As reported by Nature News, scientists in Japan now have official permission to treat people with heart disease with stem cells. Led by cardiac surgeons at Osaka University, they’ll be used to regenerate damaged muscle, also a common feature post-heart attack.

Stem cells clearly show a lot of promise in the medical realm. Derived from already differentiated cells and then chemically reprogrammed to return to a somewhat primitive state, or acquired in their stem cell state as is, they represent a sort of biological magic: With a little prodding from researchers, they can turn into any type of cell that’s required.

The potential is clear to see, and so far, they’ve been used to see if we can grow organs in a laboratory setting, provide the body with a way of killing off and immunizing itself against cancerous cells, and – as a new case exemplifies – mend the heart.

In this case, induced pluripotent stem cells (IPSCs) will be used; they are derived from skin or blood cells, and have been transmogrified back to their basic, precursor state.

On May 16, the Japanese health ministry gave medical practitioners permission to graft IPSC-generated tissues – each containing 100 million heart-muscle cells – and graft them onto disease-riddled human hearts. Previous work on pigs seem to show that they heal damaged tissue, but not through integration. Instead, they release chemicals that induce growth and regeneration in the damaged cells.

A 2016 paper, coordinated by Dr Yoshiki Sawa of Osaka University, describes these pig heart tests. It noted that “cardiac function showed significantly more improvement in juvenile than in adult pigs,” which hints that there are some nuances to the procedure whose translation to human hearts may not be entirely clear yet.

These grafts will initially be given to three people, and will represent the second clinical application of IPSCs anywhere in the world. If successful, effective, and safe, the team will apply to begin a larger clinical trial. The ultimate aim is that it will be sold as a commercially available treatment.

Japan has a fast-track system for regenerative medicine as of 2014, so if all goes to plan, it’ll become available sooner rather than later. As noted by Nature News, though, critics worry that this system – designed to save lives before they're lost – may be prone to error through a lack of data.

Japanese research institutions are increasingly looking to stem cells to fix our malfunctioning bodies and save lives. As reported by The Japan Times, scientists from Kyoto University recently used similarly reprogrammed stem cells to restore function to brain cells in monkeys, which hints at their potential for fighting Parkinson’s.

Another Japanese example, however, reminds us that we’re a while away from perfecting the craft: A clinical trial in humans to reverse blindness using stem cells had to be stopped in 2015 due to a risk of tumor development. In pretty much all cases, we’re still taking our first few baby steps with stem cells.

Thankfully, other countries are doubling-down on their stem cell research too. The latest example comes courtesy of the University of California San Francisco (UCSF), which involved an experimental procedure involving an in utero, bone marrow-derived stem cell transplant for a critically ill second-trimester fetus.

This rescued her from a lethal form of thalassemia, a genetic blood disorder that was causing her heart to swell and her partly developed form from getting enough oxygen. Her condition may or may not be cured, but considering how fetuses with heart conditions are often resigned to die in the womb, this is incredible stuff.