Problems with Cure for Diabetes

[Marat]

A major research effort to develop a cure for diabetes has hit a roadblock which has not yet been explained. To cure type 1 diabetics, transplanting a whole pancreas or pancreatic beta cells exposed to the immune system is fairly ineffective, since the initial autoimmune disease which causes diabetes in the first place persists to damage the replacement islets, which have to be additionally protected against conventional rejection by highly toxic immunosuppressive drugs which are more damaging to the body than diabetes itself is. The shortage of donor islets and pancreatic tissue is also so extreme that even if the procedure worked perfectly, fewer than 1% of diabetics would be helped by this intervention.

 

An alternative is implanting porcine islet cells contained in a differentially permeable membrane which lets insulin out but keeps out the parts of the immune system that would normally cause hyperacute rejection of xenotransplant tissue. These membranes allow enough oxygen, blood, and nutrients to enter for the porcine islets to survive and for the islets to sense the required insulin amounts they should produce, and they also allow toxic metabolic by-products to be cleared.

 

But the first experiments on human subjects in Russia have now established that these encapsulated islets only survive from about a few months to at most a year and a half, and there seems to be no way to extend that lifespan. Since surgical intervention is required to replenish the islet cell supplies every time they fail, this 'cure' would soon prove impractical, since repeated surgeries would cause too much damage from scar tissue formation and adhesions. Also, since it now costs about $150,000 for each opening of the abdomen to restore the islet supply, this approach would be too expensive to be practical if the islets cannot be made to last.

 

So, does anyone have some speculative suggestions as to what is going wrong? Could this be some effect of humeral immunity on the graft? Are toxins failing to clear adequately and is this suffocating the graft? Is the oxygen, blood, and nutrient supply to the graft insufficient? Personally, I suspect some role in this failure from the initial autoimmunity which causes type 1 diabetes, since the graft failure among different patients varies greatly in both time of onset and extent, just as the degree of autoimmunity does.