A new trial has transplanted islet cells from donor pancreas into a patient, leading her to produce her own insulin. This is a medical breakthrough and should be supplanted by more organ donation
By Shobha John
When Anu Kumar, 70, a chronic diabetic from Del-hi, heard of a trial which could lead to a biological cure for diabetes and make people like her insulin-free, she was hopeful. “I have been on insulin injections for the last 30 years. I inject myself on my stomach and sometimes it can be painful. It would be a relief if my body can be made to produce insulin.”
Kumar is optimistic about a medical breakthrough achieved by scientists in the US. On August 18, 2015, Wendy Peacock, a Type 1 diabetic from San Antonio, Texas, underwent a minimally invasive procedure whereby islets cells (insulin-producing cells) from a donor pancreas were transplanted to her body, leading her to produce her own insulin naturally for the first time. This was part of a trial by the Diabetes Research Institute (DRI) at the University of Miami Miller School of Medicine.
This could well spell a new dawn for diabetics. It is estimated that every three seconds, at least one patient develops diabetes worldwide. In India, diabetes is an epidemic. There are 65.1 million diabetics and 77.2 million pre-diabetics in our country and more and more people are getting it. By 2035, India could have close to 109 million diabetics.
Most have Type 2 diabetes, where the body gradually loses the ability to process blood sugar, whereas those with Type 1 diabetes, which is hereditary, have their islet cells destroyed by the immune system. The US trial is being carried out only on those with severe Type 1 diabetes so that they can achieve insulin independence.
DRI’s global network of diabetes res-earchers wants to develop a biological cure for diabetes by restoring natural insulin production and normalizing blood sugar levels for them. And it is in this regard that DRI received approval from the US Food and Drug Administration to go ahead with a Phase I/II clinical trial that will test islets transplanted inside a body.
In the trial on Wendy Peacock, islet cells from the pancreas were put within a bio-degradable “scaffold”. This is implanted on the surface of the omentum, a tissue covering abdominal organs and which serves as a transplant site. “The omentum is rich in blood vessels and so there is a better chance of success here,” says Dr Ambrish Mithal, chairman and HOD, Endocrinology and Diabetes, Medanta. They aren’t implanted in the liver as it could lead to inflammation. “They also can’t be implanted in the pancreas as this organ is actually a bag of enzymes and would end up digesting anything in it. The pancreas can’t be touched,” he said.
The donor islets are implanted into the scaffold and combined with the patient’s plasma and thrombin (an enzyme), creating a gel-like material that sticks to the omentum and holds the islets in place (see picture). The omentum is folded over around the biodegradable scaffold. Over time, the body will absorb the gel, leaving the islets intact. Meanwhile, new blood vessels are formed, which provide oxygen and other nutrients to the cells.
The scientists who made this possible are naturally thrilled. Camillo Ricordi, director of DRI reportedly said: “The first subject in our Phase I/II pilot BioHub trial is now completely off insulin with an excellent glucose profile. These are the best post-transplant results we’ve seen in an islet recipient.”
BIOHUB, A MINI-ORGAN
According to the DRI website, its researchers are focused on two platforms for a BioHub, a biodegradable scaffold and a bioengineered scaffold. Both mimic the pancreas by giving islets space, oxygen and nutrients. It also
prevents islets from clumping together. Incidentally, a BioHub is a mini-organ that mimics the pancreas to restore insulin.
The bioengineered scaffold is a sponge-like disc compatible with the body. It is made of 10 percent silicone, while the rest is open space with tiny pores to house the islets.
Incidentally, these islets are called the Islets of Langerhans. These are clusters of cells, with each “islet” having 3,000 to 4,000 cells. A healthy adult pancreas will have some one million islets. There are several types of cells in the islet which work to regulate blood sugar. One of them, the beta cells, sense sugar in the blood and release the right amount of insulin so that normal levels are maintained. However, in the case of Type 1 diabetes, the immune system attacks these beta cells, destroying them. The body can no longer produce insulin, causing the patient to rely on those in the market.
There are certain hurdles that remain in the making of the BioHub. The first is getting a regular supply of islet cells. “The cells can only be got from donor pancreas,” said Dr Mithal. “But with organ donation in India being abysmally low, there is a shortage of islet cells,” he said. Even in the US, organ donation is critically low—about 1,700 pancreases were available in 2014—and would hardly suffice for those with diabetes.
“Pancreatic transplants have been done in the past with moderate success and are usually done on critical patients who also need kidney transplants,” said Dr Mithal. However, islet cells, he said, can also be taken from fetal, stem and animal cells, but these have not met with much success.
Incidentally, it was only with the passing of the Transplantation of Human Organs Act, 1994, that transplants could be done from brain dead donors. Earlier, only live donations were possible. However, the act prohibits the commercial sale of organs. It restricts donation of organs only to first degree relatives (immediate family) of the recipient. This has led to a severe shortage of organs, be it kidneys, liver, heart, lungs or pancreas.
The second hurdle, like all transplants, is for the recipient to accept the cells from the donor without the need for immune-suppressants all his life. It is still too early to know how long the implanted cells will continue to produce insulin without the need for these drugs.
Immune-suppressants are strong drugs which “suppress” the immune system and expose the patient to infections. Scientists are, therefore, trying to protect these transplanted cells by wrapping them in a tight coating and giving low-dose drugs only at the site of the transplant.
Another issue with Type 1 diabetics is that as their immune system had attacked their islet cells, it leads to diabetes in the first place. This phenomenon is called “auto-immunity” and scientists are trying to see that it doesn’t happen again when the islet cells are transplanted to the omentum. This would make the whole exercise pointless.
However, this trail is still a breakthrough in the field of diabetes and India would do well to watch out for it.