Saturday 25 August 2012

How can I donate stem cells or bone marrow?

Since my latest relapse of Hodgkin's Lymphoma, and the doctors informing me that my treatment plan involves an Allogeneic (from a donor) Stem Cell Transplant, a few people have asked me about how they could donate stem cells (or bone marrow), so if you are interested in becoming a donor and would like to find out more information, or you are just curious about what is involved, then read on!

Before I explain the donation process itself, I should probably provide a little background on where stem cells (and bone marrow) are located in your body and what they actually do.  Bone marrow is the flexible tissue found in the centre of all of your large bones, and is where stem cells are produced.  Stem cells develop into either: white cells to fight infection; red cells to carry oxygen to and remove waste from organs and tissues in your body; or platelets to stop bleeding (e.g. if you cut yourself).  Should you donate stem cells (or bone marrow), then a sufficient amount is collected (by methods explained later), and much like with blood donations your levels soon return back to normal.

When a patient is in need of an Allogeneic Stem Cell Transplant, finding a suitable donor is one of the very first steps, and this involves tissue typing.  Tissue typing is the name given to the process of matching the patient to the donor; This is necessary as in all likelihood two randomly chosen people are extremely unlikely to be compatible for transplantation.  With Allogeneic Stem Cell Transplants, only about three in every ten patients find a match amongst their family, and for the remaining patients it is necessary to search the various donor registers for a match.  Countries around the world maintain their own donor registers, but they collaborate to find matches, hence whilst searches will likely start with donor registers close to home, it may prove necessary to search world-wide to find a particular patient a suitable match, as some patients have rare tissue types.

Note: My sister was tested to see whether she was a match for me, which she was not, but that was probably a good thing, as I'm not sure whether I could have afforded her quoted price per stem cell!

Whilst not everyone can register as a potential donor (factors such as age, health and medical history need to be taken into account), a lot of people can do.  For the majority of people that do register, they never go on to be an actual donor, as a patient requiring their tissue type is never encountered.  However, donors have been known to donate more than once, at their own discretion of course.

In the UK, you can join one of three registers, and they are operated by the Anthony Nolan charity, NHS and Welsh Blood Service.  For simplicity I will focus on the Anthony Nolan charity, as it doesn't also require you to be a blood donor; However, you may wish to consider the other registers, for reasons such as the different age restrictions.  The registration process for the Anthony Nolan charity involves a fairly short medical questionnaire that will probably take you around about ten minutes to complete.  After successfully completing the questionnaire, you will be sent a saliva test kit, which once returned can be used to determine your tissue type and record the results (along with your details) on the register.  You do have to be aged between 16 and 30 to register, and you need to pass the medical exclusion criteria.  There are no costs involved to yourself, and should you ever become an actual donor, any travel and hotel arrangements will also be made for you.

Note: The saliva test kit enables preliminary matching, and should you appear to be a match for a patient, it will be necessary for some blood tests to take place to ensure that you are definitely a match, and that you are a healthy donor, e.g. you won't pass any infections on to the patient.

When it comes to the process of donating itself, there are two methods available: The first of the methods is a bone marrow harvest, and the second is a peripheral blood stem cell collection.  The first tends to be favoured for donating to younger children, and clinical trials have suggested that it results in a slightly lower probability of the patient developing chronic graft versus host disease (cGVHD); GVHD is where the donor's stem cells (or bone marrow) produces white cells that attack some of the patient's organs and tissues, due to it incorrectly identifying them as damaged, foreign or an infection.  The second is the least invasive of the methods, is by far the most commonly used, has the advantage of the patient recovering from the transplantation quicker (typically by a few days), and clinical trials have suggested that it results in a lower risk of the transplant failing to take.

The bone marrow harvest method, which is the most invasive of the two, involves the donor going into theatre, having a general anaesthetic, and finally a large needle being inserted into their hip bone (in the lower back) in order to extract sufficient bone marrow.  The general anaesthetic will avoid any pain being felt during the procedure, but once it wears-off some discomfort may be noticed for a few days, which can be masked by taking some paracetamol, if the donor feels the need.  Having had a few bone marrow biopsies myself during the course of my treatment, which involves a very similar procedure, my personal experience is that the discomfort is easily tolerated without painkillers.  Either way, this method involves a two-night stay in hospital, just for observation purposes after the general anaesthetic, hence you will be well looked after, before finally returning to your normal life; You may wish to have a few extra recovery days though to fully recuperate from the procedure.

The peripheral blood stem cell collection method, which is the least invasive of the two, involves a two step process: The first step requires having an injection in the stomach for a few days (each administered by a nurse at your home or office), so that the stem cells are encouraged to migrate out of the bone marrow into the blood stream, thus allowing them to be collected in the second step.  The second step involves having a small cannula inserted into both arms, one for extracting the blood, and another for returning it; Inbetween the blood will go through a machine that will filter-out the stem cells, so that they can eventually be donated to the patient.  The daily injections are similar to having a vaccination, i.e. you hardly feel anything, but they can cause some bone/joint/lower back pain that without taking paracetamol can be quite painful.  Having experienced this myself on a few occasions (when taking a single concentrated dose, rather than the lower daily doses), I know how much it can hurt, but the good news is that paracetamol is amazingly effective at masking the pain, so if you do start to feel any slight discomfort from them, you can be confident that you will be fine if you take some paracetamol.  The filtering of the stem cells is an uneventful process, which takes around four hours or so to complete, during which time you can just sit and read or something, as you won't feel a thing.  It is sometimes necessary for the donor to go through the filtering process a couple of times (once per day), as sufficient stem cells are not collected on the first attempt.  When I went through the process myself, more than enough were collected in one session, which I believe tends to be the case (especially for younger males), so it was all over and done with pretty quickly really.  Once the filtering is complete, you are free to return to your normal life; You will likely feel fine, as the side effects from the injections wear-off pretty quickly, i.e. typically within about twenty-four hours.

Note: For both methods, the donors on the Anthony Nolan register will have the in-hospital procedures at a specialist collection centre, usually in London.

Which ever method is chosen, you will likely come out of it thinking that was much easier than I expected, as neither are anything to worry about.  Even better still, you will probably be feeling proud of yourself for donating your stem cells (or bone marrow), and potentially saving someone's life!

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