A Pig Cornea Transplant Can Help the Blind to See

Inside a cavernous, brightly lit shed, row upon row of pigs snuffle and shuffle around in their pens. Pork is big business in China, and this farm in the Guangdong Province in the south of the country has 2,000 pigs. These animals are bred for their meat - but there's now a new use for the pig parts that aren't destined for the dinner table.

Pig Bred for its Meat and Corneas

(Pig Eyes in Jars Above)

Once the pigs are killed, their corneas - the thin, transparent films that cover the front of the eye - are removed from some of them and set aside, to be transplanted into humans. 

A few hours' drive away is China's oldest, and largest, eye hospital - the Zhongshan Ophthalmic Centre. China accounts for a fifth of the world's blind people: about eight million of its 1.4-billion population.

Dr Yuan Jin

As Dr Yuan Jin walks around the busy ward, he tells me that corneal disease is responsible for between 3.5 and five million of these cases. Injury or infection of the cornea, if untreated, can eventually lead to loss of sight - and for many, the only hope is a transplant. But the waiting list is extremely long. Once the main source of organs in China was from executed prisoners. But last year, the government stopped this controversial practice, and instead began encouraging people to sign up to donate their corneas after death. Few, though, are choosing to do so. Yuan explains: "In China, people have traditional opinions. They don't like to give their corneas. This is the main reason why we can carry out just 5,000 cornea transplants a year."

Today he is examining the eyes of patients who have been given pigs' corneas. The Chinese government gave the go-ahead for this experimental procedure last year, and about 200 operations have now been carried out. Fifty-eight-year-old Wu Pinggui is one of the latest recipients. One of his corneas became infected after an insect flew into his eye. "I didn't take care of the injury and it got worse," he tells me. "My eyes became red, swollen and painful." Eventually he lost his sight in that eye - and subsequently lost his job as a security guard. Now, 24 hours after surgery, some sight is returning. I ask him if he was surprised to be offered an animal's cornea. "I wasn't too surprised, I trusted the doctor's decision," he says.

CRMI Laboratory

Just 35 years ago, the city of Shenzhen was a fishing village. Today it's been transformed into a hub for innovation, and China Regenerative Medicine International (CRMI), the company that has developed the new cornea procedure, has its laboratory here.

Dr Shao Zhengkang

"We tried many animals - goats, dogs, pigs and cows," says Dr Shao Zhengkang, the company's chief executive, explaining that it took 10 years of research. Finally we found the structure of porcine corneas is very similar to a human's." Inside the lab there are flasks filled with corneas that have been removed from the pigs. They are milky white and glutinous - and need to undergo a process called decellularisation. Essentially the pig cells are stripped away, removing the animal DNA, proteins and lipids.

Cornea Tissue with Pig Cells Before Removal

Anything that could cause the patient's body to reject the tissue has to go. All viruses and bacteria are also inactivated, to prevent any diseases crossing from the animals into humans.

Just the basic shape, the collagen scaffolding, of the cornea is left behind. Once transplanted, it is then repopulated with the patient's human cells. Shao shows me the final product. The cornea looks like a contact lens. CRMI has spent 1bn Chinese Yuen (£100m, or $150m) developing it, but Shao admits the treatment is still at an early stage. "It's very different from the traditional treatment. It's totally new. So it takes time to introduce to hospitals, patients and society," Dr Shao says. The company says the success rate for the operations is above 90% - about the same rate achieved with human transplants. But some believe that China is moving too quickly, without assessing the risks - or the ethics. Animal-to-human-transplantation is just one area where China is straying on to controversial ground. Work on stem cells, cloning and gene-editing of embryos is also making waves in the international scientific community.

In the hospital, Wu Pinggui's check-up has gone well. His eye is still a little red, but the healing process has begun. He says this will make a big difference to his life - and he hopes that when he's better, he'll be able to find a new job.  "I think some people have the view that China is at a frontier in science, and therefore there's a lot of ambition and appetite to explore the latest technology," says Charlotte Liu from Springer Nature. "And therefore, in that context, the time and the effort required to debate, to discuss and fully understand the consequences before embarking on something is probably not entirely there." But she says increasing scrutiny from other researchers around the world does seem to be changing this. "Science is still relatively young in China," she argues. "And the culture of doing science and ethics needs time to develop and cultivate."