The failing heart is the focus of much of the early work to develop stem cell therapies. There are many good reasons for this: the heart is an organ of compartively simply structure (versus, say, lungs), well understood, and the market for any improvements over present therapies is both lucrative and vast. Any sane person would pay the cost of heart surgery for a procedure that was both far less risky and more beneficial to long term health.
The time and expense required to move therapies from lab to clinic is now so huge, however, that significant improvements are achieved in the laboratory well before applications of the early results are available to the public. This is yet another thing to blame on the ridiculous nature of the FDA's regulatory requirements. So much good could be achieved in the absence of that stifling bureaucracy.
Here's an illustrative piece for those of us who have been following progress in first generation stem cell therapies: incremental improvements in delivery, the ability to isolate and culture more useful stem cell populations, and researcher experience is producing improvements in the outcome without any great change in the basic model. Find stem cells, put them in the patient, and then stand back and watch the resulting regeneration.
Clinical trials of myocardial stem cell therapy traditionally have relied on surgery - infusing the stem cells directly into the heart or injecting them into the myocardium, the heart muscle - invasive methods that can result in harmful scar tissue, arrhythmia, calcification or small vessel blockages.
"In our research with a swine model of heart failure," said Lee, "we've found that only 1-to-2 percent of [mesenchymal stem cell ] MSCs infused into the myocardium grafted into the heart, and there was no evidence that they differentiated into heart muscle cells. In addition, diseased tissue is not a healthy environment for cell growth.
"For these reasons, and because patients with heart failure are not good surgical risks, it made sense to explore a non-invasive cell delivery approach," said Lee. "An important feature of MSCs is their ability to produce a plethora of tissue healing effects, known as "tropic factors," which can be harnessed for stem cell therapy for heart failure.
"Since skeletal muscle is the most abundant tissue in the body and can withstand repeated injection of large number of stem cells, we thought it would be a good method to deliver MSCs," Lee said. "We hypothesized that MSCs, via secretion of these functionally synergistic trophic factors, would be able to rescue the failing heart even when delivered away from the myocardium.This study proves our hypothesis"
this non-invasive procedure increased myocytes, or heart cells, by two-fold and reduced cardiac tissue injury by 60 percent. The therapy also improved function of the left ventricle, the primary pumping chamber of the heart, by 40 percent and reduced fibrosis, the hardening of the heart lining that impairs its ability to contract, by up to 50 percent.
It's a very good illustration of the current understanding of how stem cell transplants work - it's largely due to biochemical signals emitted by the new stem cells. They issue marching orders and cells already present in the body act upon them. This suggests that the next phase of regenerative research is to do away with stem cells as a part of the therapy and focus instead on replicating the beneficial signaling mechanisms directly.