Seventy-five years ago the type of diabetes that affected children andyoung adults was lethal. In the 1990’s investigators found that a hormone, thatwas produced in Islets of Langerhans, was not being produced in diabetespatients.
This hormone, called insulin, enables other cells to take up sugarglucose from the blood for energy. Diabetes patients who were not making insulinhad glucose from food accumulating in the blood while other tissues werestarving. Their are two types of diabetes. Type 1 diabetes has ceased completelyfrom making insulin and the people who had this kind usually died. Type 2diabetes still makes a little insulin so suffers of this type usually lived. In the 1920’s prospects for people who suffered from type 1 diabetesincreased when it was learned that insulin extracted from animals and placed inhumans could prevent death.
Unfortunately, this is not a cure. Patients can getpotentially fatal diabetes-related disorders. These include blindness and, orkidney failure. Atherososclerosis, numbness and pain in extremities caused bynarrowed vessicles, may also be a problem. These effects are caused becauseinsulin injections can’t perfectly mimic naturally made insulin. That’s why a therapy that maintains glucose values within normal fromthe begging is needed.
An ideal treatment would be the implantation of islets. This, in theory, would only have to be done once and would insure proper insulinproduction. Successful grafts would also prevent diabete-related ills. At Paul E.
Lacy’s lab, experiments have been done for twenty- five yearson such a process. At first they were just trying to understand the mechanics ofhormone secretion. To start this they needed a way to separate islet clustersfrom the pancreas. These constitute only 2% of the entire pancreas, though, andare scattered throughout it. In 1967 they found a solution and took the isletsfrom rats.
These islets were transplanted in inbred rats to see if it wouldcontrol insulin production in diabetes patients. It was a success and kept bloodsugar levels normal. It even fixed early complications in the eyes and thekidneys. The next step was to test the process on humans. Unfortunately, theprocess that was used to separate rat islets from the pancreas did not work onhumans. They had to find a new way to solve the problem.
The problem took a fewyears to solve but in the mid 1980’s they finally found a semi-automatic methodto do it. This method managed to isolate 400,000 islets from the pancreas. Itwould take just the amount they estimated to maintain the blood sugar level. In 1986 the first experiment started. A lot of immune-suppresent drugsare needed so the foreign tissue would not be rejected. These drugs are risky,though, so the experiment was performed on patients who have had kidneytransplants and are already on these drugs.
They decided that the best place toplace the islets was into the portal vein leading to the pancreas. This wouldgive the islets nourishment from the beginning and would be less risky thanplacing them directly into the pancreas. The results were encouraging. Subjects were given 400,000 islets and thegrafts worked. But it was not enough to stop insulin injection. Later when theislets were increased to 800,000, the insulin injections were able to be stopped,at least for a time.
They also learned that the islets could be frozen andstored. Since 1990 about 145 patients have had the process done. Most wereunable to control the blood sugar level. Strain on the islets may have been aproblem and in some cases enough probably weren’t used. Doctors are proposing to give these transplants with graphs even thoughthe results weren’t perfect. The process is less costly and easier than completepancreas transplantation.
Many concepts have been considered though to solve the last part of theproblem. One is being looked into by Kevin J. Lafferty. That is, that if youdestroy passenger luekocytes, the tissue would not be rejected. This has beenattributed to the theory that it takes two signals for host white blood cells toattack foreign agents. These two signals are sent by the passenger luekocytes.
Unfortunately, to destroy these luekocytes you also destroy the hormone-producing cells. Joseph M. Davie has devised a culturing technique, though, thatkills the passenger luekocytes without hurting the hormone-producing cells. Heplaced 1,500 treated islets from one rat strain to a portal vein of another.There was no rejection! Unfortunately, the individual islets .
