Modell Reha-Management der Bau-Berufsgenossenschaft Hannover

Trauma und Berufskrankheit - Störungen und Komplikationen im Heilverfahren können auch durch nichtmedizinische Faktoren beeinflusst werden. Reha-Management ist ein Konzept, welches zu...     

Efficient depletion of alloreactive donor T lymphocytes based on expression of two activation-induced antigens (CD25 and CD69)

T lymphocytes play an important role in allogeneic bone marrow/stem cell transplantation by supporting engraftment and immune recovery. Moreover, donor T cells have been shown to mediate the so-called graft-versus-leukaemia effect and are, therefore, increasingly used for adoptive immunotherapy. However, T-cell infusions are associated with the risk of a graft-versus-host reaction, which may lead to a life-threatening disease. To overcome this problem, we followed a new strategy for the exclusive depletion of alloreactive cells. We activated allogeneic T cells by cultivation on an adherent cell layer derived from peripheral blood. We then depleted activated cells based on the expression of CD25, CD69 or both activation-induced antigens using magnetic cell sorting. Mixed lymphocyte culture (MLC) reactions and helper T-lymphocyte precursor cell frequency (HTLP-f) assays demonstrated that this technique led to a significant decrease in alloreactivity of 'donor' cells, which at the same time preserved reactivity against third-party cells. The lowest level of alloreactivity was found when CD25 and CD69 antibodies were used together for depletion. This corresponds with our observation that expression of CD25 or CD69 may partially represent different activation pathways. We conclude that ex vivo depletion of CD25- and CD69-expressing alloreactive cells may help to overcome limitations of adoptive immunotherapy.     

Unrelated stem cell transplantation in multiple myeloma after a reduced-intensity conditioning with pretransplantation antithymocyte globulin is highly effective with low transplantation-related mortality

We investigated the feasibility of unrelated stem cell transplantation in 21 patients with advanced stage II/III multiple myeloma after a reduced-intensity conditioning regimen consisting of fludarabine (150 mg/m(2)), melphalan (100-140 mg/m(2)), and antithymocyte globulin (ATG; 10 mg/kg on 3 days). The median patient age was 50 years (range, 32-61 years). All patients had received at least one prior autologous transplantation, in 9 cases as part of an autologous-allogeneic tandem protocol. No graft failure was observed. At day 40 complete donor chimerism was detected in all patients. Grade II to IV acute graft-versus-host disease (GVHD) was seen in 8 patients (38%), and severe grade III/IV GVHD was observed in 4 patients (19%). Six patients (37%) developed chronic GVHD, but only 2 patients (12%) experienced extensive chronic GVHD. The estimated probability of nonrelapse mortality at day 100 was 10% and at 1 year was 26%. After allografting, 40% of the patients achieved a complete remission, and 50% achieved a partial remission, resulting in an overall response rate of 90%. After a median follow-up of 13 months, the 2-year estimated overall and progression-free survival rates are 74% (95% CI, 54%-94%) and 53% (95% CI, 29%-87%), respectively. A shorter progression-free survival was seen in patients who already experienced relapse to prior autograft (26% versus 86%, P =.04). Dose-reduced conditioning with pretransplantation ATG followed by unrelated stem cell transplantation provides durable engraftment and donor chimerism, reduces substantially the risk of transplant-related organ toxicity, and induces high remission rates.     

Amphotropic and VSV-G-pseudotyped retroviral vectors transduce human hematopoietic progenitor cells with similar efficiency

One restriction of retroviral gene transfer into hematopoietic stem cells is the low level of amphotropic virus receptor. In the present study, we examined whether retroviral vectors pseudotyped with the G-protein of vesicular stomatitis virus (VSV) can overcome this restriction. Human progenitor cells purified by magnetic beads and cell sorting were transduced with an amphotropic or VSV-G-pseudotyped retroviral vector containing the truncated human nerve growth factor receptor as a marker gene. Cells were prestimulated with flt-3 ligand, stem cell factor, and interleukin-3 and transduced on fibronectin. Marker gene expression was analyzed by flow cytometry. Transduction efficiencies of amphotropic and VSV-G-pseudotyped virus for CD34+ cells did not differ significantly. Gene transfer into CD34+CD38- cells, which are enriched in more immature progenitors, was not restricted and transfer efficiencies for this subset were also similar for both pseudotypes. The addition of fibronectin improved gene transfer with the amphotropic vector considerably (5- to 19.3-fold, mean 12.6), while the effect on the VSV-G-pseudotype was far less pronounced (1- to 3.9-fold, mean 2.1, P = 0.04). In conclusion, high levels of gene transfer to human hematopoietic progenitors were achieved with an optimized transduction protocol, and transduction efficiencies could not be improved further by the use of VSV-G-pseudotypes.     

Side effects of retroviral gene transfer into hematopoietic stem cells

Recent conceptual and technical improvements have resulted in clinically meaningful levels of gene transfer into repopulating hematopoietic stem cells. At the same time, evidence is accumulating that gene therapy may induce several kinds of unexpected side effects, based on preclinical and clinical data. To assess the therapeutic potential of genetic interventions in hematopoietic cells, it will be important to derive a classification of side effects, to obtain insights into their underlying mechanisms, and to use rigorous statistical approaches in comparing data. We here review side effects related to target cell manipulation; vector production; transgene insertion and expression; selection procedures for transgenic cells; and immune surveillance. We also address some inherent differences between hematopoiesis in the most commonly used animal model, the laboratory mouse, and in humans. It is our intention to emphasize the need for a critical and hypothesis-driven analysis of "transgene toxicology," in order to improve safety, efficiency, and prognosis for the yet small but expanding group of patients that could benefit from gene therapy.     

Mutagenesis by retroviral transgene insertion: risk assessment and potential alternatives

Focus on retroviral gene transfer into hematopoietic cells has previously led to a proposed classification of side effects and discussion of issues related to combinatorial toxicity (including oncogenicity) of genetic interventions. Recent data underline that this discussion has to be broadened to any type of stable transfer technology. This review summarizes insights obtained in cell culture and animal models that were specifically designed to evaluate side effects of transgene insertion and new approaches of insertion site targeting. Ongoing research aims to reduce side effects of therapeutic transgene insertion by dose optimization and definition of contributing risk factors.     

A novel 'sort-suicide' fusion gene vector for T cell manipulation

Retroviral suicide gene vectors have successfully been used in clinical studies to improve the safety of adoptive immunotherapy with allogeneic T lymphocytes in the treatment of malignant and viral diseases. At the same time these studies have revealed several problems that are yet to be resolved including impaired T cell function due to long ex vivo culture. Here we present new retroviral vectors co-expressing truncated CD34, a gene transfer marker which ensures rapid enrichment of transduced cells using commercially available GMP-approved devices, and a splice-corrected variant of Herpes simplex virus thymidine kinase (scHSVtk) which confers high sensitivity to the prodrug ganciclovir. We show that a retroviral hybrid vector, MP71, based on the myeloproliferative sarcoma virus (MPSV) and the murine embryonic stem cell virus (MESV), encoding a tCD34/scHSVtk fusion protein mediates high expression of the 'sort-suicide' selection marker, thereby allowing for highly efficient purification and selective elimination of transduced cells.