Improve The Efficiency Of PBSC Collection Using CD34+ Cell As A Predicator And Large Volume Leukoapheresis

OBJIECTIVE The fast engraftment of PBSC is determined by the number and quality of CD34+ ce lls infused. However, the collection of PBSC is time consume and expensive. Thus , to collect as more as CD34+ cells is the main purpose of PBSC collection and t his project. In this project we try to study how to improve the collection effi ciency from the following two aspects: (1)The mobilization regimen of chemothe rapy plus cytokine can increase the number of CD34+ cells in the blood significa ntly, but the peak value of CD34+ cells appeared in the blood changes greatly an d the definite day to initiate the apheresis is hard to determined, which is dif ferent from that by the mobilization regimen of cytokine only. The concentration of CD34+ cells in the blood was used to predictive the apheresis product and ti ming; (2)Large volume leukoapheresis (LVL) process more volume of blood and co llect more CD34+ cells theoretically compared to the regular or standard volume apheresis which is time consume and inconvenient. The purpose on LVL in this pr oject is to study the collection efficiency under different blood inlet flow rat e, the safety of LVL and the kinetics of CD34+ cells released from the bone marr ow. METHODS The PBSC collection is performed through a continued blood cell separator aimed on the mononuclear cells collection. 63+14 patients were mobilized using chemoth erapy plus G-CSF and 17 patients and 7 heath donors were mobilized using G-CSF o nly. CD34+ cell counts and other blood cell in the peripheral blood and the aphe resis components were assessed. Multiple samples were collected during LVL from 21 patients with acute myelogenous leukemia or multiple myeloma. The relationshi p between the number of WBC and CD34+ cells in the peripheral blood and in the a pheresis component was analyzed using rank correlation andlinear regression analysis. Examinations of the differences in collection effici encies as a function of several explanatory variables were studied in regression models using generalized estimating equations, which are unaffected by intra-pa tient correlations that may exist as a result of the multiple sample points from individual patients. Both univariate and multivariate models were examined. RESTULTSThe median of CD34+ cells in the preapheresis peripheral blood was 12.26 x 106/l and in the apheresis component was 1.31 x 106/kg. The correlation coefficient f or CD34+ cells/l in the peripheral blood with CD34+ cells x 106/kg in the aphere sis component was 0.87 (n=216 collections). This correlation existed for many pa tients and collection variables. However, patients with AML had fewer CD34+ cell s in the apheresis components at any level of peripheral blood CD34+ cell count compared to patients with BCA or NHL and to allogeneic donors. Components collec ted from patients with CD34+ cell counts below 10 x 106/l in the peripheral bloo d contained a median of 0.75 x 106 CD34+ cells/kg. When the WBC count in the blo od was below 5.0 x 109/l, the median level of CD34+ cells in the peripheral bloo d was 5.6 x 106/l (range, 1.0-15.5 x 106/l). A very poor correlation was found b etween the WBC count in the blood and CD34+ cell yield ((=0.12, n=158 collection s). The patients receiving LVL experienced a slow decline in blood CD34+ cell concen trations during the apheresis procedure. The level of platelet in the blood dec reased 47.5±12.9% of the initiate level after the collection. The correlation c oefficient for the number of platelet before and after in the blood is 0.94(n=2 1). The number of CD34+ cells in the blood decreased 42.3±22.0% of the start l evel. The number of CD34+ cells collected exceeded the number in the peripheral blood at the start of the procedure by an average of 3.0-fold. With the increa sed blood volume processed, the possibility of reach the target number of CD34+ cell increased. The efficiency of collection for CD34+ cells averaged 92.6%and did not vary by speed of blood processing, diagnosis, or mobiliz...