A novel triple purge strategy for eliminating chronic myelogenous leukemia (CML) cells from autografts

The dark side of granulocyte-colony stimulating factor: a supportive therapy with potential to promote tumour progression

Granulocyte-colony stimulating factor (G-CSF) is one of several cytokines that can expand and mobilize haematopoietic precursor cells from bone marrow. In particular, G-CSF mobilizes neutrophils when the host is challenged by infection or tissue damage. Severe neutropenia, or febrile neutropenia is a life-threatening event that can be mitigated by administration of G-CSF. Consequently, G-CSF has been used to support patients undergoing chemotherapy who would otherwise require dose reduction due to neutropenia. Over the past 10-15 years it has become increasingly apparent, in preclinical tumour growth and metastasis models, that G-CSF can support tumour progression by mobilization of tumour-associated neutrophils which consequently promote tumour dissemination and metastasis. With the increasing use of G-CSF in the clinic, it is pertinent to ask if there is any evidence of a similar promotion of tumour progression in patients. Here, we have reviewed the preclinical and clinical data on the potential contribution of G-CSF to tumour progression. We conclude that, whilst the evidence for a promotion of metastasis is strong in preclinical models and that limited data indicate that high serum G-CSF levels in patients are associated with poorer prognosis, no studies published so far have revealed evidence of increased tumour progression associated with supportive G-CSF use during chemotherapy in patients. Analysis of G-CSF receptor positive cohorts within supportive trials, as well as studies of the role of G-CSF blockade in appropriate tumours in the absence of chemotherapy could yield clinically translatable findings.

Ex vivo virotherapy with myxoma virus does not impair hematopoietic stem and progenitor cells

BACKGROUND

Relapsing disease is a major challenge after hematopoietic cell transplantation for hematological malignancies. Myxoma virus (MYXV) is an oncolytic virus that can target and eliminate contaminating cancer cells from auto-transplant grafts. The aims of this study were to examine the impact of MYXV on normal hematopoietic stem and progenitor cells and define the optimal treatment conditions for ex vivo virotherapy.

METHODS

Bone marrow (BM) and mobilized peripheral blood stem cells (mPBSCs) from patients with hematologic malignancies were treated with MYXV at various time, temperature and incubation media conditions. Treated BM cells from healthy normal donors were evaluated using flow cytometry for MYXV infection, long-term culture-initiating cell (LTC-IC) assay and colony-forming cell (CFC) assay.

RESULTS

MYXV initiated infection in up to 45% of antigen-presenting monocytes, B cells and natural killer cells; however, these infections were uniformly aborted in >95% of all cells. Fresh graft sources showed higher levels of MYXV infection initiation than cryopreserved specimens, but in all cases less than 10% of CD34(+) cells could be infected after ex vivo MYXV treatment. MYXV did not impair LTC-IC colony numbers compared with mock treatment. CFC colony types and numbers were also not impaired by MYXV treatment. MYXV incubation time, temperature or culture media did not significantly change the percentage of infected cells, LTC-IC colony formation or CFC colony formation.

CONCLUSIONS

Human hematopoietic cells are non-permissive for MYXV. Human hematopoietic stem and progenitor cells were not infected and thus unaffected by MYXV ex vivo treatment.

Cell-specific multifunctional processing of heterogeneous cell systems in a single laser pulse treatment

Current methods of cell processing for gene and cell therapies use several separate procedures for gene transfer and cell separation or elimination, because no current technology can offer simultaneous multifunctional processing of specific cell subsets in highly heterogeneous cell systems. Using the cell-specific generation of plasmonic nanobubbles of different sizes around cell-targeted gold nanoshells and nanospheres, we achieved simultaneous multifunctional cell-specific processing in a rapid single 70 ps laser pulse bulk treatment of heterogeneous cell suspension. This method supported the detection of cells, delivery of external molecular cargo to one type of cells and the concomitant destruction of another type of cells without damaging other cells in suspension, and real-time guidance of the above two cellular effects.

Ex vivo graft purging and expansion of autologous blood progenitor cell products from patients with multiple myeloma

Autologous peripheral blood progenitor cell (PBPC) transplantation is the treatment of choice for selected myeloma patients. However, tumor cells contaminating the apheresis product are a potential source of relapse. Here we report a sequential purging strategy targeting mature and immature clonogenic myeloma cell populations in the autograft. Thawed PBPC products of myeloma patients were treated with rituximab to kill CD138(-)20(+) B cells (highly clonogenic immature cells), and bortezomib to target CD138(+) cells (normal and differentiated myeloma plasma cells), followed by coculture with allogeneic mesenchymal stem cells (MSC) from normal donors. After 7 days of coculture, nonadherent cells were removed and cultured in the absence of MSC for an additional 7 days. Then, efficacy of purging (removal of CD138(-)20(+) and CD138(+) cells) was assessed by flow cytometry and PCR. We used our ex vivo purging strategy to treat frozen aphereses from 16 patients. CD138(+) and CD138(-)20(+)(19(+)) cells present in the initial products were depleted more than 3 and 4 logs, respectively based on 10(6) flow-acquisition events, and to levels below the limit of detection by PCR. In contrast, total nucleated cell (TNC), CD34(+) cell, and colony-forming cell numbers were increased by approximately 12 to 20, 8-, and 23-fold, respectively. Overall, ex vivo treatment of apheresis products with rituximab, bortezomib, and coculture with normal donor MSC depleted mature and immature myeloma cells from clinical aphereses while expanding the normal hematopoietic progenitor cell compartment.

Stem cell harvesting protocol research in autologous transplantation setting: Large volume vs. conventional cytapheresis

Background/Aim. The use of peripheral blood as a source of hematopoietic stem cells (SCs) is progressively increasing and has nearly supplanted bone marrow transplantation. Interpatient variability in the degree and kinetics of SC mobilization into peripheral blood is an expected event after conventional chemotherapy-based treatment, followed by sequential administration of recombinant granulocyte-colony- stimulating factor (rHu-CSF). In this study, specific factors associated with the application of two different SC-harvesting approaches, including the use of large volume leukapheresis (LVL) vs. repetitive conventional apheresis (RCA), were analyzed. The basic goal of the study was to evaluate the influence of apheresis protocol (collection timing, processed blood volume and cell yield) upon the clinical outcome of transplantation. Methods. Results obtained by LVL (76 pts) and RCA (20 pts - control group) were compared. The SC mobilizing regimen used was cyclophosphamide (4-7 g/m2) or polychemotherapy and rHuG-CSF 10-16 ?g/kg of body mess (bm) per day. Cell harvesting was performed using COBE-Spectra (Caridian-BCT, USA). The volume of processed blood in LVL setting was ? 3.5 - fold of the patient's circulating blood quantity (ranged from 12.7 to 37.8 l). All patients tolerated well the use of intensive treatment, without any side or adverse effects. Our original controlled-rate cryopreservation was carried out with 10% dimethyl sulfoxide (DMSO) using Planer R203/200R or Planer 560-16 equipments (Planer Products Ltd, UK). Total nucleated cell (NC) and mononuclear cell (MNC) counts were examined by flow cytometry (Advia-2120 Bayer, Germany; Technicon H-3 System, USA). The CD34+ cell surface antigen was investigated by the EPICS XL-MCL device (Coulter, Germany). Results. Performing LVL-apheresis, high-level MNC and CD34+ cell yields (7.6?4.6 ? 108/kg bm and 11.8?6.5 ? 106/kg bm, respectively) were obtained. As a result, rapid hematopoietic reconstitution ("graft-healing") - on the 9.4th and 12.4th day for granulocytes and platelets, respectively was achieved. Using repetitive conventional apheresis (2-3 procedures), the total MNC count was high (8.2?7.0 ? 108/kg bm), but the total CD34+ yield was lower 10.8?9.9 due to inferior CD34+ vs. MNC ratio. Conclusion. The results obtained suggest that well-timed LVL-apheresis increased SC-yield in cell harvest, resulting in faster bone marrow repopulation and hematological reconstitution, as well as better overall clinical outcome of transplantation. These results necessitate additional examinations of CD34+ subsets ratio in cell harvest.