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Gene therapy is a promising therapeutic approach to treat primary immunodeficiencies. Indeed, the clinical trial for the Wiskott–Aldrich Syndrome (WAS) that is currently ongoing at the Hannover Medical School (Germany) has recently reported the correction of all affected cell lineages of the hematopoietic system in the first treated patients. However, an extensive study of the clonal inventory of those patients reveals that LMO2, CCND2 and MDS1/EVI1 were preferentially prevalent. Moreover, a first leukemia case was observed in this study, thus reinforcing the need of developing safer vectors for gene transfer into HSC in general. Here we present a novel self-inactivating (SIN) vector for the gene therapy of WAS that combines improved safety features. We used the elongation factor 1 alpha (EFS) promoter, which has been extensively evaluated in terms of safety profile, to drive a codon-optimized human WASP cDNA. To test vector performance in a more clinically relevant setting, we transduced murine HSPC as well as human CD34+ cells and also analyzed vector efficacy in their differentiated myeloid progeny. Our results show that our novel vector generates comparable WAS protein levels and is as effective as the clinically used LTR-driven vector. Therefore, the described SIN vectors appear to be good candidates for potential use in a safer new gene therapy protocol for WAS, with decreased risk of insertional mutagenesis. Fil: Avedillo Diez, Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas; Argentina. Hannover Medical School; Alemania Fil: Zychlinski, Daniela. Hannover Medical School; Alemania Fil: Coci, Emanuele G.. Hannover Medical School; Alemania Fil: Galla, Melanie. Hannover Medical School; Alemania Fil: Modlich, Ute. Hannover Medical School; Alemania Fil: Dewey, Ricardo. Hannover Medical School; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas; Argentina Fil: Schwarzer, Adrian. Hannover Medical School; Alemania Fil: Maetzig, Tobias. Hannover Medical School; Alemania Fil: Mpofu, Nonsikelelo. Hannover Medical School; Alemania Fil: Jaeckel, Elmar. Hannover Medical School; Alemania Fil: Boztug, Kaan. Hannover Medical School; Alemania Fil: Baum, Christopher. Hannover Medical School; Alemania Fil: Klein, Christoph. Hannover Medical School; Alemania Fil: Schambach, Axel. Hannover Medical School; Alemania

The absorption of nutrients in the small intestine and the control of blood glucose levels are crucial to ensure energy homeostasis of the organism. These functions can be severely impaired by diseases like type I diabetes, short bowel syndrome, and inflammatory bowel disease, for which the standard treatment involves either life-long replacement, immunosuppression, or transplantation, and is often not satisfactory. After outlining the diseases and established as well as experimental approaches, this chapter summarizes recent preclinical and clinical studies on novel therapeutic options relating to regenerative medicine, including growth factors and stem cells.

Using variants of the murine BW5147 lymphoma cell-line, we have previously identified 3 monoclonal antibodies (MAbs) that discriminate between metastatic and nonmetastatic BW5147-derived T-cell hybridomas and lymphomas, as well as BW5147-unrelated T-lymphomas. These MAbs were reported to recognize an identical membrane-associated sialoglycoprotein, termed "metastatic T-cell hybridoma antigen" (MTH-Ag). Here, we document that the expression pattern of the MTH-Ag on metastatic and nonmetastatic BW5147 variants correlates with that of the P-selectin glycoprotein ligand 1 (PSGL-1), a sialomucin involved in leukocyte recruitment to sites of inflammation. Moreover, the MAbs against the MTH-Ag recognize PSGL-1 when it is transfected in MTH-Ag-negative BW5147 variants, suggesting that the MTH-Ag is PSGL-1. Overexpression of MTH-Ag/PSGL-1 in MTH-Ag-negative BW5147 variants did not affect their in vivo malignancy. Yet, down-regulation of MTH-Ag/PSGL-1 expression on metastatic, MTH-Ag-positive BW5147 variants, using an RNA interference (RNAi) approach, resulted, in a dose-dependent manner, in a significant reduction of liver and spleen colonization and a delay in mortality of the recipient mice upon intravenous inoculation. Collectively, these results demonstrate that, although MTH-Ag/PSGL-1 overexpression alone may not be sufficient for successful dissemination and organ colonization, MTH-Ag/PSGL-1 plays a critical role in hematogenous metastasis of lymphoid cancer cells.

Regulatory CD4+CD25+Foxp3+ T cells (Tregs) play an important role in the induction of allospecific tolerance. However tolerance in solid organ transplantation by mere transfer of Tregs has been difficult. Besides this the stability of the differentiation phenotype of Tregs has recently been questioned. We therefore aimed in generating large numbers of stable allospecific Tregs from naive T cells by retroviral transduction with Foxp3. These were tested in an immunogenic skin transplantation model (C57BL/6BALB/c). We established a system of transduction of mouse T cells with ecotropic retroviruses expressing Foxp3 and Thy1.1 as a surface marker to follow up transduced T cells. Alloantigen-specific Tregs were generated by stimulating naive recipient CD4+ T cells with irradiated donor splenocytes. CD25+ and/or CD69+ allospecific recipient CD4+ T cells were isolated and transduced with Foxp3. Alloantigen-specific Foxp3 T cells (iTregs) showed high expression for the Treg markers Foxp3, CTLA4 and GITR. They could suppress a MLR in an alloantigen-specific manner. Furthermore, they could be expanded up to 18 fold in vitro while maintaining their Treg phenotype and expression of lymph node homing markers like CCR7 and CD62L. iTregs prevented skin graft rejection without the need for chronic immunosuppression and recipients showed systemic allospecific allotolerance. Alloantigen-specific Tregs were far more potent than polyspecific Tregs. Mechanisms of tolerance were graft specific homing, expansion and long-term persistence of Tregs within the graft (>100 days, 90% of intragraft Tregs were alloantigen-specific). In fact, tolerance could be transferred with re-transplantation of the tolerant graft onto secondary recipients. Third party grafts were readily rejected demonstrating specificity of tolerance. Due to the Foxp3 transduction, iTregs did not lose their Treg phenotype. The results prove that large numbers of stable alloantigen-specific Tregs can be generated from a polyclonal repertoire of naive T cells. This is the first time that allotolerance was achieved in a non-lymphopenic transplant model using skin grafts in an immunogenic strain combination. Therefore, antigen-specific Tregs might have a huge therapeutic potential after solid organ transplantation.