Differentiation, Survival, and Function of hESC-Derived Cardiomyocytes
Heart disease is the leading cause of death in the United States. Each year, more than 1 million people suffer from heart attacks. Many of the therapies available to doctors today are aimed at mitigating the damage during heart attacks (e.g., by placing drug-eluting stents in the artery), preventing worsening of symptoms (e.g., by aspirin, beta-blockers, ACE inhibitors, and lipid lowering drugs), or improving blood flow to the heart (e.g., by bypass surgery). These approaches are often ineffective in the long run because heart damage is irreversible, given that the heart generally cannot regenerate new heart muscles. This explains why, despite the best treatments available, patients with severe chronic heart failure have an astounding mortality rate of 20-30% per year. Furthermore, more than 400,000 new cases of congestive heart failure are diagnosed each year. Therefore, there is a great need to find new therapies aimed at the underlying process that will regenerate normal heart tissues in patients.One of the most promising areas of therapeutic research today involves the use of human embryonic stem cells (hESCs). hESCs have the unique ability to self regenerate and to transform into more specialized cell types. For these reasons, researchers are examining whether hESC derived cardiac cells can help regenerate heart cells and improve heart function. Most of the initial studies done in small animals so far have shown that indeed this is the case. However, current methods of differentiating hESC into cardiac cells is still not very efficient. Researchers typically end up with 5-40% of cardiac cells at best. Improving the efficiency and scaling up the production of these hESC-derived cardiac cells is one of our major goals in this grant.
Another problem facing clinicians and researchers alike is that they have limited means of monitoring where the hESC-derived cardiac cells go, how long they survive in the heart, when they proliferate, and whether they can transform into heart muscles. Instead, they rely on indirect and often subjective measures for determining efficacy, such as changes in quality of life reported by patients, how long they can exercise on the treadmill, and whether there is any increase in blood flow after stem cell transplant. As for researchers, they have to sacrifice the animals at serial time points to analyze data. This limitation, unfortunately, prevents them from understanding how stem cells work to improve heart function over time. Therefore, we have teamed up with other scientists who use sophisticated imaging devices to track the fate of transplanted cells and process them afterwards using genomics analysis. These efforts will ultimately help explain the mechanism of how hESC-derived cardiac cells can improve cardiac function.
Coronary artery disease is the number one killer in the US. Even under optimal medical management, heart disease patients still frequently suffer adverse consequences such as repeated hospitalizations for chest pain and refractory heart failure symptoms. Stem cell based therapy may one day treat this devastating disease effectively. Human embryonic stem cells (hESC), for example, can transform into cardiac cells and provide an unlimited source of cell supply for cardiac regenerative therapy application. Rather than limited mitigation of symptoms, if hESC fulfills its full potential, it is foreseeable that diseased hearts may be repaired and restored to health.
A major challenge to future clinical application of hESC-derived cardiac cells is to scale up production of these cells. Another concern is that these cells may become rejected or may cause tumor after transplantation. Thus, it is crucial to understand how these cells behave inside the living subject before advancing to clinical trials. Our grant is designed to address all 3 questions in a logical and effective manner: (1) how to scale up production of hESC-derived cardiac cells, (2) how to minimize immunogenicity and tumorigencity complications, and (3) how to determine their functional roles in living subjects using novel imaging techniques.
Answers to these questions will lead to markedly improved cell transplant protocols that are more reproducible, quantifiable, and beneficial. With our experienced multidisciplinary team members, we are confident that we have the scientific and medical expertise to complete this project.