Pig cells could be used to deliver insulin to Type 1 diabetes patients via an implant under the skin, potentially freeing sufferers from the need to have regular insulin injections, according to researchers from Glasgow Caledonian University.
Because sufferers of Type 1 diabetes are unable to produce the hormone insulin in their pancreas to regulate blood sugar levels they need regular insulin injections.
Human cell transplants are already being used to treat some Type 1 patients. The technique - called islet transplantation - takes cells from the pancreas of a dead human donor which are then implanted into the liver of a Type 1 patient where they begin to produce insulin. However, the treatment is expensive (though in the UK it is available for a few on the NHS) and patients also need to take drugs to suppress the immune system to stop the cells being rejected, which can have unpleasant side effects.
One New Zealand company is exploring this technique using cells from pigs that are bred in an environment free from common viruses.
But while the Glasgow research also employs the idea of xeno-transplantation, where living cells, tissues or organs are transferred from one species to another, rather than implanting cells from the pancreas, they want to deliver it through the skin. The team is building on an earlier study, which suggested that in primates, microcapsules implanted under the skin could correct diabetes for up to six months.
Dr Linda Scobie, a Reader in Clinical Virology at Glasgow Caledonian, said: “The implant would have significant advantages over other treatments. We believe there will be little risk of the body rejecting the implant and unlike in other transplants, the patient doesn’t have to undergo immune suppression, a process which can leave patients open to a life-threatening infection.”
Scobie said the implant would be made from an alginate matrix which, when it was placed under the skin, would be vascularised by the body. Pigs were ideal she said “in order to obtain large amounts of insulin producing cells that are just not available from human sources.”
The research comes on the back of the Xenome project, which had funding from the EU to develop genetically engineered pigs that could be used in the field of transplantation.
But pig-cell insulin implants are still some way off - the project has only just received funding for pre-clinical (non-human trials) and work to produce genetically modified pigs free from viruses or other health problems is also ongoing.
Paul Johnson, Professor and Director of the Islet Transplant Programme in the Oxford Centre for Diabetes, said the use of pig islets for islet transplantation was one of the two main areas of investigation in the search for a ready supply of islets of Langerhans (the pancreatic cells that secrete hormones, including insulin, into the blood) to transplant into Type 1 diabetes patients. The other was stem-cell derived islets.
“There are a number of challenges remaining before animal islets can be used routinely in humans,” Johnson said. “These include the immune challenges of transplanting across species, the challenges of animal viruses and other infections (many of which are unknown and therefore undetectable), and the ethical/social considerations.
"One approach to the immune challenges is to place the islets within protective capsules (made from alginate) in an attempt to "hide” the islets from the immune-system of the patient. This capsule technology is attracting considerable attention at present with plenty of good science being conducted.“
But, he warned: "It is vital that the immune and infection challenges/concerns are rigorously addressed and resolved before clinical trials are conducted.”
The project is yet another strand of work using pigs in human health, which has included the idea of transplanting whole pig organs into humans or even growing human organs inside pigs for use in transplant operations to tackle a shortage of human donor organs.
In 2012, South Korean scientists said they had transplanted the heart of a cloned pig into a monkey.
But xeno-transplantation is controversial for ethical as well as biological and regulatory reasons, and research in this field is banned in Australia. In 2004, researchers were surprised to find that cells could fuse; pigs that were given human stem cells while foetuses later had pig, human and hybrid cells.
However, a 2003 survey found that respondents were more positive towards the idea of receiving animal cells than a whole organ.