Indian scientists are using tissue engineering to give diabetes patients new insulin-making cells……...CLICK & SEE
Biomaterials scientist Prabha Nair is pitting her expertise of polymers to hold out a new line of hope for patients with diabetes who are dependent on insulin shots. In her laboratory, she has used two structures fashioned out of polymer materials to normalise blood sugar in rats with diabetes for up to 90 days. One of the polymer structures is designed to make insulin-secreting cells function properly, while the other is intended to protect such cells from threats that might emerge from the body’s immune system.
Nair and her colleagues at the government-funded Sree Chitra Tirunal Institute of Medical Sciences and Technology (SCTIMST), Thiruvananthapuram have combined two applications of polymers to tackle two major obstacles that have held back a promising but experimental treatment for diabetes from widespread use. The treatment, called islet cell transplantation, involves the removal of insulin-secreting cells from the pancreas of a deceased organ donor and their implantation into a patient with diabetes.
It is nearly a decade since researchers at the University of Alberta in Edmonton, Canada, demonstrated that islet cell transplantation may help patients with diabetes acquire normal blood sugar levels and achieve some level of freedom from the need for insulin.
A review of islet transplantation on 225 patients between 1999 and 2006 had revealed several benefits — including reduced need for insulin, improved blood glucose control, and lowered risk of hypoglycemia, according to the National Institute of Diabetes and Digestive and Kidney Disorders in the US. Two years after the islet transplantation, about one-third of the recipients were free of the need for insulin shots, the review suggested.
Islet cell transplantation, however, is not standard therapy yet. “There is a critical shortage of islet cells because of a shortage of organ donors,” says Nair, a scientist in the division of tissue engineering and regeneration technologies at the SCTIMST.
Patients who receive islet cells need to take immunosuppressive drugs throughout their lives to prevent their immune systems from destroying the implanted cells. These drugs have side effects including an increased risk of cancer.
The SCTIMST researchers harvested a class of cells known as pancreatic progenitor cells from mice and placed them in a cocktail of appropriate biochemicals where they turn into insulin-secreting islet-like cells.
The scientists then loaded these islet-like cells into three-dimensional scaffolds constructed out of a gelatin, a natural polymer, and polyvinylpyrrolidone, a synthetic polymer. The islet-like cells proliferate on the scaffolds and serve as a potential source of insulin.
In experiments, the scientists observed that rats with diabetes that received these islet cell-bearing scaffolds alone died within 20 days. Their scaffold cells had been attacked by the rats’ immune systems, leading to the destruction of tissue and the failure of the implantation.
“We also designed a polymer capsule to shield the implanted islet cells from the immune system,” Nair told KnowHow. When the scientists combined the scaffolding, also called tissue engineering, with encapsulation, the rats survived for up to 90 days.
The rats were models for type-I, or insulin-dependent diabetes, but researchers say the tissue engineering and encapsulation strategy may also be considered as a possible option for patients with adult-onset diabetes who need insulin injections. Given the differences in the lifespans of rats and humans, some researchers believe the 90-day freedom from insulin observed in the laboratory animals may be equivalent to several years in humans — although exactly how long is still a subject of debate.
“These results are really exciting,” says Aroop Dutta, a tissue engineering specialist and founder of ExCel Matrix Biologicals, a Hyderabad-based start-up in biomaterials and tissue engineering, who was not connected with the research in Thiruvananthapuram.
“There just aren’t enough human-derived islet cells for the large numbers of diabetes patients dependent on insulin. Animal cells or stem cell-based approaches are the only viable options as sustained sources of islet cells,” he adds.
The results of the SCTIMST’s experiments were published last Friday in the journal Acta Biomaterialia. The researchers say their use of islet cells from mice in rats with diabetes suggests that the polymer capsule that keeps the immune system at bay may facilitate xenotransplants — the use of cells or organs across species — as an option for reversing diabetes. “But there is still much work to be done,” Nair cautions.
“We’ll need to establish that this also works in large animals,” she said. The SCTIMST group plans to initiate studies in pigs with diabetes. If the technique is indeed shown to work in large animals too, it could be ready for human clinical trials within two or three years.
Source : The Telegraph ( kolkata, India)
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