Human satellite cells have regenerative capacity and are genetically manipulable

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Abstract

Muscle satellite cells promote regeneration and could potentially improve gene delivery for treating muscular dystrophies. Human satellite cells are scarce; therefore, clinical investigation has been limited. We obtained muscle fiber fragments from skeletal muscle biopsy specimens from adult donors aged 20 to 80 years. Fiber fragments were manually dissected, cultured, and evaluated for expression of myogenesis regulator PAX7. PAX7⁺ satellite cells were activated and proliferated efficiently in culture. Independent of donor age, as few as 2 to 4 PAX7⁺ satellite cells gave rise to several thousand myoblasts. Transplantation of human muscle fiber fragments into irradiated muscle of immunodeficient mice resulted in robust engraftment, muscle regeneration, and proper homing of human PAX7⁺ satellite cells to the stem cell niche. Further, we determined that subjecting the human muscle fiber fragments to hypothermic treatment successfully enriches the cultures for PAX7⁺ cells and improves the efficacy of the transplantation and muscle regeneration. Finally, we successfully altered gene expression in cultured human PAX7⁺ satellite cells with Sleeping Beauty transposon–mediated nonviral gene transfer, highlighting the potential of this system for use in gene therapy. Together, these results demonstrate the ability to culture and manipulate a rare population of human tissue-specific stem cells and suggest that these PAX7⁺ satellite cells have potential to restore gene function in muscular dystrophies.

Authors

Andreas Marg, Helena Escobar, Sina Gloy, Markus Kufeld, Joseph Zacher, Andreas Spuler, Carmen Birchmeier, Zsuzsanna Izsvák, Simone Spuler

Development and translational imaging of a TP53 porcine tumorigenesis model

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Abstract

Cancer is the second deadliest disease in the United States, necessitating improvements in tumor diagnosis and treatment. Current model systems of cancer are informative, but translating promising imaging approaches and therapies to clinical practice has been challenging. In particular, the lack of a large-animal model that accurately mimics human cancer has been a major barrier to the development of effective diagnostic tools along with surgical and therapeutic interventions. Here, we developed a genetically modified porcine model of cancer in which animals express a mutation in TP53 (which encodes p53) that is orthologous to one commonly found in humans (R175H in people, R167H in pigs). TP53^R167H/R167H mutant pigs primarily developed lymphomas and osteogenic tumors, recapitulating the tumor types observed in mice and humans expressing orthologous TP53 mutant alleles. CT and MRI imaging data effectively detected developing tumors, which were validated by histopathological evaluation after necropsy. Molecular genetic analyses confirmed that these animals expressed the R167H mutant p53, and evaluation of tumors revealed characteristic chromosomal instability. Together, these results demonstrated that TP53^R167H/R167H pigs represent a large-animal tumor model that replicates the human condition. Our data further suggest that this model will be uniquely suited for developing clinically relevant, noninvasive imaging approaches to facilitate earlier detection, diagnosis, and treatment of human cancers.

Authors

Jessica C. Sieren, David K. Meyerholz, Xiao-Jun Wang, Bryan T. Davis, John D. Newell Jr., Emily Hammond, Judy A. Rohret, Frank A. Rohret, Jason T. Struzynski, J. Adam Goeken, Paul W. Naumann, Mariah R. Leidinger, Agshin Taghiyev, Richard Van Rheeden, Jussara Hagen, Benjamin W. Darbro, Dawn E. Quelle, Christopher S. Rogers

Incorporation of therapeutically modified bacteria into gut microbiota inhibits obesity

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Abstract

Metabolic disorders, including obesity, diabetes, and cardiovascular disease, are widespread in Westernized nations. Gut microbiota composition is a contributing factor to the susceptibility of an individual to the development of these disorders; therefore, altering a person’s microbiota may ameliorate disease. One potential microbiome-altering strategy is the incorporation of modified bacteria that express therapeutic factors into the gut microbiota. For example, N-acylphosphatidylethanolamines (NAPEs) are precursors to the N-acylethanolamide (NAE) family of lipids, which are synthesized in the small intestine in response to feeding and reduce food intake and obesity. Here, we demonstrated that administration of engineered NAPE-expressing E. coli Nissle 1917 bacteria in drinking water for 8 weeks reduced the levels of obesity in mice fed a high-fat diet. Mice that received modified bacteria had dramatically lower food intake, adiposity, insulin resistance, and hepatosteatosis compared with mice receiving standard water or control bacteria. The protective effects conferred by NAPE-expressing bacteria persisted for at least 4 weeks after their removal from the drinking water. Moreover, administration of NAPE-expressing bacteria to TallyHo mice, a polygenic mouse model of obesity, inhibited weight gain. Our results demonstrate that incorporation of appropriately modified bacteria into the gut microbiota has potential as an effective strategy to inhibit the development of metabolic disorders.

Authors

Zhongyi Chen, Lilu Guo, Yongqin Zhang, Rosemary L. Walzem, Julie S. Pendergast, Richard L. Printz, Lindsey C. Morris, Elena Matafonova, Xavier Stien, Li Kang, Denis Coulon, Owen P. McGuinness, Kevin D. Niswender, Sean S. Davies

CTLA4 aptamer delivers STAT3 siRNA to tumor-associated and malignant T cells

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Abstract

Intracellular therapeutic targets that define tumor immunosuppression in both tumor cells and T cells remain intractable. Here, we have shown that administration of a covalently linked siRNA to an aptamer (apt) that selectively binds cytotoxic T lymphocyte–associated antigen 4 (CTLA4^apt) allows gene silencing in exhausted CD8⁺ T cells and Tregs in tumors as well as CTLA4-expressing malignant T cells. CTLA4 expression was upregulated in CD8⁺ T cells in the tumor milieu; therefore, CTLA4^apt fused to a STAT3-targeting siRNA (CTLA4^apt–STAT3 siRNA) resulted in internalization into tumor-associated CD8⁺ T cells and silencing of STAT3, which activated tumor antigen–specific T cells in murine models. Both local and systemic administration of CTLA4^apt–STAT3 siRNA dramatically reduced tumor-associated Tregs. Furthermore, CTLA4^apt–STAT3 siRNA potently inhibited tumor growth and metastasis in various mouse tumor models. Importantly, CTLA4 expression is observed in T cells of patients with blood malignancies, and CTLA4^apt–STAT3 siRNA treatment of immunodeficient mice bearing human T cell lymphomas promoted tumor cell apoptosis and tumor growth inhibition. These data demonstrate that a CTLA4^apt-based siRNA delivery strategy allows gene silencing in both tumor-associated T cells and tumor cells and inhibits tumor growth and metastasis.

Authors

Andreas Herrmann, Saul J. Priceman, Maciej Kujawski, Hong Xin, Gregory A. Cherryholmes, Wang Zhang, Chunyan Zhang, Christoph Lahtz, Claudia Kowolik, Steve J. Forman, Marcin Kortylewski, Hua Yu

Epigenetic reprogramming induces the expansion of cord blood stem cells

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Abstract

Cord blood (CB) cells that express CD34 have extensive hematopoietic capacity and rapidly divide ex vivo in the presence of cytokine combinations; however, many of these CB CD34⁺ cells lose their marrow-repopulating potential. To overcome this decline in function, we treated dividing CB CD34⁺ cells ex vivo with several histone deacetylase inhibitors (HDACIs). Treatment of CB CD34⁺ cells with the most active HDACI, valproic acid (VPA), following an initial 16-hour cytokine priming, increased the number of multipotent cells (CD34⁺CD90⁺) generated; however, the degree of expansion was substantially greater in the presence of both VPA and cytokines for a full 7 days. Treated CD34⁺ cells were characterized based on the upregulation of pluripotency genes, increased aldehyde dehydrogenase activity, and enhanced expression of CD90, c-Kit (CD117), integrin α6 (CD49f), and CXCR4 (CD184). Furthermore, siRNA-mediated inhibition of pluripotency gene expression reduced the generation of CD34⁺CD90⁺ cells by 89%. Compared with CB CD34⁺ cells, VPA-treated CD34⁺ cells produced a greater number of SCID-repopulating cells and established multilineage hematopoiesis in primary and secondary immune–deficient recipient mice. These data indicate that dividing CB CD34⁺ cells can be epigenetically reprogrammed by treatment with VPA so as to generate greater numbers of functional CB stem cells for use as transplantation grafts.

Authors

Pratima Chaurasia, David C. Gajzer, Christoph Schaniel, Sunita D’Souza, Ronald Hoffman

Intravital imaging of podocyte calcium in glomerular injury and disease

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Abstract

Intracellular calcium ([Ca²⁺]_i) signaling mediates physiological and pathological processes in multiple organs, including the renal podocyte; however, in vivo podocyte [Ca²⁺]_i dynamics are not fully understood. Here we developed an imaging approach that uses multiphoton microscopy (MPM) to directly visualize podocyte [Ca²⁺]_i dynamics within the intact kidneys of live mice expressing a fluorescent calcium indicator only in these cells. [Ca²⁺]_i was at a low steady-state level in control podocytes, while Ang II infusion caused a minor elevation. Experimental focal podocyte injury triggered a robust and sustained elevation of podocyte [Ca²⁺]_i around the injury site and promoted cell-to-cell propagating podocyte [Ca²⁺]_i waves along capillary loops. [Ca²⁺]_i wave propagation was ameliorated by inhibitors of purinergic [Ca²⁺]_i signaling as well as in animals lacking the P2Y2 purinergic receptor. Increased podocyte [Ca²⁺]_i resulted in contraction of the glomerular tuft and increased capillary albumin permeability. In preclinical models of renal fibrosis and glomerulosclerosis, high podocyte [Ca²⁺]_i correlated with increased cell motility. Our findings provide a visual demonstration of the in vivo importance of podocyte [Ca²⁺]_i in glomerular pathology and suggest that purinergic [Ca²⁺]_i signaling is a robust and key pathogenic mechanism in podocyte injury. This in vivo imaging approach will allow future detailed investigation of the molecular and cellular mechanisms of glomerular disease in the intact living kidney.

Authors

James L. Burford, Karie Villanueva, Lisa Lam, Anne Riquier-Brison, Matthias J. Hackl, Jeffrey Pippin, Stuart J. Shankland, János Peti-Peterdi

Development of a conditionally immortalized human pancreatic β cell line

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Abstract

Diabetic patients exhibit a reduction in β cells, which secrete insulin to help regulate glucose homeostasis; however, little is known about the factors that regulate proliferation of these cells in human pancreas. Access to primary human β cells is limited and a challenge for both functional studies and drug discovery progress. We previously reported the generation of a human β cell line (EndoC-βH1) that was generated from human fetal pancreas by targeted oncogenesis followed by in vivo cell differentiation in mice. EndoC-βH1 cells display many functional properties of adult β cells, including expression of β cell markers and insulin secretion following glucose stimulation; however, unlike primary β cells, EndoC-βH1 cells continuously proliferate. Here, we devised a strategy to generate conditionally immortalized human β cell lines based on Cre-mediated excision of the immortalizing transgenes. The resulting cell line (EndoC-βH2) could be massively amplified in vitro. After expansion, transgenes were efficiently excised upon Cre expression, leading to an arrest of cell proliferation and pronounced enhancement of β cell–specific features such as insulin expression, content, and secretion. Our data indicate that excised EndoC-βH2 cells are highly representative of human β cells and should be a valuable tool for further analysis of human β cells.

Authors

Raphaël Scharfmann, Severine Pechberty, Yasmine Hazhouz, Manon von Bülow, Emilie Bricout-Neveu, Maud Grenier-Godard, Fanny Guez, Latif Rachdi, Matthias Lohmann, Paul Czernichow, Philippe Ravassard

Sphingosine-1-phosphate receptor 1 reporter mice reveal receptor activation sites in vivo

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Abstract

Activation of the GPCR sphingosine-1-phosphate receptor 1 (S1P1) by sphingosine-1-phosphate (S1P) regulates key physiological processes. S1P1 activation also has been implicated in pathologic processes, including autoimmunity and inflammation; however, the in vivo sites of S1P1 activation under normal and disease conditions are unclear. Here, we describe the development of a mouse model that allows in vivo evaluation of S1P1 activation. These mice, known as S1P1 GFP signaling mice, produce a S1P1 fusion protein containing a transcription factor linked by a protease cleavage site at the C terminus as well as a β-arrestin/protease fusion protein. Activated S1P1 recruits the β-arrestin/protease, resulting in the release of the transcription factor, which stimulates the expression of a GFP reporter gene. Under normal conditions, S1P1 was activated in endothelial cells of lymphoid tissues and in cells in the marginal zone of the spleen, while administration of an S1P1 agonist promoted S1P1 activation in endothelial cells and hepatocytes. In S1P1 GFP signaling mice, LPS-mediated systemic inflammation activated S1P1 in endothelial cells and hepatocytes via hematopoietically derived S1P. These data demonstrate that S1P1 GFP signaling mice can be used to evaluate S1P1 activation and S1P1-active compounds in vivo. Furthermore, this strategy could be potentially applied to any GPCR to identify sites of receptor activation during normal physiology and disease.

Authors

Mari Kono, Ana E. Tucker, Jennifer Tran, Jennifer B. Bergner, Ewa M. Turner, Richard L. Proia

Protein kinetic signatures of the remodeling heart following isoproterenol stimulation

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Abstract

Protein temporal dynamics play a critical role in time-dimensional pathophysiological processes, including the gradual cardiac remodeling that occurs in early-stage heart failure. Methods for quantitative assessments of protein kinetics are lacking, and despite knowledge gained from single-protein studies, integrative views of the coordinated behavior of multiple proteins in cardiac remodeling are scarce. Here, we developed a workflow that integrates deuterium oxide (²H₂O) labeling, high-resolution mass spectrometry (MS), and custom computational methods to systematically interrogate in vivo protein turnover. Using this workflow, we characterized the in vivo turnover kinetics of 2,964 proteins in a mouse model of β-adrenergic–induced cardiac remodeling. The data provided a quantitative and longitudinal view of cardiac remodeling at the molecular level, revealing widespread kinetic regulations in calcium signaling, metabolism, proteostasis, and mitochondrial dynamics. We translated the workflow to human studies, creating a reference dataset of 496 plasma protein turnover rates from 4 healthy adults. The approach is applicable to short, minimal label enrichment and can be performed on as little as a single biopsy, thereby overcoming critical obstacles to clinical investigations. The protein turnover quantitation experiments and computational workflow described here should be widely applicable to large-scale biomolecular investigations of human disease mechanisms with a temporal perspective.

Authors

Maggie P.Y. Lam, Ding Wang, Edward Lau, David A. Liem, Allen K. Kim, Dominic C.M. Ng, Xiangbo Liang, Brian J. Bleakley, Chenguang Liu, Jason D. Tabaraki, Martin Cadeiras, Yibin Wang, Mario C. Deng, Peipei Ping

Cell-specific translational profiling in acute kidney injury

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Abstract

Acute kidney injury (AKI) promotes an abrupt loss of kidney function that results in substantial morbidity and mortality. Considerable effort has gone toward identification of diagnostic biomarkers and analysis of AKI-associated molecular events; however, most studies have adopted organ-wide approaches and have not elucidated the interplay among different cell types involved in AKI pathophysiology. To better characterize AKI-associated molecular and cellular events, we developed a mouse line that enables the identification of translational profiles in specific cell types. This strategy relies on CRE recombinase–dependent activation of an EGFP-tagged L10a ribosomal protein subunit, which allows translating ribosome affinity purification (TRAP) of mRNA populations in CRE-expressing cells. Combining this mouse line with cell type–specific CRE-driver lines, we identified distinct cellular responses in an ischemia reperfusion injury (IRI) model of AKI. Twenty-four hours following IRI, distinct translational signatures were identified in the nephron, kidney interstitial cell populations, vascular endothelium, and macrophages/monocytes. Furthermore, TRAP captured known IRI-associated markers, validating this approach. Biological function annotation, canonical pathway analysis, and in situ analysis of identified response genes provided insight into cell-specific injury signatures. Our study provides a deep, cell-based view of early injury-associated molecular events in AKI and documents a versatile, genetic tool to monitor cell-specific and temporal-specific biological processes in disease modeling.

Authors

Jing Liu, A. Michaela Krautzberger, Shannan H. Sui, Oliver M. Hofmann, Ying Chen, Manfred Baetscher, Ivica Grgic, Sanjeev Kumar, Benjamin Humphreys, Winston A. Hide, Andrew P. McMahon