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Background: Human pluripotent stem cells (hPSCs) hold great promise for applications in regenerative medicine. However, the safety of cell therapy using differentiated hPSC derivatives must be improved through methods that will permit the transplantation of homogenous populations of a specific cell type. To date, purification of progenitors and mature cells generated from either embryonic or induced pluripotent stem cells remains challenging with use of conventional methods. Results: We used lentivectors encoding green fluorescent protein (GFP) driven by the liver-specific apoliprotein A-II (APOA-II) promoter to purify human hepatic progenitors. We evaluated both integrating and integration-defective lentivectors in combination with an HIV integrase inhibitor. A human embryonic stem cell line was differentiated into hepatic progenitors using a chemically defined protocol. Subsequently, cells were transduced and sorted at day 16 of differentiation to obtain a cell population enriched in hepatic progenitor cells. After sorting, more than 99% of these APOA-II-GFP-positive cells expressed hepatoblast markers such as α-fetoprotein and cytokeratin 19. When further cultured for 16 days, these cells underwent differentiation into more mature cells and exhibited hepatocyte properties such as albumin secretion. Moreover, they were devoid of vector DNA integration. Conclusions: We have developed an effective strategy to purify human hepatic cells from cultures of differentiating hPSCs, producing a novel tool that could be used not only for cell therapy but also for in vitro applications such as drug screening. The present strategy should also be suitable for the purification of a broad range of cell types derived from either pluripotent or adult stem cells. [ABSTRACT FROM AUTHOR]

The liver is associated with many diseases including metabolic and cholestatic diseases, cirrhosis as well as chronic and acute hepatitis. However, knowledge about the mechanisms involved in the pathophysiology of these diseases remains limited due to the restricted access to liver biopsies and the lack of cellular models derived from patients. The liver is the main organ responsible for the elimination of xenobiotics and thus hepatocytes have a key role in toxicology and pharmacokinetics. The induced pluripotent stem cells generated from patients with monogenic metabolic disorders, for which the corresponding gene is identified, are relevant in vitro models for the study of the mechanisms involved in generation of pathologies and also for drug screening. Towards this aim, robust protocols for generating liver cells, such as hepatocytes and cholangiocytes, are essential. Our study focused on familial hypercholesterolemia disease modeling, as well as on establishing a protocol for generation of functional cholangiocytes from pluripotent stem cells., (© Société de Biologie, 2016.)

Midkine (MDK) is a member of a new family of neurotrophic factors considered as rate-limiting growth and angiogenic factors implicated in the onset, invasion, and metastatic process of neuronal tumors, including neuroblastoma. We showed that all neuroblastoma cell lines highly expressed MDK, indicating that it is a critical player in tumor development, which may henceforth represent an attractive therapeutic target. We showed that the knockdown of MDK expression by siRNA led to a marked and significant decrease in neuroblastoma (IGR-N91 and SH-SY5Y) cell proliferation in vitro. Using a new strategy, we then evaluated the antitumor effect of a truncated MDK protein, lacking the C-terminal 81-121 portion of the molecule (MDKΔ81-121), which may act as a dominant-negative effector for its mitogenic, angiogenic, and tumorigenic activities by heterodimerizing with the wild-type protein. In vitro studies showed that MDKΔ81-121 selectively inhibited MDK-dependent tumor cells and was able to strongly reduce endothelial cell proliferation and migration and to induce ER stress-mediated apoptosis. We then investigated the effects of MDKΔ81-121 in vivo using electrotransfer of a plasmid encoding a secretable form of MDKΔ81-121 into tibialis cranialis muscles of nude mice. We showed that MDKΔ81-121 dramatically inhibited (up to 91%) tumor development and growth. This inhibition was correlated with the detection of the MDKΔ81-121 molecule in plasma and the suppression of intratumor neovascularization. Our findings demonstrate that MDK inhibition is a tractable therapeutic target for this lethal pediatric malignancy., (©2014 American Association for Cancer Research.)