Illustration: umg/eva meyer-besting
A cultured piece of heart wall, made from pluripotent stem cells, can restore damaged cardiac tissue. Implantation appears to be safe in macaques and humans.
A ‘patch’ made from stem cells can repair heart damage. A team of predominantly German biomedical researchers has demonstrated this following studies in rhesus monkeys and a human patient (Nature, 29 January). The cardiac function of rhesus monkeys that had previously suffered a heart attack improves durably after implantation of the patch. No serious side effects arise – unlike earlier attempts at cardiomyocyte implantation, which were associated with such complications.
Implanting cardiomyocytes derived from stem cells had previously seemed a promising method for repairing tissue damage, but this turned out to be a false promise for the time being. The method can produce serious side effects: cardiac arrhythmias and tumour growth. Such side effects do not occur with the German team’s patches. The patches are in effect a cultured piece of heart wall. The researchers produce them by inducing pluripotent stem cells to differentiate into cardiomyocytes and connective tissue cells, which are then seeded onto a specially made scaffold.
The German team first tested their heart wall patches in rats and then in rhesus monkeys (Macaca mulatta). Implantation in rats proved safe, allowing the researchers to obtain approval to proceed with studies in macaques. The rhesus monkeys in question first sustained cardiac damage through a heart attack and were subsequently implanted with a heart wall patch adapted for rhesus monkeys. The researchers examined the outcome of this procedure at three and six months. At both time points, the earlier damage appeared to have partially recovered. The thickness of the heart wall had increased, cardiac contractility improved, and the volume of blood ejected with each heartbeat had also increased. Coronary vessels likewise appeared to be functioning normally.
On the strength of these promising results, the researchers obtained approval to conduct a clinical trial in cardiac patients. To this end, they developed a heart wall patch from human pluripotent stem cells. The clinical trial is still ongoing, but the German team present the first results in the current Nature article. These concern the data from a patient with severe heart failure who participated in the clinical trial and successfully underwent a heart transplant three months after implantation of the heart wall patch. The explanted heart was thereby made available for histological analysis. Cardiac muscle tissue appears to have increased as a result of the patch, and the patient experienced no serious side effects from the procedure. The clinical trial is scheduled to continue until 2028.