Good manufacturing practice-compliant validation and preparation of BM cells for the therapy of acute myocardial infarction.

BACKGROUND: Intracoronary application of BM-derived cells for the treatment of acute myocardial infarction (AMI) is currently being studied intensively. Simultaneously, strict legal requirements surround the production of cells for clinical studies. Thus good manufacturing practice (GMP)-compliant collection and preparation of BM for patients with AMI was established by the Cytonet group. METHODS: As well as fulfillment of standard GMP requirements, including a manufacturing license, validation of the preparation process and the final product was performed. Whole blood (n=6) and BM (n=3) validation samples were processed under GMP conditions by gelafundin or hydroxyethylstarch sedimentation in order to reduce erythrocytes/platelets and volume and to achieve specifications defined in advance. Special attention was paid to the free potassium (<6 mmol/L), some rheologically relevant cellular characteristics (hematocrit <0.45, platelets <450 x 10(6)/mL) and the sterility of the final product. RESULTS: The data were reviewed and GMP compliance was confirmed by the German authorities (Paul-Ehrlich Institute). Forty-five BM cell preparations for clinical use were carried out following the validated methodology and standards. Additionally three selections of CD34+ BM cells for infusion were performed. All specification limits were met. Discussion In conclusion, preparation of BM cells for intracoronary application is feasible under GMP conditions. As the results of sterility testing may not be available at the time of intracoronary application, the highest possible standards to avoid bacterial and other contaminations have to be applied. The increased expense of the GMP-compliant process can be justified by higher safety for patients and better control of the final product.

Productive infection of primary human endothelial cells by pig endogenous retrovirus (PERV).

The potential risk of viral transmission in the setting of xenotransplantation has gained major attention. Different porcine cell types have been shown to release retroviral particles, which are infectious for human cell lines in vitro. However, there are only a few data on whether PERV (pig endogenous retrovirus) is able to infect primary human cells. In this study we have analyzed endothelial cells, vascular fibroblasts, mesangial cells, mononuclear cells, hematopoetic stem cells and bone marrow stromal cells for PERV transmission. We now provide evidence for primary human endothelial cells, vascular fibroblasts, and mesangial cells to be susceptible to PERV transmission. PERV infection was productive in endothelial cells and mesangial cells. Our data confirm and extend former reports concerning the PERV infection of human cells. The PERV infection of different primary human cells represents further significant evidence for a viral risk during xenotransplantation. In this context, special attention should be directed towards productive infection of human endothelial cells: in the setting of xenotransplantation this cell type will have close contact with porcine cells and PERV particles.

Competitive cytokeratin 19 RT-PCR for quantification of breast cancer cells in blood cell suspensions.

Detection of residual tumor cells in BM and PBPC products has been correlated with worse outcome of breast cancer patients. Still, there is a considerable demand for studies investigating the influence of the actual tumor cell number on prognosis, as quantification routinely has been cumbersome and time consuming and, thus, was evaded. We developed and evaluated a competitive RT-PCR-ELISA assay for cytokeratin 19 (CK19) with standard curve quantification that allows quantification of multiple samples within a working day; mRNA isolation, RT-PCR reaction, and automated ELISA detection were carried out using commercial kits. Results were expressed as OD420nm ratios of CK19 and an internal competitor. Values were then converted into tumor cell numbers using a standard curve of MCF-7 tumor cells. The assay had high specificity because of primers and capture probes with great heterogeneity to both published pseudogenes, which was confirmed by BLAST sequence alignment. We achieved a sensitivity of detecting 1 tumor cell per 10(6) mononuclear cells (MNC). Between-batch precision (n = 8) for quantification was consistent and reasonable, with a coefficient of variation around 25%. Therefore, this assay should be suitable and sufficient for routine quantification of tumor cell numbers in BM or PBPC samples.

Comparative evaluation of commonly used clones and fluorochrome conjugates of monoclonal antibodies for CD34 antigen detection.

CD34+ cell enumeration is currently the most appropriate technique for hematopoietic graft quality control. At the same time, numerous CD34 mAb have become commercially available. This study was designed to compare the commonly used clones 8G12 and QBEND-10 with the new clones 581 and BIRMA-K3. All available fluorochrome conjugates were tested: FITC, PE, and PE-Cy5 or PerCP for QBEND, BIRMA, 581, and 8G12 and FITC and PE for 581. Bone marrow from healthy donors (n = 5) and leukapheresis samples (n = 16) were stained, according to each manufacturer's protocol and analyzed using the FACScan. The following parameters were evaluated: % CD34+ cells detected and percentage of deviation from the median within each sample; mean channel fluorescence intensity of the CD34+ cells; resolution index (median channel fluorescence intensity of CD34+ cells/monocytes), % overlapping of CD34+ cell and monocyte fluorescence; proportion of CD34+ events after blocking with the same unlabeled clone; values of compensation requirements. Tables with results for each evaluated parameter separately were created, and rank points were applied. These scores represented the quality performance of the studied clones and fluorochrome conjugates and may be summarized as follows: 581 and 8G12 produced the best results, followed by BIRMA-K3 and QBEND10. The fluorochrome sequence was PE, PE-Cy5, PerCP, and FITC. However, all PE conjugates of the studied clones provided highly comparable results and conditions for CD34+ cell enumeration. When antigen coexpression must be studied and another dye than PE must be applied for CD34+ cell discrimination, the PE-Cy5 conjugates should be preferred.

Outcome of peripheral blood stem cell mobilization in advanced phases of CML is dependent on the type of chemotherapy applied.

High-dose chemotherapy with autologous transplantation of in vivo purged PBSC is a novel investigational approach to treating chronic myelogenous leukemia (CML) patients not responsive to conventional therapy with interferon-alpha (IFN-alpha) and not eligible for allogeneic transplantation. PBSC mobilization using either '5+2/7+3'-type chemotherapy or 'mini-ICE/ ICE' chemotherapy was investigated in 43 patients with advanced phases of Philadelphia (Ph)-positive CML. Thirty patients were in late chronic phase (>12 months post diagnosis) and 13 patients in accelerated phase (AP) or blast crisis (BC). Contamination with Ph-positive cells was evaluated in harvests from 37/43 patients. The outcome of PBSC mobilization was dependent on the type of chemotherapy administered: a complete or major cytogenetic response (<35% Ph-positive metaphases) in leukapheresis collections was obtained in ten of 15 patients treated with 'mini-ICE/ICE' but in only three of 28 patients treated with '5 + 2/7 + 3' chemotherapy. One patient (1/43) in blast crisis died during mobilization therapy (2%). Twenty-five patients underwent PBSC transplantation and all of them engrafted successfully. Transplantation-related mortality was 0%. The data show that in advanced phases of CML the chance of harvesting Ph-negative peripheral blood stem cells depends on the type of chemotherapy used for mobilization.

Chemotherapy-induced mobilization of karyotypically normal PBSC for autografting in CML.

High-dose chemotherapy with autologous transplantation of in vivo purged PBSC is a new and interesting therapeutic option for CML patients not eligible for allogeneic transplantation. We investigated the feasibility and toxicity of this approach in 57 patients with Ph-positive CML. For mobilization of Ph-negative PBSC, patients were treated either with '5 + 2/7 + 3'- type chemotherapy or with 'mini-ICE/ICE' chemotherapy followed by administration of G-CSF. Fourteen patients were in early chronic phase, 30 patients in late chronic phase and 13 patients in accelerated phase (AP) or blast crisis (BC). Cytogenetic responses in the PBSC harvests were dependent on both disease stage and type of chemotherapy: in late chronic phase and AP/BC, a complete or major cytogenetic response could be obtained in nine out of 13 patients treated with 'mini-ICE/ICE' but only in three out of 23 patients treated with '5 + 2/7 + 3' chemotherapy. However, in early chronic phase a Ph-negative autograft could be obtained in three out of eight patients upon mobilization with '5 + 2' chemotherapy. Thirty-one patients underwent PBSC transplantation and all of them successfully engrafted. Post-transplant cytogenetic analysis was available on 21 cases, of whom seven achieved a complete or major cytogenetic response, with two minor cytogenetic remissions. One patient (1/57) in blast crisis died during mobilization therapy (1.8%). Transplantation related mortality was 0%. This study demonstrates that mobilization of Ph-negative PBSC after myelosuppressive chemotherapy is feasible in CML patients and is associated with acceptable toxicity. Autologous transplantation of in vivo purged PBSC is a safe procedure with rapid and complete hematopietic recovery.

Sustained decrease of peripheral lymphocytes after allogeneic blood stem cell aphereses.

48 healthy donors underwent peripheral blood stem cell (PBSC) apheresis for allogeneic transplantation beginning on day 4 of G-CSF (2 x 5 microg/kg) mobilization. In one to four (median two) large-volume mononuclear cell aphereses, a median of 55.9 x 10(9) of lymphocytes (range 21.0-109.2 x 10[9]) were collected, an amount comparable to lymphocyte numbers removed by therapeutic lymphaphereses in autoimmune diseases. Mean peripheral lymphocyte counts decreased from premobilization values of 2.31 x 10(9)/l to 1.31 x 10(9)/l at a median of 34 d (1 month) and 1.53 x 10(9)/l at a median of 327 d (11 months). The decrease in peripheral lymphocyte counts was significantly correlated with the number of lymphocytes removed and the number of aphereses. Neutrophil and platelet counts returned to normal values after 1 month whereas monocyte counts and haemoglobin concentrations were significantly decreased at 1 month but not at 11 months.

Site-directed C3a receptor antibodies from phage display libraries.

Recent cloning of the human C3a receptor (C3aR) revealed that this receptor belongs to the large family of rhodopsin-type receptors. A unique feature of the C3aR is the large second extracellular loop comprising about 175 amino acid residues. We constructed combinatorial phage Ab libraries expressing single chain Fv Abs from BALB/c mice immunized with the affinity-purified second extracellular loop of the C3aR, fused to glutathione-S-transferase. A panel of anti-C3aR single chain Fv fragments (scFvs) was selected after four rounds of panning using the second extracellular loop of the C3aR, fused to the maltose binding protein as Ag. Sequencing of the clones obtained revealed three different groups of scFvs, the epitopes of which were mapped to two distinct regions within the loop, i.e., positions 185 to 193 and 218 to 226, representing the immunodominant domains of the loop. By flow cyotmetric analyses, the scFvs bound to RBL-2H3 cells transfected with the C3aR, but not to cells transfected with the C5aR or to nontransfected RBL-2H3 cells. In addition, the scFvs bound to the human mast cell line HMC-1. Immunofluorescence studies showed C3aR expression on polymorphonuclear granulocytes and monocytes, but not on lymphocytes. In addition, no C3aR expression was observed on human erythrocytes or platelets. Surprisingly, none of the scFvs alone or in combination inhibited C3a-induced Ca2+ mobilization from RBL-2H3 cells transfected with the C3aR. In addition, C3a did not displace binding of the scFvs to the receptor, strongly suggesting that the N-terminal part of the second extracellular loop is not involved in ligand binding.

A comparative review of methods for T cell depletion in the prophylaxis of graft-versus-host disease.

Graft-versus-host disease (GVHD) remains the major problem to be overcome in transplantation of allogeneic haemopoietic stem cells. Using immunosuppressive prophylaxis with cyclosporin and methotrexate, moderate to severe acute GVHD develops in approximately 45% of transplant recipients with an HLA-identical sibling donor and in >75% of patients from unrelated HLA-identical or partially matched related donors. The pathophysiology of GVHD is complex and still incompletely described. Experimental and clinical data indicate that GVHD is largely mediated by immunocompetent T cells in the donor stem cell graft which are reactive against recipient (host) tissues. Depletion of these immunocompetent T cells from the stem cell graft offers a way to effectively prevent GVHD. The first section of this review describes the technical principles of different methods of T cell depletion. The advantages, limitations and level of T cell depletion achievable by physical methods or by positive and negative immunoselection procedures using monoclonal antibodies are comprehensively discussed. A short section concentrates on technical problems in the enumeration of T cells in the context of depletion efficiency. In the section on clinical studies, the focus is on the efficacy of different T cell depletion methods in avoiding GVHD in different clinical settings. The various methods are compared in transplantation from HLA-identical and nonidentical siblings or matched unrelated donors. The major drawbacks of T cell depletion are discussed in detail. Failure of engraftment and graft rejection is a more frequent problem following T cell-depleted transplants, particularly with HLA nonidentical donor-recipient pairs. An increase in leukaemic relapse rate is seen in certain haematological malignancies, especially in chronic myeloid leukaemia. Delayed recovery of anti-infectious immunity occurs, leading to an increased incidence of cytomegalovirus and Epstein-Barr virus related problems. The aim of this review is not only to give an overview of published studies but also to review strategies to circumvent the drawbacks of TCD. Consequently, we attempt to describe the potential role of cells removed by different depletion methods in graft protection, anti-infectious immunity and graft-versus-leukaemia reactivity. Finally, the possibility of recovering all components of the original graft and readministering them in controlled amounts and at controlled times is discussed. This strategy of 'balanced component therapy' may allow the combination of a low rate and severity of GVHD without the disadvantages of T cell depletion.

A phase I/II study of sequential, dose-escalated, high dose ifosfamide plus doxorubicin with peripheral blood stem cell support for the treatment of patients with advanced soft tissue sarcomas.

BACKGROUND: This Phase I/II study investigates increasingly high doses of ifosfamide combined with full dose doxorubicin chemotherapy supported with peripheral blood stem cells (PBSC) and granulocyte-colony stimulating factor (G-CSF) in patients with metastatic soft tissue sarcoma (STS). METHODS: Patients with histologically proven metastatic or advanced adult STS without prior treatment received doxorubicin, 75 mg/m2, on Day 1 followed by 4-day continuous infusion of ifosfamide at 5 consecutive dose levels starting with 8 g/m2 and escalating to 16 g/m2 in increments of 2 g/m2. Three patients per dose level and a maximum of 5 treatment cycles per level at 3-week intervals were planned. Each cycle was followed by G-CSF and retransfusion of PBSC. PBSC separation was performed prior to chemotherapy by steady state mobilization with G-CSF. RESULTS: Eighteen patients (median age, 45 years, range, 25-57 years) were included, with 4, 3, 4, 4, and 3 patients assigned to Levels 1-5, respectively. Metastatic sites included the lungs in 12 patients (67%), lymph nodes in 8 patients (44%), and the liver in 5 patients (28%). Nine patients (50%) achieved objective responses with 4 complete responses (22%) and 5 partial responses (28%). Lung metastases and a histology of synovial sarcoma or malignant fibrous histiocytoma were favorable features for response to therapy. The median survival for all patients was 13+ months (range, 3-19+ months). Hematotoxicity was manageable and treatment could be administered at a median interval of 24 days. One case of World Health Organization Grade 3 neurotoxicity occurred. Nephrotoxicity was dose-limiting, with 1 patient in Level 4 (WHO Grade 2) and 2 patients in Level 5 (WHO Grade 3). CONCLUSIONS: Multiple cycles of dose-intensive therapy with doxorubicin and high dose ifosfamide can be administered safely with PBSC support. Nephrotoxicity is dose-limiting for ifosfamide at total doses of 16 g/m2. Multiple cycles of high dose chemotherapy at short treatment intervals using ifosfamide at a dose of 14 g/m2 should be investigated further in a neoadjuvant setting in patients with STS.

CD34 positive blood cells for allogeneic progenitor and stem cell transplantation.

The transplantation of allogeneic peripheral blood progenitor cells (PBPC) provides complete and sustained hematopoietic and lymphopoietic engraftment. In healthy donors, large amounts of PBPC can be mobilized with hematopoietic growth factors. However, the high content of immunocompetent T-cells in apheresis products may expose recipients of allogeneic PBPC to an elevated risk of acute and chronic graft-versus-host disease. Thus, the use of appropriate T-cell reduction, but not depletion might reduce this risk. The hazards of graft rejection and a higher relapse rate can be avoided by maintaining a portion of the T-cells in the graft. The positive selection of CD34+ cells from peripheral blood preparations simultaneously provides an approximately 1000-fold reduction of T-cells. These purified CD34+ cells containing committed and pluripotent stem cells are suitable for allogeneic transplantation and can be used in the following instances: 1. As hematopoietic stem and progenitor cell transplantation instead of bone marrow cells, from HLA-identical family donors; 2. for increasing the stem cell numbers from HLA-mismatched or three HLA-loci different family donors in order to reduce the incidence of rejection but without increasing the T-cell number; 3. boosting of poor marrow graft function with stem cells from the same family donors; 4. transplantation from volunteer matched unrelated donors; 5. split transplantation of CD34+ and T-cells; 6. addition of ex vivo expanded CD34+ cells to blood cell or bone marrow transplantation; 7. generation of antigen specific immune effector cells and antigen presenting cells for cell therapy.

Imprecision of counting CFU-GM colonies and CD34-expressing cells.

Determinations of committed haemopoietic progenitor cells, namely CFU-GM (colony-forming unit-granulocyte/macrophage) and of CD34-expression haemopoietic cells as assessed by multiparameter flow cytometry are routine diagnostic tools in haemopoietic cell therapy. Generally, the tests are used to optimise the timing and management of cytapheresis and to assess the engraftment potential of the harvested cells. Both measurements, however, are at best surrogate markers, as an adequate routine test which effectively assesses the short- and long-term repopulating haemopoietic cell is not available. Nonetheless, cell threshold doses have been established. Above these thresholds rapid engraftment is almost invariable but below these thresholds the outcome is variable. In this study we have focussed on the imprecision in counting haemopoietic cells, as assessed as CFU-GM and as CD34-expressing cells. The data on both tests have been analysed from six European institutions. The coefficient of variation in CFU-GM colony counting was about 30%, whereas the coefficient of variation in flow cytometric counting of CD34-expressing cells was about 10%. These data suggest that the technical imprecision in enumerating progenitor cells, particularly CFU-GM, at low levels, might make a major contribution to the clinical variability observed after transplantation of sub-threshold progenitor cell dose.

The human C3a receptor is expressed on neutrophils and monocytes, but not on B or T lymphocytes.

The pathophysiological relevance of the complement split product C3a as a proinflammatory mediator is still ill defined. The expression pattern of the human C3a receptor (C3aR) can provide important clues for the role of this anaphylatoxin in inflammation. There is strong evidence for C3aR expression on basophils, and eosinophils, but additionally, only on tumor cell lines of leukemic or hepatic origin. It is unclear whether neutrophils also express the C3aR, but need a costimulus provided by eosinophils for certain biological responses, or whether neutrophils lack the C3aR and respond to C3a via a secondary stimulus generated by eosinophils, i.e., by an indirect mode. In the present study, polyclonal antiserum raised against the second extracellular loop of the C3aR was used to characterize C3aR expression on peripheral blood leukocytes. For high degree purification of neutrophils, a negative selection method was established that decreased the contamination with CD9(bright+) eosinophils down to <0.2%. Flow cytometric analyses, functional assays, and binding assays on highly purified neutrophils confirmed C3aR expression and coupling. Monocytes were identified as an additional C3aR-positive cell population of the peripheral blood. The expression of the C3aR on eosinophils could be confirmed. In contrast, the receptor could not be detected on unchallenged B or T lymphocytes (or lymphocyte-derived Raji cells).

The C terminus of the human C5a receptor (CD88) is required for normal ligand-dependent receptor internalization.

The biological effects of the potent inflammatory mediator C5a, a complement split product, on human neutrophils and monocytes are limited by the rapid internalization of its specific receptor (C5aR, CD88). The C terminus of the C5aR is phosphorylated after stimulation with C5a of phorbol ester, and this phosphorylation might lead to receptor internalization. In this context, we have studied the effects on C5aR internalization of C5a, phorbol 12-myristate 13-acetate (PMA), the protein kinase inhibitor staurosporine, and pertussis toxin on rat basophilic RBL.2H3 cells stably transfected with the human wild-type or mutant C5aR. C5aR mutants lacked either part of the cytosolic C terminus, including suggested major phosphorylation sites, or a putative phosphorylation motif for protein kinase C in the third cytosolic loop. Additionally, agonist-induced internalization was analyzed on HEK293 cells co-transfected with C5aR and the pertussis toxin-resistant G protein alpha subunit, G alpha 16. Staurosporine-sensitive agonist-dependent C5aR internalization could be detected, suggesting that C5aR phosphorylation, most likely of the C terminus, participates in this type of internalization. In contrast, PMA-induced C5aR internalization seems to be independent of putative phosphorylation sites in either the truncated section of the C terminus or the third cytosolic loop. The phorbol ester-induced C5aR internalization may, therefore, be caused by an indirect and less specific effect of protein kinase C on the internalization machinery. Manipulation of the pertussis toxin-sensitive or -resistant G protein-dependent signal transduction had no effect on ligand-induced internalization.

Technical and safety aspects of blood and marrow transplantation using G-CSF mobilized family donors.

An allogeneic transplantation programme using immunoselected blood progenitor and bone marrow CD34+ cells has been established. Thirteen healthy HLA-matched, MLC negative sibling donors received two doses of 5 micrograms kg-1 G-CSF (s.c. daily) for 5 days. On days 4 and 5, large-volume mononuclear cell aphereses were performed (COBE Spectra) and on day 5 one unit of autologous blood was obtained. Mononuclear cells were pooled and cryopreserved after CD34+ cell-immunoselection on day 5. Bone marrow (BM) of the same donors was procured under routine conditions 10-45 days later (median: 27 days). The final graft consisted of blood CD34+ cells with either complete BM (n = 5) or immunoselected BM CD34+ cells (n = 8). The present paper describes the progenitor cell mobilization and apheresis protocol and analyzes the cell loss by BM and peripheral blood progenitor cell (PBPC) donation. Considerably larger amounts of mononuclear cells (CD45+), T-lymphocytes (CD3+) and platelets were lost by the apheresis as compared to bone marrow without apparent immediate clinical consequences for the donors. Owing to cross-cellular contamination of the apheresis concentrate, blood platelet count (PC) significantly decreased (mean PC after the second apheresis 116 x 10 microL-1); furthermore on average 3.04 x 10(10) CD3+ cells were removed by two apheresis sessions. This loss did not lead to long-term total lymphocyte count changes (2370 microL-1 versus 1889 microL-1) as observed during the long-term follow-up of 7/13 donors (mean 290 days). Subjectively, the PBPC collections were better accepted than BM donations in all but one family donor.

Flow cytometry evaluation of the in vitro influence of four i.v. anaesthetics on respiratory burst of neutrophils.

Exposure of neutrophils to anaesthetic agents may alter their functional characteristics and in patients undergoing long-term sedation this may be clinically relevant. We have investigated the in vitro influence of propofol, thiopentone, methohexitone and midazolam on phorbol 12-myristate 13-acetate (PMA)-induced respiratory burst of neutrophils by the intracellular oxidative transformation of dihydrorhodamine-123 to the fluorescent dye rhodamine-123 via flow cytometry. We tested in vitro concentrations similar to sedating, anaesthetic, 10-fold sedating and 10-fold anaesthetic plasma concentrations. All drugs showed similar inhibition of respiratory burst at sedating concentrations (1-6%). At anaesthetic concentrations, propofol produced significantly higher mean inhibition (7.3%) compared with thiopentone (4.5%) and methohexitone (0.9%). At 10-fold anaesthetic concentrations inhibition of respiratory burst by propofol was almost complete (90.8%) and significantly higher than that by thiopentone (29.2%) and methohexitone (1.8%). Methohexitone and midazolam had only minimal effects at all concentrations. The effect of the solvent of propofol (10% Intralipid) was similar to that of propofol. Thus suppression of respiratory burst of neutrophils by propofol may be caused by this lipid carrier.