Pig cell transplants may treat human diabetes

 作者:隗荨     |      日期:2019-03-02 07:02:01
By Emma Young A treatment for type 1 diabetes that involves injecting pig cells into human patients is about to be trialled in Russia. The researchers say the treatment could provide a much cheaper, more accessible alternative to human cell transplants, but concerns about xeno-transplantation remain an issue. In people with type 1 diabetes, the islet cells of the pancreas do not produce enough insulin to regulate blood glucose effectively. The standard treatment is insulin injections. Transplants of human islet cells are being carried out, but there is a shortage of donors and the procedure can cost $300,000 per patient. Patients also have to take immunosuppressant drugs for life, which can cause unpleasant side effects. Living Cell Technologies (LCT), based in New Zealand, is extracting neonatal islet cells from pigs specially bred to be free from common viruses, bacteria and parasites. These pig cells are then coated in alginate, a derivative of seaweed, which allows glucose, insulin and oxygen to pass through, but blocks antibodies. As a result, and in theory, patients should not need to take immunosuppressants. Treatment could cost an estimated US$25,000 per patient, says Paul Tan, CEO of LCT. “This is a very reasonable line of investigation,” says Maarten Kamp, a diabetes expert at the Gold Coast Hospital in Southport, Queensland, Australia. “Certainly, there isn’t going to be enough human pancreatic tissue available for transplantation.” The year-long trial on six people, based at the ANO Institute of Biomedical Research in Moscow, will be run according to US Food and Drug Administration (FDA) standards and is scheduled to start in a few months. It will investigate the safety and effectiveness of the treatment. The coated pig cells are designed to release insulin in response to blood glucose levels, mimicking the action of pancreatic islet cells in healthy people. About 25 millilitres of the pinhead-sized capsules will be implanted into the abdomen, around the liver and spleen of each patient. This will happen during two operations, spaced six months apart. LCT hopes to run similar trials in New Zealand later this year. If those go well, it will apply to run Phase II trials in the US. Convincing the FDA to give the go-ahead will not be easy, however. “It is very difficult to get a breed of pigs that would meet FDA criteria,” says Tan. MicroIslet, a biotech company based in San Diego, US, had also been developing encapsulated pig islet cells for treating type 1 diabetes, but its latest announcements focus instead on encapsulated human cells. Some countries, such as Australia, also have moratoria on research involving xeno-transplantation. A previous study revealed that pig and human cells can actually fuse in the animal, leading to DNA from the two species becoming mixed (see Pig/human chimeras contain cell surprise). LCT says it has worked extensively on tests for viruses for both pigs and people, as well as on biologically ‘clean’ herds, so it will be able to show – it hopes – that viruses are not transferred. The company is also developing a treatment for Huntington’s disease,