Potency testing of mesenchymal stromal cell growth expanded in human platelet lysate from different human tissues.

BACKGROUND: Mesenchymal stromal cells (MSCs) have been largely investigated, in the past decade, as potential therapeutic strategies for various acute and chronic pathological conditions. MSCs isolated from different sources, such as bone marrow (BM), umbilical cord tissue (UCT) and adipose tissue (AT), share many biological features, although they may show some differences on cumulative yield, proliferative ability and differentiation potential. The standardization of MSCs growth and their functional amplification is a mandatory objective of cell therapies. The aim of this study was to evaluate the cumulative yield and the ex vivo amplification potential of MSCs obtained from various sources and different subjects, using defined culture conditions with a standardized platelet lysate (PL) as growth stimulus. METHODS: MSCs isolated from BM, UCT and AT and expanded in human PL were compared in terms of cumulative yield and growth potential per gram of starting tissue. MSCs morphology, phenotype, differentiation potential, and immunomodulatory properties were also investigated to evaluate their biological characteristics. RESULTS: The use of standardized PL-based culture conditions resulted in a very low variability of MSC growth. Our data showed that AT has the greater capacity to generate MSC per gram of initial tissue, compared to BM and UCT. However, UCT-MSCs replicated faster than AT-MSCs and BM-MSCs, revealing a greater proliferation capacity of this source irrespective of its lower MSC yield. All MSCs exhibited the typical MSC phenotype and the ability to differentiate into all mesodermal lineages, while BM-MSCs showed the most prominent immunosuppressive effect in vitro. CONCLUSIONS: The adoption of standardized culture conditions may help researchers and clinicians to reveal particular characteristics and inter-individual variability of MSCs sourced from different tissues. These data will be beneficial to set the standards for tissue collection and MSCs clinical-scale expansion both for cell banking and for cell-based therapy settings.

Culture of human cell lines by a pathogen-inactivated human platelet lysate.

Alternatives to the use of fetal bovine serum (FBS) have been investigated to ensure xeno-free growth condition. In this study we evaluated the efficacy of human platelet lysate (PL) as a substitute of FBS for the in vitro culture of some human cell lines. PL was obtained by pools of pathogen inactivated human donor platelet (PLT) concentrates. Human leukemia cell lines (KG-1, K562, JURKAT, HL-60) and epithelial tumor cell lines (HeLa and MCF-7) were cultured with either FBS or PL. Changes in cell proliferation, viability, morphology, surface markers and cell cycle were evaluated for each cell line. Functional characteristics were analysed by drug sensitivity test and cytotoxicity assay. Our results demonstrated that PL can support growth and expansion of all cell lines, although the cells cultured in presence of PL experienced a less massive proliferation compared to those grown with FBS. We found a comparable percentage of viable specific marker-expressing cells in both conditions, confirming lineage fidelity in all cultures. Functionality assays showed that cells in both FBS- and PL-supported cultures maintained their normal responsiveness to adriamycin and NK cell-mediated lysis. Our findings indicate that PL is a feasible serum substitute for supporting growth and propagation of haematopoietic and epithelial cell lines with many advantages from a perspective of process standardization, ethicality and product safety.

Counting of leukocytes in samples from G-CSF mobilized donors, leukapheresis products, and cord blood: the performances of an analyzer with dedicated profiles.

INTRODUCTION: Accurate white blood cell counting (WBC) and differential count by blood analyzers could allow a more informative characterization of granulocyte colony-stimulating factor (G-CSF) mobilized blood (MB), leukapheresis products (LP), and cord blood (CB). However, reliable counting by a blood cell analyzer in this setting is a major challenge owing to quali-quantitative abnormalities of blood cells. METHODS: We evaluated the performances of the analyzer Pentra DX 120 by Horiba ABX working with dedicated cell-gating profiles, which generate three-part differential counts in samples obtained from donors' MB, LP, and CB. The results of the analyzer were compared to counts obtained by flow cytometry and manual counts, the latter performed for reference validation and in the case of discrepant results between study and reference counts. RESULTS: Pentra DX 120 generated highly correlated counts (R > 0.91 in all cases) to those obtained by flow cytometry in all samples (MB, LP, and CB) with high degree of count accuracy in most cases and referred to WBC absolute count and differential count including lymphocytes (LYM) %, monocytes (MON) %, and polymorphonuclear leukocytes (PMN) %. Accuracy, judged by the difference between study and reference counts and expressed as percentage of reference count, ranged from 0.8% to 8.6%, and sporadic loss of accuracy occurred for MON % only in no more than 10% of CB samples. CONCLUSION: The ABX Pentra DX 120 provided accurate WBC count and differential count during MB, LP, and CB analyses and allowed a better characterization of donors' hematologic status and graft composition.

Expression of CD133-1 and CD133-2 in ovarian cancer.

Cancer stem cells have been isolated from several solid tumors including prostate, colon, liver, breast, and ovarian cancer. Stem cells isolated from nervous system and prostate express CD133 antigen, which is widely used to isolate hematopoietic stem and progenitor cells. The aims of this study were to investigate the expression of the CD133-1 and CD133-2 epitopes in primary ovarian tumors and to biologically characterize CD133(+) ovarian cancer cells, also according to clinicopathologic parameters. Tissue specimens were obtained at primary surgery from 41 ovarian carcinomas; eight normal ovaries and five benign ovarian tumors were also collected. Flow cytometry with monoclonal antibodies against CD133-1 and CD133-2 epitopes was employed. FACS (fluorescence activated cell sorting) analysis enabled the selection of CD133(+) cells, whose epithelial origin was confirmed by immunofluorescence analysis with monoclonal anti-cytokeratin 7. CD133(+) cells gave rise to a 4.7 +/- 0.9-fold larger number of colonies than that documented in CD133(-) population (P < 0.001). Moreover, CD133(+) cells showed an enhanced proliferative potential compared to CD133(-) cells. The percentages of CD133-1- and CD133-2-expressing cells were significantly lower in normal ovaries/benign tumors with respect to those in ovarian carcinoma. Both the percentages of CD133-1- and CD133-2-expressing cells were significantly lower in omental metastases than in primary ovarian cancer (P = 0.009 and 0.007 for CD133-1- and CD133-2-expressing cells, respectively). There seems not to be any difference in the distribution of the percentage of CD133-1- and CD133-2-expressing cells according to clinicopathologic parameters and response to primary chemotherapy. CD133-1 and CD133-2 may be useful in order to select and enrich the population of CD133(+) ovarian tumor cells, which are characterized by a higher clonogenic efficiency and proliferative potential.

Accurate prediction of autologous stem cell apheresis yields using a double variable-dependent method assures systematic efficiency control of continuous flow collection procedures.

BACKGROUND AND OBJECTIVES: Stem cell collection is a standard procedure for the procurement of autologous grafts to rescue myelosuppression induced by high-dose treatments. Accurate prediction of collection yields may contribute to optimize planning and quality control of collection. MATERIALS AND METHODS: Data of 313 autologous haematopoietic stem cell (AHSC) evaluable collections performed in 208 patients with haematologic and non-haematologic neoplasms from seven centres were prospectively analysed to test the accuracy of yield predictions generated by a formula that required the input of peripheral blood (PB) CD34+ cell precount and desired PB volume to be processed. Data were matched in a standard linear regression, in a zero-point regression analysis and tested for prediction accuracy. Further 165 AHSC collections were analysed on a single-centre basis, using yield predictions as reference standards. RESULTS: Analysis showed high levels of correlation between measured collection yields (my) and predictions (py) (R = 0.85; P = 0.000000) as well as high degree of prediction accuracy (my vs. py at paired t-test: P = 0.114781; median my/py ratio = 1.23). Analysis of additional 165 AHSC collections on a single-centre basis showed that the analysed centres had 70% or more measured yields comprising the 0.6-1.8 interval of the my/py ratio. The observance of the 'efficiency' my/py interval assured collection quality control in these centres confirming the reliability of the method. CONCLUSIONS: This prediction method generates accurate and immediate yield predictions allowing collection planning and rapid efficiency control. As a consequence of our study, four centres out of seven use the described method to plan both leukapheresis number and single-procedure blood processing volume while the remaining three centres plan leukapheresis number on the basis of our predictions, maintaining a fixed single-procedure 200 ml/kg blood volume processing, according to their centre AHSC collection policy.

Stem cell-based treatments for gynecological solid tumors.

BACKGROUND AND OBJECTIVE: We have recently assisted to an increasing scientific interest and a new research effort in the field of stem cell-based therapy. Since the late 1980s hematopoietic stem cells (HSC) have been used to set up therapeutic strategies for the treatment of solid tumors such as gynecological cancers. In this context, different approaches have been suggested and clinically investigated. STATE OF THE ART: In the autologous setting we can describe the well-known use of HSC as hematologic support to high-dose chemotherapy regimens, and the use of HSC as a source of dendritic cells for cancer vaccination protocols. In our institution a long-term experience has been developed in high-dose chemotherapy with autologous HSC transplantation as first-line treatment of advanced ovarian cancer, and in the use of cytokines both for HSC collection and for post-transplantation hematopoietic recovery and immune reconstitution. An alternative approach consists of allogenic HSC transplantation following either myeloablative/standard or non-myeloablative/reduced conditioning regimens, which have been proposed as new adoptive immunotherapeutic treatments for different non-hematologic malignancies. PERSPECTIVES: Future strategies in the use of HSC in oncology comprise the possibility of HSC ex-vivo expansion, the use of umbilical cord blood HSC, and the development of HSC-based gene-therapy programs. Further investigations are expected in the new field of cancer stem cells.

A human umbilical cord stem cell rescue therapy in a murine model of toxic liver injury.

BACKGROUND: Several studies have demonstrated that bone marrow contains a subpopulation of stem cells capable of participating in the hepatic regenerative process, even if some reports indicate quite a low level of liver repopulation by human stem cells in the normal and transiently injured liver. AIMS: In order to overcome the low engraftment levels seen in previous models, we tried the direct intraperitoneal administration of human cord blood stem cells, using a model of hepatic damage induced by allyl alcohol in NOD/SCID mice. METHODS: We designed a protocol based on stem cell infusion following liver damage in the absence of irradiation. Flow cytometry, histology, immunohistochemistry and RT-PCR for human hepatic markers were performed to monitor human cell engraftment. RESULTS: Human stem cells were able to transdifferentiate into hepatocytes, to improve liver regeneration after damage and to reduce the mortality rate both in both protocols, even if with qualitative and quantitative differences in the transdifferentiation process. CONCLUSIONS: We demonstrated for the first time that the intraperitoneal administration of stem cells can guarantee a rapid liver engraftment. Moreover, the new protocol based on stem cell infusion following liver damage in the absence of irradiation may represent a step forward for the clinical application of stem cell transplantation.

Stem cells in gynecology and obstetrics.

Over the past 10 years, we have become involved in a new research effort and an increasing scientific interest in the field of stem cell-based therapy. We are therefore able to describe different areas in which stem cell research can be applied and developed in gynecology and obstetrics. I) Hematopoietic stem cells have been used to set up therapeutic strategies for the treatment of gynecological solid tumors such as ovarian cancer. In this context different autologous or allogeneic transplantation approaches have been proposed and clinically investigated. II) Umbilical cord blood, which was often considered a waste material of the delivery, actually represents a precious source of stem cells that can be used for cell-based treatments of malignancies and inherited diseases. III) A feto-maternal cell traffic has recently been demonstrated through the placental barrier during pregnancy. This cellular exchange also includes stem cells from the fetus, which can generate microchimerisms in the mother and contribute to tissue repair mechanisms in different maternal organs. IV) Stem cells can be used for prenatal transplantation to treat different severe congenital diseases of the fetus. Nevertheless, several problems need to be solved to achieve an efficient in utero stem cell transplantation. Recent reports have pointed out the importance of timing in prenatal stem cell transplantation procedures and have shown the advantage of an early stem cell injection. An ultrasound-guided intracelomic approach could allow this possibility.

Efficacy of granulocyte transfusions for neutropenia-related infections: retrospective analysis of predictive factors.

BACKGROUND: The transfusion of G-CSf-primed granulocytes (GTX) might represent an important treatment option for neutropenia-related infections unresponsive to conventional antimicrobial therapies and to recombinant hematopoietic growth factors. However, few studies to date have identified the factors that can predict clinical outcome and the patient populations who are likely to benefit most from GTX. The primary endpoint of the present retrospective study was to evaluate the efficacy of GTX in 22 patients with hematological malignancies who developed neutropenia-related bacterial and fungal infections that were unresponsive to appropriate antimicrobial therapies. METHODS: Peripheral blood granulocytes were collected by continuous-flow leukapheresis from HLA-identical siblings after priming with G-CSF. The response to GTX was classified as 'favorable' if clinical symptoms and signs of infection resolved or 'unfavorable' if clinical symptoms and signs of infection were unchanged or worsened. Control of infection at Day 30 after the enrollment in the GTX program was considered as the outcome variable in multiple regression analysis. RESULTS: Two patients died of infection before receiving the granulocyte concentrates. Bacterial infections (monomicrobial or mixed bacteremias) were documented in 11 patients, whereas fungal infections (fungemia or focal fungal infections) were diagnosed in seven patients. In two patients, no infecting agent could be isolated (clinical infection). Control of infection at Day 30 after the first GTX was achieved in 10 of 20 assemble patients. Overall, 54% of patients with bacterial infections had a favorable response, compared with 57% of patients with fungal infections. No differences in terms of survival were found when comparing patients with bacterial and those with fungal infections at a median follow-up 90 days from the first GTX. In univariate analysis, disease status before GTX, e.g., complete or partial remission, and spontaneous recovery of the neutrophil count were significantly associated with control of infection. when multivariate regression models were formed, the recovery 0.5 x 10 (9)/L PMN was the only parameter that significantly and independently correlated with a favorable response to GTX. DISCUSSION: GTX can be used to successfully treat bacterial as well as fungal infections in severely neutropenic patients when administered early after the onset of febrile neutropenia in patients with remission of the underlying disease and who are likely to recover marrow function.

Administration of low-dose interleukin-2 plus G-CSF/EPO early after autologous PBSC transplantation: effects on immune recovery and NK activity in a prospective study in women with breast and ovarian cancer.

This study evaluated the effects of low-dose IL-2 plus G-CSF/EPO on post-PBSC transplantation (PBSCT) immune-hematopoietic reconstitution and NK activity in patients with breast (BrCa) and ovarian cancer (OvCa). To this end, two consecutive series of patients were prospectively assigned to distinct post-PBSCT cytokine regimens (from day +1 to day +12) which consisted of G-CSF (5 microg/kg/day) plus EPO (150 IU/kg/every other day) in 17 patients (13 BrCa and 4 OvCa) or G-CSF/EPO plus IL-2 (2 x 10(5) IU/m(2)/day) in 15 patients (10 BrCa and 5 OvCa). Hematopoietic recovery and post-transplantation clinical courses were comparable in G-CSF/EPO- and in G-CSF/EPO plus IL-2-treated patients, without significant side-effects attributable to IL-2 administration. In the early and late post-transplant period a significantly higher PMN count was observed in G-CSF/EPO plus IL-2-treated patients (P = 0.034 and P = 0.040 on day +20 and +100, respectively). No significant differences were found between the two groups of patients in the kinetics of most lymphocyte subsets except naive CD45RA(+) T cells which had a delayed recovery in G-CSF/EPO plus IL-2 patients (P = 0.021 on day +100). No significant difference was observed between NK activity in the two different groups, albeit a significantly higher NK count was observed in G-CSF/EPO plus IL-2 series on day +20 (P = 0.020). These results demonstrate that low-dose IL-2 can be safely administered in combination with G-CSF/EPO early after PBSCT and that it exerts favorable effects on post-PBSCT myeloid reconstitution, but not on immune recovery.

The role of hematopoietic stem cells in the treatment of ovarian cancer.

In recent years hematopoietic stem cells (HSC) have been the object of new research efforts and scientific advances. Therapeutic strategies have been set up using HSC for the treatment of solid tumors such as ovarian cancer. In this context different approaches have been proposed and clinically investigated. The "autologous" approach refers to the use of HSC as hematologic support to high-dose chemotherapy regimens, and to the use of HSC as an abundant source of dendritic cells for cancer vaccination protocols. Our institution has developed a long-term experience in high-dose chemotherapy with autologous HSC transplantation as first-line treatment of advanced ovarian cancer, and in the use of cytokines both for the HSC collection and for the post-transplantation hematopoietic recovery. Moreover, the "allogeneic" approach with HSC consists of the allogeneic transplantation with both myeloablative/standard or nonmyeloablative/reduced conditioning regimens, which has been proposed as a new adoptive immunotherapeutic treatment for different nonhematologic malignancies. Perspectives in the use of HSC in oncology comprise the possibility of an HSC ex vivo expansion, the use of umbilical cord blood HSC, and the development of future HSC-based gene-therapy programs.

Transforming growth factor-beta1 transcriptionally activates CD34 and prevents induced differentiation of TF-1 cells in the absence of any cell-cycle effects.

A number of cytokines modulate self-renewal and differentiation of hematopoietic elements. Among these is transforming growth factor beta1 (TGF-beta1), which regulates cell cycle and differentiation of hematopoietic cells, but has pleiotropic activities depending on the state of responsiveness of the target cells. It has been previously shown by us and other authors that TGF-beta1 maintains human CD34(+) hematopoietic progenitors in an undifferentiated state, independently of any cell cycle effects, and that depletion of TGF-beta1 triggers differentiation accompanied by a decrease in CD34 antigen expression. In the present work, we show that exogenous TGF-beta1 upregulates the human CD34 antigen in the CD34(+) cell lines TF-1 and KG-1a, but not in the more differentiated CD34(-) cell lines HL-60 and K-562. We further studied this effect in the pluripotent erythroleukemia cell line TF-1. Here, TGF-beta1 did not effect cell growth, but induced transcriptional activation of full-length CD34 and prevented differentiation induced by differentiating agents. This effect was associated with nuclear translocation of Smad-2, activation of TAK-1, and with a dramatic decrease in p38 phosphorylation. In other systems TGF-beta1 has been shown to activate a TGF-beta-activated kinase 1 (TAK1), which in turn, activates p38. The specific inhibitor of p38 phosphorylation, SB202190, also increased CD34 RNA expression, indicating the existence of a link between p-38 inhibition by TGF-beta1 and CD34 overexpression. Our data demonstrate that TGF-beta1 transcriptionally activates CD34 and prevents differentiation of TF-1 cells by acting independently through the Smad, TAK1 and p38 pathways, and thus provide important clues for the understanding of hematopoietic development and a potential tool to modify response of hematopoietic cells to mitogens or differentiating agents.

Immune reconstitution after autologous peripheral blood progenitor cell transplantation: effect of interleukin-15 on T-cell survival and effector functions.

OBJECTIVE: The aim of this study was to evaluate the occurrence of T-cell spontaneous apoptosis (A(spont)) and its modulation in vitro by the interleukin-2 receptor (IL-2R) gamma-chain (gammac)-signaling cytokine IL-15 in patients transplanted with autologous peripheral blood progenitor cells (PBPC) for hematologic malignancies. MATERIALS AND METHODS: Patients were examined on days 30-60, 60-90, and 90-120 after PBPC infusion. Dissipation of mitochondrial transmembrane potential, a hallmark of T-cell apoptosis, has been detected using the fluorescent probe 3,3'-dihexyloxacarbocyanine iodide, after short-term T-cell culture in the absence or presence of exogenous cytokines. Expression of Bcl-2 family members has been studied by flow cytometry and reverse transcriptase polymerase chain reaction. T-cell proliferative responses to recall antigens have been estimated in autologous mixed leukocyte cultures. RESULTS: A(spont) was seen in 45% +/- 6% of CD4(+) and 55% +/- 6% of CD8(+) T cells cultured in the absence of cytokines. Of interest, IL-15 and, to a lesser extent, its structural cousin IL-2 counteracted T-cell A(spont) by inhibiting the processing of caspase-3 and up-regulating Bcl-2 mRNA and protein levels. Cell division tracking confirmed that IL-15 did not rescue T cells from A(spont) by promoting proliferation but rather acted as a genuine survival factor. Addition of a gammac-blocking antibody to cytokine-conditioned cultures abrogated both apoptosis inhibition and Bcl-2 induction by IL-15, suggesting involvement of the IL-2Rgammac signal transduction pathway. Whereas cytokine-unprimed posttransplant T cells mounted inadequate responses to recall antigens, T cells conditioned with IL-15 expanded vigorously, indicating restoration of antigen-specific proliferation. CONCLUSIONS: T cells recovering after autologous PBPC transplantation are highly susceptible to spontaneous apoptosis in vitro. This phenomenon can be counteracted by the gammac-signaling cytokine IL-15. These findings suggest that IL-15 might be a promising immunomodulating agent to improve postgrafting T-cell function.

High-dose chemotherapy as a consolidation approach in advanced ovarian cancer: long-term results.

The aim of this study was to assess the long-term impact of high-dose chemotherapy (HDC) as consolidation in a large series (n = 55) of advanced chemosensitive ovarian cancer patients who were optimally cytoreduced at time of first surgery or at interval debulking surgery (IDS). HDC consisted of carboplatin (600 mg/m(2) days 1 and 2), etoposide (450 mg/m(2) days 1 and 2) and melphalan (50 mg/m(2), days 3 and 4). The primary endpoint of the study was the assessment of time to progression (TTP) and overall survival (OS). In September 2000 the overall population had a median follow-up of 55 months (range 17--137) and a TTP of 35 months with a 5-year TTP rate of 35% (CI 95%: 21--49) whereas OS averaged 75 months with a 5-year OS of 59% (CI 95%: 45--73). In patients achieving optimal primary cytoreduction the median TTP was 44 months with a 5-year rate of 43% (CI 95%: 26--60). In the same series the 5-year OS rate was 62% (CI 95%: 45--79) (median OS = 75 months). In patients who were optimally cytoreduced at the time of IDS the median TTP was 25 months and the 5-year TTP rate was 22% (CI 95%: 3--41) and median OS was 46 months with a 5-year OS rate of 50% (CI 95%: 27--73). HDC with hematopoietic support could represent an effective approach for the treatment of advanced optimally cytoreduced ovarian cancer patients with chemosensitive disease. Patients who underwent IDS because of unresectable tumors at the time of first surgery had the greater survival benefit from HDC.

Docetaxel and epirubicin plus G-CSF as mobilizing treatment to support high-dose chemotherapy in breast cancer.

BACKGROUND: In order to combine an active regimen with a simultaneous efficient mobilization of peripheral blood precursor cells (PBPC), we explored the combination of Docetaxel 75 mg/m2 and Epirubicin 120 mg/m2 with G-CSF 5 mcg/Kg/day s.c. to mobilize PBPC in breast cancer patients to support high-dose chemotherapy (HDC). PATIENTS AND METHODS: Forty patients were enrolled: 27 high risk and 13 metastatic. The entire procedure, including chemotherapy and PBPC collection, was on an outpatient basis. RESULTS: The median day of starting apheresis was day +10 (range 10-12) and the average value of circulating CD34+ cells at peak was 175/microliter (range 33-403). The median yield of CD34+ cells per apheresis was 8.76 x 10(6)/Kg (range 1.83-27.87). None of the patients developed side effects which required hospitalization. All patients enrolled successively received HDC as consolidation treatment. High risk patients received one and metastatic patients two HDC with PBPC reinfusion. All patients obtained a complete engraftment. No significant differences between high-risk and metastatic patients were observed. CONCLUSIONS: Our study suggests that the combination of Docetaxel, Epirubicin, and G-CSF is feasible, safe and efficient outpatient mobilizing treatment for patients with breast cancer receiving HDC.

Peripheral blood progenitor cell collection after epirubicin, paclitaxel, and cisplatin combination chemotherapy using EPO-based cytokine regimens: a randomized comparison of G-CSF and sequential GM-/G-CSF.

BACKGROUND: The peripheral blood progenitor cell (PBPC) mobilization capacity of EPO in association with either G-CSF or sequential GM-CSF/G-CSF was compared in a randomized fashion after epirubicin, paclitaxel, and cisplatin (ETP) chemotherapy. STUDY DESIGN AND METHODS: Forty patients with stage IIIB, IIIC, or IV ovarian carcinoma were enrolled in this randomized comparison of mobilizing capacity and myelopoietic effects of G-CSF + EPO and GM-/G-CSF + EPO following the first ETP chemotherapy treatment. After ETP chemotherapy (Day 1), 20 patients received G-CSF 5 microg per kg per day from Day 2 to Day 13 and 20 patients received GM-CSF 5 microg per kg per day from Day 2 to Day 6 followed by G-CSF 5 microg per kg per day from Day 7 to Day 13. EPO (150 IU per kg) was given every other day from Day 2 to Day 13 to all patients in both arms of the study. Apheresis (two blood volumes) was performed during hematologic recovery. RESULTS: The magnitude of CD34+ cell mobilization and the abrogation of patients' myelosuppression were comparable in both study arms; however, GM-/G-CSF + EPO patients had significantly higher CD34+ yields because of a higher CD34+ cell collection efficiency (57.5% for GM-/G-CSF + EPO and 46.3% for G-CSF + EPO patients; p = 0.0009). Identical doses of PBPCs mobilized by GM-/G-CSF + EPO and G-CSF + EPO drove comparable hematopoietic recovery after reinfusion in patients treated with identical high-dose chemotherapy. CONCLUSION: The sequential administration of GM-CSF and G-CSF in combination with EPO is feasible and improves the PBPC collection efficiency after platinum-based intensive polychemotherapy, associating high PBPC mobilization to high collection efficiency during apheresis.

Role of DNA-dependent protein kinase in recognition of radiation-induced DNA damage in human peripheral blood mononuclear cells.

The DNA-dependent protein kinase (DNA-PK) complex plays a crucial role in radiation-induced DNA damage recognition. The complex includes the ku heterodimer, which comprises ku 70 and ku 80 subunits, that binds DNA termini of breaks without sequence specificity, and the catalytic subunit DNA-PKCS: The activation of the DNA-PK complex was studied in X-irradiated peripheral blood mononuclear cells (PBMC) from subjects of different ages. Radiation-induced changes in the DNA-binding activity of the ku heterodimer, and in the concentrations of ku 70, ku 80, DNA-PKcs and phosphorylated ku 80 were determined in nuclear and cytoplasmic extracts. DNA-binding activity was increased by irradiation only in the nuclear extract of PBMC from young, but not from elderly subjects, whereas it was found unchanged in cytoplasmic extracts regardless of age. The radiation-induced activation of the DNA-PK complex may result from the increased concentrations of ku 80 and DNA-PKcs in the cytoplasm of PBMC from young, but not from elderly subjects, leading to a higher concentration of phosphorylated ku 80 which readily migrates to the nucleus where, after dimerization with ku 70, binds to DNA breaks. These findings suggest major steps involved in DNA-PK activation, and the intracellular and molecular changes that may account for the age-dependent impairment of DNA repair capacity in irradiated mammalian cells.

T-cell apoptosis induced by granulocyte colony-stimulating factor is associated with retinoblastoma protein phosphorylation and reduced expression of cyclin-dependent kinase inhibitors.

Peripheral blood progenitor cells (PBPC) mobilized by granulocyte colony-stimulating factor (G-CSF) promptly engraft allogeneic recipients after myeloablative chemotherapy for hematologic malignancies. Surprisingly, no exacerbation of acute graft-vs-host disease has been observed despite a 10-fold higher T-cell content in PBPC compared with bone marrow allografts. Because G-CSF can suppress T-cell proliferation in response to mitogens and enhance their activation-induced apoptosis, we examined the molecular mechanisms underlying G-CSF-induced immune dysfunction. Normal allogeneic lymphocytes were challenged with phytohemagglutinin in the presence of serum collected after G-CSF administration (postG) to healthy PBPC donors, and the expression of key components of the cell cycle and apoptotic machineries was investigated by flow cytometry and Western blotting. Lymphocyte stimulation was associated with collapse of mitochondrial transmembrane potential, hypergeneration of reactive oxygen intermediates, and activation of caspase-3 and DNA fragmentation. Lymphocytes were arrested in a G(1)-like phase of the cell cycle, as measured by G(1)-phase cyclin expression and bromodeoxyuridine (BrdUrd) incorporation. Cell tracking experiments confirmed the occurrence of a lower number of population doublings in postG compared with preG cultures. Unexpectedly, the phosphorylation state of the protein encoded by the retinoblastoma susceptibility gene (pRB) was unaltered in postG cultures, and the inhibition of cell cycle progression occurred without the recruitment of the cyclin-dependent kinase inhibitors p15(INK4B), p16(INK4A), and p27(Kip1). We eventually evaluated the ability of antioxidant/cytoprotectant agents to prevent the G-CSF-induced mitochondrial dysfunction and inhibition of cell cycle progression. Of interest, both N-acetylcysteine and amifostine reduced apoptotic cell death by 45% on average, inhibited the activation/processing of caspase-3, and increased BrdUrd incorporation in postG cultures. Based on these experimental findings, a model is proposed in which T-cell activation in the presence of serum immunoregulatory factor(s) induced by G-CSF is associated with a molecular phenotype mimicking the G(1)-S transition and consisting of pRB phosphorylation, lack of CDKI recruitment, and reduced cyclin-E expression. The putative relationship between lymphocyte mitogenic unresponsiveness and apoptosis induction would occur at the level of key molecules shared by the cell cycle and apoptotic machineries. Whether the G-CSF-mediated modulation of lymphocyte functions in vitro is beneficial in transplantation medicine remains to be determined.