Development of Technologies Toward Cardiac Repair with Human Embryonic Stem Cells
Heart failure can result from either myocardial ischemia or infarction, and is the leading cause of mortality in California, the United States and other developed countries. A potential therapy to repair the heart consists of transplant of cardiac cells which will replace the damaged or diseased heart. Successful transplants will require defining the best source of cells to use for transplant, and the kinds of cells to use , for example, cardiac muscle cells, or cells which will help to build new blood vessels. We will also need to be able to provide enough cells, which will require standardized protocols for cell amplification and purification. Another important factor will be techniques which help the cells to survive after being transplanted. To define the optimal cell type, and how to amplify them, it is important to have a model system for human cardiovascular cells. Human embryonic stem cells (hESCs) are an ideal model because they can be amplified to large numbers, and they have the potential to become a number of different cardiac cell types. Not only are hESCs an ideal experimental model, they may themselves be able to provide cardiac cells for heart repair. Building functional heart tissue requires interaction between a number of different kinds of cardiac cells, including muscle cells and blood vessel cells. To investigate the potential of these different cell populations for cardiac repair, it will be important to be able to identify them and purify them from hESC cultures. This will require generating some model hESC lines which will make it easier to identify certain cardiac cell populations, and to work out conditions for growing large numbers of them. To generate these model hESC lines, we need to develop technologies so that we can specifically "knockin" some reporter genes (usually genes which make the cells a particular fluorescent color) to mark specific cardiac cell populations. These reporters are expressed when hESCs differentiate to specific cell types. Fuorescently marked cells can then be easily "seen" with a fluorescent microscope, and purified, based on sorting methods which recognize the fluorescent marker. The diseased heart is a relatively hostile environment for transplanted cells, so they do not survive very well. It is necessary to create a more friendly environment for cell transplants, by adding factors which improve survival, and by providing a more friendly environment using biomaterials to deliver the cells. Our proposed studies will try to improve several technologies required to repair diseased heart with cell transplants. We will optimize technologies to generate specific reporter hESC lines. We will also define specific growth conditions which will amplify specific cardiac populations, and that can be scaled up. We will also investigate methods for transplanting cells into infarcted heart in rat model systems, to optimize cell delivery and cell survival.
Heart failure can result from either myocardial ischemia or infarction, and is the leading cause of mortality in California, the United States and other developed countries. One potential therapy for heart failure is replacement of damaged cardiac tissue with healthy tissue, by cell transplant. Our experiments will develop several technologies that will be required to investigate the potential of different cardiac cell types for use in cell transplant, to amplify appropriate donor cell populations,and also to improve their survival in the diseased heart.