IMPLANTATION OF THIGH MYOCYTES INTO PATIENT HEART TO TREAT POST-MYOCARDIAL INFACTION HEART INCONTRACTILITY

Millions of people die of Myocardial Infaction and Ischemic heart disease each year. Some of those who survive after myocardial infaction (usually those who has only localized infacted area of heart muscle) also suffered from Chronic Heart Insufficiency. What is Heart Insufficiency? It is a decrease of pumping capability and pumping power of the heart after the heart muscles had dead from ischemia. These people (who has heart insufficiency) have to be continuously treated with drugs such as Diuretics (Furosemide) and ACEI (Enalapril) to decrease the workload of the heart and slow down the exacerbation of the heart failure. But these medical treatment doesn’t work for long and finally will fail to maintain the patient’s heart pumping power.Furthermore, in patient with large area of heart muscle damage, these medication doesn’t provide good effect on patient, their cardiac ejection fraction still remain low.

Thus, there was a new method of treatment start in America which they try to extract some myoblast from patient own thigh muscle tissues and then culture the muscle tissue in lab follow by injection of those cultured muscle tissue into patient’s infacted region of heart. No adverse events have been encountered in the first American trial of autologous myoblast injections into the myocardia of patients whose hearts have been severely damaged by myocardial infarctions or congestive heart failure, it was reported at an international congress on endovascular interventions sponsored by the Arizona Heart Institute.

Although the small trial was not designed to prove efficacy, clear evidence demonstrates that a portion of the skeletal muscle–derived myoblasts survive and grow in the heart, offering the promise of building functional regenerated tissue in patients facing the prospect of death without a heart transplant.

Thus far, researchers have documented an average 10% improvement in patients’ ejection fractions and a measurable increase in viable cardiac tissue following autologous myoblast transplantation.

Dr. Nabil Dib, interventional cardiology chief of cardiovascular research at the Arizona Heart Institute in Phoenix, said that no complications or unexpected sequelae have been encountered during or after myoblast transplantation in 10 patients treated at five U.S. sites since August 2000, even though some patients have received as many as 300 million myoblasts during the procedure.

An 11th patient, a 75-year-old man who had suffered an MI 3 months previously, received an autologous myoblast transplant in conjunction with coronary artery bypass graft (CABG) surgery during a live session at the congress. A PET scan revealed that his anterior wall was completely dead, and that he had a diseased anterior descending artery and left ventricle. A huge region of the septum was failing to contract, Dr. Dib said.

Dr. Edward B. Diethrich, medical director of the Arizona Heart Institute, said that revascularization would be of some help to this patient but would not be sufficient to prolong his life or improve his quality of life to a meaningful degree.

Skeletal muscle cells were obtained from the patient’s thigh several weeks prior to the surgery and cultured by Diacrin Inc., a Massachusetts company that specializes in processing of cells for transplantation. The resulting myoblasts were warmed in the operating room before Dr. Diethrich injected 100 million cells in evenly distributed portions to 10 locations throughout the portion of the heart damaged by the MI.

A precise map, used to guide placement of the cells, was created using the Biosense Corp.’s NOGA electromechanical voltage navigational system. This is a key factor in the transplantation process since it can highlight the most damaged regions of the patient’s heart. The procedure went well, with no complications.

According to the protocol, 12 patients will receive from 10 million to 300 million autologous cells in conjunction with CABG or a left ventricular assist device. Along with the Arizona Heart Institute, study participants include the University of California, Los Angeles; Temple University, Philadelphia; the University of Michigan, Ann Arbor; and the Cleveland Clinic.
Eventually, plans call for development of an internally placed catheter to deliver the autologous cells directly to the heart from a site within a patient’s skeletal muscle, as opposed to obtaining and delivering cells through open surgery.

A European trial of 10 patients who received from 0.5 billion to 1 billion cells in conjunction with CABG was not as problem free as the American trial. A mean 15% reduction in ejection fraction was offset by four cases of supraventricular tachycardia. Dr. Dib and Dr. Diethrich said it remains unknown why this complication occurred and has not surfaced in the American trial.
The budding technology, combined with impressive success in animal models and now early clinical trials, make myoblast transplantation one of the most exciting advances in cardiology today, capable perhaps of alleviating the desperate shortage and great need for donor hearts.
“All of this [research]is embryonic, but it is kind of embryonic with a jet behind it. It is moving very, very rapidly, he said.

Just 2,000 donor hearts are available for transplantation per year, but hundreds of thousands of patients are potential recipients, having suffered an MI or irreversible damage from congestive heart failure.

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