GENE THERAPY: A BREAKTHROUGH IN DIABETES TREATMENT.
Mohamed Yousuf BHUGUN (DMLT, MSc (UK), FIBMS.)
International Liaison Officer ( North America) / Research Scientist
Association of Biomedical Analysts (ABA)
A team of Canadian scientists at the University of Alberta in Edmonton has successfully been able to inject the insulin-encoding gene in fertilized mouse eggs causing special cells, called K cells, to release insulin into the bloodstream. This is considered as a breakthrough in the treatment of diabetes mellitus (DM), a disease that affects more than 2 million Canadians, more than 10% of the Mauritian population and 1 in 20 of the adult world population.
People with DM, mainly insulin-dependent (IDDM or type 1) must frequently monitor their blood glucose levels by taking insulin injections. With this gene therapy, diabetic patients may one day be free from the hassle of insulin shots and avoiding at the same time the long-term complications including heart and kidney diseases, blindness and limp amputation.
As the co-researchers T. Kieffer and A. Cheung reported in the December issues of the journals Science and Nature, the innovative part is that the K cells are triggered to produce insulin in response to meals and in proportion to the amount of carbohydrates consumed. This is vital as a delay in the release of the hormone or a failure to shut down the insulin secretion during normoglycaemia can result in serious complications namely hypoglycaemic shock. The blood glucose level can drop to dangerously low level causing tremors, confusion, coma and even death.
The K cells are found in the stomach and upper intestine where they are responsible for the secretion of a hormone called the GIP into the blood in response to rising blood glucose level. In fact, the GIPís function is to signal the beta cells in the pancreas to start releasing insulin. The insertion of the insulin-encoding gene will cause the K cells to directly produce insulin and monitor the blood glucose level.
In the experiment, the mice were given the insulin-encoding gene in the embryonic stage where it was incorporated into every cell of their bodies. But only the K cells in the gut were capable of using the gene to produce insulin. The next step is however, to find a way of inserting the gene directly into the cells. The Canadian researchers believe that this might not be difficult as the digestive tract is readily accessible by non-invasive method. In addition, the gut is an attractive target as it is one of the most rapidly renewing tissues in the body. So, it may be possible to deliver the gene to stem cells that differentiate into several types of cells, including K cells, in the lining of the stomach and intestines. That would eventually create a permanent supply of insulin-producing K cells which themselves number in billions.
However, people wonít be able to benefit from this research for a long time as it will take some years before the testing is a complete success in animals and eventually in humans.