Feature | May 19, 2011| Dave Fornell

Resurrecting Dead Heart Tissue

Stem cells may offer new cath lab treatments

For years researchers have experimented with stem cells in attempts to regrow myocardium in patients who suffer permanent tissue damage from myocardial infarction. A handful of companies are pushing forward with clinical trials of their technologies in an effort to show this futuristic concept has promise.

Several sessions discussed cell therapies in April at the American College of Cardiology (ACC) 2011 meeting. Speakers said stem cells can be derived from a variety of sources, including cardiac tissue, human embryos, placentas, bone marrow and adipose tissue. Other forms of regenerative cells being researched include progenerator cells and platelet-rich plasma.

“Cell therapy is no longer science fiction,” said Andre Terzic, M.D., Ph.D., Mayo Clinical Center for Regenerative Medicine, Rochester, Minn. However, while the technology exists to collect stem cells and deliver them to patients, research is still needed in cell retention.  Currently, only 5-10 percent of stem cells injected into patients are retained in the tissues they are meant to repair, which he said greatly reduces their effectiveness.

“You can’t expect only 60,000 cells to replace the function of the millions of cells that were lost in an infarction,” Terzic said.

His current research is focused on which proteins help increase cell uptake in damaged tissues.

“The heart is a regenerative organ and we clearly should try to maximize this repair process nature has provided for us,” said Andreas Zeiher, M.D., University of Frankfurt, Germany.  

He agrees meta-analysis of several trials of progenerator cells has shown only moderate improvement of about 3.7 percent increase in left ventricular ejection fraction. However, he said the technology shows promise and if any increase in cardiac function can be reclaimed, it may help prevent or delay the decline seen in heart failure patients.

“If your pump function recovers, there is no remodeling of the heart,” Zeiher explained. “If there is no recovery of pump function, your heart enlarges.”

The cardiac myocytes do not always persist in these treatments, but when they do, he said patients see sustained heart function improvement. Zeiher also said this leads to lower rates of death, ICD implantations and revascularization.

Using Patients’ Fat to Rebuild Their Hearts

“Stem cell therapy is kind of a niche in cardiology, but it does not have a broad base yet because of the lack of clinical evidence,” said Marc Hedrick, president and CEO, Cytori Therapeutics. His company has developed a therapy using adult stem cells derived from the patient’s own fat tissue.  “Overall, the results have been mixed.”

Hedrick said about 5 percent of adipose tissue is composed of stem and progenerator cells, which he says is two or three times greater than bone marrow. After fat tissue is removed using a specialized syringe, Cytori’s Celution technology uses a multi-step process to separate stem cells and progenerator cells using processes involving buoyancy, centrifuge and filtration. The purification process takes about an hour.

The stem cells are then injected into the patient via cardiac catheterization using one of two methods, depending if the patient is suffering from chronic or acute heart disease, Hedrick said. For an infarct, a catheter is guided into the left ventricle, and  about 15 needle catheter injects are made into the infarct tissue.  Hedrick said the procedure uses an electrophysiology (EP) cardiac mapping process to determine the exact location and boundaries of the infarct. The catheter is navigated and the precise placement of the injections are guided using EP mapping and cardiac ablation navigation software.

For patients with chronic ischemia, he said stem cells can be released directly into the affected coronary vessel.

Cytori has conducted two small clinical trials in Europe, which totaled 41 patients. Hedrick said the results were “highly statistically relevant.” Results from the APOLLO study were reported at the International Conference on Cell Therapy for Cardiovascular Disease in February. The study results show tissue death following a heart attack was reduced from 32 percent down to 15 percent.

APOLLO co-principal investigator Henricus J. Duckers, M.D., Ph.D., head of molecular cardiology, Thoraxcentre, Erasmus University Hospital, Rotterdam, the Netherlands, said the therapy was associated with a significantly lower incidence of ventricular tachyarrhythmias (VT). A total of three VT episodes were reported in the treated group as compared to 10 in the control group. The analysis of Holter recordings also showed lower incidence of premature ventricular contractions (PVC).  Five PVCs per treated patient, per day, were reported whereas in placebo-treated patients, the number of PVCs reported per patient, per day, was 72.  

With these data, Cytori hopes to gain CE mark approval in Europe by early 2012 as the first stem cell treatment for acute myocardial infarction patients. Hedrick said the company has also committed to conducting a larger, 300-patient study to collect further evidence of the treatments efficacy.

“Even with a patient on maximum medical therapy on their Bataan death march toward a heart transplant, we can extend out the time before they need to be on that list by 18 months,” Hedrick said.

The cost to care for a patient in advanced heart failure can be up to $150,000 annually. Hedrick argues stem cell therapy holds promise as an alternative that would be much less expensive and could significantly reduce mortality.

He said PCI can reduce infarct size by 5-10 percent, but he hopes stem cells may reduce the damage further.  “We want to reduce the heart attack size by half,” Hedrick said. “If you can change the size of a heart attack down by 50-75 percent, that is significant.”

Related Content

News | Heart Failure| October 02, 2015
Cyberonics Inc. announced results from the extension of the ANTHEM-HF clinical study (ENCORE Study). Results of the...
Tryton Side Branch Stent, clinical trial results, Catheterization and Cardiovascular Interventions

Tryton Side Branch Stent image courtesy of Tryton Medical

News | Stents Bifurcation| October 02, 2015
October 2, 2015 — Tryton Medical Inc.
AtriCure, cryoFORM cryoablation probe, launch
Technology | Ablation Systems| October 02, 2015
AtriCure Inc. launched the cryoFORM cryoablation probe, which offers increased probe flexibility to adapt to a variety...
Brilinta, 60 mg dose available, U.S. pharmacies
Technology | Antiplatelet and Anticoagulation Therapies| October 02, 2015
AstraZeneca announced that Brilinta (ticagrelor) 60-mg tablets are now available in U.S. pharmacies. On Sept. 3, 2015,...
Intact Vascular, TOBA II study, Tack Endovascular System

Image courtesy of Intact Vascular

News | Peripheral Arterial Disease (PAD)| October 01, 2015
Intact Vascular Inc. announced the U.S. Food and Drug Administration has granted conditional approval for a U.S. and...
Cook Medical, Zilver PTX, Japan PMS study, CIRSE 2015, two-year results

Image courtesy of Cook Medical

News | Stents Peripheral| October 01, 2015
Kimihiko Kichikawa, M.D., department of radiology at Nara Medical University in Japan, reported two-year results of the...
Stentys, CE Mark for self-apposing stent, lower limb artery disease, below-the-knee arteries, critical limb ischemia, PES BTK-70 trial

Image courtesy of Stentys

News | Stents Peripheral| October 01, 2015
Stentys announced that the company’s drug-eluting stent received CE Mark for treatment of below-the-knee (BTK) arteries...
raysafe, i2, staff dose monitoring
News | Radiation Dose Management| October 01, 2015
October 1,2015 — The first and only system that delivers real-time X-ray radiation dose monitoring for physicians and
Johns Hopkins, sticky gel, stem cells, rat hearts, heart attacks

Hydrogel applied to beating rat hearts improves stem cell uptake by the heart muscle and speeds up tissue healing after heart attack. Image courtesy of Johns Hopkins Medicine.

News | Stem Cell Therapies| September 29, 2015
A sticky, protein-rich gel created by Johns Hopkins researchers appears to help stem cells stay on or in rat hearts and...
News | Cath Lab| September 29, 2015
The Innovation Institute announced that Boston Scientific has signed an agreement to become the founding medical device...
Overlay Init