Transplantation of enriched CD34-positive autologous marrow into breast cancer patients following high-dose chemotherapy: influence of CD34-positive peripheral-blood progenitors and growth factors on engraftment

A Comprehensive Investigation to Reveal the Relationship Between Plasmacytoid Dendritic Cells and Breast Cancer by Multiomics Data Analysis

Plasmacytoid dendritic cells (pDC) are an essential immune microenvironment component. They have been reported for crucial roles in linking the adaptive and immune systems. However, the prognostic role of the pDC in breast cancer (BRCA) was controversial. In this work, we collected large sample cohorts and did a comprehensive investigation to reveal the relationship between pDC and BRCA by multiomics data analysis. Elevated pDC levels were correlated with prolonged survival outcomes in BRCA patients. The distinct mutation landscape and lower burden of somatic copy number alterations (SCNA) and lower intratumoral heterogeneity were observed in the high pDC abundance group. Additionally, a more sensitive immune response and chemotherapies response were observed in the high pDC group, which implicates that patients with high pDC abundance can be benefited from the combination of chemotherapy and immunotherapy. In conclusion, the correlation between pDC abundance and BRCA patients' overall survival (OS) was found to be positive. We identified the molecular profiles of BRCA patients with pDC abundance. Our findings may be beneficial in aiding in the development of immunotherapy and elucidating on the precision treatment for BRCA.

Benefits of Pre-harvest Peripheral Blood CD34 Counts Guided Single Dose Therapy with PLERIXAFOR in Autologous Hematopoietic Stem Cell Transplantation: A Retrospective Study at a Tertiary Care Institute in India

Peripheral blood is a convenient source of stem cells for hematopoietic stem cell transplantation. However, in autologous transplants, the harvest failure rates are high because of inadequate mobilization using G-CSF alone. Plerixafor is a potent mobilizer when used with G-CSF. However, its routine use is limited by high cost. This is a retrospective study done at a tertiary care oncology centre in India. All the harvest records were analyzed between Jan 2015 and Nov 2017. May 2016 onwards pre-harvest peripheral blood CD34 count was done in all cases of autologous transplants on day 4 of G-CSF therapy and they were given a single dose of Plerixafor if counts were < 20 cell per cumm. The results were compared amongst various groups. A total of 321 cases were analyzed. 172/321 were allogenic transplant cases of which 5% (n = 7) failed to achieve a target live stem cell dose of > 2 million per kg of the recipient. The overall failure rate in autologous group (n = 149) was 27% (n = 41) (p ≤ 0.001 auto vs. allo). The failure rate was higher (36%, n = 28/77) when no intervention with Plerixafor was done. The overall failure rate in the group treated with pre-harvest 34 count based single dose therapy of Plerixafor was 18% (n = 13/72, p = 0.01). However, within this intervention group, the patients who had pre-harvest peripheral blood CD34 above the desired cutoff had a higher failure rate of 21% (p = 0.13). Pre-harvest CD34 count based intervention with Plerixafor help optimizing the cost.

Human primary CD34+ cells transplantation for critical limb ischemia

BACKGROUND

The goal of this study was to characterize the properties of human CD34⁺ cells in culture and investigate the feasibility and efficacy of CD34⁺ transplantation in a mouse model of limb ischemia and in patients with no-option critical limb ischemia.

METHODS

Human CD34⁺ cells isolated from peripheral blood and grown in culture for up to four passages stained positively for the surface markers CD34 and CD133 and showed high viability after cryopreservation and recovery. Seven days after surgery to induce limb ischemia, ischemic muscles of nude mice were injected with CD34⁺ cells. Two weeks later, mice were scored for extent of ischemic injury, and muscle tissue was collected for immunohistochemical analysis of vascular endothelial cells and RT-PCR analysis of cytokine expression.

RESULTS

Injury scores of CD34⁺ -treated, but not control, mice were significantly different before and after transplantation. Vascular density and expression of VEGF and bFGF mRNAs were also significantly increased in the treated mice. Patients with severe lower extremity arterial ischemia were injected with their own CD34⁺ cells in the affected calf, foot, or toe. Significant improvements were observed in peak pain-free walking time, ankle-brachial index, and transcutaneous partial oxygen pressure. These findings demonstrate that growth of human CD34⁺ cells in vitro and cryopreservations are feasible.

CONCLUSION

Such cells may provide a renewable source of stem cells for transplantation, which appears to be a feasible, safe, and effective treatment for patients with critical limb ischemia.

Detection of Breast Cancer Cells in the Bone Marrow or Peripheral Blood: Methods and Prognostic Significance

Tumor cells can reach every anatomic district, organ and tissue through the peripheral blood circulation. Tumor cell shedding is considered an early event in the multi-phase process of metastasis, and the possibility of detecting tumor cells in the bloodstream and/or bone marrow before clinical evidence of distant metastases needs to be explored. The use of new sophisticated diagnostic and investigative techniques has boosted the study of tumor cell contamination of bone marrow and peripheral blood. Molecular techniques, such as reverse-transcriptase polymerase chain reaction, may be useful tools to reach this target, but, today, immunocytochemistry is still considered the gold standard to assess new techniques to detect isolated tumor cells in hematopoietic tissue. Little is known about the biology of isolated tumor cells in the peripheral blood or bone marrow. Two crucial points need to be evaluated: the identification of specific markers of breast cancer cells with clonogenic potential and their biologic properties, and the prognostic impact of the detection of isolated tumor cells in the bone marrow or peripheral blood stem cell collections.

Autologous peripheral blood stem cell harvest: Collection efficiency and factors affecting it

BACKGROUND

Harvest of hematopoietic progenitor cells via leukapheresis is being used increasingly for transplants in India. Adequate yield of cells per kilogram body weight of recipient is required for successful engraftment. Collection efficiency (CE) is an objective quality parameter used to assess the quality of leukapheresis program. In this study, we calculated the CE of the ComTec cell separator (Fresenius Kabi, Germany) using two different formulae (CE1 and CE2) and analyzed various patient and procedural factors, which may affect it.

MATERIALS AND METHODS

One hundred and one consecutive procedures in 77 autologous donors carried out over 3 years period were retrospectively reviewed. Various characteristics like gender, age, weight, disease status, hematocrit, preprocedure total leukocyte count, preprocedure CD34 positive (CD34+) cells count, preprocedure absolute CD34+ cell count and processed apheresis volume effect on CE were compared. CE for each procedure was calculated using two different formulae, and results were compared using statistical correlation and regression analysis.

RESULTS

The mean CE1 and CE2 was 41.2 and 49.1, respectively. CE2 appeared to be more accurate indicator of overall CE as it considered the impact of continued mobilization of stem cells during apheresis procedure, itself. Of all the factors affecting CE, preprocedure absolute CD34+ was the only independent factor affecting CE.

CONCLUSION

The only factor affecting CE was preprocedure absolute CD34+ cells. Though the mean CE2 was higher than CE1, it was not statistically significant.

Stem cell therapy and breast cancer treatment: review of stem cell research and potential therapeutic impact against cardiotoxicities due to breast cancer treatment

A new problem has emerged with the ever-increasing number of breast cancer survivors. While early screening and advances in treatment have allowed these patients to overcome their cancer, these treatments often have adverse cardiovascular side effects that can produce abnormal cardiovascular function. Chemotherapeutic and radiation therapy have both been linked to cardiotoxicity; these therapeutics can cause a loss of cardiac muscle and deterioration of vascular structure that can eventually lead to heart failure (HF). This cardiomyocyte toxicity can leave the breast cancer survivor with a probable diagnosis of dilated or restrictive cardiomyopathy (DCM or RCM). While current HF standard of care can alleviate symptoms, other than heart transplantation, there is no therapy that replaces cardiac myocytes that are killed during cancer therapies. There is a need to develop novel therapeutics that can either prevent or reverse the cardiac injury caused by cancer therapeutics. These new therapeutics should promote the regeneration of lost or deteriorating myocardium. Over the last several decades, the therapeutic potential of cell-based therapy has been investigated for HF patients. In this review, we discuss the progress of pre-clinical and clinical stem cell research for the diseased heart and discuss the possibility of utilizing these novel therapies to combat cardiotoxicity observed in breast cancer survivors.

Fetal bovine bone marrow is a rich source of CD34+ hematopoietic progenitors with myelo-monocytic colony-forming activity

The CD34 glycoprotein is an important marker of hematopoietic stem cells. We used a polyclonal rabbit anti-bovine CD34 antibody to stain fetal and adult bovine bone marrow cells. Flow cytometry revealed a low side scatter (SSC(low)) population of cells that were CD34(+) but negative for leukocyte lineage markers CD11b, CD14 or CD2. Hematopoietic colony assays with CD34(+) and CD34(-) bone marrow cells suggested that the colony-forming potential in SSC(low) bone marrow cells was confined to the CD34(+) fraction. In contrast, this population was not enriched for cells expressing high aldehyde dehydrogenase activity, a metabolic marker that has been used to characterize hematopoietic stem cells. Thus, the CD34 antigen can be used to identify and isolate bovine bone marrow cells exhibiting clonogenic potential in vitro. Moreover, the proportion of CD34(+) cells is very high in fetal bovine bone marrow, indicating it as a rich source of hematopoietic progenitors.

Initial CD34+ cell-enrichment of cord blood determines hematopoietic stem/progenitor cell yield upon ex vivo expansion

Since umbilical cord blood (UCB), contains a limited hematopoietic stem/progenitor cells (HSC) number, successful expansion protocols are needed to overcome the hurdles associated with inadequate numbers of HSC collected for transplantation. UCB cultures were performed using a human stromal-based serum-free culture system to evaluate the effect of different initial CD34(+) cell enrichments (Low: 24 ± 1.8%, Medium: 46 ± 2.6%, and High: 91 ± 1.5%) on the culture dynamics and outcome of HSC expansion. By combining PKH tracking dye with CD34(+) and CD34(+) CD90(+) expression, we have identified early activation of CD34 expression on CD34(-) cells in Low and Medium conditions, prior to cell division (35 ± 4.7% and 55 ± 4.1% CD34(+) cells at day 1, respectively), affecting proliferation/cell cycle status and ultimately determining CD34(+)/CD34(+) CD90(+) cell yield (High: 14 ± 1.0/3.5 ± 1.4-fold; Medium: 22 ± 2.0/3.4 ± 1,0-fold; Low: 31 ± 3.0/4.4 ± 1.5-fold) after a 7-day expansion. Considering the potential benefits of using expanded UCB HSC in transplantation, here we quantified in single UCB units, the impact of using one/two immunomagnetic sorting cycles (corresponding to Medium and High initial progenitor content), and the average CD34(+) cell recovery for each strategy, on overall CD34(+) cell expansion. The higher cell recovery upon one sorting cycle lead to higher CD34(+) cell numbers after 7 days of expansion (30 ± 2.0 vs. 13 ± 1.0 × 10(6) cells). In particular, a high (>90%) initial progenitor content was not mandatory to successfully expand HSC, since cell populations with moderate levels of enrichment readily increased CD34 expression ex-vivo, generating higher stem/progenitor cell yields. Overall, our findings stress the importance of establishing a balance between the cell proliferative potential and cell recovery upon purification, towards the efficient and cost-effective expansion of HSC for cellular therapy.

Characterization of a Novel Monoclonal Antibody (27H2) Recognizing Human CD34 Class III Epitope

BACKGROUND

Monoclonal antibodies (mAbs) recognizing Class III epitope of CD34 are essential for flow cytometric diagnosis of leukemia.

METHODS

27H2 mAb was developed from a mouse alternatively immunized with human acute leukemia cell lines, KG1 and Molm-1. Using flow cytometric analysis of various leukemic cell lines and peripheral blood, immunohistochemical study of frozen tonsil, we characterized 27H2 mAb. Antigen immunoprecipitated with 27H2 mAb immunobloted with anti-CD34 mAb. A case of bone marrow sample of acute lymphoblastic leukemia (ALL) patient was obtained at CBNU Hospital. For epitope identification enzyme treatment with neuraminidase and O-sialoglycoprotein endopeptidase (OSGE) and blocking assay with known classIII mAb (HPCA-2) were done.

RESULTS

Only KG1 and Molm-1 revealed positive immunoreactivity. Immunohistochemical staining disclosed strong membranous immunoreactivity on high endothelial venules. Antigen immunoprecipitated by 27H2 mAb showed approximately 100 kDa sized band immunoblotted with anti-CD34 under non-reducing conditions. Epitope recognized by 27H2 mAb disclosed resistancy to both neuraminidase and OSGE treatment and completely blocked with known class III mAb preincubation. CD34 positive leukemic cells in BM of pre B cell ALL patient detected by FITC-conjugated 27H2 and HPCA-2 were identified with similar sensitivity.

CONCLUSION

A novel murine mAb recognizing class III epitope of human CD34 with high affinity, which is useful for flow cytometric diagnosis of leukemia, was developed.

Intra-operative preparation of autologous bone marrow-derived CD34-enriched cellular products for cardiac therapy

BACKGROUND AND AIMS

With the advent of regenerative therapy, there is renewed interest in the use of bone marrow as a source of adult stem and progenitor cells, including cell subsets prepared by immunomagnetic selection. Cell selection must be rapid, efficient and performed according to current good manufacturing practices. In this report we present a methodology for intra-operative preparation of CD34(+) selected autologous bone marrow for autologous use in patients receiving coronary artery bypass grafts or left ventricular assist devices.

METHODS AND RESULTS

We developed a rapid erythrocyte depletion method using hydroxyethyl starch and low-speed centrifugation to prepare large-scale (mean 359 mL) bone marrow aspirates for separation on a Baxter Isolex 300i immunomagnetic cell separation device. CD34 recovery after erythrocyte depletion was 68.3 ± 20.2%, with an average depletion of 91.2 ± 2.8% and an average CD34 content of 0.58 ± 0.27%. After separation, CD34 purity was 64.1 ± 17.2%, with 44.3 ± 26.1% recovery and an average dose of 5.0 ± 2.7 × 10(6) CD34(+) cells/product. In uncomplicated cases CD34-enriched cellular products could be accessioned, prepared, tested for release and administered within 6 h. Further analysis of CD34(+) bone marrow cells revealed a significant proportion of CD45(-) CD34(+) cells.

CONCLUSIONS

Intra-operative immunomagnetic separation of CD34-enriched bone marrow is feasible using rapid low-speed Hetastarch sedimentation for erythrocyte depletion. The resulting CD34-enriched product contains CD45(-) cells that may represent non-hematopoietic or very early hematopoietic stem cells that participate in tissue regeneration.

Predictors of high yield and purify of CD34(+) cell-selected PBPC, collected from patients with multiple myeloma

BACKGROUND

Wide ranges i n cell recovery and purity may be observed following CD34(+) cell selection of mobilized HPC componetns. Characteristics of the mobilized HPC, associated with isolation of a high CD34(+) cell yield and purity following cell selection, have yet to be defined.

METHODS

Cell number and purities were determined before and after 56 CD34(+) cell-selection procedures, performed using the CellPro Ceprate SC system from April 1997 to February 1998. HPC were collected from 28 patients with multiple myeloma, following cyclophosphamide (60mg/kg) and G-CSF (10microg/kg) mobilization.

RESULTS

A medium of 47.9% (range 1.5-109.6%) CD34(+) cells were recovered in the enriched (ENR) fraction. A linear correlation existed between total CD34(+) cells in the ENR fraction and total CD34(+) cells in the START fraction (R2=0.93); there was a logarithmic correlation between CD34 ENR fraction purity and START fraction purity (R2=0.73). A START CD34(+) cell purity > 0.42% improved purity in the ENR fraction. A median of one (range one to nine) procedure was required to isolate 2 x 10 6 CD34(+) cells/kg. Three patients pretreated with alkylating agents failed to mobilized adequate numbers of HPC.

DISCUSSION

Isolation of highly purified CD34(+) cell-selected components using the Ceprate SC system in dependent on the CD34(+) purity of the lekapheresis component collected. Mobilization regimens should be used to maximize CD34(+) cell purity in stem cell authografts if CD34(+) cell selection is to be performed. Similar strategies should be used to evaluate other cell-selection devices as they become available.

Improved post-thaw recovery of peripheral blood stem/progenitor cells using a novel intracellular-like cryopreservation solution

BACKGROUND AIMS

Peripheral blood stem cells (PBSC) have become the preferred stem cell source for autologous hematopoietic transplantation. A critical aspect of this treatment modality is cryopreservation of the stem cell products, which permits temporal separation of the PBSC mobilization/collection phase from the subsequent high-dose therapy. While controlled rate-freezing and liquid nitrogen storage have become 'routine' practice in many cell-processing facilities, there is clearly room for improvement as current cryopreservation media formulations still result in significant loss and damage to the stem/progenitor cell populations essential for engraftment, and can also expose the patients to relatively undefined serum components and larger volumes of dimethylsulfoxide (DMSO) that can contribute to the morbidity and mortality of the transplant therapy.

METHODS

This study compared cryopreservation of PBSC in a novel intracellular-like, fully defined, serum- and protein-free preservation solution, CryoStor (BioLife Solutions Inc.), with a standard formulation used by the Fred Hutchinson Cancer Research Center (FHCRC). Briefly, human PBSC apheresis specimens were collected and 5 x 10(7) cells/1 mL sample vial were prepared for cryopreservation in the following solutions: (a) FHCRC standard, Normosol-R, 5% human serum albumin (HAS) and 10% DMSO; and (b) CryoStor CS10 (final diluted concentration of 5% DMSO). A standard controlled-rate freezing program was employed, and frozen vials were stored in the vapor phase of a liquid nitrogen freezer for a minimum of 1 week. Vials were then thawed and evaluated for total nucleated cell count (TNC), viability, CD34 and granulocytes by flow cytometry, along with colony-forming activity in methylcellulose.

RESULTS

The PBSC samples frozen in CryoStor CS10 yielded significantly improved post-thaw recoveries for total viable CD34(+), colony-forming units (CFU) and granulocytes. Specifically, relative to the FHCRC standard formulation, cryopreservation with CS10 resulted in an average 1.8-fold increased recovery of viable CD34(+) cells (P=0.005), a 1.5-fold increase in CFU-granulocyte-macrophage (GM) numbers (P=0.030) and a 2.3-fold increase in granulocyte recovery (P=0.045).

CONCLUSIONS

This study indicates that use of CryoStor for cryopreservation can yield significantly improved recovery and in vitro functionality of stem/progenitor cells in PBSC products. In addition, it is important to note that these improved recoveries were obtained while not introducing any extra serum or serum-derived proteins, and reducing the final concentration/volume of DMSO by half. Further in vitro and in vivo studies are clearly necessary; however, these findings imply use of CryoStor for cryopreservation could result in improved engraftment for those patients with a lower content of CD34(+) cells in their PBSC collections, along with reducing the requirement for additional apheresis collections and decreasing the risk of adverse infusion reactions associated with higher exposure to DMSO.

Differences amid bone marrow and cord blood hematopoietic stem/progenitor cell division kinetics

Human hematopoietic stem/progenitor cells (HSC) isolated based upon specific patterns of CD34 and CD38 expression, despite phenotypically identical, were found to be functionally heterogeneous, raising the possibility that reversible expression of these antigens may occur during cellular activation and/or proliferation. In these studies, we combined PKH67 tracking with CD34/CD38 immunostaining to compare cell division kinetics between human bone marrow (BM) and cord blood (CB)-derived HSC expanded in a serum-free/stromal-based system for 14 days (d), and correlated CD34 and CD38 expression with the cell divisional history. CB cells began dividing 24 h earlier than BM cells, and significantly higher numbers underwent mitosis during the time in culture. By d10, over 55% of the CB-cells reached the ninth generation, whereas BM-cells were mostly distributed between the fifth and seventh generation. By d14, all CB cells had undergone multiple cell divisions, while 0.7-3.8% of BM CD34(+) cells remained quiescent. Furthermore, the percentage of BM cells expressing CD34 decreased from 60.8 +/- 6.3% to 30.6 +/- 6.7% prior to initiating division, suggesting that downmodulation of this antigen occurred before commencement of proliferation. Moreover, with BM, all primitive CD34(+)CD38(-) cells present at the end of culture arose from proliferating CD34(+)CD38(+) cells that downregulated CD38 expression, while in CB, a CD34(+)CD38(-) population was maintained throughout culture. These studies show that BM and CB cells differ significantly in cell division kinetics and expression of CD34 and CD38, and that the inherent modulation of these antigens during ex vivo expansion may lead to erroneous quantification of the stem cell content of the expanded graft.

Prognostic influence of minimal residual disease detected by flow cytometry and peripheral blood stem cell transplantation by CD34+ selection in childhood advanced neuroblastoma

OBJECTIVE

To determine whether neuroblastoma (NB) minimal residual disease (MRD) in bone marrow (BM) detected by flow cytometry could predict prognosis and whether tumor cell purging by CD34(+) cell selection prior to transplantation will impact on disease-free survival.

METHODS

NB MRD in BM was evaluated by flow cytometry with CD45-FITC-/CD81-PE+/CD56-PECy5+ monoclonal antibodies cocktail. Peripheral blood stem cell (PBSC) was enriched via positive CD34(+) cell selection by magnetic-activated cell separation system (MACS).

RESULTS

Eleven of 31 patients with CD45(-)/CD81+/CD56+ cells by flow cytometry at diagnosis became negative after an average of four courses of chemotherapy. All 11 patients remained alive without evidence of disease. Thirteen of the 20 patients with positive MRD relapsed and 1 patient died from disease (mean 25.8 months). There was a significant difference between these two groups. MRD in BM was tested before PBSC transplantation (PBSCT) for 19 NB patients. Fourteen was negative, 4 of them relapsed and 10 patients remained alive without evidence of disease. Another 5 patients with positive MRD, all of them relapsed (mean 17 months after PBSCT) with a significant difference between these two groups. Fourteen of 19 PBSC were purged with CD34(+) selection procedure. Six of 14 relapsed (mean 18.43 months after PBSCT). Five patients did not purge for CD34(+) selection, and 3 of them relapsed with no significant difference between these two groups.

CONCLUSIONS

Positive MRD in BM after an average of four courses of chemotherapy and before PBSCT is an unfavorable factor for stage IV NB. CD34(+) selection purging for PBSCT may not improve the prognosis for children with neuroblastoma in advanced stage.

Optimal ex vivo expansion of neutrophils from PBSC CD34+ cells by a combination of SCF, Flt3-L and G-CSF and its inhibition by further addition of TPO

BACKGROUND

Autologous mobilised peripheral blood stem cell (PBSC) transplantation is now a standard approach in the treatment of haematological diseases to reconstitute haematopoiesis following myeloablative chemotherapy. However, there remains a period of severe neutropenia and thrombocytopenia before haematopoietic reconstitution is achieved. Ex vivo expanded PBSC have been employed as an adjunct to unmanipulated HSC transplantation, but have tended to be produced using complex cytokine mixtures aimed at multilineage (neutrophil and megakaryocyte) progenitor expansion. These have been reported to reduce or abrogate neutropenia but have little major effect on thrombocytopenia. Selective megakaryocyte expansion has been to date ineffective in reducing thrombocytopenia. This study was implemented to evaluate neutrophil specific rather than multilineage ex vivo expansion of PBSC for specifically focusing on reduction or abrogation of neutropenia.

METHODS

CD34+ cells (PBSC) were enriched from peripheral blood mononuclear cells following G-CSF-mobilisation and cultured with different permutations of cytokines to determine optimal cytokine combinations and doses for expansion and functional differentiation and maturation of neutrophils and their progenitors. Results were assessed by cell number, morphology, phenotype and function.

RESULTS

A simple cytokine combination, SCF + Flt3-L + G-CSF, synergised to optimally expand and mature neutrophil progenitors assessed by cell number, phenotype, morphology and function (superoxide respiratory burst measured by chemiluminescence). G-CSF appears mandatory for functional maturation. Addition of other commonly employed cytokines, IL-3 and IL-6, had no demonstrable additive effect on numbers or function compared to this optimal combination. Addition of TPO, commonly included in multilineage progenitor expansion for development of megakaryocytes, reduced the maturation of neutrophil progenitors as assessed by number, morphology and function (respiratory burst activity).

CONCLUSION

Given that platelet transfusion support is available for autologous PBSC transplantation but granulocyte transfusion is generally lacking, and that multilineage expanded PBSC do not reduce thrombocytopenia, we suggest that instead of multilineage expansion selective neutrophil expansion based on this relatively simple cytokine combination might be prioritized for development for clinical use as an adjunct to unmanipulated PBSC transplantation to reduce or abrogate post-transplant neutropenia.

Methods in cell separations

Research in the field of cell biology and biomedicine relies on technologies that fractionate cell populations and isolate rare cell types to high purity. A brief overview of methods and commercially available products currently used in cell separations is presented. Cell fractionation by size and density and highly selective affinity-based technologies such as affinity chromatography, fluorescence-activated cell sorting (FACS) and magnetic cell sorting are discussed in terms of throughput, yield, and purity.

Low-dose lenograstim is as effective as standard dose in shortening neutrophil engraftment time following myeloablative chemotherapy and peripheral blood progenitor cell rescue

Granulocyte colony-stimulating factor (G-CSF) is widely used following myeloablative chemotherapy (high-dose therapy; HDT) and peripheral blood progenitor cell rescue (PBPCR) to reduce neutrophil engraftment time. The dose and duration required to gain maximum clinical and economic benefit has not been fully investigated. This double blind placebo-controlled randomised trial was performed to determine whether short course low-dose or standard-dose Lenograstim (L) would influence recovery of haematopoiesis following HDT and PBPCR. Sixty-one patients were randomised between May 1999 and November 2004, to receive standard-dose lenograstim (263 microg/d), low-dose lenograstim (105 microg/d) or placebo injections. These commenced on day +5 following PBPCR and continued until neutrophil engraftment [absolute neutrophil count (ANC)] > or = 0.5 x 10(9)/l. Patients received standard supportive care until haemopoietic recovery. Both standard- and low-dose lenograstim resulted in a significantly shorter median time to neutrophil recovery (ANC > or = 0.1 x 10(9)/l:10.0 vs. 11.0 d, P = 0.025; ANC > or = 0.5 x 10(9)/l:11.0 vs. 14.0 d, P = 0.0002) compared with placebo. There was no significant difference in blood product support, antibiotic usage, documented infection, overall survival or relapse-free survival between the groups. Short course low-dose lenograstim is as effective as standard-dose in reducing neutrophil engraftment time following HDT and PBPCR.

A Novel HSV-1 Virus, JS1/34.5−/47−, Purges Contaminating Breast Cancer Cells From Bone Marrow

PURPOSE

Oncolytic herpes simplex virus type 1 (HSV-1) vectors show considerable promise as agents for cancer therapy. We have developed a novel recombinant HSV-1 virus (JS1/34.5-/47-) for purging of occult breast cancer cells from bone marrow of patients. Here, we evaluate the therapeutic efficacy of this oncolytic virus.

EXPERIMENTAL DESIGN

Electron microscopy was used to determine whether human breast cancer and bone marrow cells are permissive for JS1/34.5-/47- infection. Subsequently, the biological effects of JS1/34.5-/47- infection on human breast cancer cells and bone marrow were established using cell proliferation and colony formation assays, and the efficiency of cell kill was evaluated. Finally, the efficiency of JS1/34.5-/47- purging of breast cancer cells was examined in cocultures of breast cancer cells with bone marrow as well as bone marrow samples from high-risk breast cancer patients.

RESULTS

We show effective killing of human breast cancer cell lines with the JS1/34.5-/47- virus. Furthermore, we show that treatment with JS1/34.5-/47- can significantly inhibit the growth of breast cancer cell lines without affecting cocultured mononuclear hematopoietic cells. Finally, we have found that the virus is effective in destroying disseminated tumors cells in bone marrow taken from breast cancer patients, without affecting the hematopoietic contents in these samples.

CONCLUSION

Collectively, our data show that the JS1/34.5-/47- virus can selectively target breast cancer cells while sparing hematopoietic cells, suggesting that JS1/34.5-/47- can be used to purge contaminating breast cancer cells from human bone marrow in the setting of autologous hematopoietic cell transplantation.

Immune reconstitution after purified autologous and allogeneic blood stem cell transplantation compared with unmanipulated bone marrow transplantation in children

Immune reconstitution is critical for the long-term success of haematopoietic stem cell transplantation (HSCT). We prospectively analysed immune reconstitution parameters after transplantation of autologous (group 1; n = 10) and allogeneic (group 2; n = 12) highly purified CD34+ peripheral blood stem cells (PBSC) and unmanipulated allogeneic bone marrow (BM) (group 3; n = 9) in children. Median follow-up after HSCT was 56 (group 1), 61 (group 2), and 40.5 months (group 3). Median CD34-cell dose transplanted in the three groups was 9.4 x 10(6)/kg, 20.3 x 10(6)/kg, and 4.25 x 10(6)/kg recipient's body weight (BW) respectively. Complete haematopoietic engraftment was seen in all patients without any significant differences between the three groups. T-cell reconstitution at 6 months was significantly delayed in autologous peripheral blood stem cell transplantation (PBSCT) compared with allogeneic BM transplantation (P < 0.028) and allogeneic PBSCT (P < 0.034). At 3 months after transplantation numbers of CD56+/3- natural killer cells were higher in the allogeneic PBSC group (P < 0.01) compared with the BM group. The numbers of proven bacterial and viral infections were equally distributed between the three groups. In conclusion, recipients of allogeneic highly purified CD34+ PBSC or unmanipulated BM have higher lymphocyte subset counts at 6 months after transplantation than recipients of autologous CD34-selected PBSC. Infection rates and outcome, however, were not significantly different.

Hematopoietic stem cell antigen CD34: role in adhesion or homing

CD34 is highly glycosylated surface antigen of enormous clinical utility in the identification, enumeration, and purification of engraftable lymphohematopoietic progenitors for transplantation. However, recently its importance in the specific marking of most immature hematopoietic stem/progenitor cells have been questioned by addressing long-term reconstitution capability of CD34(-) hematopoietic cellular fractions. These controversies have stimulated a demand for elucidation of the structure, function, and molecular interactions of CD34 to define exactly its biological significance in clinical regimens. There is accumulating data showing the participation of CD34 in adhesion or perhaps homing of lymphohematopoietic progenitors. On the other hand, CD34 has been demonstrated to down-regulate cytokine-induced differentiation and proliferation of CD34(+) cells. Studies in CD34 knockout mice revealed normal hematopoiesis but a profound delay in hematopoietic reconstitution after sublethal irradiation of the mice. In short, CD34 expression is likely to represent a specific state of hematopoietic development that may have altered adhering properties with expanding and differentiating capabilities in both in vitro and in vivo conditions. This article focuses on the adhesive properties of CD34 and its potential role in homing, which are likely to mimic lymphocyte homing to the inflammatory sites.

Hematopoietic stem cells

Hematopoietic stem cells (HSCs) have the capacity to self-renew and the potential to differentiate into all of the mature blood cell types. The ability to prospectively identify and isolate HSCs has been the subject of extensive investigation since the first transplantation studies implying their existence almost 50 years ago. Despite significant advances in enrichment protocols, the continuous in vitro propagation of human HSCs has not yet been achieved. This chapter describes current procedures used to phenotypically and functionally characterize candidate human HSCs and initial efforts to derive permanent human HSC lines.

Isolation and transplantation of highly purified autologous peripheral CD34+ progenitor cells: purging efficacy, hematopoietic reconstitution following high dose chemotherapy in patients with breast cancer: results of a feasibility study in Japan

BACKGROUND

High-dose chemotherapy with autologous stem cell support may have some therapeutic impact on certain groups of the patients with advanced breast cancer(BRCA). Since stem cell contamination by tumor cells might contribute to relapse, development of a tumor cell purging technique would improve the clinical outcome. The present study was undertaken to evaluate the purging efficacy of autologous mobilized CD34+peripheral stem cells in patients with breast cancer (BRCA) in an advanced stage or relapse.

METHODS

CD34+cells were selected from autologous peripheral blood stem cells (PBSC) using a clinical scale of magnetic-activated cell sorting system (CliniMACS), followed by high-dose chemotherapy with transplantation of CD34+ selected cells. Amplification of cytokeratin 19 (CK19) and 20 (CK20) gene in leukapheresis products were measured to evaluate the performance of tumor cell elimination.

RESULTS

Seven patients were entered into this study. After leukopheresis, 1 patient was dropped form this study due to poor mobilization. Among 6 patient, a total of 8 CD34+ selection was performed. The median purity and recovery rate of the CD34+ cells post selection was 85.1% (range 62.5-98.1%) and 74.2% (range 50.2-90.2%), respectively. After isolation of CD34+cells, the elimination rate in the logarithmic transformation of CK19 was 2.77 log, and that of CK20 were 2.43 log and 2.53 log. In 4 patients, high-dose chemotherapy was performed, followed by the transplantation of the isolated CD34+cells. Rapid neutrophil recovery, as well as platelet recovery was seen with a median time to reach 0.5 x 109/l neutrophils of 9 days(range 8-9), and 20 x 109/l platelets of 12 days (range 10-13). There was no treatment related death and no serious adverse events directly associated with the selection procedure or infusion of selected cells.

CONCLUSIONS

The present study demonstrated that the CliniMACS system is a highly effective positive selection method and that a high purging efficacy could be obtained without compromising the hematopoietic reconstitution capacity of the graft in BRCA patients undergoing high-dose chemotherapy.

Development of a gene therapy based bone marrow purging system for leukemias

Although viable gene therapy based methods have been reported for the selective removal or purging of contaminating epithelial derived cancer cells from stem cell grafts, similar strategies for the purging of leukemia cells have been significantly less efficient. Hematopoietic cells are difficult targets for transduction with currently available vectors. Polylysine based molecular conjugate vectors (MCV) were previously found to effectively transduce both normal and malignant hematopoietic cells. A panel of human leukemia cell lines as well as CD34+ selected primary human hematopoietic progenitor cells (HPC) were tested for differential gene expression utilizing different promoters. Reporter gene expression under the control of RSV and SV40 promoters showed a 6-log fold increase in leukemia cells when compared to primary HPC. Using a polylysine based recombinant molecular conglomerate vector (recMCV) encoding the HSV-tk suicide gene under control of RSV, we demonstrated effective and specific cell killing in all leukemia cell lines as well as in primary human leukemia cells derived from chemotherapy refractory patients, while HPC survived under the same conditions at approximately 20% viability. These proof of principle experiments demonstrate that gene therapy technology could be utilized to successfully purge leukemia cells from HPC.

Endothelial Progenitor Cells for Vasculogenesis

Postnatal vasculogenesis is considered to be involved in neovascularization of adult tissues, because bone marrow-derived endothelial progenitor cells (EPCs) were isolated from circulating mononuclear cells in peripheral blood and were shown to incorporate into sites of physiological and pathological neovascularization and to differentiate into mature endothelial cells. EPCs might have an attractive potential therapeutic application for cardiovascular ischemic diseases as a novel cell-based strategy mainly via a vasculogenesis mechanism.

Stem-cell transplantation for the treatment of advanced solid tumors

Over the past two decades, high-dose chemotherapy (HDC) with autologous stem-cell transplantation (ASCT) has been explored for a variety of solid tumors in adults, particularly breast cancer, ovarian cancer and non-seminomatous germ-cell tumors. The results of prospective phase II studies seemed superior in many cases to the outcome expected with standard-dose chemotherapy (SDC). The value of HDC for adult solid tumors remains, in most instances, a controversial issue, currently under the scrutiny of randomized phase III trial evaluation. ASCT pursuing an immune graft-versus-tumor effect has been evaluated in recent years for patients with advanced and refractory solid malignancies. This article reviews the results of the main phase II and III studies of HDC with ASCT, as well as the preliminary experience using allogeneic transplantation for solid tumors.

Endothelial progenitor cells for postnatal vasculogenesis

In the past decade, researchers have defined committed stem or progenitor cells from various tissues, including bone marrow, peripheral blood, brain, liver, and reproductive organs, in both adult animals and humans. Whereas most cells in adult organs are composed of differentiated cells, which express a variety of specific phenotypic genes adapted to each organ's environment, quiescent stem or progenitor cells are maintained locally or in the systemic circulation and are activated by environmental stimuli for physiological and pathological tissue regeneration. Recently, endothelial progenitor cells (EPCs) were isolated from peripheral blood CD34, Flk-1, or AC133 antigen-positive cells, which are considered to include a hematopoietic stem cell population, and were shown to be incorporated into foci of neovascularization. This finding, that circulating EPCs may home to sites of neovascularization and differentiate into endothelial cells in situ, is consistent with "vasculogenesis," a critical paradigm for embryonic neovascularization, and suggests that vasculogenesis and angiogenesis may constitute complementary mechanisms for postnatal neovascularization. Previous reports demonstrating therapeutic potential of EPC transplantation in animal models of hindlimb and myocardial ischemia opened the way to the clinical application of cell therapy: the replacement of diseased or degenerating cell populations, tissues, and organs. In this review, we summarize biological features of EPCs and speculate on the utility of EPCs for vascular and general medicine.

Prognostic analysis of early lymphocyte recovery in patients with advanced breast cancer receiving high-dose chemotherapy with an autologous hematopoietic progenitor cell transplant

PURPOSE

The purpose of this study was to evaluate the prognostic effect of early posttransplant lymphocyte recovery in patients with advanced breast cancer receiving high-dose chemotherapy with autologous hematopoietic progenitor cell transplantation.

EXPERIMENTAL DESIGN

We analyzed the effect of the absolute lymphocyte count on day +15 posttransplant on freedom from relapse and overall survival in patients with high-risk primary breast cancer or metastatic breast cancer, enrolled between 1990 and 2001 in prospective high-dose chemotherapy trials, using a uniform regimen of cyclophosphamide, cisplatin, and 1,3-bis(2-chloroethyl)-1-nitrosourea.

RESULTS

Four hundred and seventy-six patients (264 high-risk primary breast cancer and 212 metastatic breast cancer patients) were evaluated at median follow-up of 8 years (range, 1.5-11 years). The disease-free survival and overall survival rates in the high-risk primary breast cancer group were 67% and 70%, respectively. Patients with metastatic breast cancer patients had 21.8% disease-free survival and 31.5% overall survival rates. Day +15 absolute lymphocyte count correlated with freedom from relapse (P = 0.007) and overall survival (P = 0.04) in the metastatic breast cancer group, but not in the high-risk primary breast cancer group (P = 0.5 and 0.8, respectively). The prognostic effect of absolute lymphocyte count in metastatic breast cancer was restricted to those patients receiving unmanipulated peripheral blood progenitor cells (P = 0.04). In contrast, absolute lymphocyte count had no significant effect in those metastatic breast cancer patients receiving bone marrow or a CD34-selected product. In multivariate analyses, the prognostic effect of day +15 absolute lymphocyte count in metastatic breast cancer was independent of other predictors, such as disease status, pre-high-dose chemotherapy treatment, number of tumor sites, or HER2.

CONCLUSIONS

Early lymphocyte recovery is an independent outcome predictor in metastatic breast cancer patients receiving high-dose chemotherapy and an autologous peripheral blood progenitor cell transplant. These observations suggest that immune strategies targeting minimal posttransplant residual disease may prove worthwhile.

Endothelial Progenitor Cell Culture for Vascular Regeneration

A certain population of mononuclear cells in the peripheral blood is capable of contributing to new vessel formation by differentiating into endothelial cells. The basis for native as well as therapeutic neovascularization is not restricted to angiogenesis but includes postnatal vasculogenesis. These cells were discovered by Asahara in 1997 and named endothelial progenitor cells (EPCs). Clinical usefulness of EPCs from human peripheral blood is also suggested in the animal experiments. These results indicate that administering EPCs can be a new clinical strategy for treating ischemic disease, diabetic retinopathy, or neoplasm in which the promotion or inhibition of neovascular formation is critical. However, expansion of EPCs ex vivo is not currently suitable for the clinical setting because of the animal products that are necessary for EPC expansion. To approach the autologous cell-based clinical application of EPCs, we established EPC culture using auto serum. In this article, we will discuss the sources that can generate EPCs and show the usefulness and potential of EPC culture using auto serum in the basic and clinical setting of neovascular formation.

Prognostic significance of occult tumor cells in the apheresis products of patients with advanced breast cancer receiving high-dose chemotherapy and autologous hematopoietic progenitor cell support

We prospectively evaluated the prognostic significance of occult tumor cells (OTCs) contaminating the peripheral blood progenitor cell apheresis products of patients with advanced breast cancer receiving high-dose chemotherapy. Immunocytochemistry of peripheral blood progenitor cells was performed in 242 patients with high-risk primary breast cancer (HRPBC) and in 111 patients with metastatic breast cancer (MBC). OTCs were detected in 6.6% of HRPBC patients and in 16.2% of MBC patients (P = .005). In HRPBC, OTCs correlated with worse prognostic scores and larger tumor sizes, but not with axillary nodal status, hormone receptors, or HER2. In the MBC group, OTCs correlated with bone marrow involvement and with disease status at transplantation. The number of apheresis procedures was not associated with the risk of contamination. In HRPBC patients, at a median follow-up of 7 years (range, 1.5-11 years), the presence of OTCs correlated with worse event-free survival (P = .007) and overall survival (P = .002). In the MBC group, OTCs correlated with worse event-free survival (P = .04), but not overall survival (P = .2). In multivariate analyses, the presence of OTCs had an independent adverse effect on outcome in HRPBC, but not MBC. Our observations imply a direct role of OTCs in posttransplantation relapse in HRPBC.

Ex vivo purging of leukemia cells using tumor-necrosis-factor-related apoptosis-inducing ligand in hematopoietic stem cell transplantation

The aim of this study was to evaluate the potential of tumor-necrosis-factor-related apoptosis-inducing ligand TRAIL to eradicate leukemia cell lines, while sparing normal hematopoietic stem cells. Human Jurkat and Molt-4 cell lines were used to optimize the purging process in umbilical cord blood (UCB) mononuclear cells. The Jurkat cell line was TRAIL sensitive and TRAIL-resistant Molt-4 cell line became sensitive after being treated with TRAIL and a low dose of doxorubicin (0.1 micro M), but UCB mononuclear cells remained resistant. DR4 expression was increased when Jurkat cells were treated with TRAIL, and DR5 expression increased after exposing Molt-4 cells to TRAIL plus a low dose of doxorubicin for 24 h. The expression of DR4 and DR5 in UCB mononuclear cells was unchanged after treatment with TRAIL, a low-dose doxorubicin, or TRAIL plus a low dose of doxorubicin. In TRAIL-sensitive Jurkat cells, caspases 8, 9, 3, and 7 were activated by TRAIL treatment and activation of caspases was augmented by TRAIL plus a low dose of doxorubicin than TRAIL or a low dose of doxorubicin alone in Molt-4 cells. Experiments involving mixture of UCB mononuclear cells and Jurkat or Molt-4 cells showed a marked eradication of leukemia cells and the limiting dilution assay demonstrated an eradication rate of more than 4 logs after 24 h incubation with 100 ng/ml of TRAIL in Jurkat cells. In the case of Molt-4 cells, the eradication rate was about 3 logs when TRAIL was used in combination with a low dose of doxorubicin. No significant decrease in the number of granulocyte-macrophage colony-forming unit) (CFU-GM) colonies was detected when UCB mononuclear cells were treated with TRAIL in combination with a low dose of doxorubicin. These results suggest that TRAIL offers the possibility of being used as an ex vivo purging agent for autologous transplantation in hematologic malignancies.

Syngeneic hematopoietic stem cell transplantation for women with metastatic breast cancer

Metastatic breast cancer has been a common indication for autologous hematopoietic stem cell transplantation (HSCT). Previous reports indicate 3-year survival and progression-free survival (PFS) rates after autotransplant to be about 30 and 15%, respectively. Most deaths are from recurrent disease. One potential cause for high relapse rates is graft contamination with tumor. We describe 14 women with metastatic breast cancer transplanted between 1991 and 1998 with hematopoietic cells from identical twins. Median age was 41 y (range 34-50). Most women (12 of 14) were treated with mastectomy, and all received anthracycline-based regimens in their pretransplant course; nine women also received a taxane, seven radiotherapy and three hormonal therapy. Four women were in complete remission (one CR, three CRU) at transplant, five were in partial remission, two had stable disease and two had progressive disease. Eight women have died, one of treatment-related causes and seven of progressive breast cancer. Three-year survival was 48% (21-71%) and 3-year PFS was 21% (5-45%). Although the number of patients is small, outcomes for women transplanted with syngeneic grafts are similar to those of women receiving autologous grafts. This suggests that residual cancer in the patient is the major contributor to relapse after transplantation for breast cancer.

Clinical applications of CD34+ cell-selected peripheral blood stem cells

Peripheral blood stem cells (PBSC) are increasingly used for stem cell transplantation after high dose chemotherapy. CD34+ cell selection has also been done for use in autologous transplantation studies Bone marrow (BM) may contain tumor cells at the time of harvesting, and on re-infusion, these cells could contribute to a subsequent relapse. Similarly, tumor cell contamination of PBSC collections has been found in a number of studies. Therefore, purging contaminating tumor cells may prevent cases of relapse. As most tumor cell types do not express CD34 antigen, one of the most widespread applications of CD34+ cell selection is likely to be in tumor cell purging. Similarly, CD34+ cell selection has aided allogeneic transplantation studies. Acute graft-versus-host disease (aGVHD) is a major cause of morbidity and mortality in cases of allogeneic transplantation. As aGVHD is mediated by donor T cells, removal of T cells from the graft by CD34+ cell selection may ensure prophylaxis against aGVHD. Further, high-dose immunosuppression followed by CD34+ cell-selected stem cell rescue is theoretically reasonable as a therapeutic tool for patients with autoimmune disease resistant to conventional therapy. However, patients given T cell-depleted transplantation have an increased risk of opportunistic infection as well as malignancies related to immunosuppression; therefore, close monitoring is warranted. We describe here clinical applications of CD34+ cell-selected PBSC for a variety of diseases, with special emphasis on the efficacy as well as drawbacks of this novel technique.

Immunological properties of mononuclear cells from blood stem cell harvests following mobilization with erythropoietin + G-CSF in cancer patients

BACKGROUND

Although the recombinant granulocyte colony-stimulating factor (G-CSF) is a good CD34 cell mobilizer, the effects of G-CSF mobilization on the immune effector function of the individual is not always optimal. We studied the functional and phenotypic properties of peripheral blood stem cells (PBSC) collected from 15 cancer patients mobilized with G-CSF plus recombinant erythropoietin (EPO).

METHODS

The patients received EPO (300 U/kg) and (G-CSF 1 microg/kg) per day as mobilizing cytokines and an autologous graft product was collected with at least daily apheresis procedures until a target number of CD34 cells and mononuclear cells were obtained. Mononuclear cells from the first four PBSC collections were tested for their natural killer (NK), activated NK and lymphokine activated killer (LAK) cytotoxicity in vitro against K562 and Raji tumor target cells.

RESULTS

There was a significant increase in NK, activated NK and LAK cytotoxicity in EPO + G-CSF mobilized cells when compared to mononuclear cells from premobilization blood baseline values. Although there was no increase in CD3+ T cells, there was a significant increase in myeloid cells (CD14+), B-cells (CD20+) and NK cells (CD56+) following mobilization. There was no difference in T cell response to the mitogens PHA and Con-A, but there was an increase in B-cell response to PWM following mobilization. Thus, the combination of EPO + G-CSF not only mobilized hematopoietic precursor cells but also increased the number of immune effector cells in the PBSC collections.

CliniMACS CD34-selected cells to support multiple cycles of high-dose therapy

BACKGROUND

Traditionally, following high-dose therapy (HDT), unmanipulated autologous PBPC are infused. Alternatively, purified CD34+ cells can now be obtained by immunomagnetic separation using the CliniMACS device. Limited data currently exist examining hemopoietic recovery with such cells.

METHODS

Ten patients with advanced breast cancer had PBPC mobilized with docetaxel (100 mg/m2) and G-CSF (10 microg/kg per day), harvested and processed using the CliniMACS CD34-selection device and equally divided into three aliquots for cryopreservation. Unmanipulated 'back-up' cells were also collected on a separate day of the same mobilization, divided into three and cryopreserved. Patients subsequently received three cycles of HDT with cyclophosphamide (4 g/m2), thiotepa (300 mg/m2) and paclitaxel (175 mg/m2). The intent was for patients to receive CD34-selected cells to support each of the three cycles of HDT (i.e., 1/3 for each cycle). If, however, hemopoietic recovery was delayed after Cycle 1, 1/3 of the unmanipulated cells were infused following Cycle 2 and the remaining CD34-selected cells (2/3) were used to support Cycle 3.

RESULTS

PBPC from 10 patients underwent CD34-selection with a resulting median purity of 93% (range: 76-98%) and yield of 62% (range: 16-93%). Of the 10 patients, only two were able to be supported with CD34-selected cells for all three cycles of HDT. The remaining eight patients required unmanipulated 'back-up' cells to support Cycle 2. Three patients also required infusion of 'back-up' unmanipulated cells because of persistent neutropenia (n = 1) or thrombocytopenia (n = 2) following cycles initially supported by CD34-selected cells. The median number of CD34-selected cells (x 10(6)/kg) infused per cycle was 1.5 (0.7-2.6) (n = 20) and unselected cells was 1.7 (1.4-2.8) (n = 10). Comparing hemopoietic recovery between cycles of HDT supported by CD34-selected (n = 20) and unmanipulated cells (n = 10) there was a significant slowing with the CD34-selected cells; time to ANC > 1.0 = 13 days versus 10 days, platelets > 20 = 17 days versus 13 days, > 50 = 25 versus 17 days (all P values < 0.001). There was no correlation between the dose of CD34-selected cells infused and neutrophil/platelet recovery.

DISCUSSION

We have demonstrated that, although unmanipulated PBPC achieve rapid hemopoietic recovery (at modest CD34 doses of < or = 2.8 x 10(6)/kg), CliniMACS-selected CD34+ cells (in the doses utilized in this study of < or = 2.6 x 10(6)/kg) result in significantly prolonged recovery.

Normal human bone marrow CD34(+)CD133(+) cells contain primitive cells able to produce different categories of colony-forming unit megakaryocytes in vitro

OBJECTIVE

To evaluate the megakaryocyte potential of normal bone marrow (NBM) CD34(+)CD133(+) cells, a subset offering a possible alternative for clinical CD34 immunoselection, we evaluated their colony-forming unit megakaryocyte (CFU-Mk) content and their ability to produce clonogenic Mk progenitors in comparison with the CD133(-) subset.

MATERIALS AND METHODS

Sorted NBM CD34(+)CD133(+) and CD34(+)CD133(-) subsets were evaluated for Mk clonogenic capacity before and after in vitro proliferation in serum-free liquid culture containing kit ligand, Flt3 ligand, thrombopoietin, interleukin-3, and interleukin-6. The segregation of CFU-Mk according to the expression of CD34, CD133, and CD41 was compared between fresh BM cells and expanded cells.

RESULTS

Although the fresh NBM CD133(-)CD34(+) subset included two thirds CFU-Mk, only the CD133(+) subset contained primitive cells able to produce all categories of CFU-Mk in vitro. Immunophenotyping confirmed that CD41 antigen is nonspecific for Mk lineage and showed that the usual CD34(+)CD41(+) subset does not specifically define a CFU-Mk population. The segregation of CFU-Mk before and after expansion according to CD34, CD41, or CD133 was modified in relation with down-regulation of CD34 and CD133 antigens and up-regulation of CD41 antigen.

CONCLUSIONS

The NBM CD133(+) subset contains primitive cells able to generate CFU-Mk, a subset probably relevant to platelet recovery after infusion. The alteration of antigen expression during in vitro proliferation calls for caution in the identification of the different categories of Mk subsets produced and in the assessment of their predictivity for in vivo platelet production.

Mobilization and transduction of CD34(+) peripheral blood stem cells in patients with X-linked chronic granulomatous disease

As a single-gene defect in phagocytes, the X-linked form of chronic granulomatous disease (X-CGD) is a disorder potentially amenable to gene therapy by transfer of a functional copy of the gp91(phox) gene into hematopoietic stem cells (HSC). Although antimicrobial agents and interferon-gamma (IFN-gamma) have significantly improved its prognosis, CGD is still associated with high morbidity and mortality. The disease can be cured by bone marrow transplantation (BMT); however, BMT in CGD has been associated with unacceptably high rates of morbidity, mortality, and graft failure, except in very selected cases in which an HLA-identical donor is available. Prerequisites for a clinical gene therapy of CGD are an efficient mobilization of peripheral blood stem cells (PBSC) as well as the preservation of their viability and hematopoietic potential following transduction and ex vivo culture. We show that (i) mobilization and collection of CD34(+) cells after a 4-week IFN-gamma-free period by G-CSF results in sufficient numbers of cells for transplantation; (ii) the quality of collected stem cells is not altered in comparison to cells obtained from healthy volunteers as assessed by long-term culture initiating cells (LTC-IC) and progenitor cell expansion; (iii) retroviral transfer of the gp91(phox) gene under defined, serum-free conditions leads to high and stable reconstitution of the respiratory burst activity in X-CGD neutrophils derived from transduced CD34(+) progenitor and LTC-IC. Withdrawal of IFN-gamma in CGD patients may improve mobilization of CD34(+) stem cells by G-CSF. The gene transfer conditions established here are applicable to a clinical approach for gene therapy of X-CGD.

Circulating hematopoietic progenitor cells in a fetus with alpha thalassemia: comparison with the cells circulating in normal and non-thalassemic anemia fetuses and implications for in utero transplantations

Our aim was to evaluate the number of progenitor cells circulating in an alpha-thalassemic fetus during its infusion in utero with paternal CD34(+) and adult red cells and to compare those values with those circulating in normal and non-thalassemic anemic fetuses of matched gestational age. The treatment of the alpha-thalassemic fetus has been described elsewhere. Fetal blood was obtained from normal and anemic fetuses by fetal blood sampling for diagnostic or therapeutic purposes according to a protocol approved by the human subject committee. The number of progenitor cells in fetal blood was estimated on the basis of the number of colonies they gave rise to in semisolid cultures. The alpha-thalassemic fetus, as did the other fetuses analyzed, contained high numbers (10(6)-10(7) depending on the age) of progenitor cells, values which were higher than the number (10(4)-10(5)) of paternal progenitor cells being transplanted. Progenitor cells with adult characteristics (adult kinetics of differentiation) were detected rapidly (10 min) after the CD34(+) cell infusion, but were not detectable 2-3 weeks after the transplant. These results indicate that adult progenitor cells do not have a numerical advantage when transplanted into alpha-thalassemic fetuses.

CD34+-enriched-CD19+-depleted autologous peripheral blood stem cell transplantation for chronic lymphoproliferative disorders: high purging efficiency but increased risk of severe infections

OBJECTIVE

The main objective of this work was to decrease the incidence of relapse after autologous stem cell transplantation with a "double purging" procedure.

METHODS

We used a "positive" (CD34) and "negative" (CD19) double selection method to improve the efficacy of "single purging" of hematopoietic harvests in poor-prognosis lymphoproliferative disorders. All patients included in the study had a positive molecular marker of their disease. Minimal residual disease (MRD) was studied by flow cytometry and PCR techniques during the purging procedure and after transplantation.

RESULTS

Twenty-six patients fulfilled entry criteria. Median age of patients was 50 years (range: 33-66); 17 were male and 9 female. Thirteen (50%) of the patients mobilized an adequate number of CD34+ cells (>or=3 x 10(6)/kg) to proceed with the double-selection protocol. Twelve of the 13 harvests became PCR negative after purging. Ten patients were grafted with the selected products and all but one engrafted without delay. After a median follow-up of 30 months, 2 of 10 patients suffered a molecular relapse at 7 and 19 months respectively. The earlier relapse was observed in the patient who received a MRD+ product. Only one patient experienced a clinical relapse. Three patients died due to obliterans bronchiolitis, pneumococcal sepsis, and septic shock of unknown origin, respectively, and three others presented life-threatening infections.

CONCLUSION

Therefore, CD34+/CD19+ positive/negative selection is an effective purging approach in patients with chronic lymphoproliferative disorders. This favorable effect is, however, counterbalanced by the high frequency of life-threatening infections.

Purging in autologous hematopoietic stem cell transplantation using adenosine triphosphate (ATP) and 4-hydroperoxycyclophosphamide (4-HC)

In this study, we show potent in vitro purging induced by adenosine triphosphate (ATP) for leukemic cells. The treatment of murine L1210 leukemic cells with 2mM of ATP in vitro for 3h was able to reduce the number of leukemic clonogenic cells by about one order of magnitude presumably by changing the permeability of the leukemic cell membrane. Furthermore, the incubation of L1210 cells with ATP (2mM) and low dose 4-hydroperoxycyclophosphamide (4-HC, 2 microg/ml) for 3h resulted in at least a four-log reduction of clonogenic L1210 cells. Only a slight degree of toxicity to pluripotent hematopoietic stem cells (CFU-S) was observed in both treatment protocols. To determine the efficacy of pharmacological purging by ATP, we designed a murine system to mimic the conditions expected in the clinical setting of autologous transplantation using simulated partial remission marrow (SPRM) which was prepared by mixing normal marrow cells and L1210 cells at a ratio of 9:1. After the SPRM cells were incubated in vitro at a concentration of 1 x 10(6)/ml with both ATP (2mM) and low dose 4-HC (2 microg/ml) for 3h, 5 x 10(4) of the cells were then injected into lethally irradiated 9 weeks male BDF1 mice. All the mice given untreated-SPRM died of leukemia by day 27, whereas none of the recipients transplanted treated-grafts had died by day 70, thus suggesting that the combination use of ATP and 4-HC may be a potentially effective way to purge leukemic cells in autologous stem cell transplantation. The mechanism of the selective killing of leukemic cells is assumed that 4-HC is effectively incorporated into leukemic cells by increasing the permeability of the cell membrane by ATP. Taken together, this simple and rapid procedure is able to purge leukemic cells from autologous bone marrow grafts.

Purging of contaminating breast cancer cells from hematopoietic progenitor cell preparations using activation enhanced cell death

Activation enhanced cell death (AECD) involves stimulating cells with growth or activation signals while concurrently blocking calcium influx. In this study, we have evaluated the effect of AECD on human breast cancer cells. MCF-7 or MDA-MB-231 cells treated with Ca2+ influx blockers econazole or ketotifen for 24 h underwent a dose-dependent, irreversible loss of viability, and clonogenicity. Two-hour treatment of these cells with higher concentrations of the drugs also resulted in loss of clonogenicity, but morphological indicators of cell death were apparent only after longer incubation. Loss of clonogenicity could be enhanced almost 10-fold by co-stimulation of the cells with the agonists EGF or bombesin. Econazole was also effective in inducing cell death in multi-drug resistant MCF-7adr cells. Human hemopoietic progenitor cell sensitivity to econazole or ketotifen was evaluated by colony assay. Under conditions resulting in 2.5-3 logs of breast cancer cell loss, 60-70% of hemopoietic progenitors could be recovered. We further evaluated the effect of econazole on breast cancer cells present in mobilized hemopoietic cells obtained from patients undergoing high dose chemotherapy with autologous stem cell support. In six of eight samples evaluated, cytokeratin-positive breast cancer cells could be detected by immunofluorescence microscopy and colony formation. Breast cancer colonies were reduced 60-500-fold or more after exposure to econazole while hemopoietic colonies were typically reduced only 2-fold. In all cases, addition of EGF as an activator either had no evaluable effect or enhanced breast cancer cell loss. We conclude that Ca2+ influx blockade with concurrent EGF stimulation is a promising approach for purging breast cancer cells from hemopoietic progenitor cell preparations.

Endothelial progenitor cells for vascular regeneration

The basis for native as well as therapeutic neovascularization is not restricted to angiogenesis but includes postnatal vasculogenesis. Our laboratory and others' have established that bone marrow-derived endothelial progenitor cells (EPCs) are present in the systemic circulation, are augmented in response to certain cytokines and/or tissue ischemia, and home to as well as incorporate into sites of neovascularization. Given the background, EPCs have been investigated as therapeutic agents in these studies of supply-side angiogenesis under pathological as well as physiological conditions. This review discusses the therapeutic potential of EPCs for cardiovascular ischemic diseases.