“Current interventions don’t address the degeneration that can occur after a heart attack. You need other types of therapies to help with those,” says Garry Duffy of the Royal College of Surgeons in Ireland. Duffy is the coordinator of the Amcare project, which strives to develop such a therapy.
The project’s work focuses on the delivery of stem cells to regenerate the damaged muscle. While such approaches are already being trialled, Amcare intends to take the technique another step ahead by improving the heart wall’s uptake of the stem cells.
The partners cooperating in the project are developing materials that will boost the cells’ chances of survival and keep them fixed in the targeted area. They are also designing surgical devices that will enable surgeons to position these materials with their load of stem cells in or on the patient’s heart. The cells themselves are extracted from fatty tissue donated by adults undergoing liposuction.
A sticky problem…
“The heart’s main function is to pump blood around the body, but to do that it requires a blood supply itself. If that blood supply is cut off, the heart doesn’t receive nutrients or oxygen. The result is a heart attack or myocardial infarction, which causes cell death in the tissue,” Duffy explains.
Over time, this damage can spread, he adds, gradually reducing the organ’s ability to pump sufficient amounts of blood — particularly in situations where physical effort is involved. “The heart no longer has the reserve to increase output,” Duffy says. “Of course, this doesn’t happen for every patient.” The condition can develop if the damaged area is particularly large.
Stem cells can reverse the damage to the muscle, but keeping them in place long enough to do their thing is a challenge. “The heart is always beating,” says Duffy, “so if you inject something, it is going to be squirted right back out.” A promising technique currently being tested enables up to 20% of the injected stem cells to take hold, he notes.
Amcare is hoping to achieve a retention rate of 50%, which would significantly reduce the number of stem cells needed for successful treatment. To do so, it delivers the cells in a biomaterial that adheres to the heart wall.
This material also contains a substance that promotes cellular growth. It keeps the transplanted stem cells healthy in the oxygen- and nutrient-deprived area they are meant to revitalise and protects the local heart cells from further degradation.
The delivery medium is available as a gel or as a patch, to be placed on the inside of the heart wall or on the outside, respectively. Both are inserted by means of minimally invasive surgery using dedicated medical devices also designed by the project, and dissolve within a few days. The gel is injected into the heart with a catheter that is put into the patient’s groin and led up through the blood vessels. The patches are deployed through a small incision between the ribs.
Amcare will end in October 2017. By this time, the partners intend to complete the development of the technique along with the associated materials and instruments. Clinical trials could begin the following year, and the new therapy could then be made available to patients within another four years or so, says Duffy.
This is an exciting prospect in itself, but heart attack survivors are not the only ones who stand to benefit. The concept could be adapted to other situations where retention of therapeutic agents is an issue — such as the transplantation of pancreatic cells for the treatment of diabetes. Another EU-funded project, named Drive, will pursue this promising line of research.