Collecting stem cells
Stem cells are collected from the blood or occasionally from the bone marrow. You may have your stem cells collected a few days or weeks before the high-dose treatment.
The first step in collecting stem cells from the blood is to encourage them to move from the bone marrow into the blood. This is called mobilising stem cells.
You’ll usually be given chemotherapy, followed by a course of daily 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). You or a relative can be taught to give these injections, or you can go to your GP or the hospital to have them.
Your blood will be tested regularly to check the level of stem cells. Once there are enough stem cells in the blood, they will be collected.
For a small number of people, not enough stem cells move into the blood for an adequate collection. People with lymphoma and myeloma may be given a new drug called plerixafor (Mozobil®) to help increase the number of stem cells. It’s given by injection after four days of G-CSF. The side effects are usually mild and include diarrhoea, feeling sick (nausea) and irritation at the injection site.
Collecting stem cells from the blood
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Collecting the stem cells takes 3–4 hours, and you can usually have it done as a day patient.
You’ll lie down on a couch, and a short thin tube (cannula) will be put into a vein in each arm or sometimes into a vein at the top of your leg. If you already have a central line or an implantable port, this can be used instead.
Each cannula is connected by tubing to a machine called a cell separator. Your blood goes from one arm through the tubing into the cell separator and is then returned to you through the cannula in your 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. They are then stored until you need them. If not enough stem cells are collected, you can have a second collection done another day.
Collecting stem cells from the bone marrow
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Although it’s more common for stem cells to be collected from your blood, sometimes stem cells are collected from the bone marrow. This is done under a general anaesthetic or an anaesthetic given into the spine so you won’t feel any pain. Usually bone marrow is taken from the bones at the back of the hip bones (pelvis).
A sample of bone marrow is usually taken from the back of the hip bone
Rarely, it’s taken from the breastbone (sternum) or from the front of the pelvis. 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 – only about 10–15% of the body’s total. This leaves plenty for your needs, and the body quickly replaces the bone marrow that’s been removed.
You’ll usually have to stay in hospital overnight to recover. It’s common to feel sore for a few days afterwards, but this can be relieved by taking regular painkillers. You’ll be given a supply of painkillers to take home if needed. There may also be some bruising from where the bone marrow was taken that may last for a few weeks.