CD34+/CD41a+ cells best predict platelet recovery after autologous peripheral blood stem cell transplantation

Abstract

Summary:Reliable markers for megakaryocytic reconstitution after peripheral blood stem cell transplantation (PBSCT) have not been established. To determine a convenient and reliable predictor, we measured the number of megakaryocyte progenitor cells in PBSC grafts by clonogenic and flow cytometric assays. Seventeen patients with hematological and solid malignancies were included in this study. For the clonogenic assay, we used thrombopoietin (TPO) as a growth factor to evaluate the maximum number of megakaryocyte progenitor cells. Using a flow cytometric assay, we examined the expression of platelet glycoproteins on CD34 + cells to count the number of megakaryocyte progenitor cells. We used buffer containing EDTA to prevent platelet adhesion to CD34 + cells and selected CD34 + cells by immunomagnetic beads. The best correlation was observed between the number of CD34 + /CD41a + cells and the time to platelet recovery (P = 0.0205), rather than the total number of CD34 + cells. In addition, a close correlation was observed between the number of CD34 + /CD41a + cells and colony-forming unit megakaryocyte (CFU-MK) (P = 0.0018). These observations suggest that the number of CD34 + /CD41a + cells is the best predictor for platelet reconstitution after PBSCT. Keywords: PBSCT; platelet recovery; CD34; CFU-MK; thrombopoietinAutologous peripheral blood stem cell transplantation (PBSCT) has been increasingly used following high-dose chemotherapy with or without total body irradiation (TBI) for patients with hematologic or nonhematologic malignancies. 1,2 Chemotherapy and/or hematopoietic growth factors have been used to mobilize stem and progenitor cells into blood for transplantation. [3][4][5][6] However, the minimum number of stem cells for engraftment has not been fully elucidated, and the factors which predict the tempo of hematopoietic recovery are also undefined. Several reports have shown a correlation between the number of colony-forming unit granulocyte-macrophage (CFU-GM) and CD34 + cells Correspondence: Dr C Shimazaki, Second Department of Medicine, Kyoto Prefectural University of Medicine, 465 Kawaramachi-Hirokoji, Kamigyoku, Kyoto, 602, Japan Received 22 November 1997; accepted 27 January 1998 and the time to granulocyte recovery. 7-9 As for platelet recovery, few studies have been reported; some have shown that the number of CFU-GM and CD34 + cells correlate with platelet recovery, 7-14 but others have not shown a significant correlation. 15,16 Recently, specific markers for megakaryocyte progenitors such as colony-forming unit megakaryocyte (CFU-MK) and CD34 + /CD41 + or CD34 + /CD61 + cells have predicted platelet engraftment in PBSCT. 13,14,16,17 Thrombopoietin (TPO), the ligand for the c-mpl receptor, has been shown to stimulate the growth of megakaryocyte colonies in vitro. [18][19][20] The number and size of CFU-MK induced by TPO was greater than that induced by any other combination of growth factors, suggesting that TPO may be useful for assaying CFU-MK. 21 Based on these observations, we analyzed th...

Pegfilgrastim successfully mobilizes megakaryocyte progenitors into the peripheral blood in subjects with solid tumours

“…There was a positive dose-response relationship with increasing dose of pegfilgrastim and the mean peak CFU-MK count for patients who received pegfilgrastim 18 mg was statistically significantly higher than that seen in the filgrastim group. The correlation between CD41a and CFU-MK based on our data and that of others 17 has shown that CD41a can be used as a surrogate marker. The side effect profiles of pegfilgrastim and filgrastim in this study were very similar.…”

“…6,8,36 This has been shown to be directly related to the CD34 þ and CD41a þ content of the apheresis product. 17,26 Additionally, no clinically significant neutralizing Ab have been described with G-CSF 37 and it is known to have an excellent safety profile and manageable side effects. 38 Newer mobilizing agents such as AMD3100, a bicyclam compound which inhibits binding of SDF-1 to cognate receptor CXCR4 on CD34 þ stem cells, when combined with G-CSF augments mobilization, but this has not yet been shown to result in speedier platelet recovery.…”

“…25 Analysis of platelet GPs on CD34 þ cells has shown that megakaryocytic reconstitution and platelet recovery post G-CSFprimed PBPC transplantation correlate better with number of CD34 þ /CD41a þ cells infused than total number of CD34 þ cells. 17 In addition, a close correlation has been observed between the number of CD34 þ /CD41a þ cells and colony-forming unit megakaryocyte (CFU-MK). 17,26 Pegfilgrastim (Neulasta) is a polyethylene glycol-filgrastim conjugate with a longer half-life than the parent molecule (filgrastim) and a sustained duration of action, allowing several daily injections of filgrastim to be replaced by a single injection of pegfilgrastim.…”

“…17 In addition, a close correlation has been observed between the number of CD34 þ /CD41a þ cells and colony-forming unit megakaryocyte (CFU-MK). 17,26 Pegfilgrastim (Neulasta) is a polyethylene glycol-filgrastim conjugate with a longer half-life than the parent molecule (filgrastim) and a sustained duration of action, allowing several daily injections of filgrastim to be replaced by a single injection of pegfilgrastim. 27,28 The noninferiority of pegfilgrastim to filgrastim, as measured by the duration of severe neutropenia in breast cancer patients undergoing chemotherapy, has been established in two large, randomized, double-blind clinical trials.…”

“…14,15 Platelet recovery is also dependent on CD34 þ and CD34 þ / CD41a þ cell dose delivered to the patient and the use of cytokines in the post transplant period. 10,16,17 G-CSF, a lineage-specific growth factor, stimulates the proliferation and differentiation of neutrophil precursors and functional activation of mature neutrophils. 18 Human recombinant G-CSF is a proficient mobilizer of CD34 þ stem cells in the cytokine-alone 13,19,20 and chemotherapy plus cytokine settings.…”