Cell engraftment, survival and integration during transplantation procedures represent the crux of cell-based therapies. Thus, there have been many studies focused on improving cell viability upon implantation. We used severe oxidative stress to select for a mouse mesoangioblast subpopulation in vitro and found that this subpopulation retained self-renewal and myogenic differentiation capacities while notably enhancing cell survival, proliferation and migration relative to unselected cells. Additionally, this subpopulation of cells presented different resistance and recovery properties upon oxidative stress treatment, demonstrating select advantages over parental mesoangioblasts in our experimental analysis. Specifically, the cells were resistant to oxidative environments, demonstrating survival, continuous self-renewal and improved migration capability. The primary outcome of the selected cells was determined in in vivo experiments in which immunocompromised dystrophic mice were injected intramuscularly in the tibialis anterior with selected or non-selected mesoangioblasts. Resistant mesoangioblasts exhibited markedly enhanced survival and integration into the host skeletal muscle, accounting for a more than 70% increase in engraftment compared with that of the unselected mesoangioblast cell population and leading to remarkable muscle recovery. Thus, the positive effects of sorting on mesoangioblast cell behaviour in vitro and in vivo suggest that a selection step involving oxidative stress preconditioning may provide a novel methodology to select for resistant cells for use in regenerative tissue applications to prevent high mortality rates upon transplantation.

The Myc promoter-binding protein-1 (MBP-

See Covering the Cover synopsis on page 862. BACKGROUND & AIMS:Pancreatic ductal adenocarcinoma (PDA) is an aggressive tumor, and patients typically present with late-stage disease; rates of 5-year survival after pancreaticoduodenectomy are low. Antibodies against ␣-enolase (ENO1), a glycolytic enzyme, are detected in more than 60% of patients with PDA, and ENO1-specific T cells inhibit the growth of human pancreatic xenograft tumors in mice. We investigated whether an ENO1 DNA vaccine elicits antitumor immune responses and prolongs survival of mice that spontaneously develop autochthonous, lethal pancreatic carcinomas. METHODS:We injected and electroporated a plasmid encoding ENO1 (or a control plasmid) into Kras G12D /Cre (KC) mice and Kras G12D /Trp53 R172H /Cre (KPC) mice at 4 weeks of age (when pancreatic intraepithelial lesions are histologically evident). Antitumor humoral and cellular responses were analyzed by histology, immunohistochemistry, enzyme-linked immunosorbent assays, flow cytometry, and enzyme-linked immunosorbent spot and cytotoxicity assays. Survival was analyzed by Kaplan-Meier analysis. RESULTS: The ENO1 vaccine induced antibody and a cellular response and increased survival times by a median of 138 days in KC mice and 42 days in KPC mice compared with mice given the control vector. On histologic analysis, the vaccine appeared to slow tumor progression. The vaccinated mice had increased serum levels of anti-ENO1 immunoglobulin G, which bound the surface of carcinoma cells and induced complement-dependent cytotoxicity. ENO1 vaccination reduced numbers of myeloid-derived suppressor cells and T-regulatory cells and increased T-helper 1 and 17 responses. CONCLU-SIONS: In a genetic model of pancreatic carcinoma, vaccination with ENO1 DNA elicits humoral and cellular immune responses against tumors, delays tumor progression, and significantly extends survival. This vaccination strategy might be developed as a neoadjuvant therapy for patients with PDA.

The human PVT-1 gene is located on chromosome 8 telomeric to the c-Myc gene and it is frequently involved in the translocations occurring in variant Burkitt's lymphomas and murine plasmacytomas. It has been proposed that PVT-1 regulates c-Myc gene transcription over a long distance. To get new insights into the functional relationships between the two genes, we have investigated PVT-1 and c-Myc expression in normal human tissues and in transformed cells. Our findings indicate that PVT-1 expression is restricted to a relative low number of normal tissues compared to the wide distribution of c-Myc mRNA, whereas the gene is highly expressed in many transformed cell types including neuroblastoma cells that do not express c-Myc. Reporter gene assays were used to dissect the PVT-1 promoter and to identify the region responsible for the elevated expression observed in transformed cells. This region contains two putative binding sites for Myc proteins. The results of transfection experiments in RAT1-MycER cells and chromatin immunoprecipitation (ChIP) assays in proliferating and differentiated neuroblastoma cells indicate that PVT-1 is a downstream target of Myc proteins.