Nonobese diabetic-severe combined immunodeficient mice transplantation of volume-reduced and thawed umbilical cord blood transplants following closed-system immunomagnetic cell selection.
BACKGROUND
Protocols for the expansion of human umbilical cord blood (UCB) progenitors begin with the selection of CD34+ cells from stored frozen and thawed units. Use of an immunomagnetic selection procedure within a closed blood bag system for volume-reduced UCB transplants was evaluated, and the influence of CD34 cell selection on in vivo engraftment potential was studied.


METHODS
Eleven thawed buffy coat-processed UCB units were processed within a standard blood bag with a washing solution. In six independent experiments, the same dosage of 2 x 104 CD34+ cells from paired selected and nonselected samples was transplanted into NOD-SCID mice. In two experiments, cells from the negative fraction were also transplanted.


RESULTS
The purity of CD34+ cells after selection was correlated with the removal of supernatant after the first washing step and therefore with adequate removal of damaged or dead cells (r=0.86, p < 0.01). Mice transplanted with unselected UCB cells had more human cells within their marrow than animals transplanted with selected cells (8.6 +/- 5.9% selected group vs. 19.8 +/- 14.2% unselected group; p=0.04), whereas no engraftment could be observed transplanting cells from the two negative fractions. A higher percentage of human CD45+ cells in the unselected group were found to be positive for CD38, CD14, CD33, and CD19, indicating a higher potential for these unselected progenitors to differentiate into myeloid cells and B cells.


CONCLUSIONS
Processing of volume-reduced and thawed UCB transplants within a closed-bag system before immunomagnetic CD34+ cell selection allows for the preparation of CD34+ cells of significant purity at technically useful cell recoveries. However, these experiments indicate a potential impairment of engraftment capacity for the CD34+ cell-enriched fraction.
Eichler
Hermann
H
Institute of Transfusion Medicine and Immunology, Red Cross Blood Service of Baden-Württemburg-Hessen, Faculty of Clinical Medicine Mannheim, University of Heidelburg, Friedrich-Ebert-Strasse 107, D-68167 Mannheim, Germany. h.eichler@blutspende.de
Beck
Christian
C
Schröder
Bernd
B
Nguyen
Xuan Duc
XD
Klüter
Harald
H
D000818:Animals; D018952:Antigens, CD34 / Q000032:analysis; D001793:Blood Preservation / Q000295:instrumentation / Q000379:methods*; D036101:Cord Blood Stem Cell Transplantation; D015925:Cryopreservation / Q000379:methods*; D005240:Feasibility Studies; D005347:Fibroblasts / Q000378:metabolism / Q000637:transplantation; D006082:Graft Enhancement, Immunologic; D006085:Graft Survival; D006412:Hematopoietic Stem Cells / Q000737:chemistry / Q000166:cytology; D006801:Humans; D018189:Immunomagnetic Separation / Q000295:instrumentation; D007377:Interleukin-3 / Q000235:genetics / Q000378:metabolism; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D011828:Radiation Chimera; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014183:Transplantation, Heterologous
D018952:Antigens, CD34; D007377:Interleukin-3; D011993:Recombinant Fusion Proteins