Page 314 - Essential Haematology

300 / Chapter 23 Stem cell transplantation

Figure 23.2 Peripheral blood
stem cell (PBSC) collection: a
donor undergoing collection of
PBSCs on a cell separator.

future it is possible that stem cell populations may Because of the relatively small numbers of stem cells
also be expanded in vitro . collected from a single cord, they are most useful
Granulocyte colony - stimulating factor (G - CSF) for children who do not have a fully matching
is given to patients or donors as a course of injec- sibling or unrelated donor. Less stringent human
tions (typically 10 μ g/kg/day for 4 – 6 days) until the leucocyte antigen (HLA) matching is needed.
white cell count starts to rise. PBSC collections are Double cord donations may be needed to obtain

then taken and, depending on the effi ciency of stem sufficient stem cells for adult recipients.

cell mobilization, repeated collections may be

needed for up to 3 days. The adequacy of the col-
lection may be assessed by: Stem c ell p rocessing
+
6
1 CD34 cell count. Generally > 2.0 × 10 /kg are After collection the stem cell harvest can be proc-
needed for transplantation. essed with removal of red cells and concentration of
2 In vitro colony assays, particularly granulocyte – the mononuclear cells. Autologous collections may
‘
macrophage colony - forming unit (CFU - GM) be purged ’ by chemotherapy or antibodies in
5
(see p. 3) , of which 1 – 5 × 10 /kg would be con- an attempt to remove residual malignant cells.
sidered adequate for transplantation. Allogeneic collections may be treated with antibod-
ies to remove T cells to reduce graft - versus - host
+
disease (GVHD). CD34 stem cells may be selected
Bone m arrow c ollection from both types of harvest (Fig. 23.3 ).
The donor is given a general anaesthetic and 500 –

1200 mL marrow is harvested from the pelvis. Th e Conditioning
marrow is anticoagulated and a mononuclear cell
count is taken to assess the yield, which should be Prior to infusion of haemopoietic stem cells patients
8
approximately 2 – 4 × 10 nucleated cells/kg body receive chemotherapy, sometimes in combination
weight of the recipient. with total body irradiation (TBI; Fig. 23.1 ) in a

procedure called conditioning . This is designed to
’
eradicate the patient s haemopoietic and immune
Umbilical c ord b lood
system and, if present, malignancy. In addition, in
Fetal blood is a rich source of haemopoietic stem the setting of allogeneic SCT, by suppressing the
cells which may be collected from cord blood. host immune system it helps to prevent rejection of