Giacomo Menichella

CD34+/CD105+ cells are enriched in primitive circulating progenitors residing in the G0 phase of the cell cycle and contain all bone marrow and cord blood CD34+/CD38low/− precursors

A subset of circulating CD34+ cells was found to express CD105 antigen. Sorting experiments showed that most granulocyte–macrophage colony‐forming units (GM‐CFU) and burst‐forming units — erythroid (BFU‐E) were retained in the CD34+/CD105− fraction, whereas rare GM‐CFU/BFU‐E were generated from CD34+/CD105+ cells. Megakaryocytic aggregates were entirely retained in the CD34+/CD105+ fraction. Neutralizing doses of an anti‐TGF‐β1 antibody demonstrated CD34+/CD105+ cells capable of colony‐forming activity without any significant effect on CD34+/CD105− cells. Cloning of secondary colonies revealed that CD34+/CD105+ cells had a significantly higher secondary cloning efficiency than CD34+/CD105− cells. CD34+/CD105+ cells had a significantly higher long‐term culture‐initiating cell (LTC‐IC) frequency than CD34+/CD105− cells. Kinetic analysis showed that 75% of CD34+/CD105+ cells consisted of DNA 2n G0Ki‐67− cells whereas 82% of CD34+/CD105− were DNA 2n G1Ki‐67+ cells, and this latter subset showed a RNA content consistently higher than CD34+/CD105+ cells. CD34+/CD105+ progenitors were CD25+, whereas CD34+/CD105− contained a small CD25+ subset. Three‐colour analysis of bone marrow and cord blood CD34+ cells demonstrated that all the CD34+/CD38low/− primitive precursors were contained in CD34+/CD105+ cells. Extensive characterization of these CD105+ precursors indicated that they have biological properties associated with primitive haematopoietic precursors.

Autologous blood stem cell harvesting and transplantation in patients with advanced ovarian cancer

We investigated the feasibility of a programme of autologous blood stem cell (ABSC) harvesting and transplantation in 13 patients with advanced ovarian cancer, previously untreated by chemotherapy or radiotherapy and entering a phase II study of high‐dose cisplatin, etoposide and carboplatin with haematopoietic stem cell rescue. Prior to high‐dose treatment all patients underwent two courses of cisplatin and cyclophosphamide. An 8‐fold increase of the peripheral colony forming unit granulocytic‐macrophage (CFU‐GM) was observed during recovery from myelosuppression after the first chemotherapy course. The second course determined a 2·5‐fold increase of peripheral CFU‐GM. In 70% of enrolled patients (nine patients) we were able to perform ABSC harvesting by leukaphereses; in the apheresed patients we harvested an average of 20·8 × 104/kg CFU‐GM (range 10·9–37·0). Haematopoietic trilineage engraftment, established as the number of days necessary to reach white blood cells (WBC) >1·0 × 109/1, polymorphonuclear leucocytes (PMN) >0·5 × 109/1 and platelets (PLT) >50·109/1. occurred very promptly and was sustained in the same series after high‐dose cisplatin, carboplatin and etoposide, followed by autologous blood stem cell transplantation (ABSCT). In our experience we found a significant correlation (r = 0·77; P<0·05) between CFU‐GM infused dose and the engraftment speed of PMN. We conclude that the combination of cisplatin and cyclophosphamide is effective in mobilizing haematopoietic progenitors in the peripheral blood of patients with advanced ovarian cancer, previously untreated by chemora‐diotherapy. Moreover, ABSCT is capable of rapidly restoring the haematopoietic function after high‐dose treatment and for this reason it represents a particularly advisable therapeutic option for the treatment of solid tumours because these patients are commonly older than 50 and can be excluded from bone marrow transplantation.

Further investigations on the expression of HLA-DR, CD33 and CD13 surface antigens in purified bone marrow and peripheral blood CD34± haematopoietic progenitor cells

Summary. We evaluated the HLA‐DR, CD33 and CD13 antigen expression on CD34± haematopoietic progenitor cells (HPC) isolated from the bone marrow (BM) and peripheral blood (PB) of normal donors. The majority of both BM and PB CD34± HPC expressed CD13 and HLA‐DR. The coexpression of CD34 and CD33 was found in a minor CD34± subset. After 7 d of culture in the presence of interleukin‐3 and granulocyte‐macrophage colony‐stimulating factor, CD33 expression was detected in about 50% of HPC. At this point CD34 antigen expression was lost and CD13 and HLA‐DR expression was partially lost. After 14 d of culture, the majority of HPC were CD33±. HPC maintained the capacity to generate colony forming unit granulocyte‐macrophage but they lost the capacity to generate burst forming unit‐erythroid. A correlation was found between the percentage of CD34±/HLA‐DR± cells and the total number of colony forming cells in unfractionated samples from BM and PB of patients with malignancies. These studies demonstrate that, in normal conditions, only a minor subset of CD34± cells coexpress CD33 antigen either in BM or in PB and CD33 antigen is a lineage marker which is coexpressed with HLA‐DR and CD13 on a progenitor committed to the granulocytic‐macrophagic lineage.

Antiproliferative activity of quercetin on normal bone marrow and leukaemic progenitors

We used an in vitro clonogenic assay in semi‐solid medium to test the sensitivity of normal bone marrow and acute myeloid and lymphoid leukaemia progenitors to the flavonol quercetin. We have studied 14 acute myeloid (AML) and four acute lymphoid (ALL) leukaemias. All ALL and the vast majority of AML (12/14) had a high sensitivity to quercetin with more than 50% growth inhibition at 2 × 10−6 M quercetin. One M3‐AML was partially quercetin‐sensitive displaying 60% surviving AML‐colony forming units (CFU‐AML) at a quercetin concentration of 10−5 M. One M1‐AML was resistant to the growth inhibitory effect of quercetin at a concentration of 2 × 10−5 M. The clonogenic efficiency of both AML and ALL positively correlated with leukaemic colony‐forming unit (CFU‐L) sensitivity to quercetin suggesting that this parameter can be useful in predicting quercetin responsiveness of leukaemic cells. We have also studied the effect of various quercetin concentrations on colony formation by normal bone marrow cells. At a quercetin concentration of 10−5 M, we observed (in five different experiments) a mean recovery of 53% and 65% of erythroid blast‐forming units (BFU‐E) and granulocyte‐macrophage colony‐forming units (CFU‐GM), respectively. Thus, normal bone marrow appeared partially resistant to quercetin, being inhibited less than 50% by quercetin concentration higher than 2 × 10−5 When normal bone marrow were deprived in CD34 + haematopoietic progenitors the resultant population became highly sensitive to quercetin, with a mean recovery of BFU‐E and CFU‐GM of 5% and 12% of controls respectively in the presence of 2 × 10−5 M quercetin. Furthermore, CD34 progenitors, positively selected, appeared fully resistant to quercetin concentrations as high as 2 × 10−5 M. Thus, CD34 + progenitors are a quercetin‐resistant component in normal bone marrow. In conclusion, our results further provide a biological basis for the therapeutic use of quercetin, considering that this compound could inhibit leukaemic cell growth without suppressing normal haematopoiesis.

Haemopoietic reconstitution after autologous blood stem cell transplantation in patients with malignancies: a multicentre retrospective study

A retrospective study was undertaken to evaluate the efficacy of autologous blood stem cell transplantation (ABSCT) in terms of haemopoietic reconstitution after ablative chemotherapy or chemo‐radiotherapy. 55 patients with malignancies, observed in four Italian institutions from January 1987 to June 1991, were eligible for evaluation. This series included 19 non‐Hodgkins lymphoma, 11 multiple myeloma, nine ovarian cancer, seven Hodgkins disease, seven non‐lymphocytic leukaemia, one acute lymphoblastic leukaemia, one neuroblastoma. 522 PBSC collections were performed on 55 patients. Following ABSCT, the rate of engraftment was positively related to the dose of CFU‐GM infused and negatively to the presence of bone marrow involvement at conditioning. 48 patients out of 55 transplanted (87%) had rapid, complete and sustained engraftment. Three patients (5%) died of transplant‐related complications. Considering that 60% of the patients in this series were in partial remission or in progressive disease at the time of ABSCT, we conclude that ABSCT is a safe approach for the use of ablative conditioning therapy in patients with a wide scope of malignancies, provided that a large number of CFU‐GM have been collected after mobilizing treatment.

Immunological reconstitution after high-dose chemotherapy and autologous blood stem cell transplantation for advanced ovarian cancer

We evaluated the immunological reconstitution of patients who underwent high-dose chemotherapy and autologous blood stem cell transplantation (ABSCT) for advanced ovarian cancer. Sixty days after transplantation a complete reconstitution of lymphocytes and of the CD3, CD4, CD8, CD19, and CD16/56 subsets was observed in this series. A significant increase in the count of interleukin-2 receptor expressing lymphocyte (CD25) was found on day +60 after transplantation compared to that obtained at diagnosis and before transplantation. A significantly higher lymphokine-activated killer (LAK) precursor activity was seen on day +60 compared to the values obtained at diagnosis and before transplantation while natural killer activity did not show any significant variation. We conclude that ABSCT gives prompt and complete immunohaematopoietic reconstitution after high-dose treatment. Moreover, our data support the feasibility of interleukin-2/LAK therapy as consolidative therapy after ABSCT.

Functional, phenotypic and molecular characterization of cytokine low-responding circulating CD34+haemopoietic progenitors

Circulating CD34+ cell populations characterized by a low rate (up to five) or high rate (more than five) of cell divisions were isolated from 8 d cultures in the presence of stem cell factor (SCF), interleukin‐3 (IL‐3), granulocyte‐macrophage colony stimulating factor (GM‐CSF), granulocyte colony stimulating factor (G‐CSF), erythropoietin (EPO), Flt3 ligand and Peg‐rHu megakaryocyte growth and development factor (Peg‐rHuMGDF) using the fluorescent dye 5,6‐carboxyfluorescein diacetate succinimidyl ester (CFDA‐SE) and flow cytometric cell sorting. Phenotypic characterization of cells which had experienced up to five divisions (CFDA‐SEbright) showed a similar surface antigen expression to starting, freshly isolated CD34+ cells. Conversely, cells which experienced more than five divisions (CFDA‐SEdim) showed a differentiating behaviour, down‐regulating CD34 antigen and acquiring differentiation markers. CFDA‐SEbright cells were significantly enriched in CD105 (endoglin) positive precursors as compared to both freshly isolated CD34+ and CFDA‐SEdim cells. Functional analysis indicated that CFDA‐SEbright had a 3‐fold and 10‐fold greater cumulative cloning efficiency as compared to freshly isolated CD34+ cells and CFDA‐SEdim cells, respectively. CFDA‐SEbright cells retained the vast majority of LTC‐IC and showed a LTC‐IC frequency 2.8‐fold higher than that found in freshly isolated CD34+ cells. RT‐PCR and Western blot analyses showed significantly higher bcl‐2 RNA and protein levels in CFDA‐SEbright cells as compared to freshly isolated CD34+ and CFDA‐SEdim cells. This study indicates that cytokine low‐responding circulating CD34+ cells (CFDA‐SEbright cells) represent a functionally, phenotypically and molecularly distinct multipotent progenitor population with biological properties associated with primitive precursors.

High-dose carboplatin, etoposide and melphalan (CEM) with peripheral blood progenitor cell support as late intensification for high-risk cancer: non-haematological, haematological toxicities and role of growth factor administration.

The present report describes the non-haematological toxicity and the influence of growth factor administration on haematological toxicity and haematopoietic recovery observed after high-dose carboplatin (1200 mg m(-2)), etoposide (900 mg m(-2)) and melphalan (100 mg m(-2)) (CEM) followed by peripheral blood progenitor cell transplantation (PBPCT) in 40 patients with high-risk cancer during their first-line treatment. PBPCs were collected during the previous outpatient induction chemotherapy programme by leukaphereses. CEM administration with PBPCT was associated with low non-haematological toxicity and the only significant toxicity consisted of a reversible grade III/IV increase in liver enzymes in 32% of the patients. Haematopoietic recovery was very fast in all patients and the administration of granulocyte colony-stimulating factor (G-CSF) plus erythropoietin (EPO) or granulocyte-macrophage colony-stimulating factor (GM-CSF) plus EPO after PBPCT significantly reduced haematological toxicity, abrogated antibiotic administration during neutropenia and significantly reduced hospital stay and patients hospital charge compared with patients treated with PBPCT only. None of the patients died early of CEM plus PBPCT-related complications. Low non-haematological toxicity and accelerated haematopoietic recovery renders CEM with PBPC/growth factor support an acceptable therapeutic approach in an adjuvant or neoadjuvant setting.

High-dose Chemotherapy with Autologous Peripheral Stem Cell Support in Advanced Ovarian Cancer

Twenty patients with advanced (stage III-IV), previously untreated ovarian carcinoma were treated by: (a) induction chemotherapy (40 mg/m2 cisplatin, days 1-4; 1.5 g/m2 cyclophosphamide, day 4; every 4 weeks for two cycles) followed by (b) intensification chemotherapy (100 mg/m2 cisplatin, day 1; 650 mg/m2 etoposide, day 2; 1.8 g/m2 carboplatin, day 3). Eligibility criteria further included: age less than 55 years, moderately good to poor tumour grade, macroscopic (> 0.5 cm) residual tumour. Autologous peripheral stem cells were recruited after the induction cycles and, to ensure haematological support, autologous bone marrow harvesting was routinely performed in the first 14 cases. Haematological support consisted of autologous peripheral stem cells and autologous bone marrow transplant in 16 and four patients, respectively. All patients are evaluable for toxicity and 19 for pathological response, one being dead of systemic mycosis 35 days after the autologous bone marrow transplant. Severe extra-haematological toxicities were the following: gastrointestinal (100%), neurological (10%), hepatic (10%). Pathological response was detected in 84% of cases (CR 37%, microscopic PR 26%, macroscopic PR 21%). Median follow-up times of 48 and 41 months have been reached respectively from enrolment and second-look. Four-year 62% overall and 57% progression-free survivals have been reached. Ten patients are still alive with NED (six of seven with CR, three of five with microscopic PR, and one of four with macroscopic PR). Autologous peripheral stem cell transplant significantly reduced the duration of aplasia compared with autologous bone marrow transplant, and toxicity was proved to be manageable in those patients undergoing autologous peripheral stem cell transplant. The prolonged disease-free survival in patients showing CR and microscopic PR suggests that further investigation on this new approach is worthwhile.

Expansion of granulocyte colony–stimulating factor/chemotherapy–mobilized CD34+ hematopoietic progenitors: Role of granulocyte-macrophage colony-stimulating factor/erythropoietin hybrid protein (MEN11303) and interleukin-15

Ex vivo stroma-free static liquid cultures of granulocyte colony-stimulating factor (G-CSF)/chemotherapy-mobilized CD34+ cells were established from patients with epithelial solid tumors. Different culture conditions were generated by adding G-CSF, granulocyte-macrophage colony-stimulating factor (GM-CSF), Flt3 ligand (Flt3), megakaryocyte growth and development factor (Peg-rHuMGDF), GM-CSF/erythropoietin (EPO) hybrid protein (MEN11303), and interleukin-15 (IL-15) to the basic stem cell factor (SCF) + interleukin-3 (IL-3) + EPO combination. This study showed that, among the nine different combinations tested in our 5% autologous plasma-containing cultures, only those containing IL-3/SCF/Flt3/MEN11303 and IL-3/SCF/Flt3/MEN11303/IL-15 significantly expanded colony-forming unit granulocyte-macrophage (CFU-GM), burst-forming unit erythroid (BFU-E), long-term culture-initiating cells (LTC-IC), CD34+, and CD34+/CD38- cells after 14 days of culture. Particularly, the addition of IL-15 to IL-3/SCF/Flt3/MEN11303 combination produced a significant increase of LTC-IC, with an average 26-fold amplification as compared to input cells, without any detrimental effect on CFU-GM and BFU-E expansion. This combination also produced a statistically significant 3.6-fold expansion of primitive CD34+/CD38- cells. Moreover, this study confirms the previously described erythropoietic effect of MEN11303, which, in our experience, was the only factor capable of expanding BFU-E. Compared to equimolar concentrations of GM-CSF and EPO, MEN11303 hybrid protein showed a significantly higher capacity of expanding CFU-GM, BFU-E, LTC-IC, CD34+, and CD34+/CD38- cells when these cytokines were tested in combination with IL-3/SCF/Flt3. These cultures indicated that Peg-rHuMGDF addition to IL-3/SCF/EPO/Flt3 does not affect CFU-GM and BFU-E expansion but, unlike G-CSF or GM-CSF, it does not decrease the ability of Flt3 to expand primitive LTC-IC. These studies indicate that, starting from G-CSF/chemotherapy-mobilized CD34+ cells, concomitant expansion of primitive LTC-IC, CFU-GM, BFU-E, CD34+, and CD34+/CD38- cells is feasible in simple stroma-free static liquid cultures, provided IL-3/SCF/Flt3/MEN11303/IL-15 combination is used as expanding cocktail in the presence of 5% autologous plasma.