Cath Lab Digest - May 2008 - (Page 10)

10 ON THE HORIZON MAY 2008 The premise of MyoCell therapy is that a heart lacking muscle requires muscle progenitor cells to effectively recover function. Other stem cells, that may not mature into a muscle cell, may not offer the same potential for recovery as those cells that are programmed to become muscle. Myoblasts are inherently ischemia-resistant, and as an autologous therapy, lack the immunologic response associated with allogeneic cells. The 6-month final results of What kind of system is used to deliver the cells? While the biologics side or the stem cell side of this research is rapidly progressing, catheter delivery systems might take longer to mature. As mentioned, some of the studies that have implanted myoblasts into the heart muscle or the damaged regions of hearts in patients involved direct injection at the time of surgery, using a needle that enters the wall of the heart from the outside, the United States and function similarly. The catheter is placed in the left ventricle and the interventional cardiologist navigates it to the region where a previous heart attack has occurred (target area). A needle is extended at the distal tip of the catheter, through which cells are injected. The initial placement of the catheter is by fluoroscopic guidance, although some catheters do have advanced guidance mechanisms. In the MARVEL study, as with other cell and gene studies, we will utilize the NOGA® XP Cardiac Navigation System (Biosense Webster). This will enable the operator to detect the location of the catheter tip in threedimensional space and make measurements of local ventricular function, such as its ability to contract or to generate voltage. It allows us to more precisely localize target regions for injection. Even though this technology requires additional guidance and imaging equipment, it should not be a barrier for most cath labs in moving forward with either clinical studies or approved therapies that use these techniques. How are the cells stored? Does anything need to be done with them at the cath lab before they are injected into the patient? Fortunately, Bioheart and others working with these types of cells have created a user-friendly system for cell procurement. The first step in the process involves a skeletal muscle biopsy of the patient, removing a 5-10 gram piece of tissue from the patient’s leg muscle. The tissue is sent to Bioheart, progenitor cells (myoblasts) are isolated and then put into a series of culture cycles that increase their number to whatever the target is for a given study. (In the SEISMIC study, this number ranged from 150–800 million cells, with a mean of around 600 million cells.) It takes approximately two weeks to produce the desired yield of cells. The total timeframe between the biopsy and the reinjection of those cells into the heart is about 2-3 weeks. Once the cells are harvested, they are placed in a self-contained shipping unit. This unit includes a cooling element to maintain the cells at a certain temperature and a digital thermometer to monitor changes during transportation to the clinical site. Cells remain stable for 96 hours, offering a fair-sized window around which a clinical team can plan the injection procedure. The cells arrive at the clinical site in a small sterile intravenous infusion bag. At the procedure table, the cells are drawn up into 1 ml syringes for injection. It is all very straightforward and qualifies as ‘minimal processing’, the idea being to keep it simple and not to be faced with a complex recipe of cell preparation for each patient. What did you find most important about the results of the SEISMIC trial? There are several very key points that came out of this study which support findings in other studies and put to rest prior concerns with myoblast strategies. First of all, there had been some concerns of arrhythmogenicity, that might increase the incidence of arrhythmias. SEISMIC showed us that this seems not to be the case, and is further supported in the recent surgical study, the Myoblast Autologous Graft in Ischemic Cardiomyopathy (MAGIC) trial, in results reported by Dr. Philippe Menasché a little over a year ago. I think we can be much, much less concerned about adverse rhythm, although we will remain vigilant in our data. In terms of efficacy, even though this was not a double-blinded study, SEISMIC demonstrated positive signals that were alluded to earlier, such as suggested improvement in symptoms (New York Heart Association functional class level and 6-minute walk distances), ventricular performance and volumetric changes. While an important result of SEISMIC is safety, it adds to the aggregate clinical trial experience of improvement in ventricular function. One of the very early reports about SEISMIC (which we should note came out prior to Prof. Serruys’ presentation at ACC) stated that patient symptoms improved but heart function essentially remained unchanged. Yes, on the surface, there is a disconnect. However, there are several ways to look at these observations. First, we need to reconsider how best to measure ventricular function. The clinical and scientific communities have depended on a number, the ejection fraction (EF), as the principal measure of cardiac function. In fact, EF is a fairly imprecise and somewhat variable number even in a single patient, because it represents the SEISMIC study, presented by Prof. Serruys at the American College of Cardiology (ACC) in April 2008, add to prior data presented at the ACC (March 2007) and the American Heart Association (November 2007). We are in a unique position to make important inroads that hopefully will lead to clinical benefit for patients. Virtually all signals from preliminary studies, such as SEISMIC, suggest this to be the case. rather than entering the wall of the heart from the inside, as with an endoventricular catheter. There have been a few catheters designed for the percutaneous approach. Our preliminary work was done with a catheter designed and manufactured by Bioheart. The MARVEL study (sponsored by Bioheart) is using a different catheter, developed by a Johnson & Johnson company. Catheter systems used for this purpose are all still investigational in

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Cath Lab Digest - May 2008 The King Faisal Specialist Hospital and Research Centre Cell Therapy in the Cath Lab for Heart Failure: A Look at MyoCell® Therapy and the SEISMIC Trial Performance Improvement Strategies Speed Up Treatment Times in the Management of ST-Elevation Myocardial Infarction (STEMI) Patients Contents Clinical Editor’s Corner Commentary: Performance Improvement Strategies Speed Up Treatment Times in the Management of ST-Elevation Myocardial Infarction (STEMI) Patients Ask the STEMI Expert Comparing Drug-Eluting Stents and Bare-Metal Stents SICP: The Ten-Minute Interview with… Christopher Kambak, RT(R) Cardiac Cath Lab Economics in a Public Hospital of a Developing Country Keeping Your Heart & Vascular Employees: Proven Ideas for an Effective Retention Plan Unspoken Words Ask the Clinical Instructor Society of Invasive Cardiovascular Professionals Meetings Calendar Education Center What Do You Think? Clinical & Industry News Classifieds Advertisers Index

Cath Lab Digest - May 2008

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