6.1 What is actually transplanted?

A deceased-donor pancreas contains digestive tissue, ducts, blood vessels, connective tissue, and islets. Clinicians do not simply place the whole pancreas into the recipient during an islet infusion. A specialized laboratory must separate the tiny islets from the surrounding tissue.

Schematic

From donor pancreas to functioning graft

  1. 1

    Recover a donor pancreas

  2. 2

    Digest tissue and isolate islets

  3. 3

    Test viability and potency

  4. 4

    Infuse islets into the portal vein

  5. 5

    Cells lodge in the liver and reconnect to blood

  6. 6

    Immunosuppression protects the graft

Every handoff loses cells, which is why starting quality and immune protection matter.

The pancreas is perfused with enzymes that loosen the extracellular material holding it together. Mechanical processing breaks tissue into smaller pieces. The resulting mixture is purified, and the islet-rich fraction is tested for cell quantity, viability, purity, sterility, and function.

This is difficult because isolation itself stresses cells. Warmth, enzymes, mechanical force, loss of blood supply, and time outside the body can reduce viability.

6.2 Why put pancreatic cells in the liver?

Islets are commonly infused through a catheter into the portal vein. They travel into small vessels in the liver and lodge there.

The liver is not the islets’ original home, but it offers practical advantages: access through the portal circulation, a large blood supply, and exposure to nutrients arriving from the intestine.

It also has disadvantages. Early inflammatory and clotting reactions can destroy cells. Oxygen is limited until the graft reconnects to blood vessels. Local drug exposure and the liver environment may stress the graft. Some patients require more than one infusion to achieve enough functioning mass.

Concept questionWhy might researchers need more donor islets than the number of beta cells normally present in a healthy pancreas?

Explanation

Many cells are lost during isolation, infusion, early inflammation, and revascularization. The liver site also does not reproduce every advantage of the native pancreas. A larger starting dose compensates for these losses.

6.3 Evidence from Lantidra

In 2023, the FDA approved Lantidra—donislecel-jujn—for selected adults with T1D who have repeated severe hypoglycemia despite intensive management and education.

The result answers a foundational question: if enough functioning islet cells survive in a person with T1D, they can restore clinically meaningful endogenous control for years.

This is clinical and regulatory evidence that transplanted islets can restore endogenous insulin secretion in selected patients.

6.4 Why immunosuppression changes the conclusion

Donor cells carry foreign HLA identity. Without immune control, the recipient can reject them. Conventional transplant drugs suppress several immune pathways broadly enough to protect the graft.

That protection comes with costs. Depending on the regimen, risks can include serious infection, kidney injury, blood-count abnormalities, malignancy risk, metabolic effects, and medication interactions. In the Lantidra studies, some serious adverse reactions led clinicians to stop immunosuppression; graft function and insulin independence were then lost.

A

Biological success

Donor islets can survive, sense glucose, secrete insulin, and sometimes eliminate external insulin for years.

B

Population limitation

Each product depends on scarce donor tissue, specialist processing, an invasive infusion, and chronic immune-suppressing treatment.

6.5 How donor-islet transplantation informs current research

Donor islets provide a benchmark for stem-cell products. New cells must approach the glucose responsiveness of human islets. New implant sites must preserve enough living mass. New immune strategies must protect function without creating unacceptable risk.

Donor transplantation establishes that cell replacement can function in selected patients. Current research seeks to retain this biological benefit while reducing dependence on donor tissue and systemic immunosuppression.

Review questions

Review the chapter concepts.

  1. Describe the path from donor pancreas to infused islet product.
  2. Why is the liver used, and what disadvantages does it create?
  3. What did the Lantidra studies establish?
  4. Why can stopping immunosuppression lead to loss of graft function?
  5. Which requirements for durable beta-cell replacement remain incompletely addressed by donor-islet transplantation?

Use these questions to identify concepts that require additional review.