University news

Computer scientists from the University of Glasgow are playing a key role in the NHS’s living donor kidney transplant programme which saw the first multiple kidney transplants involving three couples take place at the end of last year.

They have devised a computer program which matches donors to patients whose original willing donor is clinically incompatible, enabling organs to be swapped anonymously between people on the same day in different parts of the UK.

One of the first three-way donations to be carried out took place on 4 December 2009 at three different hospitals across the UK, involving six people. All are now in good health following surgery¹.

The ability to carry out live donations between people who are not genetically or emotionally-related only became possible following the introduction of the Human Tissue Act 2004 and the Human Tissue (Scotland) Act 2006² – before then patients could only receive organs that had been removed from donors who had died, or via a live donation from a compatible family-member or friend.

If no suitable organ was found in this instance, the patient would have to continue with kidney dialysis while they waited for a donated organ.

Now, however, patients and their donors can register on a paired donation database managed by NHS Blood and Transplant (NHSBT) where matching runs are carried out approximately every three months in a bid to identify potential paired or multiple matches. Currently around 150 patients and their donors are listed on the database, and it is hoped that this figure will continue to grow.

Their information – including age, blood group, and human leukocyte antigen (HLA) antibodies, as well as their location – is fed into a computer by NHSBT staff.

Seconds after receiving an anonymised version of the data which indicates only compatible donor and recipient matches and their ‘scores’, the Glasgow program provides information on potential two- and three-way exchange matches which are then double and triple-checked and returned to NHSBT the same day.

The computer program used by the University to match donors and patients evolved from one originally written by honours student Kirstin MacDonald, under supervision from Dr David Manlove, senior lecturer in the Department of Computing Science, and Dr Péter Biró, research assistant.

The Department has now received a contract from NHSBT to develop the program further so they can use it in-house. This would provide results even quicker because it would be on-site and work directly from NHSBT’s own database, which could also be updated immediately.

The project to develop the program further will be carried out by Dr Manlove, and research assistant Dr Gregg O’Malley, with further involvement from Dr Péter Biró.

Dr Manlove, who has been collaborating with NHSBT on the paired donation matching scheme since July 2008, said: “We aim for an optimal solution that will give as many people a transplant as possible, and create donor-recipient pairs that have the highest-compatibility scores.

“Three-way donations are much harder to carry out as there are many more factors to coordinate to ensure that everyone receives an organ. So for example, all the operations must be carried out at the same time so that no-one can withdraw and break the chain, leaving someone without a kidney once their loved-one has received an organ.

“In theory you could match up as many people as you like – they’ve done 12-way transplants in the US – but it is much more complicated and there are more and more risk factors with a larger number of people involved.

“Ultimately when trying to find suitable organs for a patient, our remit is to identify the option that is most likely to result in a successful transplant, and in many cases that may be a two-way donation, rather than a three-way one.”

The program, written in Matlab – a numerical computing language – uses well-established techniques to solve an integer programming problem that is tailored towards the specific optimality criteria of NHSBT. Specifically, the program must avoid trying out every possible solution, as the number of permutations can be astronomically large.

Dr Manlove added: “A key challenge going forward will be to ensure the program continues to work quickly when the data-set is much larger.

“When we first started working with the NHSBT in June 2007, it could take 16 hours to find suitable matches involving two-way donations from 100 pairs, so we’ve really cut that time drastically.

“Because this paired donation matching program is just one part of a very large process, it wouldn’t be helpful for it to cause unnecessary delays. You really don’t want to wait more than a few minutes, so we’ll need to investigate new techniques and algorithms that will address this challenge.”

Anyone who is currently awaiting a kidney donation who has a willing donor who is incompatible with them can ask their consultant or local transplant centre about getting involved in a pooled transplant arrangement.

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For more information contact Stuart Forsyth in the University of Glasgow Media Relations Office on 0141 330 4831 or email s.forsyth@admin.gla.ac.uk

Notes to Editors
1. ‘Three-way kidney transplant success’, BBC News Online, 8 March 2010
2. The Human Tissue Act 2004 repealed and replaced the Human Tissue Act 1961, the Anatomy Act 1984 and the Human Organ Transplants Act 1989 as they relate to England and Wales, and the corresponding Orders in Northern Ireland, and links to the Human Tissue (Scotland) Act 2006

NHS Blood and Transplant is a Special Health Authority and the organ donor organisation for the UK. It also has responsibility within England and North Wales for the provision of a reliable and efficient supply of blood, blood products and associated services to the NHS

The Human Tissue Authority is the watchdog responsible for licensing organisations that store and use human tissue for the purposes of research, patient treatment, post-mortem examination, teaching and public exhibitions. It also gives approval for organ and bone marrow donations from living people.

First published: 17 March 2010