Heart disease is the leading cause of death in the U.S. for both men and women, killing 610,000 Americans each year. Someone in the U.S. has a heart attack every 42 seconds. A recent study has revealed that stem cells derived from one Macaque monkey transplanted into five other animals helped them heal after a heart attack. This could pave the way for using stem cells from one person in the treatment of other people with heart attacks.
It is now possible to reprogram any almost any cell in the body into a pluripotent stem cell or iPSC that can become any cell in the body. These iPSCs are made by adding four genes that change the genes used in specialized cells such skin cells. The new genes restart genes from early development, allowing these cells to become almost any type of cell in the body. Under very specific laboratory conditions iPSCs can be then used to make cells to repair damaged organs, such as neurons to treat damaged or diseased brains, heart muscle cells or cardiomyocytes to treat a heart attack or any other cells in other damaged organs.
Harvesting cells from an individual to make iPSCs to treat that person would greatly help to avoid the type of rejection that you would see in organ transplantation. However, it is very laborious and expensive to make iPSCs for each person needing cell replacement therapy. Also, treatment after a heart attack requires the infusion of a large number of heart cells derived from iPSCs, which would also consume quite a bit of time and expense. What if iPSCs could be generated from one person and then used to create large numbers of heart cells that could be stored and used to treat several people? Just as in organ transplantation, you would have to use a donor whose cells were compatible with the recipient so that the cells would not be rejected.
To test this possibility, researchers created iPSCs from one macaque and used them to treat five other monkeys with heart attacks. Skin cells were isolated from the donor macaque and four genes were used to reprogram them into iPSCs. The iPSCs were then programmed to develop into cardiomyocytes. Five hundred million cells were injected into the damaged hearts of five organ-matched monkeys. After 12 weeks, there was no rejection of the donor cells in monkeys treated with two anti-rejection drugs that are routinely used in humans after transplantation.
The implanted heart cells became integrated into the recipient hearts and developed the electrical connections required for them to beat. The recipient hearts’ contractile functions were improved at four and 12 weeks after receiving the grafted heart cells.
This study demonstrates that grafted heart cells improve the contractile functions of the heart and could benefit humans after a heart attack. This study provides hope that rather than having a permanent scar in the heart muscle after a heart attack and decreased function, this type of therapy could replace the dead heart cells with new cells that would then function normally.