). Bar, 100 μm.
B, Human troponin-I staining of naïve versus CP hMSC treated hearts, counterstained with
α-Actinin (red), demonstrated engraftment of human cells. Cell cycle activation,
documented by Ki-67 expression (yellow, arrows), noted in human troponin positive and
endogenous cardiomyocytes. C, Confocal evaluation of collateral vessels from CP hMSC
treated hearts demonstrated human-specific CD-31 (PECAM-1) staining. D, Human lamin
staining (arrows) co-localized with nuclei of smooth muscle in vessels from CP hMSC
treated but not saline or naïve treated hearts. Bar, 20 μm for B-D.

In a paper from February 2013 (Bartunek J, et al., Journal of the American College of Cardiology (2013), doi: 10.1016/j.jacc.2013.02.071), Terzic and his team has reported on the administration of BM-MSCs into the hearts of 34 heart patients. Of these patients, 21 were implanted with their own BM-MSCs that had undergone guided cardiopoiesis and the other 12 received standard therapy for heart patients with no transplanted cells.

The results from this study were striking to say the least. According to Terzic, “The benefit to patients who received cardiopoietic stem cell delivery was significant.” Cardiologist Charles Murry wrote in an editorial, “Six months after treatment, the cell therapy group had a seven percent absolute improvement in EF (ejection fraction) over baseline, versus a non-significant change in the control group. The improvement in EF is dramatic, particularly given the duration between the ischemic injury and cell therapy. It compared favorably with our most potent therapies in heart failure.”

This clinical trial, known as the C-CURE trial, which stands for Cardiopoietic Stem Cell Therapy in Heart Failure. was an international, multi-center trial that treated enrolled patients from hospitals in Belgium, Serbia, and Switzerland. This trial represents the culmination of almost a decade of work by Terzic and others. “Discovery of rare stem cells that could inherently promote heart regeneration provided a critical clue. In following this natural blueprint, we further developed the know-how needed to convert patient-derived stem cells into cells that can reliably repair a failing heart.”

For this trial, Mayo Clinic partnered with Cadio3 Biosciences, which is a bio-science company in Mort-Saint-Guilbert, Belgium. This company provided advance product development, manufacturing scale-up, and clinical trial execution.  Adaptation of this exciting new technology to the clinic could mean a new exciting fix for heart patients.

Induced Pluripotent Stem Cells Improve Hearts

Mayo Clinic Investigators have shown that induced pluripotent stem cells, which were made from particular cells in the skin called “fibroblasts,” were differentiated into heart muscle cells and used to treat mice with heart disease. This proof-of-principle study shows that is might be possible to use iPSCs to fix hearts after a heart attack with iPSCs.

Timothy Nelson, the principal author of this study, said that this study “establishes the real potential for using iPS cells in cardiac treatment. iPSCs have already been used to treat sickly cell anemia, Parkinson’s disease and hemophilia A in laboratory mice. This experiment, which was also done in mice, further extends the clinical conditions that iPSCs might treat.

This is an exciting result, but there is a caveat I must mention. Christine Mummery and her colleagues have shown that even though human embryonic stem cell transplantation improves the condition of the heart after a heart attack in rodents after four weeks, examination of these same rodents twelve weeks after the transplants reveals that the improvements have largely disappeared.  In this study, the mice were examined after four weeks and not after twelve. Therefore, this study might be in the same category as those done with human embryonic stem cells. If the improvements could be shown to last even up to twelve weeks after the transplantations, then I think we would have something really to crow about. However, as it is, while this result is interesting, it is simply not conclusive.