Bone marrow is generally harvested from the posterior iliac crest, as either an inpatient or outpatient procedure. Marrow may also be aspirated from the anterior iliac crests and sternum if required. The amount required to achieve haematopoiesis is 10-15ml/kg of recipient body weight.6
Peripheral blood stem cells
Through a process of mobilisation, haematopoietic stem cells are relased from the bone marrow into the blood. Current mobilization strategies include the use of cytokines alone or cytokines combined with myelosuppressive antineoplastic agents. An ideal mobilisation regimen:5
- achieves adequate engraftment following autologous transplant
- has a low toxicity profile
- results in a minimal number of apheresis procedures.
Through the process of apheresis, whole blood is separated into its components and stem cells can be collected and stored. Venous access via the antecubital vein may be used. A dual-lumen central venous catheter may be needed if venous access is inadequate.5
Effects related to the collection procedure are usually well tolerated. They include:5, 7
- citrate toxicity leading to hypocalcaemia
Cord blood is harvested via a 16-gauge needle through the umbilical vein once the placenta has been delivered. The median volume harvested is 100ml.7
Prior to storage and/or administration, stem cells may be manipulated. They may be enriched with CD34+ cells or 'purged' by removing T lymphocytes or malignant cells.29
Processing of an HSCs includes sterility testing, blood typing and a reduction in fluid volume.5
Cells are cryopreserved until administration. Key principles of cryopreservation include:5
- reduce of the number of mature blood cells in the graft
- protect the cells from ice formation and dehydration during freezing using a cryoprotectant such as dimethylsufloxide or hydroxyethyl starch
- dilute cryoprotectant with saline or tissue culture media
- reduce the risk of cell injury by adding plasma protein to the graft
- cool at a controlled rate
- store at a temperature below -120°C in liquid nitrogen or mechanical freezers
Allogeneic stem cells are generally transfused into a recipient within 24 to 72 hours of collection and do not require cryopreservation.
Outline the education that would be provided to a person undergoing a bone marrow harvest.
Summarise the discharge education for a person following a bone marrow harvest.
Outline the aetiology, assessment, and interventions to prevent and manage the following effects of peripheral blood stem cell harvest:
- Citrate toxicity