Juan Carlos Izpisua Belmonte is a revolutionary and like most revolutionaries, he is ahead of his time. As the man behind the human-pig chimera experiment, he has received extensive criticism. But now, it seems his contemporaries are full of praise.

Belmonte’s foray into science was not traditional. He was forced to drop out of school at the age of eight to work – and only returned to education at 16. Noticing his exceptional intellect, teachers persuaded him to enroll at the University of Valencia.

Yet, he had no interest in science – he wanted to study philosophy. However, seeing the beautiful building of the pharmacy department – he registered there instead, on a whim. Despite obtaining a PhD in adipose tissue, he found the subject boring. Only when he moved to Germany to work in a lab doing pioneering work on the genes that control the body patterns of embryos, did he find his niche.

He was able to unite his interest in philosophy and natural aptitude in science and ask questions like how could a single cell unfold into a unique individual? And how much, really, separated humans from other animals?

This difference in thinking is what has made other scientists take notice

“He thought differently,” Ron Evans from the Salk Institute who recruited Belmonte said, ”and the combination of his thinking and meticulous execution was exciting.” Belmonte’s career is driven by his obsession with salamanders’ ability to regrow any body parts perfectly – and his desire to find out whether humans might one day, be able to do the same.

His pursuit led him to discover two new types of human stem cells including one, which can create every type of cell and can also form tissues like the placenta and amniotic sac. His lab has also reverse-engineered ageing in adult mice cells, helped edit heart disease genes in human embryos – and was part of the effort to create three-parent embryos.

“It’s hard to know where to start, he’s doing so many different things,” said Paul Knoepfler, a stem cell researcher at University of California. “You get the sense he’s sort of fearless.” This taste for pushing boundaries has given him a growing fan base.

“Juan Carlos is both rigorous and intrepid enough to take bold risks and then produce science that surprises us all,” expressed Dr George Daley, a stem cell researcher and dean of Harvard Medical School.

His dogged perseverance helped him

Belmonte’s interest in regeneration is because they are like “small embryos outside the body,” he said and Belmonte wanted to know if he could create organs outside the body for desperate people waiting for organ transplants. However he found that despite repeated trial and error, he was not able to make steam cells grow into cell types, let alone organs.

“We were trying to imitate nature with very little knowledge,” he said. They could not “educate the cells in the Petri dish.” It was when he rafted tissue from an embryonic mouse limb bud onto the wing bud of a chick embryo, and found development proceeded normally, that he realised development was similar across species.

Belmonte then began trying to grow human organs inside pig embryos although he and the scientific community initially did not think it would work. “The pig embryo sees the human cells as an invader. The natural response is to find a way to kill them,” Jun Wu, a senior researcher in Belmonte’s lab said. “We didn’t expect we’d find any human cells.”

But, they did – even if only one in 100,000 human cells survived. The fact that he even managed to make it work finally made his critics sit up and take notice.

He wants his research to be used only to help people

Belmonte is now working on improving the human cell count in organs by introducing cells of different ages to see which are accepted the most – using body region-specific stem cells which are more effective, and also CRISPR to edit out host genes that can be replaced with human ones.

He is struggling to continue his research around laws preventing him from doing so on ethical grounds, though. In fact, the National Institutes of Health in America was scrambling to formulate its policy on work on human chimeras following Belmonte’s application for a grant.

“There are no policies in place for what he’s working on,” said Knoepfler, “It’s all uncharted territory, and he’s one of the folks who is pushing us into that territory.”

Despite pressure from bioethicists and religious groups, Hank Greely, director of the Centre for Law and the Biosciences at Stanford University, opined that it may not be difficult for Belmonte to gain permission.

“Juan Carlos has always seemed aware of these issues,” said Greely.

According to Belmonte, “we’re in a critical moment in human evolution. Everything that has happened in the past billion years follows two rules: random mutation and natural selection.”

“We’re now at a moment in history where we don’t have to follow Darwin’s rules. We need to be conscious of that.” MIMS

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