Treating diabetics with insulin-producing cells

While infusion pumps can go some way towards mimicking normal control of blood insulin levels, transplantation of insulin-producing pancreatic cells should effectively cure the diabetic patient. This approach has been adopted thus far with almost 200 patients, with encouraging results. 

Initial experiments in the 1970s using inbred strains of rats illustrated the feasibility of this approach. Insulin-producing pancreatic islet cells donated by one set of rats were transplanted into other rats of the same strain, first made diabetic by injection with drugs such as streptozotocin, which destroy the pancreatic B cells. 

Such islet grafts permanently returned blood glucose levels in the diabetic animals to normal values. Even more encouraging, this treatment prevented development of diabetic-associated complications of kidney and eye function (which, in human diabetics, can lead to kidney failure and partial blindness). 

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HORMONES OF THERAPEUTIC INTEREST 321 Treating diabetics with insulin-producing cells... 

Insulin is necessary for controlling type 1 diabetes mellitus that is caused by a marked decrease in the amount of insulin produced by die pancreas. Insulin is also used to control the more severe and complicated forms of type 2 diabetes mellitus. However, many patients can control type 2 diabetes with diet and exercise alone or with diet, exercise, and an oral antidiabetic drug (see section Oral Antidiabetic Dmgp ). Insulin may also be used in the treatment of severe diabetic ketoacidosis (DKA) or diabetic coma. Insulin is also used in combination with glucose to treat hypokalemia by producing a shift of potassium from die blood and into die cells. 

Numerous studies have indicated that pro-inflammatory mediators (cytokines) are involved in the destruction of the insulin-producing p-cells of the pancreas in the development of type I diabetes. Tabatabaie et al. introduced cytokines and PBN into the pancreas of rats. The analysis of pancreatic extracts revealed that the cytokines stimulate the formation of lipid radicals. Radical generation did not occur in rats treated with streptozotocin, which destroys the P-cells.33 Evidence for the role of radicals in diabetes has also been provided by spin trapping studies in pancreatic homogenates, showing that streptozotocin, which is often used to induce the condition in laboratory animals, stimulates OH production.332 Other workers, using EPR to observe the decay of a spin probe in the abdomen of mice (at 1.2 GHz), have demonstrated that strep-... 

Glucophage is an antidiabetic drug prescribed to treat Type II diabetes. Type II diabetes is also called non-insulin-dependent diabetes mellitus. Individuals who have Type II diabetes are usually unable to produce enough insulin naturally (in response to the food they ingest) or suffer cell insulin receptor-site insensitivity. However, Glucophage can be prescribed by a doctor for Type I diabetics as a means of additional glucose (blood sugar) control in unison with insulin injections. 

Chronic Diseases. Xenotransplantation has the potential to treat many chronic diseases that cause cell death. For example, in diabetes, pancreatic cells that produce insuhn are destroyed. Encapsulation is being tested as a means of introducing porcine islet cells (pancreatic cell structures from pigs) into human patients with diabetes. The encapsulated porcine cells help these patients produce the insulin that they would otherwise have to inject into themselves. 

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