Digital platform openness: Drivers, dimensions and outcomes

This multi-method study aims to shed light on digital platforms' decisions regarding their openness. Platform openness results from a series of decisions on how open a platform is regarding: (a) suppliers, (b) customers, (c) complementary service providers, as well as to (d) product categories and (e) channels. By conducting a scoping literature review, we analyze the current body of knowledge about the drivers, dimensions and outcomes of platform openness. Using an expert panel discussion and analysis of real-world digital platforms, we confront this existing knowledge with current business challenges to identify research challenges. We address how future research can advance platform research by tackling these challenges

Inhibition of glycolysis modulates prednisolone resistance in acute lymphoblastic leukemia cells

Treatment failure in pediatric acute lymphoblastic leukemia (ALL) is related to cellular resistance to glucocorticoids (eg, prednisolone). Recently, we demonstrated that genes associated with glucose metabolism are differentially expressed between prednisolone-sensitive and prednisolone-resistant precursor B-lineage leukemic patients. Here, we show that prednisolone resistance is associated with increased glucose consumption and that inhibition of glycolysis sensitizes prednisolone-resistant ALL cell lines to glucocorticoids. Treatment of prednisolone-resistant Jurkat and Molt4 cells with 2-deoxy-D-glucose (2-DG), lonidamine (LND), or3-bromopyruvate (3-BrPA) increased the in vitro sensitivity to glucocorticoids, while treatment of the prednisolone-sensitive cell lines Tom-1 and RS4; 11 did not influence drug cyto-toxicity. This sensitizing effect of the glycolysis inhibitors in glucocorticoid-resistant ALL cells was not found for other classes of antileukemic drugs (ie, vincris-tine and daunorubicin). Moreover, down-regulation of the expression of GAPDH by RNA interference also sensitized to prednisolone, comparable with treatment with glycolytic inhibitors. Importantly, the ability of 2-DG to reverse glucocorticoid resistance was not limited to cell lines, but was also observed in isolated primary ALL cells from patients. Together, these findings indicate the importance of the glycolytic pathway in glucocorticoid resistance in ALL and suggest that targeting glycolysis is a viable strategy for modulating prednisolone resistance in ALL

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Clonal analysis is important for many areas of hematopoietic stem cell research, including in vitro cell expansion, gene therapy, and cancer progression and treatment. A common approach to measure clonality of retrovirally transduced cells is to perform integration site analysis using Southern blotting or polymerase chain reaction-based methods. Although these methods are useful in principle, they generally provide a lowresolution, biased, and incomplete assessment of clonality. To overcome those limitations, we labeled retroviral vectors with random sequence tags or "barcodes." On integration, each vector introduces a unique, identifiable, and heritable mark into the host cell genome, allowing the clonal progeny of each cell to be tracked over time. By coupling the barcoding method to a sequencing-based detection system, we could identify major and minor clones in 2 distinct cell culture systems in vitro and in a long-term transplantation setting. In addition, we demonstrate how clonal analysis can be complemented with transgene expression and integration site analysis. This cellular barcoding tool permits a simple, sensitive assessment of clonality and holds great promise for future gene therapy protocols in humans, and any other applications when clonal tracking is important. (Blood. 2010;115(13):2610-2618

The H3.3K27M oncohistone affects replication stress outcome and provokes genomic instability in pediatric glioma

While comprehensive molecular profiling of histone H3.3 mutant pediatric high-grade glioma has revealed extensive dysregulation of the chromatin landscape, the exact mechanisms driving tumor formation remain poorly understood. Since H3.3 mutant gliomas also exhibit high levels of copy number alterations, we set out to address if the H3.3K27M oncohistone leads to destabilization of the genome. Hereto, we established a cell culture model allowing inducible H3.3K27M expression and observed an increase in mitotic abnormalities. We also found enhanced interaction of DNA replication factors with H3.3K27M during mitosis, indicating replication defects. Further functional analyses revealed increased genomic instability upon replication stress, as represented by mitotic bulky and ultrafine DNA bridges. This co-occurred with suboptimal 53BP1 nuclear body formation after mitosis in vitro, and in human glioma. Finally, we observed a decrease in ultrafine DNA bridges following deletion of the K27M mutant H3F3A allele in primary high-grade glioma cells. Together, our data uncover a role for H3.3 in DNA replication under stress conditions that is altered by the K27M mutation, promoting genomic instability and potentially glioma development

Asymmetry in skeletal distribution of mouse hematopoietic stem cell clones and their equilibration by mobilizing cytokines

Hematopoietic stem cells (HSCs) are able to migrate through the blood stream and engraft bone marrow (BM) niches. These features are key factors for successful stem cell transplantations that are used in cancer patients and in gene therapy protocols. It is unknown to what extent transplanted HSCs distribute throughout different anatomical niches in the BM and whether this changes with age. Here we determine the degree of hematopoietic migration at a clonal level by transplanting individual young and aged mouse HSCs labeled with barcoded viral vector, followed by assessing the skeletal distribution of hundreds of HSC clones. We detected highly skewed representation of individual clones in different bones at least 11 mo after transplantation. Importantly, a single challenge with the clinically relevant mobilizing agent granulocyte colony-stimulating factor (G-CSF) caused rapid redistribution of HSCs across the skeletal compartments. Old and young HSC clones showed a similar level of migratory behavior. Clonal make- up of blood of secondary recipients recapitulates the barcode composition of HSCs in the bone of origin. These data demonstrate a previously unanticipated high skeletal disequilibrium of the clonal composition of HSC pool long- term after transplantation. Our findings have important implications for experimental and clinical and stem cell transplantation protocols

Heterogeneity of young and aged murine hematopoietic stem cells revealed by quantitative clonal analysis using cellular barcoding

<p>The number of hematopoietic stem cells (HSCs) that contributes to blood formation and the dynamics of their clonal contribution is a matter of ongoing discussion. Here, we use cellular barcoding combined with multiplex high-throughput sequencing to provide a quantitative and sensitive analysis of clonal behavior of hundreds of young and old HSCs. The majority of transplanted clones steadily contributes to hematopoiesis in the long-term, although clonal output in granulocytes, T cells, and B cells is substantially different. Contributions of individual clones to blood are dynamically changing; most of the clones either expand or decline with time. Finally, we demonstrate that the pool of old HSCs is composed of multiple small clones, whereas the young HSC pool is dominated by fewer, but larger, clones.</p>