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Silberstein, Lev

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Silberstein

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Silberstein, Lev
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    Differential Stem and Progenitor Cell Trafficking by Prostaglandin E2
    (2013) Hoggatt, Jonathan; Mohammad, Khalid S.; Singh, Pratibha; Hoggatt, Amber F.; Chitteti, Brahmananda Reddy; Speth, Jennifer M.; Hu, Peirong; Poteat, Bradley A.; Stilger, Kayla N.; Ferraro, Francesca; Silberstein, Lev; Wong, Frankie K.; Farag, Sherif S.; Czader, Magdalena; Milne, Ginger L.; Breyer, Richard M.; Serezani, Carlos H.; Scadden, David; Guise, Theresa; Srour, Edward F.; Pelus, Louis M.
    SUMMARY To maintain lifelong production of blood cells, hematopoietic stem cells (HSC) are tightly regulated by inherent programs and extrinsic regulatory signals received from their microenvironmental niche. Long-term repopulating HSC (LT-HSC) reside in several, perhaps overlapping, niches that produce regulatory molecules/signals necessary for homeostasis and increased output following stress/injury 1–5. Despite significant advances in specific cellular or molecular mechanisms governing HSC/niche interactions, little is understood about regulatory function within the intact mammalian hematopoietic niche. Recently, we and others described a positive regulatory role for Prostaglandin E2 (PGE2) on HSC function ex vivo 6,7. While exploring the role of endogenous PGE2 we unexpectedly observed hematopoietic egress after nonsteroidal anti-inflammatory drug (NSAID) treatment. Surprisingly, this was independent of the SDF-1/CXCR4 axis. Stem and progenitor cells were found to have differing mechanisms of egress, with HSC transit to the periphery dependent on niche attenuation and reduction in the retentive molecule osteopontin (OPN). Hematopoietic grafts mobilized with NSAIDs had superior repopulating ability and long-term engraftment. Treatment of non-human primates and healthy human volunteers confirmed NSAID-mediated egress in higher species. PGE2 receptor knockout mice demonstrated that progenitor expansion and stem/progenitor egress resulted from reduced EP4 receptor signaling. These results not only uncover unique regulatory roles for EP4 signaling in HSC retention in the niche but also define a rapidly translatable strategy to therapeutically enhance transplantation.
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    Bayesian approach to single-cell differential expression analysis
    (Springer Nature, 2014) Kharchenko, Peter; Silberstein, Lev; Scadden, David
    Single-cell data provide a means to dissect the composition of complex tissues and specialized cellular environments. However, the analysis of such measurements is complicated by high levels of technical noise and intrinsic biological variability. We describe a probabilistic model of expression-magnitude distortions typical of single-cell RNA-sequencing measurements, which enables detection of differential expression signatures and identification of subpopulations of cells in a way that is more tolerant of noise.
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    Image-guided transplantation of single cells in the bone marrow of live animals
    (Nature Publishing Group UK, 2017) Turcotte, Raphaël; Alt, Clemens; Runnels, Judith M.; Ito, Kyoko; Wu, Juwell; Zaher, Walid; Mortensen, Luke J.; Silberstein, Lev; Côté, Daniel C.; Kung, Andrew L.; Ito, Keisuke; Lin, Charles
    Transplantation of a single hematopoietic stem cell is an important method for its functional characterization, but the standard transplantation protocol relies on cell homing to the bone marrow after intravenous injection. Here, we present a method to transplant single cells directly into the bone marrow of live mice. We developed an optical platform that integrates a multiphoton microscope with a laser ablation unit for microsurgery and an optical tweezer for cell micromanipulation. These tools allow image-guided single cell transplantation with high spatial control. The platform was used to deliver single hematopoietic stem cells. The engraftment of transplants was tracked over time, illustrating that the technique can be useful for studying both normal and malignant stem cells in vivo.
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    Myocardial Infarction Activates CCR2+ Hematopoietic Stem and Progenitor Cells
    (Elsevier BV, 2015) Dutta, Partha; Sager, Hendrik B; Stengel, Kristy R.; Nahrendorf, Kamila; Courties, Gabriel; Saez, Borja; Silberstein, Lev; Heidt, Timo; Sebas, Matthew; Sun, Yuan; Wojtkiewicz, Gregory; Feruglio, Paolo Fumene; King, Kevin Robert; Baker, Joshua N.; van der Laan, Anja M.; Borodovsky, Anna; Fitzgerald, Kevin; Hulsmans, Maarten; Hoyer, Friedrich; Iwamoto, Yoshiko; Vinegoni, Claudio; Brown, Dennis; Di Carli, Marcelo; Libby, Peter; Hiebert, Scott W.; Scadden, David; Swirski, Filip; Weissleder, Ralph; Nahrendorf, Matthias
    Following myocardial infarction (MI), myeloid cells derived from the hematopoietic system drive a sharp increase in systemic leukocyte levels that correlates closely with mortality. The origin of these myeloid cells, and the response of hematopoietic stem and progenitor cells (HSPCs) to MI, however, is unclear. Here, we identify a CCR2+CD150+CD48− LSK hematopoietic subset as the most upstream contributor to emergency myelopoiesis after ischemic organ injury. This subset has 4-fold higher proliferation rates than CCR2−CD150+CD48− LSK cells, displays a myeloid differentiation bias, and dominates the migratory HSPC population. We further demonstrate that the myeloid translocation gene 16 (Mtg16) regulates CCR2+ HSPC emergence. Mtg16−/− mice have decreased levels of systemic monocytes and infarct-associated macrophages and display compromised tissue healing and post-MI heart failure. Together, these data provide insights into regulation of emergency hematopoiesis after ischemic injury and identify potential therapeutic targets to modulate leukocyte output after MI.