Biomedical Engineering Reference
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Fig. 9.1 Stem cell collection by multiple aspirations from bone marrow
Furthermore, as for aspirate volume, precise red blood cell number and/or plasma
quantity reduction are required (by processing), especially for ABO-incompatible
(major and/or minor) transplants or when cryopreservation is intended (autologous
setting). Commonly used minimum target (after processing) of TNC count—for
both autologous and allogeneic transplants—is 2 × 10 8 /kgbm [ 26, 36 ] (Fig. 9.1 ).
The depletion of unwanted malignant cells or T-cells in final cell suspension is
achieved by the ex vivo purging procedure using immunomagnetic cell selection
[ 6 ]. These SC purification procedures (processing and purging or selection) enable
reduction of the aspirate volume, i.e., reduction of red blood cell for around 80-90%,
or even more precisely, the depletion of mentioned unwanted (malignant or T-cells)
cells with efficacy ³ 3-4 Log 10 [ 3- 6, 36 ]. Development of the ability to isolate
selected and/or ex vivo expanded SCs in a large number is expected to broaden their
beneficial therapeutic effects, since the limitation to many of SC applications has
been the absolute number of defined target cells.
Peripheral blood-derived stem cells . CD34 is the cluster designation given to a trans-
membrane glycoprotein present on SC surface and some stromal cells. Cells express-
ing the CD34 antigen (obtained from BM or PB) are capable of complete reconstitution
of hematopoiesis. The first SC harvests from PB were accomplished in “steady-state
hematopoiesis”—but using several number (6 to 9) of cell harvestings and following
cryopreservation was needed [ 32, 37 ]. Currently, SCs are harvested after mobilization
by the use of chemotherapy and/or recombinant colony-stimulating factors (rHuG-
CSF). The typical number of aphereses required is not more than one to three.
Briefly, SC harvesting from PB is performed by blood cell separators. The apher-
etic procedure is completely automated—uniform protocols are applied, with
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