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Complications of Diabetes

Islet Cell Transplantation

Introduction

Insulin is produced by specialised cells in the pancreas called islets of Langerhans. These cells were first identified in 1869, by Paul Langerhans, a German medical student.

What is islet cell transplantation?

Pancreas transplants have been performed for over 20 years. Many transplants are in fact combined pancreas and kidney transplants. Islet cell transplantation is a major breakthrough which does not require major surgery. This is an exciting development which offers the hope of a ‘cure’ for diabetes, something which was previously thought impossible.

History of islet cell transplantation

ICT was pioneered by a team of researchers in Edmonton, Canada. They have since transplanted over 50 patients. Other centres worldwide have also transplanted several hundred patients. This is still an experimental procedure which is not in widespread use, as for example ‘Kidney transplantation’.

Why islet cell transplantation?

Islet cells are the essential cells of the pancreas which make insulin. These cells are injected into the liver. It is safer than whole pancreas transplantation. It is also much easier to perform and less costly.

Is the donor alive?

No, the islets are extracted from the pancreas’ of people who have died and have previously consented to donate their organs for transplant purposes.

Does it work?

Currently around 80-90% of patients in research programs remain free of insulin injections at one year and about 75% remain free beyond three years.

Who would be considered for an islet cell transplant ?

There are three main categories of patients who do not have a functioning pancreas

  • type 1 diabetes
  • total pancreatectomy
  • chronic pancreatitis

Where is this research being done?

There are nine members of the UK Islet tranplant Consortium based around the UK.

  • Cambridge – Addenbrooke’s Hospital
  • London – King’s College Hospital, Royal Free Hospital
  • Oxford – Oxford Transplant Centre
  • Bristol – Southmead Hospital
  • Leicester – University Hospital
  • Worcester – Worcestershire Royal Hospital
  • Scotland – Edinburgh Royal Infirmary

Outline of procedure

A brief outline of a very complex procedure !

  • The procedure is carried out under a local anaesthetic.
  • Pancreas obtained from donor is ‘digested’ and islets extracted and purified.
  • A catheter is placed in the portal vein (a blood vessel related to the liver) under ultrasound guidance.
  • The purified islets are injected via the catheter into the liver.
  • The cells attach to new blood vessels and begin releasing insulin over time.

What are the problems and limiting factors?

A lack of donors and high cost are the major limiting factors. Each successful islet transplant currently needs five donor pancreases, though some groups have had success with a single donor pancreas. There are a very small number of donors in relation to very large numbers of people with diabetes. Worldwide, it is thought there are only enough organs to transplant 1 in 200 (0.5%) people with type 1 diabetes.

Your immune system is programmed to destroy ‘foreign’ cells. At present immunosuppressive drugs are needed to prevent rejection of these transplantated cells by the body. These drugs are associated with side effects which may be harmful. The long term effects of these drugs are not yet known. It is thought that taking immunosuppressive drugs increases the risk of cancer as well.

How many transplants are required?

For someone of about 70 kg, approximately 1 million islets are required (roughly equivalent to two organs). Two transplants are usually required for insulin independence.

All this sounds very complicated – what are the benefits?

The potential benefits are :

  • Good control of blood sugar may reduce the risk of complications
  • No risk of severe hypoglycaemia as encountered with intensive insulin treatment
  • Freedom from insulin injections

What are the risks attached?

There is a risk of blood clots developing in blood vessels around the liver. There also may be a slight risk of bleeding from the liver. Apart from these procedural risks the risk of ongoing immunosuppressive therapy must also be considered.

Where would I get more information?

The National Institute for Health and Clinical Excellence issued guidance on Pancreatic Islet transplantation in October 2003. See link below

http://guidance.nice.org.uk/IPG13

Diabetes UK currently funds islet transplantation research in the UK.

www.diabetes.org.uk/Research/Islet_cell_transplantation/

Is this treatment available on the NHS?

Islet cell transplantation has todate been available to a small number of patients as a research-based programme. This meant that you would have been considered for the treatment provided you agreed to be enrolled into a research study. The procedure would have been funded through a research grant.

Recent changes in NHS commissioning will lead to this service being available to patients throughout the UK. We understand that from the 1st of April 2008 funding for islet cell transplantation will be made available to patients across the UK. It is envisaged that two key centres will be identified for the provision of this service.

 

Dr Nishan Wijenaike
Consultant Diabetologist
West Suffolk Diabetes Service
Original article February 2004
Updated October 2007