Researchers have found that stem cell cultures infused with growth factors could be used to repair damaged heart tissue without the threat of patient rejection.
Ren-Ke Li (Toronto Medical Discovery Tower, Ontario, Canada) and team say that their discovery transforms aged stem cells into cells that function like much younger ones. These may one day enable scientists to grow cardiac patches for diseased or damaged hearts from a patient's own stem cells, no matter how old they are, while avoiding the risk for rejection.
Previous studies have used cells derived from a patient's own body to avoid rejection. However, until now, clinical trials using this type of therapy in cells of elderly patients have not been viable due to their limited function in comparison with cells from younger patients.
Li and team covalently immobilized two proangiogenic cytokines - vascular endothelial growth factor and basic fibroblast growth factor - onto porous collagen scaffolds. They seeded human mesenchymal stromal cells from four young (mean age 50.0 years) patients or four old (mean age 74.5 years) donors into the scaffolds, with or without growth factors.
As reported in the Journal of the American College of Cardiology, the patches were characterized and used for surgical ventricular restoration (SVR) in a rat model of myocardial infarction.
In vitro results showed that, although the cells from older donors grew at a slow rate in the scaffolds, the presence of cytokines modulated the aging-related p16 gene and enhanced cell proliferation, converting the old cell phenotype to a young phenotype.
In vivo studies showed that 28 days after SVR, patches seeded with cells from older donors did not induce functional recovery as well as patches seeded with young cells. However, cytokine-enhanced patches seeded with older cells exhibited preserved patch area, prolonged cell survival, and augmented angiogenesis.
Rats implanted with these patches had improved cardiac function. The patch became elastic tissue and the older cells were rejuvenated, note the authors.
Li and team hope that in future, they will create myocardial tissue that can be used to repair defects such as aneurysms.
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