A great deal of work is being done to come up with a method of reverting adult stem cells to an embryonic-like state without making them inherently dangerous in the process. Of course after the adult cells are returned to an embryonic-like state they have to be coaxed into becoming the type of cell that is necessary in the particular regenerative medicine application.
About a month ago a Mayo Clinic study, one that delivered embryonic stem cells to mouse embryos in the earliest stages of development, found that the resulting mice demonstrated a capacity to recover from cardiac injury in adulthood. According to Mayo this study provides the first evidence that preventive regenerative medicine can successfully be used to treat myocardial infarction through prophylactic intervention.
Mayo researchers injected mouse embryos with embryonic stem cells that had been used to successfully treat ischemic heart disease following heart attack. The resulting animals incorporated between five and 20 percent of labeled stem cell-derived tissue. They were born with no apparent abnormalities, and the tested and control groups had similar overall baseline cardiac disease risk profiles. They also demonstrated similar cardiac performance during the one year follow-up.
Now, In a proof-of-concept study, Mayo researchers have demonstrated that induced pluripotent stem (iPS) cells can be used to treat heart disease. In this study, researchers reprogrammed ordinary fibroblasts, cells that contribute to scars such as those resulting from a heart attack, converting them into stem cells that fix heart damage caused by infarction.
"This study establishes the real potential for using iPS cells in cardiac treatment," says Timothy Nelson, M.D., Ph.D., first author on the Mayo Clinic study. "Bioengineered fibroblasts acquired the capacity to repair and regenerate infarcted hearts."
This is the first application of iPS-based technology for heart disease therapy. Previously iPS cells have been used on only three other disease models: Parkinson's disease, sickle cell anemia and hemophilia A. The ultimate goal is to use iPS cells derived from patients to repair injury. Using a person's own cells in the process eliminates the risk of rejection and the need for anti-rejection drugs. One day this regenerative medicine strategy may alleviate the demand for organ transplantation limited by donor shortage, the researchers say.
"This iPS innovation lays the groundwork for translational applications," comments Andre Terzic, M.D., Ph.D., Mayo Clinic physician-scientist and senior author. "Through advances in nuclear reprogramming, we should be able to reverse the fate of adult cells and customize 'on demand' cardiovascular regenerative medicine."
Compared to non-engineered fibroblasts, the iPS cells:
- Restored heart muscle performance lost after the heart attack
- Stopped progression of structural damage in the damaged heart
- Regenerated tissue at the site of heart damage
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