Kidney transplants restore health in those suffering from renal failure, and heart transplants save the lives of those with congestive heart failure.
So, why can’t a pancreas transplant be performed to treat those with diabetes?
The question was at the center of a recent, lengthy discussion on Reddit.
The simple answer is, when it comes to treating diabetes through transplant, it’s considerably more complicated and far less effective than other procedures.
“Your kidneys, heart, and liver are organs that can weather the storm of a transplant,” explains Dr. Jennifer Dyer, pediatric endocrinologist at Central Ohio Pediatric Endocrinology and Diabetes Services (COPEDS) and someone who is known as the “EndoGoddess” in the diabetes community.
A pancreas transplant, on the other hand, is a much more risky surgery.
“The pancreas is just so delicate, and generally, it needs to be transplanted with other organs like the intestines and the liver to ensure a higher rate of success,” Dyer told Healthline. “And a full pancreas transplant isn’t typically done to repair insulin production, but instead to treat severe issues within the gastrointestinal tract, like the malabsorption of dietary fat.”
Understanding the pancreas
Contrary to common understanding, the pancreas does far more than just produce insulin.
The part of the pancreas responsible for insulin production is the “endocrine” function. The rest of the pancreas’ activity is its “exocrine” function.
The exocrine function of your pancreas secretes enzymes that enable your body to break down the macronutrients that make up the food you eat such as proteins, fats, and carbohydrates.
The endocrine function of your pancreas secretes hormones such as insulin and glucagon. Both are essential to controlling blood sugar.
Insulin makes use of the glucose in your blood (which comes largely from the food you eat) to ensure your blood sugar doesn’t rise above normal levels.
Glucagon serves to prevent low blood sugars by signaling to your liver to release glycogen, which is simply stored glucose.
Another hormone produced by the endocrine function of your pancreas is amylin, which helps to control appetite, delay the rate at which your stomach empties broken-down food into the bloodstream, and controls the amount of glycogen released by the liver.
The importance of islet cells
To restore insulin production, a patient needs an “islet cell” transplant.
Your islet cells are from the “Islets of Langerhans” portion of the pancreas, named after its discoverer, German physician Paul Langerhans.
Within each islet cell is a trio of smaller cells: beta, alpha, and delta cells. The beta cells within the islet cells are responsible for the production of insulin.
Transplanting an islet cell is not a simple procedure, nor is it a long-term solution for most people with diabetes.
In fact, because it is a considerably precarious and unreliable procedure, it’s only performed on patients with extreme hypoglycemia unawareness, said Dyer.
Hypoglycemia unawareness is a condition in which a patient no longer experiences the helpful warning signs of an oncoming low blood sugar.
Being unable to feel those symptoms (such as lightheadedness, hunger, dizziness, trembling, and confusion) is dangerous because it means the patient can’t treat the problem by eating a fast-acting source of carbohydrate to prevent blood sugar from dropping to severely low levels that can result in seizure or death.
Patients with hypoglycemia unawareness have been deemed eligible for a transplant when it’s apparent that their unpredictable and severe low blood sugars are affecting their ability to function safely on a daily basis.
The challenges of a transplant
But being eligible for an islet cell transplant doesn’t mean life is going to become effortlessly free of diabetes.
Instead, it’s simply a trade for a new variety of challenges.
“A successful islet cell transplant actually requires multiple cadavers to collect at least 40 islet cells for one patient’s transplant,” says Dyer.
Simply collecting useful islet cells is complicated because, while they are being donated by cadavers, the islet cells of a cadaver are being rapidly destroyed after that person’s death.
“It’s estimated by the NIH [National Institutes of Health] that only slightly more than half of decedent donors, which are rare enough already, are viable for islet transplantation,” explains Reddit user Yoojine in a recent, lengthy discussion on the site about islet cell transplants. “Even if you get a good donor, islet recovery rates aren’t perfect and you usually get maybe half of the islets available, sometimes far less. This then necessitates pooling of islets from multiple pancreata (the fancy scientific plural of pancreas), which currently averages out to, I believe, two good donor pancreata per recipient. It also makes living donation of islets suboptimal, since a single donor is unlikely to provide enough viable islets.”
About 40 islet cells are the crucial number because the patient’s immune system immediately starts trying to destroy them — in part because they are foreign to that body but also because the receiving patient still has the autoimmune disease of type 1 diabetes.
Transplanting 40 islet cells at one time ensures that while those islet cells will be under attack by the receiving patient’s immune system, there will be enough present to produce an adequate amount of insulin, enabling the patient to no longer need insulin injections or daily blood sugar monitoring.
However, over the course of three years, those transplanted islet cells will succumb gradually to the immune systems ongoing attack, which means another transplant is required.
In order to continue producing insulin, patients need islet cell transplants every three years for the rest of their lives.
Throughout the rest of their lives, they also will be required to take a variety of immunosuppressive drugs and anti-inflammatory medications to help ensure the survival — albeit brief — of each round of transplanted cells.
If you believe you are eligible for an islet cell transplant due to severe hypoglycemia unawareness, work with your healthcare team to contact the University of California San Francisco.
The UCSF Medical Center is one of the leading facilities in the country trained and outfitted to perform islet cell transplantation.