CD34 positive PBPC expanded ex vivo may not provide durable engraftment following myeloablative chemoradiotherapy regimens

Abstract

Summary:suppression. Finally, culture conditions may be developed which could be applied to gene transduction protocols. We have previously demonstrated that CD34 + cells, Most investigators initiate stem/progenitor cell expansion selected from peripheral blood progenitor cells (PBPC), with CD34 + cells purified by positive selection since these can be expanded in ex vivo culture and can be infused cells appear to be superior to unselected material. In in tandem with unmanipulated PBPC with little or no addition, up to a 4.0 log depletion of contaminating tumour toxicity. In this study, four patients (two non-Hodgkin's cells can be obtained using CD34 selected starting populymphoma (NHL), two multiple myeloma (MM)) lations. 7 A recent study suggested that any remaining received myeloablative conditioning prior to stem cell tumour cells do not increase in number during ex vivo rescue using ex vivo expanded cells alone. The two expansion, and this may represent a further purging patients with NHL received cyclophosphamide and total effect. 8,9 The first clinical studies using progenitor cells body irradiation (CY/TBI) and the two patients with expanded ex vivo have now been reported. 5,6,10,11 In only MM, busulphan and melphalan (Bu/M). One case one of these studies, in a small number of patients, stem received an inadequate CFU-GM dose, despite expancell rescue was performed using only the expanded cells, sion, and in one case the expanded cells were contamiwithout unmanipulated 'back-up'. 5 Brugger et al 5 expanded nated. No definitive conclusions may therefore be drawn one tenth of a standard peripheral blood progenitor cell concerning engraftment in these two cases. However, (PBPC) product prior to infusion. Six patients were transthe other two cases received high doses of committed planted with expanded cells only, and five of six experiprogenitors. Following infusion of the expanded enced rapid engraftment following high-dose, but nonmaterial, all four patients failed to show sustained myeloablative, chemotherapy. The remaining patient died neutrophil engraftment and none showed evidence of prior to the anticipated time of engraftment. platelet engraftment. Back-up, unmanipulated PBPC In our previous study, we established the safety and were therefore infused on days 14, 34, 32 and 28 and feasibility of transfusing CD34 + cells which had been selecsubsequently all four cases achieved satisfactory ted from cryopreserved PBPC and then expanded ex vivo. 6 engraftment of both neutrophils and platelets. In conTen patients received у20 × 10 4 CFU-GM/kg unmanipclusion, we feel that, CD34 + cells, expanded ex vivo using ulated PBPC in addition to an aliquot of expanded cells the conditions described in this report, may not provide (range 33-279 × 10 4 CFU-GM/kg). There were no toxic durable engraftment following fully myeloablative effects from the progenitor cells which had been generated conditioning.ex vivo. 6 Keywords: ex vivo expansion; CD34 positive; PBPC;The primary objective of this second study was to det...

Cell culture bags allow a large extent of ex vivo expansion of LTC-IC and functional mature cells which can subsequently be frozen: interest for large-scale clinical applications

“…Williams et al 26 obtained substantial expansion of myeloid precursors in ex vivo bag cultures of CD34 + leukapheresis cells stimulated with PIXY and subsequent prompt neutrophil recovery in graft recipients. Using other stimulating factors, Holyoake et al 27 reported similar results for the early phase of hematopoietic recovery in four patients. However, further investigations will be necessary to demonstrate the capacity of these expanded cells to induce long-term engraftment in patients who have undergone true myeloablative conditioning.…”

Ex vivo expansion of umbilical cord blood stem cells for transplantation: growing knowledge from the hematopoietic niche

“…Current methods to ex vivo expand umbilical cord blood cells may introduce defects that lead to engraftment failures as has been reported using expanded 25 or transduced 29 autologous CD34 þ cells. Guenechea et al 30 transplanted fresh and ex vivo-expanded CD34 þ cord blood cells into irradiated non-obese diabetic (NOD)/SCID mice and while they found no differences in engraftment at 4 months, engraftment at 3 weeks was impaired when the expanded cells were used, suggesting that expanded cells might do not facilitate engraftment.…”

“…Stem cell assays to evaluate UCB expansion With the clinical failure of ex vivo expansion when the expanded product was used as the sole stem cell source 25 and the lack of improvement when the manipulated and unmanipulated products were both infused, 21,24 the current preclinical models and predictive assays for engraftment of all cell lineages deserve further development. Long-term engraftment is dependent upon the number and engraftment ability of the HSC transplanted; therefore, the ideal assay for this purpose must be simple, quantitative and reliably demonstrate engraftment capacity.…”

Correlation Between IL‐3 Receptor Expression and Growth Potential of Human CD34 + Hematopoietic Cells from Different Tissues

“…Autologous progeny cells after culture/expansion in cytokine combination including IL-3 have been successfully infused into patients after a nonmyeloablative conditioning regimen [18]. In another study, when patients were given a myeloablative conditioning regimen, cells expanded in IL-3-containing cytokines failed to produce engraftment [19]. More recent data indicated that culture in IL-3 led to a decrease or loss of primitive hematopoietic cells with reconstitution potential [20][21][22][23].…”