Collection of stem cells by apheresis
The referral of patients or donors for stem cell apheresis
All aspects of treatment other than the stem cell collection procedure itself are the responsibility of the referring Consultant. All referrals for apheresis should be made by the consultant treating the patient or by the bone marrow transplant co-ordinator.
Initial referrals can be made to the SCI laboratory using the Request to collect and process stem cell and immunotherapy products (FRM5071) referral form.
The laboratory will confirm the arrangements for the request. The referral form together with the completed consent form (2B) and three blood samples should then be sent to the SCI laboratory (local arrangements for dispatch and receipt of blood samples may vary).
Consent the patient or donor for apheresis, virology testing and storage and discard of stem cells
Consent must be obtained for stem cell collection, for mandatory microbiological testing, and for the disposal of stem cells when no longer required. One copy of the completed consent form should be kept in the patient's notes, and another should be forwarded to the SCI laboratory (local arrangements may vary).
Inform the patient or donor
The referring clinician should inform the patient or donor of the arrangements and arrange for the individual to visit the Therapeutic Apheresis Services (TAS) unit for a vein assessment if necessary.
The unit will send the patient a letter confirming the arrangements. NHSBT information leaflets explaining peripheral blood stem cell collection are available and these may be provided to the patient although local arrangements vary.
Liaison with the apheresis co-ordinator prior to stem cell apheresis
Full blood counts and CD34+ cell levels need to be closely monitored in the days leading up to the stem cell collection in order to optimise collection yields. Any other clinical details of relevance also need to be discussed.
Although local arrangements may vary, it is common practice to hold a weekly meeting with transplant co-ordinator; a NHSBT consultant with responsibility for stem cell services and senior members of the TAS unit and the SCI laboratory generally attend.
These meetings allow scheduling arrangements to be reviewed, and any potential problems to be highlighted. It may be particularly useful to include representation from the hospital blood bank to help ensure that the patient's requirements for special blood products are understood and the details are made available to referring hospitals where patients may be receiving conditioning therapy.
Before stem cells can be collected and stored, patients will be tested for infections including:
- Hepatitis B
- Hepatitis C
- HIV 1 & 2
- HTLV-1 & HTLV-2
At least three samples for virology testing must be provided. The first sample should be taken up to 30 days before stem cell collection and sent to the SCI laboratory who will arrange for testing. Further samples will be taken by TAS staff on each day of collection. A patient found to be positive for a microbiological marker is not debarred from being apheresed but collection will often be carried out at a location other than the TAS unit and their cells will be stored in a quarantine tank.
High flow rates are required for apheresis so good venous access is essential. The patient´s veins should be large enough to accommodate a rigid 16G needle and should be carefully assessed in advance of the procedure. If there is any doubt about the suitability of venous access the TAS unit would encourage a visit for vein assessment.
Should a line be necessary, it is the responsibility of the referring clinician to ensure that the patient has a suitable, functioning line in place and ready to use by the start of the procedure. There have been problems with line insertion on the day of collection so it is preferred that lines are put in at least the day before. If there are significant delays the collection may have to be postponed.The removal of lines is the responsibility of the referring clinician.
Target yield of CD34-positive cells
The choice of mobilisation regime is the responsibility of the Consultant in charge of the patient. The SCI laboratory will communicate with the referring Consultant or their deputy on a daily basis during the period of stem cell collection and will indicate any problems anticipated in achieving the target cell dose.
Target cell doses may be specified in local guidelines and will vary depending on the disease and treatment protocol being followed. Typically requested doses are:
2 x 106 CD34+ cells/kg for backup collections
3 x 106 CD34+ cells/kg for planned autologous high dose therapy/transplant
5 x 106 CD34+ cells/kg for planned sibling allogeneic high dose therapy/transplant
10 - 20 x 106 CD34+ cells/kg for haploidentical collections
Higher stem cell doses may be required if the collection is to undergo a selection/purging process. This should be discussed at the time of referral and clearly specified on the referral form.
Summary of responsibilities
All aspects of treatment other than the stem cell collection procedure itself remain the responsibility of the referring clinician. The referring clinician should ensure that:
- the patient or donor is fit for apheresis
- the patient or donor understands the reason for the stem cell collection
- an appropriate priming regime is selected and administered
- the patient or donor is informed of the dates for priming and apheresis
- the patient or donor is consented for stem cell collection, storage and discard of stem cells, and virology testing
- confirmation of the patient's details and the requested collection procedure using the Request to collect and process stem cell and immunotherapy products form, are provided to the SCI laboratory. Additional clinical details are provided to TAS using the Request for collection of stem cells, lymphocytes or white cells form
- blood samples are made available for virology testing
- there is adequate venous access
- full blood counts are performed on the days leading up to the collection
- the hospital blood bank is informed of the collection date so that they can ensure irradiation of blood products
- the patient is transported to and from the unit
- ensuring clinical outcome data is provided to NHSBT in a timely manner
In addition to the responsibilities listed above, when stem cell apheresis is undertaken by NHSBT staff on a hospital ward or specialist unit, the referring clinician must also ensure that:
- arrangements are in place for medical and nursing support for NHSBT staff if required during the procedure
- irradiated blood has been cross-matched and is available to prime the apheresis machine for children weighing less than 25 kg
It is the responsibility of the Apheresis staff to ensure that:
- assessment of patient is undertaken on the day to ensure fitness to donate
- the patient is consented for the apheresis collection procedure
- a full blood count and a pre-apheresis collection CD34 count (if required) are checked on the first potential collection day and thereafter as necessary
- collection outcomes in terms of CD34+ cell yields etc are communicated to the referring Consultant
- all appropriate nursing and medical care is provided while the patient is on the Unit
- a summary letter is sent to the referring consultant after the last collection (although local practices may vary)
In addition to the responsibilities listed above, when apheresis is undertaken by NHSBT staff on a hospital ward or specialist unit, the TAS unit staff will also ensure that disposables are provided.