For a person living with type 1 diabetes, the idea of a treatment that restores the body’s own ability to produce insulin, rather than simply replacing it from the outside, is enormously appealing. Islet transplantation offers exactly that possibility. Instead of insulin injections or pumps, patients receive infusions of insulin-producing cells that can, in the best cases, regulate blood sugar much the way a healthy pancreas would.
Islet transplantation using cells from deceased organ donors, known as cadaveric islet transplantation, has been used clinically for over two decades and has changed the lives of many patients with the most difficult-to-manage forms of type 1 diabetes. But despite this progress, the therapy remains out of reach for the vast majority of people who could benefit from it. The reasons are structural, not simply a matter of refining the surgery. Understanding these challenges helps explain why researchers, including our team at RMS, are working toward alternative approaches to islet cell therapy.
What Are Cadaveric Islet Cells?
Scattered throughout the pancreas are small clusters of hormone-producing cells called islets, or islets of Langerhans. Within these clusters, beta cells are responsible for producing insulin, the hormone that allows the body to regulate blood sugar. In type 1 diabetes, the immune system destroys these beta cells, leaving patients dependent on external insulin for life.
Cadaveric islet cells are islets that have been recovered from the pancreas of a deceased organ donor. In a specialized laboratory, technicians use enzymes to separate the islets from the rest of the pancreatic tissue, then purify and count them before they are ready for transplant. The islets are typically infused into the patient’s liver through the portal vein, a comparatively minimally invasive procedure compared to a whole-organ pancreas transplant. Once in place, the islets can begin sensing blood sugar levels and releasing insulin on the patient’s behalf.
This approach was popularized in the early 2000s by researchers in Edmonton, Canada, whose islet transplant protocol became a widely cited benchmark for the field and demonstrated, for the first time in a rigorous multi-center trial, that islet transplantation could meaningfully improve glucose control in patients with the most severe, hard-to-manage type 1 diabetes.
How Successful is Islet Transplanatation?
It’s a common assumption that a successful islet transplant means a patient no longer needs insulin at all. In reality, the islet transplantation success rate is more nuanced than a single number, and success is generally measured by more than one yardstick.
The original Edmonton protocol trial reported insulin independence in about 44% of patients at one year. A five-year follow-up published in the journal Diabetes found that roughly 80% of patients still showed measurable islet function, but only about 10% remained fully insulin-independent, illustrating why ‘success’ is better measured by several outcomes than by insulin independence alone. Long-term studies following patients for ten to twenty years have found that the share of recipients who remain fully insulin-independent declines substantially the further out you look, even as many patients continue to benefit from more stable blood sugar and fewer dangerous low-glucose events.
Rates of insulin independence also vary considerably from one transplant center to another; a clinical reference from the National Institutes of Health’s NCBI Bookshelf puts the range at roughly 20% to 90% depending on the institution’s experience and protocol. This variability is also telling: it suggests that outcomes are shaped as much by the logistics and expertise surrounding the transplant as by the biology of the islets themselves, which points directly to the deeper structural challenges explored below.
Current treatment Limitations
For patients researching islet cell transplant diabetes treatment options, realistic expectations matter as much as the science itself. Cadaveric islet transplantation faces a series of interlocking obstacles that limit how many patients can be treated and how well the therapy performs over time.
Donor scarcity is the most fundamental constraint. A 2024 review in the journal Cells found that it typically takes islets from two to three donor pancreases to gather enough functioning cells to treat a single patient, because islets must be harvested from a deceased donor’s pancreas, and the isolation process itself is inefficient. With demand for donor organs already far outweighing supply across all forms of transplantation, this makes islet transplantation nearly impossible to scale to the full population of patients who could benefit.
Inconsistent starting material compounds the problem. Unlike a manufactured cell product, a donor pancreas cannot be standardized, and islet cell isolation outcomes vary accordingly. Donor age, body weight, and how long the organ has gone without blood flow (known as ischemia time) all affect how many viable islets can be recovered and how well they function after transplant. Longer ischemia time in particular has been linked to increased cellular stress and lower islet survival.
Immune rejection is another central hurdle. Because donor islets come from a genetically different person, the recipient’s immune system will attack them unless it is suppressed. Patients typically require lifelong immunosuppressive medication, which carries its own serious risks, including a higher likelihood of infection, kidney damage, and certain cancers. These risks are significant enough that islet transplantation is generally reserved for patients whose diabetes is severe and difficult to manage by other means, rather than offered more broadly.
Even islets that make it through isolation and infusion face an immediate, largely invisible threat. Within hours of being infused into the bloodstream, a substantial portion of transplanted islets are destroyed by a reaction called Instant Blood-Mediated Inflammatory Reaction, or IBMIR, in which clotting and inflammatory factors in the blood attack the newly infused cells before they have a chance to establish themselves. Research suggests that roughly half of transplanted islet mass can be lost this way in the earliest hours after infusion. Surviving islets then face another vulnerable window: it takes about a month for them to develop a new blood supply in their transplant site, and many cells die from lack of oxygen during that time.
Finally, the practical realities of cost and logistics limit access further. Isolating and processing islets requires specialized cell-processing facilities and a highly trained team, and in some cases the procedure is not consistently covered by insurance, adding a financial barrier on top of the clinical ones.
Regulatory and Access Barriers: The ISLET Act
The scale of these access challenges has drawn attention beyond the research community and into U.S. policy. Currently under consideration in Congress, the ISLET Act (short for Increase Support for Life-saving Endocrine Transplantation Act) would reclassify transplanted pancreatic islet cells as an organ, rather than a biological drug, shifting regulatory oversight from the FDA’s drug pathway to the agency that governs organ transplants. The bill was reintroduced in late 2025 and has drawn public support from patient advocacy organizations, including the Diabetes Research Institute Foundation.
Whether or not the legislation ultimately passes, its existence reflects something researchers in the field have long understood: the current regulatory and logistical framework around cadaveric islet transplantation was not designed for the therapy to reach large numbers of patients. That reality is part of what is driving interest in approaches that do not depend on donor organs at all.
Advances Beyond Cadaveric Islets: How RMS Is Approaching This Differently
At Regenerative Medical Solutions, our research is focused on a different starting point altogether. Rather than relying on a scarce and variable supply of donor pancreases, our team is developing insulin-producing cells derived from induced pluripotent stem cells (iPSCs), a lab-based process that does not require organ donation at any stage.
This approach is designed to address several of the structural limitations described above. Because the cells are produced under controlled laboratory conditions rather than recovered from a donor organ, quality and consistency can, in principle, be maintained in a way that is simply not possible when working with cadaveric tissue. The work is also being developed with the goal of reducing patients’ dependence on the kind of heavy, lifelong immunosuppression that cadaveric transplantation currently requires, and with the aim of a therapy that is not limited by a patient’s blood type.
This research builds on years of academic work, including NIH-funded grants and a growing patent portfolio, and remains an active area of development rather than a finished product. We believe that donor-independent islet cell therapy represents one of the more promising paths toward making cell-based diabetes treatment available to far more patients than cadaveric transplantation alone ever could.
To learn more about our ongoing stem cell research and how it may shape the future of diabetes treatment, visit our stem cell therapy page, or reach out to our team directly.
Frequently Asked Questions About Cell Models in Drug Discovery
What are cadaveric islet cells? Cadaveric islet cells are insulin-producing islets of Langerhans that have been isolated from the pancreas of a deceased organ donor for use in islet transplantation.
How does islet cell transplantation work? Islets are isolated from a donor pancreas in a specialized lab, then infused into the recipient’s liver through the portal vein, where they can begin producing insulin in response to blood sugar levels.
What is the success rate of islet transplantation? Success varies by measure and by center. In landmark trials, roughly 44% of patients achieved insulin independence at one year, but by five years only about 10% remained fully insulin-independent, even though most still showed measurable islet function. Outcomes vary widely between transplant centers.
Why is there a shortage of islets for transplant? Islets can only come from deceased organ donors, and the isolation process is inefficient enough that it typically takes two to three donor pancreases to treat a single patient, far outpacing the available donor supply.
What are the risks of cadaveric islet transplantation? The main risks stem from the lifelong immunosuppressive medication required to prevent rejection, including increased risk of infection, kidney damage, and certain cancers.
How is RMS’s approach different from cadaveric islet transplantation? RMS is developing insulin-producing cells derived from induced pluripotent stem cells (iPSCs), a lab-based process that does not depend on donor organs and is being designed to reduce reliance on heavy immunosuppression.