Collecting stem cells from a donor
Before donating stem cells, donors are offered counselling so they are fully aware of what is involved.
Donors also have a check-up and tests to make sure their health is good and that the procedure is safe for them. Blood tests are taken to check their general health and for infections including HIV, hepatitis and cytomegalovirus.
Mobilising stem cells
The first step is to give a short course of injections of a growth factor (G-CSF). Growth factors are natural substances that stimulate the bone marrow to make blood cells and increase the number of stem cells and white blood cells in the blood. The growth factor is given as a small injection under the skin (subcutaneously). The donor, or a relative, can be taught to give these injections, or they can go to their GP or the hospital to have them.
Their blood will be tested regularly, and when there are enough stem cells in the blood, they will be collected. This is usually around five days after the start of the injections. The stem cell collection often takes place on the day before or on the same day they are given to you.
Collecting stem cells from the blood
Collecting the stem cells takes 3-4 hours, and it can usually be done as a day patient. The donor lies down on a couch, and a short thin tube (cannula) will be put into a vein in each arm. Each cannula is connected by tubing to a machine called a cell separator. The donor’s blood goes from one arm through the tubing into the cell separator and is then returned to the donor through the cannula in their other arm. As the blood travels through the cell separator, it’s spun to separate out the stem cells, which are collected in a bag.
The collected stem cells are counted to make sure there are enough. Occasionally, if more stem cells are needed, the donor may have to come in for another collection.
Taking stem cells from the bone marrow
Although it’s more common for stem cells to be collected from the donor’s blood, sometimes stem cells are collected from the bone marrow. This is done under a general anaesthetic. Usually bone marrow is taken from the bones at the back of the hip bones (pelvis).
Rarely, it’s taken from the breastbone (sternum) or from the front of the hip bones. If this needs to be done, the doctor will explain more about this to you.
The doctor inserts a needle through the skin and into the bone. Bone marrow is then drawn into a syringe and placed in a sterile container. The doctor may do this a number of times during the collection, taking bone marrow from more than one area of the pelvis.
For an adult, about one litre of bone marrow is removed - that’s about 10-15% of the body’s total. This leaves plenty for the donor’s needs, and the body quickly replaces the bone marrow that’s been removed.
The donor has to stay in hospital for one or two nights. Usually they’ll feel sore for a few days afterwards, but this can be relieved by taking regular painkillers. The donor will be given a supply of painkillers to take home if needed. There may also be some bruising around where the bone marrow was taken, which may last for a few weeks.