mTORC1 and mTORC2 Differentially Regulate Cell Fate Programs to Coordinate Osteoblastic Differentiation in Mesenchymal Stromal Cells

AbstractVascular regeneration depends on intact function of progenitors of vascular smooth muscle cells such as pericytes and their circulating counterparts, mesenchymal stromal cells (MSC). Deregulated MSC differentiation and maladaptive cell fate programs associated with age and metabolic diseases may exacerbate arteriosclerosis due to excessive transformation to osteoblast-like calcifying cells. Targeting mTOR, a central controller of differentiation and cell fates, could offer novel therapeutic perspectives. In a cell culture model for osteoblastic differentiation of pluripotent human MSC we found distinct roles for mTORC1 and mTORC2 in the regulation of differentiation towards calcifying osteoblasts via cell fate programs in a temporally-controlled sequence. Activation of mTORC1 with induction of cellular senescence and apoptosis were hallmarks of transition to a calcifying phenotype. Inhibition of mTORC1 with Rapamycin elicited reciprocal activation of mTORC2, enhanced autophagy and recruited anti-apoptotic signals, conferring protection from calcification. Pharmacologic and genetic negative interference with mTORC2 function or autophagy both abolished regenerative programs but induced cellular senescence, apoptosis, and calcification. Overexpression of the mTORC2 constituent rictor revealed that enhanced mTORC2 signaling without altered mTORC1 function was sufficient to inhibit calcification. Studies in mice reproduced the in vitro effects of mTOR modulation with Rapamycin on cell fates in vascular cells in vivo. Amplification of mTORC2 signaling promotes protective cell fates including autophagy to counteract osteoblast differentiation and calcification of MSC, representing a novel mTORC2 function. Regenerative approaches aimed at modulating mTOR network activation patterns hold promise for delaying age-related vascular diseases and treatment of accelerated arteriosclerosis in chronic metabolic conditions.

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Publisher Correction: mTORC1 and mTORC2 Differentially Regulate Cell Fate Programs to Coordinate Osteoblastic Differentiation in Mesenchymal Stromal Cells

Scientific Reports ◽

10.1038/s41598-020-59865-9 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Theres Schaub ◽

Dennis Gürgen ◽

Deborah Maus ◽

Claudia Lange ◽

Victor Tarabykin ◽

...

Keyword(s):

Cell Fate ◽

Mesenchymal Stromal Cells ◽

Stromal Cells ◽

Osteoblastic Differentiation

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Immortalizing Mesenchymal Stromal Cells from Aged Donors While Keeping Their Essential Features

Stem Cells International ◽

10.1155/2020/5726947 ◽

2020 ◽

Vol 2020 ◽

pp. 1-24 ◽

Cited By ~ 1

Author(s):

María Piñeiro-Ramil ◽

Rocío Castro-Viñuelas ◽

Clara Sanjurjo-Rodríguez ◽

Silvia Rodríguez-Fernández ◽

Tamara Hermida-Gómez ◽

...

Keyword(s):

Regenerative Medicine ◽

Cell Fate ◽

Mesenchymal Stromal Cells ◽

Stromal Cells ◽

Transgene Expression ◽

Transduction Efficiency ◽

Aged Patients ◽

Differentiation Potential ◽

Medicine Research ◽

Age Related

Human bone marrow-derived mesenchymal stromal cells (MSCs) obtained from aged patients are prone to senesce and diminish their differentiation potential, therefore limiting their usefulness for osteochondral regenerative medicine approaches or to study age-related diseases, such as osteoarthiritis (OA). MSCs can be transduced with immortalizing genes to overcome this limitation, but transduction of primary slow-dividing cells has proven to be challenging. Methods for enhancing transduction efficiency (such as spinoculation, chemical adjuvants, or transgene expression inductors) can be used, but several parameters must be adapted for each transduction system. In order to develop a transduction method suitable for the immortalization of MSCs from aged donors, we used a spinoculation method. Incubation parameters of packaging cells, speed and time of centrifugation, and valproic acid concentration to induce transgene expression have been adjusted. In this way, four immortalized MSC lines (iMSC#6, iMSC#8, iMSC#9, and iMSC#10) were generated. These immortalized MSCs (iMSCs) were capable of bypassing senescence and proliferating at a higher rate than primary MSCs. Characterization of iMSCs showed that these cells kept the expression of mesenchymal surface markers and were able to differentiate towards osteoblasts, adipocytes, and chondrocytes. Nevertheless, alterations in the CD105 expression and a switch of cell fate-commitment towards the osteogenic lineage have been noticed. In conclusion, the developed transduction method is suitable for the immortalization of MSCs derived from aged donors. The generated iMSC lines maintain essential mesenchymal features and are expected to be useful tools for the bone and cartilage regenerative medicine research.

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Cellular Senescence in Lung Fibrosis

International Journal of Molecular Sciences ◽

10.3390/ijms22137012 ◽

2021 ◽

Vol 22 (13) ◽

pp. 7012

Author(s):

Fernanda Hernandez-Gonzalez ◽

Rosa Faner ◽

Mauricio Rojas ◽

Alvar Agustí ◽

Manuel Serrano ◽

...

Keyword(s):

Cell Fate ◽

Cellular Senescence ◽

Lung Fibrosis ◽

Lung Diseases ◽

Physiological Mechanism ◽

Lung Parenchyma ◽

Scar Tissue ◽

Interstitial Lung Diseases ◽

Cellular Damage ◽

Age Related

Fibrosing interstitial lung diseases (ILDs) are chronic and ultimately fatal age-related lung diseases characterized by the progressive and irreversible accumulation of scar tissue in the lung parenchyma. Over the past years, significant progress has been made in our incomplete understanding of the pathobiology underlying fibrosing ILDs, in particular in relation to diverse age-related processes and cell perturbations that seem to lead to maladaptation to stress and susceptibility to lung fibrosis. Growing evidence suggests that a specific biological phenomenon known as cellular senescence plays an important role in the initiation and progression of pulmonary fibrosis. Cellular senescence is defined as a cell fate decision caused by the accumulation of unrepairable cellular damage and is characterized by an abundant pro-inflammatory and pro-fibrotic secretome. The senescence response has been widely recognized as a beneficial physiological mechanism during development and in tumour suppression. However, recent evidence strengthens the idea that it also drives degenerative processes such as lung fibrosis, most likely by promoting molecular and cellular changes in chronic fibrosing processes. Here, we review how cellular senescence may contribute to lung fibrosis pathobiology, and we highlight current and emerging therapeutic approaches to treat fibrosing ILDs by targeting cellular senescence.

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Cellular Senescence and Mammalian Healthspan

Innovation in Aging ◽

10.1093/geroni/igaa057.2655 ◽

2020 ◽

Vol 4 (Supplement_1) ◽

pp. 742-742

Author(s):

Judith Campisi

Keyword(s):

Growth Factors ◽

Cell Fate ◽

Cellular Senescence ◽

Complex Cell ◽

Transgenic Mouse Models ◽

Bioactive Lipids ◽

Age Related ◽

Mammalian Tissues ◽

Secretory Phenotype ◽

Near Future

Abstract Cellular senescence is a complex cell fate, often induced by stress or damage, that can be beneficial or deleterious, depending on the physiological context and age of the organism. A prominent feature of senescent cells is a multi-faceted senescence-associated secretory phenotype (SASP), which includes growth factors, cytokine and chemokines, growth factors, proteases, bioactive lipids and metabolites. Senescent cells increase with age in most, if not all, mammalian tissues. Through the use of transgenic mouse models, senescent cells are now known to causally drive numerous age-related pathologies, largely through the SASP. Eliminating senescent cells, genetically or through the use of senolytic/senomorphic agents, can improve the health span, at least in mice, and hold promise for extension to humans in the near future.

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Metabolic programming of mesenchymal stromal cells by oxygen tension directs chondrogenic cell fate

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1410977111 ◽

2014 ◽

Vol 111 (38) ◽

pp. 13954-13959 ◽

Cited By ~ 73

Author(s):

J. Leijten ◽

N. Georgi ◽

L. Moreira Teixeira ◽

C. A. van Blitterswijk ◽

J. N. Post ◽

...

Keyword(s):

Cell Fate ◽

Oxygen Tension ◽

Mesenchymal Stromal Cells ◽

Stromal Cells ◽

Metabolic Programming

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Comparative Study of Ceramics Structure for Culturing Human Mesenchymal Stromal Cells

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.361-363.1067 ◽

2007 ◽

Vol 361-363 ◽

pp. 1067-1070 ◽

Cited By ~ 1

Author(s):

Asako Matsushima ◽

Noriko Kotobuki ◽

Mika Tadokoro ◽

Hajime Ohgushi

Keyword(s):

Bone Tissue ◽

Mesenchymal Stromal Cells ◽

Stromal Cells ◽

Cell Attachment ◽

Osteoblastic Differentiation ◽

Human Mscs ◽

Osteogenic Cells ◽

Human Mesenchymal Stromal Cells ◽

Viable Cells ◽

Different Types

Hydroxyapatite (HA) ceramics together with various kinds of osteogenic cells have been used in bone tissue engineering. It is well known that the ceramics structure and composition affect cell proliferation / differentiation. In this study, three different types of HA ceramics were used to investigate initial cell attachment followed by osteoblastic differentiation of human mesenchymal stromal cells (MSCs). The results indicated that micro-pore affected the cell attachment and porosity (pore diameter and inter-pore connection) was the key to allow spacious distribution of the viable cells in the ceramics. This study also confirmed that surface pore areas of HA ceramics support the differentiation of human MSCs and thus the ceramics have the capability to regenerate damaged bone tissue.

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The Role of Prep1 in the Regulation of Mesenchymal Stromal Cells

International Journal of Molecular Sciences ◽

10.3390/ijms20153639 ◽

2019 ◽

Vol 20 (15) ◽

pp. 3639 ◽

Cited By ~ 1

Author(s):

Giorgia Maroni ◽

Daniele Panetta ◽

Raffaele Luongo ◽

Indira Krishnan ◽

Federica La Rosa ◽

...

Keyword(s):

Bone Marrow ◽

Cell Fate ◽

Mesenchymal Stromal Cells ◽

Stromal Cells ◽

Molecular Mechanisms ◽

Gene Dosage ◽

Homeobox Gene ◽

Fate Decision

Molecular mechanisms governing cell fate decision events in bone marrow mesenchymal stromal cells (MSC) are still poorly understood. Herein, we investigated the homeobox gene Prep1 as a candidate regulatory molecule, by adopting Prep1 hypomorphic mice as a model to investigate the effects of Prep1 downregulation, using in vitro and in vivo assays, including the innovative single cell RNA sequencing technology. Taken together, our findings indicate that low levels of Prep1 are associated to enhanced adipogenesis and a concomitant reduced osteogenesis in the bone marrow, suggesting Prep1 as a potential regulator of the adipo-osteogenic differentiation of mesenchymal stromal cells. Furthermore, our data suggest that in vivo decreased Prep1 gene dosage favors a pro-adipogenic phenotype and induces a “browning” effect in all fat tissues.

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Biological activity of human mesenchymal stromal cells on polymeric electrospun scaffolds

Biomaterials Science ◽

10.1039/c8bm00693h ◽

2019 ◽

Vol 7 (3) ◽

pp. 1088-1100 ◽

Cited By ~ 8

Author(s):

Febriyani F. R. Damanik ◽

Gabriele Spadolini ◽

Joris Rotmans ◽

Silvia Farè ◽

Lorenzo Moroni

Keyword(s):

Biological Activity ◽

Cell Fate ◽

Structural Properties ◽

Mesenchymal Stromal Cells ◽

Stromal Cells ◽

Electrospun Scaffolds ◽

Human Mesenchymal Stromal Cells ◽

And Migration

Controlling chemical and structural properties of electrospun scaffolds provide cues to regulate cell fate and migration.

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Mapping the structure and biological functions within mesenchymal bodies using microfluidics

Science Advances ◽

10.1126/sciadv.aaw7853 ◽

2020 ◽

Vol 6 (10) ◽

pp. eaaw7853 ◽

Cited By ~ 6

Author(s):

Sébastien Sart ◽

Raphaël F.-X. Tomasi ◽

Antoine Barizien ◽

Gabriel Amselem ◽

Ana Cumano ◽

...

Keyword(s):

Cell Fate ◽

Mesenchymal Stromal Cells ◽

Stromal Cells ◽

Actin Polymerization ◽

Bone Repair ◽

Spatial Organization ◽

Molecular Signaling ◽

Correlative Analysis

Organoids that recapitulate the functional hallmarks of anatomic structures comprise cell populations able to self-organize cohesively in 3D. However, the rules underlying organoid formation in vitro remain poorly understood because a correlative analysis of individual cell fate and spatial organization has been challenging. Here, we use a novel microfluidics platform to investigate the mechanisms determining the formation of organoids by human mesenchymal stromal cells that recapitulate the early steps of condensation initiating bone repair in vivo. We find that heterogeneous mesenchymal stromal cells self-organize in 3D in a developmentally hierarchical manner. We demonstrate a link between structural organization and local regulation of specific molecular signaling pathways such as NF-κB and actin polymerization, which modulate osteo-endocrine functions. This study emphasizes the importance of resolving spatial heterogeneities within cellular aggregates to link organization and functional properties, enabling a better understanding of the mechanisms controlling organoid formation, relevant to organogenesis and tissue repair.

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