Immunological evaluation of harvested stem cells obtained by leukapheresis after chemotherapy

Harvest quality and factors affecting collection and engraftment of CD34+ cells in patients with breast cancer scheduled for high-dose chemotherapy and peripheral blood progenitor cell support

The use of CFU-GM and CD34+ cell enumeration for assessing harvest quality and factors affecting peripheral blood progenitor cell (PBPC) harvest and engraftment were investigated in 45 women with high-risk and metastatic breast cancer scheduled for dose-intensive cyclophosphamide, thiotepa, and carboplatin (CTCb). PBPC were mobilized with standard breast cancer regimens or cyclophosphamide (1.5 g/m2) and 5 micrograms/kg/day G-CSF and used together with G-CSF for hematopoietic support post-CTCb. There was a significant correlation between peripheral blood CD34+ cells/microliter and harvest CD34+/kg (r = 0.73, p < 0.0001) and between harvest CFU-GM and CD34+ cells/kg (r = 0.5, p < 0.0001). CFU-GM clonogenic assays were of no clinical use beyond that of CD34+ cell enumeration, with the latter allowing for real-time decisions regarding harvesting. Multiple stepwise regression identified the number of prior chemotherapy cycles as the only significant clinical predictor of CD34+ cell yield. For 34 patients proceeding to CTCb with PBPC support, multiple stepwise regression identified as the best predictors for engraftment CFU-GM and CD34+ cells/kg for neutrophils and CFU-GM, CD34+ cells/kg, and the number of prior cycles of chemotherapy for platelets, respectively. A threshold dose of 1 x 10(6) CD34+ cells/kg, obtained in 87% of these heavily pretreated breast cancer patients, was adequate to ensure engraftment within 15 days. There was no significant difference in length of hospital stay or blood product use between patients receiving 1-2.5 x 10(6) CD34+ cells/kg and greater than 2.5 x 10(6) CD34+ cells/kg, although median time to engraftment of neutrophils (9 days versus 8 days, p = 0.007) and platelets (12 days versus 9 days, p = 0.006) was significantly longer. The established threshold of > or = 1 x 10(6) CD34+ cells/kg will allow for more confident consideration of using aliquots of this threshold dose for hematopoietic support in sequential high-dose regimens inclusive of CTCb.

Estimation of the progenitor cell yield in a leukapheresis product by previous measurement of CD34+ cells in the peripheral blood

To assess whether measurement of CD34+ cells in the peripheral blood allows one to estimate the progenitor cell yields of subsequent leukapheresis procedures, 733 corresponding blood and leukapheresis samples were analyzed. Peripheral blood progenitor cells of cancer patients were mobilized with hematopoietic growth factors alone or postchemotherapy, and harvested processing 10 liters of blood for each leukapheresis product. The CD34+ cell count (CD34+ cells/microliter blood) correlated most closely with the progenitor cell yield in the corresponding leukapheresis product (CD34+ cells/kg bodyweight, r = 0.80), while the proportion of circulating CD34+ cells to the white blood and mononuclear cells predicted the yield less reliably (r = 0.74 and r = 0.60). The CD34+ cell yield was independent of the white blood count (r = 0.04), whereas a weak correlation was found between the mononuclear cell count and the number of CD34+ cells/kg collected (r = 0.42). It was unlikely to obtain the threshold quantity of 2.5 x 10(6) CD34+ cells/kg required for rapid engraftment when counts below 10 CD34+ cells/microliter blood were detected. At levels between 10 and 30 CD34+ cells/microliter sufficient autografts could be harvested, whereas 30-100 CD34+ cells/microliter were required to achieve this by a single leukapheresis. A surplus of CD34+ cells was likely above 100 CD34+ cells/microliter which could be useful for progenitor cell enrichment techniques. The correlation between the CD34+ cell count and progenitor cell yield was independent of the mobilizing regimen and whether leukaphereses had been performed previously. In conclusion, the number of CD34+ cells/microliter blood allows a reliable prediction of the CD34+ progenitor cell yield in subsequent leukapheresis procedures. However, rare cases of unexpectedly sufficient progenitor cell yields may be observed even at CD34+ cell levels below detection limit.

Patient condition affects the collection of peripheral blood progenitors after priming with recombinant granulocyte colony-stimulating factor

A total of 258 aphereses were performed in 79 patients with nonmyeloid malignancies after mobilization of peripheral blood stem cells (PBSC) with recombinant human granulocyte colony-stimulating factor (rhG-CSF). Apheresis products were examined for viable mononuclear cell (VMC), CD34+ cell, and clonogenic cell contents. The number of progenitors in aphereses differs in subgroups of patients with different diagnoses. However, the number of CD34+ or clonogenic cells is dependent on age and amount of chemotherapy delivered to patients before collection rather than on the nature of the disease itself. In addition, the actual dose of rhG-CSF used to mobilize PBSC and the number of VMC in aphereses influenced the clonogenicity of CD34+ cells, although the daily dose of rhG-CSF seems to play little role on the number of clonogenic cells in each individual apheresis product. CD34+ cell and CFU-C (or CFU-GM) numbers are related parameters, and the relation can be described as linear. However, the linear relation varies in different patient groups, and most of the linearity is induced by the highest sets of values. We conclude that mobilization with low doses of rhG-CSF alone is feasible and that the probability of collecting a high number of peripheral blood progenitors is increased in young patients undergoing apheresis early in the course of the disease. Although the relationship between CD34+ cells and CFUs can be described as linear in well-defined situations, its relevance may be limited because it is not a universal finding.

Circulating stem cell collection in lymphoma and myeloma after mobilization with cyclophosphamide and granulocyte colony-stimulating factor for autologous transplantation

We report the results of 72 leukapheresis procedures performed for autologous peripheral blood stem cell collection in 18 patients with lymphoma and myeloma, after combined mobilization with cyclophosphamide and granulocyte colony-stimulating factor (G-CSF). The numbers of mononuclear cells (MNCs), CD34+ cells and granulocyte-macrophage colony-forming units (CFU-GM) either in the peripheral circulation (preleukapheresis sample) or in the product obtained from leukapheresis (leukapheresis sample) were evaluated. A highly superior proportion of CD34+ cells (14-fold) and CFU-GM (5-fold) resulted from the mobilization therapy. CFU-GM and CD34+ cells were highly enriched with respect to all MNCs (relative recoveries: 2.13, range 0.3-41, and 1.08, range 0.2-8.5, respectively) due to an additional mobilization effect by the leukapheresis procedure. Also, a relatively strong linear correlation between the three different parameters was found in the leukapheresis product (CD34+:CFU-GM, r = 0.81; MNCs:CD34, r = 0.69; MNCs:CFU-GM, r = 0.75; CFU-GM:CD34+, and MNCs, r = 0.85). Our data suggest that the number of MNCs and CD34+ cells obtained after combined mobilization with cyclophosphamide and G-CSF can be used as predictor of the number of granulomonocytic progenitors.

Optimal blood stem cell mobilization using 10 micrograms/kg granulocyte colony-stimulating factor (G-CSF) alone for high-dose melphalan intensification in multiple myeloma: an intrapatient controlled study

A recent randomized multicentric French study has shown that intensification with stem cell rescue improves the response rate and progression-free survival in multiple myeloma. Transplantation with primed peripheral blood stem cells (PBSC) displays a faster hematological recovery, especially for platelets, as compared with a bone marrow stem cell graft. In multiple myeloma, the optimal mobilization method for PBSC is unknown. The present study compares mobilization with cyclophosphamide 4 g/m2 + G-CSF 5 micrograms/kg versus G-CSF 5 micrograms/kg alone versus G-CSF 10 micrograms/kg alone in two cases of multiple myeloma, using an intrapatient controlled evaluation of the amount of CD34-positive cells obtained during each leukapheresis. In both cases, the highest CD34-positive cells yield was obtained with G-CSF at 10 micrograms/kg. Despite the low number of cases, this method, devoid of life-threatening toxicity, might be of greatest interest in multiple myeloma.

Evaluation of the Fresenius cell separator AS 104 for harvesting peripheral blood stem cells in pediatric patients

In a single institution trial we carried out 35 peripheral blood stem cell harvesting procedures in 12 children with advanced malignancies to evaluate the procedure's safety and the collection efficiency of the Fresenius blood cell separator AS 104 in a pediatric population. Despite a significant mean decrease of 21% (+/-8%) in systolic blood pressure after starting the procedure, all children tolerated leukapheresis without any adverse reaction. After termination of leukapheresis there was a significant decrease of all determined hematological parameters, as compared with pre-harvest values. The mean mononuclear cell recovery was 64% (+/-26%), and in 25/35 (71%) harvesting procedures the minimum progenitor number required for safe autografting could be obtained by one single leukapheresis. We conclude that the Fresenius AS 104 blood cell separator provides a high cell yield and is a safe device for leukapheresis in pediatric patients.

Use of flow cytometric CD34 analysis to quantify hematopoietic progenitor cells

This review summarizes our experiments on flow cytometric analysis of CD34 positive mononuclear cells (MNC) and on colony formation of myeloid hematopoietic progenitor cells in the clonogenic assay. We examined MNC isolated by density centrifugation of bone marrow, cord blood and peripheral blood. The latter samples originated either from patients recovering from myelosuppressive treatment who received no growth factors or from patients treated with G-CSF or GM-CSF. We attempted to correlate the results obtained by CD34 analysis with the cloning efficiency determined after a 14 day culture period in the methylcellulose-based clonogenic assay. The highest cloning efficacy (60%-100%) was observed in cord blood, however, a good correlation was found in both untreated and GM-CSF treated peripheral blood samples in which a mean of 50% and 20% of the number of CD34 positive MNC gave rise to myeloid colonies. In bone marrow, the cloning efficacy was generally lower and ranged between 5% and 15%. The lowest values were observed in G-CSF treated peripheral blood in which colonies were grown from only 1%-9% of the CD34+ MNC. Due to the variable numbers of CD34+ lymphoid and/or more committed myeloid precursors which form either no colonies or only clusters, there was a greater variation and a lower cloning efficiency in the latter two cell sources. In conclusion, one colour CD34 analysis of cord blood MNC and untreated or GM-CSF treated peripheral blood MNC provides reliable results with respect to the content of myeloid progenitors. Analysis of bone marrow MNC and G-CSF treated peripheral blood MNC requires two colour staining using CD34 and CD45RA.(ABSTRACT TRUNCATED AT 250 WORDS)

Autotransplants with peripheral blood stem cells and clinical results obtained in children: a review

Peripheral blood stem cell transplantation (PBSCT) is increasingly used to support cancer treatment in adults and children. In this review we describe methodological aspects of PBSCT, compare it with autologous bone marrow transplantation (autoBMT), and review the first clinical results obtained with PBSCT in childhood.

Defining a therapeutic dose of peripheral blood stem cells

Peripheral blood stem cells (PBSC) are now used extensively to provide rapid and durable hematopoietic reconstitution following supralethal myeloablative therapies. A major clinical issue is the quantitation of the cells responsible for reconstitution. We review here published reports of transplants using the measurement of mononuclear cells and granulocyte-macrophage colony-forming units (CFU-GM) to quantitate PBSC. In addition, we present data from three institutions where hematopoietic recovery is correlated with doses of CFU-GM or CD34+ cells. These data suggest doses of 20 x 10(4) CFU-GM or 2 x 10(6) CD34+ cells/kg body weight that provide rapid engraftment of neutrophils and platelets.