BARP+ artificial pancreas
gives high hopes to diabetics

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BARP+
People suffering from type 1 diabetes could soon see their quality of life improve dramatically thanks to the work of the BARP+ (‘Development of a bioartificial pancreas for type 1 diabetes therapy’) project.

As the name suggests, the aim of the project is to develop a bioartificial pancreas which can be implanted into diabetics, freeing them from their regime of daily insulin injections and dietary restrictions. This artificial pancreas is not yet ready for implantation in humans, but it has already been successfully tested in small animals and preliminary experiments performed in pigs.

The project brought together 14 partners from 5 EU Member States. They include experts from fields as diverse as biochemistry, medicine, physiology, surface treatment, biomaterials, polymers and chemistry.

The project partners have already achieved a great deal; the concept for their bioartificial pancreas, in which insulin-producing cells are embedded in a membrane, has been validated by the project researchers and transplants have already been carried out in small pigs using a prototype of the device.

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Dealing with type 1 diabetes

In healthy people, blood sugar levels are regulated by a hormone called insulin, which is produced by the ß-cells of the pancreas. However, in people with type 1 diabetes, these ß-cells are destroyed by the body’s own immune system, and so the pancreas is unable to produce enough insulin.

Without insulin, blood sugar levels soar – a condition known as hyperglycaemia. Long-term exposure to high levels of glucose can damage the vital organs, and diabetics are particularly vulnerable to a range of health problems including heart disease, poor circulation, kidney problems, eye problems and nerve degeneration. Over 210 million people worldwide, including 25 million in the EU, suffer from diabetes, and 15 % of these cases are type 1 diabetes. Most type 1 diabetics are diagnosed early on in life.

Currently, sufferers of type 1 diabetes manage their condition by injecting themselves with insulin at least once a day and following a strict diet. Type 1 diabetics must also check their blood sugar levels regularly, and have frequent medical check-ups to pick up on the early signs of the complications associated with their condition.

Needless to say, many diabetics struggle with the self-discipline required to monitor their diet and lifestyle and none relish the thought of using a needle every day for the rest of their lives. Furthermore, the insulin injections do not always control blood sugar levels perfectly. All of this seriously affects diabetics’ quality of life.

Recently, advances have been made in a new treatment which involves implanting replacement pancreatic cells into a diabetes patient. However, while this treatment is effective, it is not without limitations. The first problem is the small number of cell donors.

However, the main challenge facing doctors is the fact that the human body is programmed to attack and reject any foreign tissue. To overcome this immune response, transplant patients must take immunosuppressant drugs. However, by definition, these weaken the immune system, leaving the patient vulnerable to infections.

Sneaking cells past the immune system

The BARP+ approach to the problem was to hide the implanted cells from the immune system by placing them inside a system of artificial membranes. The challenge for the researchers was to create a system which would allow the easy exchange of nutrients, oxygen and insulin while shielding the cells from the immune system.

The team had to overcome a number of problems in the design of the device, including a lack of oxygen (hypoxia), which the researchers addressed by adding fluorocarbons (inert liquid organic compounds) to the device.

The fluorocarbons also proved effective at having a beneficial effect on tissue preservation and also tackling another problem, namely the aggregation of pancreatic cells within the device. Another innovation was the use of multiple layers; this enabled the researchers to give different functions to different layers. Meanwhile, the use of a molecule which promotes the growth of blood vessels helped to ensure the device’s blood supply.

The resulting bioartificial pancreas comprises a sheet of pancreatic cells which have been encapsulated in a layer of artificial membranes. Because the system removes the need for immunosuppressive treatment, it raises the possibility of xenotransplantation – the use of pancreatic cells from non-human origin.

As there is a severe shortage of cells from human donors, animals represent an important potential source of cells and organs for transplant purposes. However, the strong immune response triggered by these animal cells represents a major barrier to xenotransplantation.

From laboratory to clinic

The team’s designs have already been tested and validated in laboratory conditions. Tests in pigs are helping scientists to establish the best location for the implant. Ideally, it should not affect the functioning of other organs, but at the same time, the cells must be able to receive the nutrients and oxygen needed to keep them alive. The scientists must also establish whether or not the fragile device can survive in close proximity to other working organs. Other tests in this phase of the project include pig-to-pig cell transplants.

The information gleaned from this work is providing researchers with the information needed for performing this sort of operation on human diabetic patients in the near future.

Until recently, very little research into the potential of a bioartificial pancreas had been carried out. Thanks to the BARP+ project, Europe now leads this young field, and type 1 diabetics everywhere can look forward to the prospect of a healthier future and a better quality of life.