Peripheral Blood Stem cell Collection (PBSC)
Peripheral Blood Stem Cell Collection is performed as an outpatient in the Clinical Apheresis Unit. Stem Cell Collection can be performed on patients or donors. The actual collection procedure for each is the same but some of the processes and timings surrounding the procedure will vary.
What are stem cells?
Blood forming stem cells are immature blood cells that are normally found in the bone marrow, for example in the hips or breast bone.
These stem cells are the ‘mother’ cells from which all mature blood cells are formed: red blood cells, white blood cells and platelets. Stem cells are essential so that all blood cells can recover after chemotherapy. A drug called GCSF will artificially stimulate the release of large numbers of stem cells from the bone marrow into the bloodstream.
How are they collected?
Stem cells are collected on a machine called a cell separator. This machine separates the blood into its various parts: white blood cells, red blood cells, platelets and the fluid part of your blood – plasma. Your stem cells are within the white blood cell layer of your blood and the machine allows us to collect the stem cells and return the rest of your blood back to you.
To do this a needle will usually be put into a large vein in each arm. The machine will then draw blood from one arm, take off the stem cells and return the rest of the ‘processed’ blood to you through the needle in your other arm. This is a continuous process and so there is only a small amount of blood (about a cup full) out of your body at any one time. If your veins are not suitable you may need to have a special tube called a central venous catheter inserted into a larger vein. This is done after a local or general anaesthetic.
Collecting stem cells usually takes 5 hours. We will collect approximately 150/250mls of stem cell fluid during the collection. On completion of the procedure, the stem cells are transported to the laboratory for processing and storage until needed.
What is it like being on the machine?
A trained nurse will care for you during the procedure to ensure your comfort and safety. The stem cells will be collected while you rest on a bed or reclining chair.
There are very few side effects with stem cell collection and any minor ones are treated simply and quickly. Potential side effects are tingling in your lips, nose or fingers or feeling light-headed or faint. Sometimes patients or donors may feel sick. The nursing staff will be able to help with this.
You can eat and drink normally during your procedure. Some people can feel quite tired for 24 hours afterward.
How many collections are required?
Two stem cell collections are usually enough but you may only need one or as many as three. These collections will be carried out over 2 or 3 days running.
The list below shows just some of the conditions which can be treated with stem cell transplant:
- Acute Lymphoblastic Leukaemia
- Acute Myeloid Leukaemia
- Aplastic Anaemia
- Chronic Lymphoblastic Lymphoma
- Chronic Myeloid Leukaemia
- Ewing’s Sarcoma
- Hodgkins Disease
- Non-Hodgkins Lymphoma
- Sickle Cell Disease
- Thalassemia Major.
The collection process for patients
Stem cells are collected from your bloodstream at very specific times. Your Consultant will refer you to the department for stem cell collection at the best time in your treatment schedule.
Before your stem cells are collected, you will attend the Clinical Apheresis Unit for a pre-collection assessment and some specific blood tests. While at the unit, they will explain the procedure and answer any questions you may have.
How do we ‘mobilise’ the stem cells into the bloodstream?
There are 2 ways that the stem cells can be stimulated to enter the bloodstream (mobilisation).
- Using growth factors (GCSF) and chemotherapy
- using growth factors (GCSF) alone
Growth factors are hormone-like substances that occur naturally in the body and help to regulate the production of blood cells. Growth factors are given as a daily injection under the skin for several days. The injections must continue each day until your stem cell collection is complete.
When do we collect the stem cells?
If you are given G-CSF alone your stem cells will be collected 4-7 days after the G-CSF is started.
If you have received chemotherapy your white cell count will fall to a very low level and then begin to rise again. Stem cells are collected as the white cell count rises rapidly. Stem cells mobilise into the bloodstream differently depending on the type of chemotherapy you have been given and so we can only give you an approximate day of collection.
We will ask you to come to the Clinical Apheresis Unit on the first possible day the stem cells will be in your bloodstream for a CD34 blood test, this is the marker for stem cells.
Collection process for donors
If your sibling has leukaemia or another bone marrow disorder you may be asked to donate your stem cells to aid their recovery.
The first step in this process is to find out if you are a suitable tissue type match for your sibling. If your sibling has volunteered your name as a potential donor, you will be invited to have a tissue-typing test performed. This is a simple blood test that may be carried out in our department or at your GP surgery.
How long does it take to get the tissue typing test result?
It takes approximately 6 weeks. We will write to you with the result. If you are a match we will invite you for an assessment visit to the Clinical Apheresis Unit.
What does an assessment visit involve?
If you are happy to be a donor it is important that we ensure that you are physically fit for the procedure. The assessment visit will include a medical examination and some blood tests. It also gives us the opportunity to talk through what it means to be a donor and the choices you have as a donor.
The assessment visit will take approximately 2 hours. It usually takes 2 weeks for all of the tests to be returned to us. We will contact you if we need to repeat any tests and will write within about 3 weeks of your visit to let you know of the results and confirm preliminary plans for the transplant if this is going ahead.
Why are my stem cells needed?
Your brother or sister has a serious blood disorder and the hope is that this can be eradicated. We know that this is possible by giving them strong chemotherapy and sometimes radiotherapy to kill off nearly all their blood cells followed by a ‘transplant’ with new blood cells called ‘stem cells’ from yourself.
What choices do I have to make?
There are two methods for collecting stem cells: Bone Marrow Harvest and Peripheral Blood Stem Cell Collection.
The decision whether to use peripheral blood stem cells or bone marrow for any transplant is not always simple and your own preferences are very important. We will explain your options to you at your assessment visit. You will find more information on the pros and cons of bone marrow donation versus peripheral blood stem cell collection in our information leaflet ‘Allogeneic blood stem cell and bone marrow donors’ which we will send you if you are a suitable tissue type match.
How do we ‘mobilise’ the stem cells into the blood stream?
Your stem cells can be stimulated to enter the blood stream (mobilisation) by using G-CSF. This is a growth factor, a hormone like substance which occurs naturally in the body and helps to regulate the production of blood cells.
G-CSF will be given to you as a daily subcutaneous (under the skin) injection for 4 days. Your stem cells will be collected on the 5th day and if we don’t have enough cells we will give you a further injection of G-CSF and collect on the 6th day also.
These outpatient stem cell collections will usually be arranged to coincide with the week your sibling is due their transplant.
How do we collect bone marrow?
Bone marrow is normally collected under general anaesthetic. You would need 2 nights in hospital, the night before and the one after collection. The bone marrow is taken from the back of your pelvis on each side using a number of needles. These sites can be a bit painful for several days after the operation.
Follow up care
Studies done elsewhere on large numbers of stem cell donors have shown very few problems but we like to monitor your blood counts at 1,3,5,7 and 10 years. We will send you a questionnaire by post and ask you to attend your GP for a blood sample.