What does it feel like to save someone's life? When the actor David Harewood signed up to be a bone marrow donor he could never have imagined the joy he would feel when he was told that he was a “match” less than two years later.

“Receiving that phone call was amazing. I was being told that I could possibly help someone else to live. I felt so emotional at the prospect of being able to help this stranger. It made me feel incredibly special,” says Harewood, 43, who is soon to star as Friar Tuck in the BBC One series Robin Hood.

Harewood joined the bone marrow register in 2006, after attending a fundraising dinner held by the African Caribbean Leukaemia Trust (ACLT). Like the Anthony Nolan Trust's Unique Match campaign, the ACLT encourages people from ethnic minorities to join the register.

“I went along to the evening really ignorant of the whole issue of bone marrow donation and the lack of ethnic minorities on the register. But I was really blown away by some of the stories,” he says. During the evening he heard from parents desperate to find a match for their children, who had lost their bone marrow through diseases such as leukaemia.

Bone marrow makes the body's blood cells from special stem cells, and without it we die; a transplant can cure conditions such as leukaemia but only if the match is perfect. One woman, the mother of a mixed-race child, particularly moved Harewood. “My daughters are mixed race, and she was saying how difficult it is to find mixed-race donors. She was weeping as she spoke,” he says.

Harewood intended to sign up to the bone marrow register immediately but work commitments intervened, and it took a stern word from his girlfriend to make him sign up. “I was at the Notting Hill Carnival when she saw an Anthony Nolan Trust recruitment clinic and said Have you actually signed up yet?' I admitted that I hadn't, so she marched me to the clinic and I signed up there and then.”

Signing up involved no more than giving a blood sample, and Harewood heard nothing else until two years later, when he received a phone call telling him that he was a match for a patient. “I felt like I'd won the lottery. It's like that big hand coming out of the sky and saying it's you'. Out of the 12 million people on the register I was the one who could provide the patient with a life-saving transplant,” he says.

A sudden change of plan

The donation procedure was arranged for a few months later, but plans quickly changed. “I was in Romania filming The Last Enemy for BBC One when the Anthony Nolan Trust phoned to say that the patient had taken a turn for the worse and that they couldn't wait until I'd finished filming, as he might not make it. It was horrifying and I got home as soon as I could.”

He flew back to the UK straight away and underwent the transplant procedure. Despite its gruesome reputation, the process of bone marrow donation is now similar to giving blood. Only rarely, in 20 percent of cases, are donors unsuitable and have to face a painful operation to extract the marrow directly from the bone.

For most patients - Harewood included - the process is relatively simple. A nurse visits every morning for four days before the procedure to administer injections that boost a donor's stem cell count, the precious cells that will replace the recipient's bone marrow (“My children wanted to know what the nurse was doing with Daddy,” Harewood says, “but my girlfriend just said that Daddy is helping to save someone's life”).

On the fifth day the donor is hooked up to a machine that takes the blood out of one arm, flows it through a filter to remove the stem cells and then back through a needle in the other arm. The donor is awake throughout the whole procedure, which takes about four hours.

Overcome by emotion

In fact, Harewood's biggest gripe about the procedure was that it was a bit dull. “It's actually quite boring. That was the only downside. I had no other side effects and it wasn't painful; I've experienced much worse pain falling off my bike.” But when the donation procedure was over, Harewood found himself unexpectedly overcome by emotion.

“I was looking at this bag full of pink liquid, which contained my stem cells, and it was really moving to think that this bag could save somebody's life. When I got home I felt quite overwhelmed. I was just hoping that this person would be OK. They could have children, and a family, and I was hoping and praying for them to pull through. For me the process was over, but for him it was only just beginning.”

Harewood caught a flight to Romania the following day to continue filming. Although the rules governing bone marrow donation mean that he is not able to know the identity of the recipient until two years after the procedure - and only then with the patient's consent - he was keen to know of his progress. Three months after the procedure he received a letter telling him that the patient was doing well.

“I'm dying to meet him, or at least to know what country he is from so that I can picture him in my mind. It's great to know that this guy is walking around with my blood cells. I wonder if he can now dance as well as me?”

Harewood maintains contact with the Anthony Nolan Trust and hopes that his experience will encourage others to join the bone marrow register. “It's an experience that I hold very close to me. The emotional rewards far outweigh any discomfort. You can lie in bed at night and think there's someone walking around in this world thanks to you. It's a life-affirming thing,” he says.

To find out more about Unique Match, visit www.uniquematch.org.uk; and for information on the Anthony Nolan Trust, www.anthonynolan.org.uk

What is bone marrow?

Bone marrow is the jelly-like substance inside bones that produces stem cells. These stem cells make white and red blood cells. The bone marrow is destroyed by disease and through aggressive treatments for disorders such as leukaemia.

How do you donate? Most people donate bone marrow through peripheral blood stem cell collection. Here, stem cells are filtered from the donor's blood by a special collector. The process takes about four hours and does not require anaesthetic or an overnight stay in hospital, but needs one to two days off work. Some donors may be unsuitable for this procedure and have to undergo the traditional extraction process, which involves removing the bone marrow directly from the bone. This requires general anaesthetic and a couple of nights in hospital.

To join Ask to join the register when next giving blood. Or visit an Anthony Nolan recruitment clinic.

For more information, visit www. anthonynolan.org.uk ; www.blood.co.uk

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