Thin sheets of engineered artificial tissue can be readily manufactured because they do not require a vasculature, perfusion of fluids is sufficient to support the cells. For some years now, researchers have developed the capability to manufacture thin heart tissue patches. A number of preclinical studies in various animal models have demonstrated that applying these patches to an injured heart promotes greater regeneration and restoration of function than normally takes place. Here, the technique is combined with a minimally invasive form of surgery as a proof of concept, and used in rats following heart attack to promote greater regeneration.
For years, scientists have been working on ways to replace damaged tissue with healthy heart cells derived from stem cells. Early efforts showed promise, but most required open-heart surgery - a procedure too risky for many patients already struggling with severe heart failure. Scientists have long hoped that stem cells could provide a way to rebuild what the body cannot. By reprogramming ordinary adult cells such as skin or blood cells into induced pluripotent stem cells (iPSCs), researchers can coax them into becoming replacement heart cells. But safely and effectively delivering engineered heart tissues made from these cells has remained a major challenge.
With this in mind, researchers developed a flexible, paper-thin patch made of nano- and microfibers coated with gelatin. This hybrid scaffold supports a blend of human heart muscle cells, blood vessel cells, and fibroblasts - cells that form the tissue's structural framework - to create a living, beating piece of heart tissue. Before transplantation, the tissue is infused with bioactive factors such as fibroblast growth factor 1 and CHIR99021 that encourage the growth of new blood vessels and help the cells survive once they are in place.
"The beauty of this design is that it can be folded like a piece of paper, loaded into a slender tube, and delivered precisely where it's needed through a small incision in the chest. Once in place, it unfolds and adheres naturally to the heart's surface." Testing in preclinical rat models showed that the minimally invasive method improved heart function, reduced scarring, enhanced vascular growth, and lessened inflammation compared with conventional approaches.
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