Large Volume Leukapheresis for Collecting Hemopoietic Progenitors: Role of CD 34+ Precount in Predicting Successful Collection

In this work we evaluated the efficacy of stem cell collection with Large Volume Procedures. (LVP), and analysed the importance of the CD34+ cell precount in promoting the collection of a sufficient number of CD34+ cells for transplantation, using the Univariate Logistic Regression analysis. Eighty-nine leukapheresis were performed in 49 patients with hematological malignancies and solid tumors, mobilized with chemotherapy plus Granulocyte Colony Stimulating Factor (G-CSF). For each procedure 15.8 liters of blood were processed. The median value of Nucleated Cells (NC) and CD34+ cells precount was respectively 8.29 × 109/ml (range 1.13÷45.4) and 43.08 × 103/ml (range 1.06÷795.2). Results show the capability of LVP to collect large quantities of hemopoietic progenitors with a median CD34+ cell total yield of 215.02 × 106 (range 5.03÷2210). The yields per patients’ body weight were: CD34+ cells 3.23 × 106/kg (range 0.081÷41.58). The regression analysis between blood cell precounts and collection yields gave the following correlations: the CD34+ cell precount correlates with CD34+ yield (r = 0.78 p < 0.00) and with CD34+ cell yield/kg (r = 0.76 p < 0.00). The number of CD34+ cells processed correlated with the number of CD34+ cells collected/kg (r = 0.83 p < 0.000). To investigate the importance of CD 34+ cell precount in promoting CD34+ cell yields ≥2.5 × 106/kg we performed a Univariate Logistic Regression analysis that showed in our patients a probability of collecting ≥2.5 × 106 CD34+/kg that rose from 0.6 to 0.95 for CD 34+ precounts that oscillated from 30 to 40 × 103 CD34+ cells/ml, respectively. The Univariate Logistic Regression gave a probability of collecting ≥2.5 × 106 CD34+ cells/kg that oscillated between 0.64÷0.98 for values of CD34+ cells processed from 6 × 106/kg to 8 × 106/kg, p <0.000. Sixty-three percent of patients reached the target dose of 2.5 × 106 CD34+ cells/kg with only one LVP. Until now 12 patients have been transplanted and all have had a prompt and complete lasting recovery. These results confirm the efficacy of LVP in harvesting hemopoietic progenitors and their ability in reconstituting hemopoiesis of transplanted patients, enabling the estimation of CD34+ precounts and CD34+ cells processed values, highly predictive for the collection of ≥2.5 × 106 CD34+ cells/kg. Furthermore, the Logistic Model suggests that the best strategy to plan a successful CD34+ cell collection procedure is to identify for each patient the amount of CD34+ cells/kg to be processed rather than the fixed processing of 3÷5 blood volumes in all patients.

Stem Cell Collection using the Dideco Excel Continuous Flow Blood Cell Separator: Parameters for Optimal Stem Cell Collection Timing

This study evaluates stem cell collection procedures performed with the Dideco Excel blood cell separator, with particular attention given to yields and separator collection efficiencies. Patients’ blood precounts and yield parameters related to the harvest capacity of the collection system were investigated. Fifty-five collection procedures were analyzed in 32 patients suffering from hematological malignancies and solid tumors and mobilized with chemotherapy plus G-CSF. The median blood volume processed in each procedure was 15.8 liters (12–19.750), with a blood flow rate of 70 ml/min. Patients had the following median blood precount value: NC 7.81×109/L, CD34+ cells 49.08×103/ml. Leukapheresis procedures gave the following yields: NC 14.95×109, MNC 10.83×109, CD34+ cells 4.37×106; yields/kg, NC 0.21×109kg, MNC 0.15×109/kg CD34+ cells 4.26×106/kg. Procedures show the following collection efficiencies: NC 10.79%, MNC 29.06%, CD34+ 42.33%, PLT 26.5%. The RBC (red blood cell) contamination of the product was (median value) 20.9 ml for each procedure, and for platelets 1.76×1011 per procedure. The CD34+ cell precounts strongly correlated with the CD34+ yields/kg (r=0.82. p=0.000). Furthermore the NC and MNC precounts correlated with the CD34+ yields/kg but only the MNC precount correlation is notable (r=0.57, p=0.000). The logistic regression analysis shows that CD34+ (p=0.008) but not NC (po=0.14), MNC (p=0.09), or PLT (p=0.53) precounts significantly influenced the collection of a sufficient dose of CD34+ cells for transplantation (≥ 2.5×106/kg). Eleven of the thirty-two patients have been transplanted till now, and all had a prompt and lasting trilineage engraftment NC >1×109/L on day 12 (10–17). Our data show that the collection system analyzed in this report is able to collect large amounts of progenitor cells, harvesting ≥2.5×106/kg CD34+ cells with a single procedure in 68.8% of patients and assuring complete recovery after stem cell transplantation.

Comparison of performance of six different cell separators in collecting peripheral blood mononuclear cells

We compared the efficacy of six different cell separators in collecting peripheral mononuclear cells to be used for autologous or homologous peripheral stem cell transplantation. The product obtained with the Dideco Vivacell cell separator showed a low percentage of mononuclear cells (38%) in the final product and a high platelet efficiency (38%). The Baxter CS3000 Plus cell separator required the longest time to load and prime the kit (18 min), it showed a high MNC efficiency (68%), with the highest percentage of MNC in the final product, the highest platelet efficiency (45%), a low red blood cell contamination in the final product (2.7 mL), the highest extracorporeal volume (450 mL) and a high percentage of technical failures (15%). The product obtained with the Fresenius AS104 cell separator with P1Y kit showed the highest final volume (297 mL), the lowest platelet efficiency (12%) and the lowest extracorporeal volume (230 mL). The same cell separator with C4Y kit showed a lower MNC efficiency (52 vs 60%) and a higher percentage of MNC in final product (63 vs 41%). The platelet contamination in final product was the lowest (18 x 10(9)/100 mL). The Haemonetics MCS3p cell separator required the lowest time to load and prime the kit (5 min), it showed the highest MNC efficiency (71%). The blood volume processed per hour (1328 mL) and the percentage of MNC in final product was lowest (32%), the extracorporeal volume (450 mL) was the highest. The Cobe Spectra cell separator allowed to process the highest blood volume per hour (3383 mL) and the final product had the lowest red blood cell contamination (2.3 mL/100 mL). The Dideco Excel cell separator required the longest time to load and prime the kit (18 min), the lowest MNC efficiency (38%), the highest platelet contamination in final product. Furthermore this machine showed the highest percentage of technical failure (20%). None of the six instruments have all the required preconditions and the ideal cell separator for peripheral stem cell apheresis at present is not available on the market.

Thrombocytopenia after high-dose chemotherapy and autologous stem cell transplantation: an unresolved problem and possible approaches to resolve it

Prolonged thrombocytopenia is a frequent clinical problem in cancer patients undergoing high-dose chemotherapy and autologous transplantation. The use of GM-CSF as an adjuvant to autologous bone marrow transplantation (ABMT) has significantly reduced the duration of neutropenia after high-dose chemotherapy but failed to accelerate platelet recovery in transplanted patients. The more rapid hematopoietic reconstitution obtained by autologous mobilized peripheral blood progenitor cell transplantation (PBPCT) after high-dose chemotherapy has resulted in its increasing use instead of ABMT. However, PBPCT does not always produce faster platelet engraftment after high-dose chemotherapy, and persistent thrombocytopenia remains a significant clinical problem in PBPC-transplanted patients. The duration of severe thrombocytopenia (requiring frequent platelet transfusions) until platelet recovery varies widely depending on the quality of the autograft and previous radiotherapy or chemotherapy. The median days to reach 20,000/microliters platelets ranged from 10 to 32 days. Pilot clinical studies in which cancer patients were transplanted with enriched CD34+ cell autografts, obtained from G-CSF-mobilized PB, showed a similar platelet recovery after high-dose chemotherapy but also wide variation among the patients. The median days to reach 20,000/microliters platelets ranged from 9 to 38 days. The dose of CFU-GM in the autograft has been identified as the best predictive factor for hematopoietic recovery (p < 0.0001) after high-dose chemotherapy and autologous PBPCT in 118 patients with hematologic malignancies. A similar assessment of the megakaryocyte progenitor cells (BFU-MK and CFU-MK) in the autograft not only could predict time to platelet recovery but also could help to optimize the number and method of mobilization of the PBPC required to shorten the problematic obligatory 2-week duration of thrombocytopenia after high-dose chemotherapy. A routine assessment of the number of BFU-MK and CFU-MK present in each autograft and correlation with platelet recovery after transplantation would enable us to define the clinical threshold cell dose required for rapid platelet recovery. Recently, several non-specific cytokines with thrombopoietic activity have been evaluated in phase I clinical trials, including interleukin-1, interleukin-3 followed by GM-CSF, interleukin-6, and interleukin-11 in cancer patients, showing an encouraging trend toward a decrease in thrombocytopenia after chemotherapy. The recently cloned specific platelet cytokine, thrombopoietin, is currently undergoing phase I clinical studies, and the results are awaited with interest.