Heart Stem Cells, LVAD May Avoid Transplants
MINNEAPOLIS, Minn. (Ivanhoe Newswire) - Statistics from the Department of Health and Human Services reveal that an average of 18 people dies waiting for organ transplants each day. There are about 2,500 hearts available and a waiting list of about 100,000 patients in need. Now, researchers at the University of Minnesota hope to bridge that gap.
"I couldn't walk, or breathe, or eat," congestive heart failure patient Allan Isaacs told Ivanhoe.
That was life with congestive heart failure for 71-year-old Isaacs, but after a left ventricular assist device was implanted into his chest, Allan's life got moving again.
"(I do)15 minutes on the elliptical and about 30 minutes on the treadmill," Allan said.
The LVAD helps pump oxygen rich blood throughout the body, but Allan's recovery may also have to do with the fact that his treatment may have included injections of his own bone marrow stem cells. Allan's taking part in a leading edge blind study at the University of Minnesota's Medical Center.
"We isolate the stem cells and when they go for surgery we inject those cells on the heart wall," Ganesh Raveendran, MD, MS, Director of the Cardiac Catheterization Laboratory at the University of Minnesota Medical Center, told Ivanhoe.
One-third of the patients receive a placebo, the rest get ten injections of stem cells into their hearts. Muscle tissue is then analyzed to, "see whether these cells have made any meaningful change, whether the cells have transformed into cardiac muscle," Dr. Raveendran explained.
In many cases an LVAD is a bridge to transplant, but researchers and Allan hope this stem cell therapy could eliminate that need.
"Now, I can do whatever I feel like doing," Allan said.
The research team at the University of Minnesota Medical Center hopes to wrap up the study by end of this year and collaborate on a multicenter study involving seven medical centers throughout the nation.
BACKGROUND: Heart transplants are performed when other treatments for heart problems haven't worked, leading to heart failure. Heart failure can be caused by coronary artery disease, a weakening of the heart muscle, failure of a previous heart transplant, valvular heart disease, or congenital heart defect. A heart transplant is not right for everyone. Each case is considered individually by a transplant center. A patient could be prevented from having a heart transplant if they are 65 or older, have another medical condition that could shorten their life, have a personal medical history of cancer, have serious blockages in the arteries in their arms or legs, or are unwilling or unable to make lifestyle changes necessary to keep the donor heart healthy. Another option for people who can't have a transplant is a ventricular assist device (VAD). It is a miniature pump implanted in their chest that helps pump blood through the body. VADs are typically used as a temporary treatment for people waiting for a heart transplant. (Source:www.mayoclinic.com)
RISKS: The most significant risk of having a heart transplant is the risk of the body rejecting the donor heart. The immune system will see the donor heart as a foreign object. It will try to attack the donor heart. Although everyone who receives a heart transplant receives immunosuppressants, close to 25 percent of heart transplant recipients still have some signs of rejection during the first year after their operation. Most of the time rejection doesn't cause any symptoms and requires only an adjustment of medications. When there are symptoms that the body is rejecting the donor heart, they can include fever, shortness of breath, weight gain, not urinating frequently, and fatigue. Other risks can include problems with the arteries, mediation side effects, cancer, and infection. (Source: www.mayoclinic.com)
NEW TECHNOLOGY: The National Institutes of Health funded a groundbreaking multicenter study known as Late TIME (Transplantation in Myocardial Infarction Evaluation) to determine if a implanting a patient's own stem cells into the heart two to three weeks following a heart attack could help to safely and effectively improved cardiac function. University researchers are also participating in a multicenter trial known as TIME, which is evaluating the success of the same stem cell therapy given three to seven days after the patient's heart attack. "There is no doubt that in recent decades, we have continued to significantly improve treatments for patients who have had heart attacks. Despite this, their heart function doesn't recover as well as it should," Ganesh Raveendran, MD, MS, Director, Section of Interventional Cardiology & Cardiovascular Fellowship Program at The University of Minnesota Medical School, was quoted as saying. "Ultimately, we hope that cell therapy will improve cardiac outcomes and quality of life for these patients." Each patient in the study will receive either injections of their own stem cells or a placebo injection during the implantation of a left ventricle assist device (LVADs). The University's study was the first in the U.S. to examine the effects of stem cell therapy during LVAD placement. One-third of the patients receive a placebo and two-thirds will receive their own stem cells. If patients in the study eventually get a heart transplant, then researchers will examine their native hearts to determine whether bone marrow stem cells have grown into cardiac cells. (Source: http://blog.lib.umn.edu/mmf/news/bulletin/2011/timely-intervention.html)
Ganesh Raveendran, MD, MS, Director, Cardiac Catheterization Laboratory at the University of Minnesota Medical Center, talks about stem-cell treatment for patients with left-ventricular assist devices (LVADs).
Can you tell us a little bit about the study that is going on? How did this idea come about?
Dr. Raveendran: So, the idea came out a few years ago when we first went to the FDA. All the stem-cell studies that had been done so far were looking at the function of the heart and some surrogate endpoints. There is no single study that had looked at the mechanistic approach of stem cell therapy, how the stem cells are going to change, and/or change failing heart muscle after they get injected. We were more interested in looking at the mechanistic changes of the cells in addition to the functional changes like all the other studies have evaluated. The only way we can look at these changes is to inject patients' stem cells into their heart muscle when they undergo LVAD implantation. When they undergo heart transplantation, we have an opportunity to take the native hearts and analyze the cells to see if they have made any meaningful changes: whether the cells have transformed into cardiac muscle, grown any new muscle, or new arteries.
Can you explain the procedure a little bit? Is the general idea that the person comes in to get the LVAD, but they get something else on top of that?
Dr. Raveendran: Yes. If patients in advanced heart failure cannot perform their normal daily activities, they come to us to see whether they would be candidates for LVAD implantation or qualify for heart transplantation. There are a limited number of hearts available for transplantation, and not all patients who qualify can get hearts right away. There are only 2,500 heart transplants done annually in this country, whereas more than 100,000 patients are waiting to get heart transplants. So there is a gap between patients who need hearts and the number of patients who can get hearts. The LVAD can be used as a bridge to a transplant. There are also patients who can‘t qualify for heart transplantation due to age or multiple medical issues; in these cases they become destination LVAD patients. We are mostly interested in the bridge-to-transplant patients. The LVAD outflow port is implanted into the left ventricle, which takes the blood from the left ventricle and routes it to the aorta. By doing so, you bypass the heart function for pumping blood to the entire body. What we are doing for these kinds of patients is when they go for surgery, we also do a bone-marrow aspiration; from the bone-marrow aspirate, we isolate the stem cells. When they get an LVAD, the study patients also have stem cells injected into their heart muscle with the hope that they will make some meaningful recovery.
What kind of change are you looking for? You talked about the mechanism, but are you looking for that to transform into muscle?
Dr. Raveendran: Yes. In terms of evaluation, we do a lot more than what regular patients receive. Before LVAD placement or stem-cell injection we do a PET scan, which is meant to check the viability of the heart muscle and the blood flow to the heart-muscle area. After these patients get an LVAD and stem-cell injection, we repeat two PET scans at set intervals to see if there is any increase in blood flow or viable tissue in the territory where we injected the stem cells. In addition to the PET scans, we perform echocardiograms to show the heart's baseline function, then what is happening to the heart function after receiving the LVAD and stem cells. Finally, we take pressure measurements of the heart chambers. Typically when a patient is having heart failure, the pressures are very high in the cardiac chambers, which lead to breathing difficulty. We want to find out what the changes to the intracardiac chamber pressures after getting the LVAD implantation and stem cells. In addition to all of this, we do something called the LVAD turndown. We slowly decrease the pump speed and take pressure measurements. When you turn down the LVAD pump speed to 6,000 rpm, there is no real support from the pump to the patient. At that time, we take measurements again to see what kind of pressures and heart function they have. This gives us an idea, without the help of the pump, how much they recovered or are recovering. That is the functional part of the study we perform.
What have you found so far?
Dr. Raveendran: We have not unblinded the study yet. We were approved by the FDA to study 24 patients, and have recruited 15 patients in this double-blind study. Patients are randomized 2 to 1, with 2/3 of the patients receiving cells and 1/3 receiving placebo.
So there are no results yet?
Dr. Raveendran: Not yet. We need to complete all 24 patients to unblind the study, and compare the results from the group of patients who received stem cells and the group of patients who did not receive stem cells.
Is it in stage 1?
Dr. Raveendran: Yes.
What are you hoping to find?
Dr. Raveendran: There are a lot of unanswered questions as far as the stem-cell therapy is concerned. Number one is how these stem cells are differentiating into cardiac muscles or arteries. Histology of the heart will tell us, and our hope is that we will find improved cardiac function and viable heart muscle. Our goal is that cell therapy will help these patients achieve higher levels of recovery. There may be a day when they can have their LVADs removed because of recovery, but that is a long-term goal. We are several years away from this.
What happens after you get the results? Do you move forward?
Dr. Raveendran: We are working on initiating a multicenter study involving seven major medical centers across the country.
So you are still recruiting for phase 1. Is that correct?
Dr. Raveendran: Yes.
Do you have any idea when you might get the rest filled, and when you could move on to phase 2?
Dr. Raveendran: We probably should be able to wrap up our study by the end of this year and start the next one.
FOR MORE INFORMATION, PLEASE CONTACT:
Ganesh Raveendran, MD, MS
Director, Section of Interventional Cardiology &
Cardiovascular Fellowship Program
University of Minnesota Medical School