Tumor cell purging by ex vivo expansion of hemopoietic stem cells from breast cancer patients combined with targeting ErbB receptors.

Tumor cell contamination might induce relapse after autologous transplantation in breast cancer patients. We used an ex vivo purging strategy to decrease the number of contaminating breast tumor cells in leukaphereses without altering the engraftment potential of the hemopoietic progenitor cells. This method is based on immunoselection of CD34+ cells derived from mobilized peripheral blood of patients with metastatic breast cancer and expansion in the presence of flt3 ligand, stem cell factor, interleukin 6, and thrombopoietin. Tumor contamination before and after culture was monitored by mammaglobin messenger RNA amplification by quantitative polymerase chain reaction. We analyzed both adherent and suspended cells obtained after 2 weeks of culture. Hemopoietic progenitors were increased among suspended cells. In this fraction, tumor cell contamination was decreased, whereas it increased within the adherent cell fraction. Experimental models using CD34+ cells from healthy donors spiked with breast cancer cells were also constructed to investigate whether treatment with anti-ErbB-receptor drugs could further reduce the tumor load without affecting the clonogenic potential of hemopoietic cells. For this purpose, we successfully assayed trastuzumab, a monoclonal antibody against ErbB-2, and gefitinib, an epidermal growth factor receptor tyrosine kinase receptor inhibitor. These results suggest that positively selected CD34+ cells from cancer patients contain tumor cells and that ex vivo expansion can reduce the tumor load of the suspended fraction. Target-based agents against ErbB-2, epidermal growth factor receptor, or both--such as trastuzumab or gefitinib--might increase the efficiency of purging.     

Serial transplantations in nonobese diabetic/severe combined immunodeficiency mice of transduced human CD34+ cord blood cells: efficient oncoretroviral gene transfer and ex vivo expansion under serum-free conditions

Stable oncoretroviral gene transfer into hematopoietic stem cells (HSCs) provides permanent genetic disease correction. It is crucial to transplant enough transduced HSCs to compete with and replace the defective host hemopoiesis. To increase the number of transduced cells, the role of ex vivo expansion was investigated. For a possible clinical application, all experiments were carried out in serum-free media. A low-affinity nerve growth factor receptor (LNGFR) pseudotyped murine retroviral vector was used to transduce cord blood CD34(+) cells, which were then expanded ex vivo. These cells engrafted up to three generations of serially transplanted nonobese diabetic/severe combined immunodeficiency mice: 54.26% +/- 5.59%, 19.05% +/- 2.01%, and 6.15% +/- 5.16% CD45(+) cells from primary, secondary, and tertiary recipient bone marrow, respectively, were LNGFR(+). Repopulation in secondary and tertiary recipients indicates stability of transgene expression and long-term self-renewal potential of transduced HSCs, suggesting that retroviral gene transfer into HSCs, followed by ex vivo expansion, could facilitate long-term engraftment of genetically modified HSCs.     

Feasibility of cord blood stem cell manipulation with high-energy shock waves: an in vitro and in vivo study

OBJECTIVE: Cord blood CD34+ cells are more uncommitted than their adult counterparts as they can be more easily maintained and expanded in vitro and transduced with lentiviral vectors. The aim of this study was to evaluate whether pretreatment with high-energy shock waves (HESW) could further enhance the expansion of cord blood progenitors and the transduction efficiency with lentiviral vectors. METHODS: Human cord blood CD34+ cells underwent HESW treatment with a wide range of energy and number of shots (from 0.22 mJ/mm2 to 0.43 mJ/mm2 and from 200 to 1500 shots). Cells were then evaluated both for their in vitro expansion ability and in vivo engraftment in primary, secondary, and tertiary NOD/SCID mice. The transduction efficiency with a lentiviral vector (LV) was also evaluated in vitro and in vivo. RESULTS: Cell viability following HESW ranged from 75 to 92%. Pretreatment with HESW significantly improved early progenitor cell expansion after short-term suspension culture. Upon transplantation in primary NOD/SCID mice, the HESW treatment enhanced progenitor cell engraftment (total human CD45(+)CD34+ cells were 10% in controls and 14.5% following HESW, human CD45(+)CD34(+)CD38(-) cells were 0.87% in controls and 1.8% following HESW). HESW treatment enhanced the transduction of a GFP+ lentiviral vector (e.g., at day 42 of culture 6.5% GFP+ cells in LV-treated cell cultures compared to 11.4% of GFP+ cells in HESW-treated cell cultures). The percentage of human GFP+ cell engrafting NOD/SCID mice was similar (34% vs 26.4% in controls); however, the total number of human cells engrafted after HESW was higher (39.6% vs 15%). CONCLUSION: The pretreatment of CD34+ cells with HESW represents a new method to manipulate the CD34+ population without interfering with their ability to both expand and engraft and it might be considered as a tool for genetic approaches.     

Sustained long-term engraftment and transgene expression of peripheral blood CD34+ cells transduced with third-generation lentiviral vectors

As mobilized peripheral blood (MPB) represents an attractive cell source for gene therapy, we investigated the ability of third-generation lentiviral vectors (LVs) to transfer the enhanced green fluorescent protein gene into MPB CD34(+) cells in culture conditions allowing expansion of transplantable human hematopoietic stem cells. To date, few studies have reported transduction of MPB cells with vesicular stomatitis virus G pseudotyped LVs. The critical issue remains whether primitive, hematopoietic repopulating cells have, indeed, been transduced. In vitro (5 weeks' culture in FLT3 ligand + thrombopoietin + stem cell factor + interleukin 6) and in vivo (serial transplantation in NOD/SCID mice) experiments show that MPB CD34(+) cells can be effectively long-term transduced by LV and maintain their proliferation, self-renewal, and multilineage differentiation potentials. We show that expansion following transduction improves the engraftment of transduced MPB CD34(+) (4.6-fold expansion of SCID repopulating cells by limiting dilution studies). We propose ex vivo expansion after transduction as an effective tool to improve gene therapy protocols with MPB. Disclosure of potential conflicts of interest is found at the end of this article.     

Multilineage engraftment of refrozen cord blood hematopoietic progenitors in NOD/SCID mice

Seven cord blood (CB) units were tested for their capacity to repopulate irradiated NOD/SCID mice after one or two successive cryopreservation procedures. In primary transplants with frozen or refrozen CB cells we observed equivalent human colonies and percentages of human CD45+ cells, with multilineage engraftment. In secondary transplants flow cytometry and polymerase chain reaction for the a satellite region of chromosome 17 showed equivalent levels of human engraftment. Since CB units have, to date, mainly been stored in individual bags, our results suggest new options for optimizing the timing of infusions of expanded and non-expanded progenitors in transplants.     

Granulocyte-colony stimulating factor upregulates ErbB2 expression on breast cancer cell lines and converts primary resistance to trastuzumab

The recombinant monoclonal antibody trastuzumab has antiproliferative effect on breast cancer (BC) cells with ErbB2 overexpression. We postulated that a mechanism able to modify ErbB2 expression enhances the antitumor effect of trastuzumab. We analyzed whether granulocyte-colony stimulating factor (G-CSF), widely used in adjuvant cancer therapy to alleviate chemotherapy-induced myelotoxicity, could influence ErbB2 expression in BC cells and patients. The expression of ErbB2 (Herceptest) was analyzed in four BC cell lines (BT474, SKBR3, ZR75.1, and T47D) treated with G-CSF and in five samples biopsies from BC patients subjected to G-CSF rescue after chemotherapy. The effects of G-CSF and trastuzumab alone or their combination on cell growth and apoptosis were investigated. G-CSF receptor was detected on all cell lines and BC patients. G-CSF induced upregulation of ErbB2 in SKBR3, ZR75, and T47D cells. This modulation was not associated with an increase in tumor cell growth in vitro. Trastuzumab alone inhibited colony formation in soft agar but did not induce apoptosis on BC cells with no or low ErbB2 genomic amplification. The combination of trastuzumab and G-CSF enhanced the inhibition of tumor colony formation and induced apoptosis on these cells. This effect was further increased by G-CSF pretreatment. Five of nine BC patients showed an increase of Herceptest score after G-CSF administration. G-CSF treatment increases ErbB2 expression in vitro and in vivo enhancing the activity of trastuzumab on BC cell lines inducing apoptosis of BC cells with low or no ErbB2 genomic amplification.     

Somatic mutations of epidermal growth factor receptor in bile duct and gallbladder carcinoma.

OBJECTIVE: Conventional therapies are still unsuccessful in patients with carcinoma arising from the biliary tract. Somatic mutations of the epidermal growth factor receptor (EGFR) gene and the activation of its downstream pathways predict the sensitivity to small-molecule inhibitors in non-small cell lung carcinoma. Therefore, we analyzed EGFR mutations and related pathways in gallbladder and bile duct carcinomas to consider the possible application of these alternative therapeutic strategies. EXPERIMENTAL DESIGN: Forty paraffin-embedded samples, including intrahepatic or extrahepatic cholangiocarcinoma and gallbladder carcinoma, were studied after tumor cell isolation by laser microdissection and sequencing of EGFR tyrosine kinase domain (exons 18-21). Activation of EGFR pathway was studied by evaluating phosphorylation of mitogen-activated protein kinase and Akt. RESULTS: None of the 40 specimens had mutations in exon 18; one had one missense point mutation in exon 19, two in exon 20, and three in exon 21. In addition, 36 of 40 specimens had the same silent mutation at codon 787 in exon 20, which was also found in peripheral blood cells from healthy donors. Tumor samples harboring EGFR mutation had phosphorylation of one or both downstream transducers analyzed. CONCLUSIONS: This is the first evidence of somatic mutations of the EGFR gene in bile duct carcinoma. Our findings suggest that a subgroup of patients with cholangiocarcinoma or gallbladder carcinoma exhibits somatic mutations of EGFR in the tyrosine kinase domain that can elicit cell signals sustaining survival and proliferation. These tumors might be further evaluated for their susceptibility to small-molecule inhibitor treatment.