Debulking blood stem cell collections by density gradient centrifugation in a closed-vessel system

Background Blood stem cells collected by apheresis are largely mononuclear cells in nature, so manipulation of blood stem-cell components frequently r equires more time and reagents than for a marrow harvest. Reducing the nucl eated cell number in mobilized blood stem-cell collections, while preservin g hematopoietic progenitor content, would make such manipulations simpler a nd less costly, but only if debulking procedures were not complex. Methods We evaluated separation of light-density cells and enrichment of CD 34+ cells from mobilized peripheral blood stem-cell collections by density gradient centrifugation over buoyant density solution 60 (BDS 60) in a sing le, closed vessel. Results Fifteen aphersis products from five normal volunteers and eight can cer patients contained 3.44 (range, 1.19-5.51) x 10(10) nucleated cells. Fo llowing processing and washing, there was a median 29% recovery of nucleate d cells, 79% recovery of CD34+ cells, 2.49-fold enrichment of CD34+ cells, 0.96-log depletion of CD3+ cells, 0.48-log depletion of CD56+ cells, and 0. 72-log depletion of CD19+ cells. Results of processing were affected by the variability in composition of the apheresis products. The enrichment of CD 34+ cells varied by donor type, and there was a logarithmic relationship be tween the preprocessing percentage of CD19+ cells. Recovery of cells after thawing and washing was acceptable for processed cells cryopreserved at con centrations over the range of 0.01-1.5 x 10(8)/mL. Discussion These results demonstrate a simple method by which an aphersis p roduct of 1-5 x 10(10) cells can be debulked effectively in a single, close d vessel.