Cord Blood Units Collected with Liquid CPD Appear to Contain Significantly More Nucleated and CD34+ Cells Than Units Collected with Dry Heparin.
Asimena Rigas Bridges*,3 and
Mark C. Walters, MD4
1 PerkinElmer/ViaCord Processing Lab, Cambridge, MA, USA, 2 ViaCord Processing Lab, ViaCord/PerkinElmer, Hebron, KY, USA, 3 ViaCord/PerkinElmer, Hebron, KY, USA, 4 Children's Hospital and Research Center, Oakland, CA, USA
Transplantation of Cord Blood Stem Cells depends primarily onthe number and potency of stem cells harvested, processed andcryopreserved. Previous studies have not compared the anti-coagulantused in collection systems with respect to their impact on thecord blood unit cell count and composition. We compared cordblood units collected in Citric Phosphate with Dextrose Buffer(CPD) or Heparin by measuring the pre-processed total nucleatedcell count (TNC), post-processed TNC, % CD34 and total numberof CD34+ cell numbers from units harvested randomly in remotehospitals in the US. Between August 2005 and May 2009, cordblood units harvested in collection bags containing lyophilized(dry) Heparin (N=65) and cord blood units harvested in FDA approvedSentinel collection bags containing 35 ml of CPD (N>6300)were processed using standard processing methods which includedeither RBC depletion or volume reduction based on initial collectedvolume. We observed significantly greater pre-processed TNCcount (9.59 +/- 5.98 x 108 Vs 7.36 +/- 4.96 x 108, p=0.003),post-processing TNC count (7.72 +/- 4.61 x 108 Vs 5.80 +/- 3.63x 108, p=0.001), % CD34+ (0.46 +/- 0.28 Vs 0.37 +/- 0.23, p=0.024)and number of CD34+ cells (2.72 +/- 2.73 x 106 Vs 1.72 +/- 1.44x 106, p=0.003) in the CPD units. Interestingly, viability bydye exclusion was 7% higher (p=0.0001) in the post-processedHeparin units despite more pre-TNC (by 24%), post-TNCs (by 29%),and more %CD34+ (by 22%) and CD34+ cells (by 54%) in the CPDunits. Post-processed CD34+ measurements relied upon gatingto select live cells (by 7AAD exclusion) and reflect a decreasein viable CD34+ cells in Heparin units. Together, these resultsindicate that units collected using CPD contain significantlymore TNCs prior to and after processing than units collectedusing Heparin. Furthermore, both the % CD34+ and total numberof CD34+ cells were significantly lower in the Heparin containingunits. Both TNC and CD34+ values are primary indicators of graftpotency in clinical studies. Cord blood units collected in thepubic cord blood system and the vast majority of cord bloodunits used in clinical transplantation have been collected inCPD. CPD is both an anti-coagulant and a preservative as itcontains Dextrose which provides a substrate for glycolysisand preserves the metabolism in cells. Heparin, which does notcontain Dextrose to preserve cell metabolism, is rarely usedas an anti-coagulant for blood collection, as it can only beuseful for blood that is to be transfused within 12 hours ofcollection because it is broken down over longer periods oftime. Also, the use of dry Heparin may adversely affect theosmolarity of the cord blood unit, thereby compromising cellularity.However, further studies are recommended to elucidate the mechanismby which dry Heparin may adversely affect the TNC and CD34 contentof cord blood units.
Disclosures:Kraus:PerkinElmer/Viacord: Employment. Foster:PerkinElmer/Viacord:Employment. Bridges:PerkinElmer/Viacord: Employment. Walters:PerkinElmer/Viacord: Membership on an entity's Board of Directorsor advisory committees.
* Asterisk with author names denotes non-ASH members.