Subcutaneous Implantation of Pancreatic Cells Shows Promise in Type 1 Diabetes

Implanting healthy pancreatic cells under the skin was shown to be a promising treatment for type 1 diabetes (T1D), according to a new study published by the Proceedings of the National Academy of Sciences. These findings suggest that the skin may be an effective way to improve insulin production and blood glucose regulation, according to the study authors.

"The skin has the advantage of being readily accessible," said senior researcher Michael Sefton, ScD. "It is also presents fewer hazards than other transplantation sites."

In patients with T1D, insulin-producing beta cells are damaged due to an immune system attack. Implanting healthy cells is expected to restore insulin function, but it has proven difficult to transplant these cells in an ideal place, according to the authors.

"Pancreatic islets are scattered throughout the pancreas in between other pancreatic cells that secrete digestive enzymes," said lead study author Alexander Vlahos, PhD candidate. "This makes it impractical to try and deliver islets to the pancreas: you would most likely be delivering it to a region of the pancreas that is secreting these enzymes."

Other organs, such as the abdominal cavity and liver, are also considered hostile environments that can damage the cells and render them ineffective.

"The accessible location of the skin makes islet transplantation a lot more manageable, especially if the patient responds negatively to the donor cells," Vlahos said. "The space under the skin has a large area so that it can support many islets, which is necessary for this approach."

The researchers decided to implant the cells under the skin since liver implantation requires too many donor cells, according to the study.

"You need to overshoot the quantity of islets when injecting into the liver because you lose about 60% of the transplanted cells within the first 48 hours," Vlahos said. "That amount of islets requires two to three donors for each recipient."

In the study, the authors injected healthy pancreatic islets under the skin. They discovered that blood glucose levels normalized within 21 days, as long as the researchers created blood vessels at the same time, according to the study.

"Pancreatic islets comprise approximately one per cent of the pancreas, but require 15% to 20% of the blood flow to the organ," Vlahos said. "We needed to ensure adequate blood flow to the islets in order for this to work."

When the islet transplants were removed, the authors found that blood glucose levels reverted back to diabetic levels, according to the study.

Additional studies are needed to determine how to best implant the cells to elicit the most benefits, according to the authors.

"The next phase of our research will involve engineering the blood vessel network first and then injecting fewer islets into the already vascularized tissue," Dr Sefton said. "A well-vascularized environment will allow more of the cells to survive and function within the host, reducing the need for multiple donors per patient."