A Human-Like Senescence-Associated Secretory Phenotype Is Conserved in Mouse Cells Dependent on Physiological Oxygen

Cellular senescence irreversibly arrests cell proliferation in response to oncogenic stimuli. Human cells develop a senescence-associated secretory phenotype (SASP), which increases the secretion of cytokines and other factors that alter the behavior of neighboring cells. We show here that “senescent” mouse fibroblasts, which arrested growth after repeated passage under standard culture conditions (20% oxygen), do not express a human-like SASP, and differ from similarly cultured human cells in other respects. However, when cultured in physiological (3%) oxygen and induced to senesce by radiation, mouse cells more closely resemble human cells, including expression of a robust SASP. We describe two new aspects of the human and mouse SASPs. First, cells from both species upregulated the expression and secretion of several matrix metalloproteinases, which comprise a conserved genomic cluster. Second, for both species, the ability to promote the growth of premalignant epithelial cells was due primarily to the conserved SASP factor CXCL-1/KC/GRO-α. Further, mouse fibroblasts made senescent in 3%, but not 20%, oxygen promoted epithelial tumorigenesis in mouse xenographs. Our findings underscore critical mouse-human differences in oxygen sensitivity, identify conditions to use mouse cells to model human cellular senescence, and reveal novel conserved features of the SASP

Human mesenchymal stromal cell-secreted lactate induces M2-macrophage differentiation by metabolic reprogramming

Human mesenchymal stromal cells (MSC) have been shown to dampen immune response and promote tissue repair, but the underlying mechanisms are still under investigation. Herein, we demonstrate that umbilical cord-derived MSC (UC-MSC) alter the phenotype and function of monocyte-derived dendritic cells (DC) through lactate-mediated metabolic reprogramming. UC-MSC can secrete large quantities of lactate and, when present during monocyte-to-DC differentiation, induce instead the acquisition of M2-macrophage features in terms of morphology, surface markers, migratory properties and antigen presentation capacity. Microarray expression profiling indicates that UC-MSC modify the expression of metabolic-related genes and induce a M2-macrophage expression signature. Importantly, monocyte-derived DC obtained in presence of UC-MSC, polarize naïve allogeneic CD4+ T-cells into Th2 cells. Treatment of UC-MSC with an inhibitor of lactate dehydrogenase strongly decreases lactate concentration in culture supernatant and abrogates the effect on monocyte-to- DC differentiation. Metabolic analysis further revealed that UC-MSC decrease oxidative phosphorylation in differentiating monocytes while strongly increasing the spare respiratory capacity proportional to the amount of secreted lactate. Because both MSC and monocytes are recruited in vivo at the site of tissue damage and inflammation, we propose the local increase of lactate concentration induced by UC-MSC and the consequent enrichment in M2-macrophage generation as a mechanism to achieve immunomodulation

Global data on earthworm abundance, biomass, diversity and corresponding environmental properties

Publisher Copyright: © 2021, The Author(s).Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ecological groups. This global dataset contains 10,840 sites, with 184 species, from 60 countries and all continents except Antarctica. The data were obtained from 182 published articles, published between 1973 and 2017, and 17 unpublished datasets. Amalgamating data into a single global database will assist researchers in investigating and answering a wide variety of pressing questions, for example, jointly assessing aboveground and belowground biodiversity distributions and drivers of biodiversity change.Peer reviewe

Global data on earthworm abundance, biomass, diversity and corresponding environmental properties

Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ecological groups. This global dataset contains 10,840 sites, with 184 species, from 60 countries and all continents except Antarctica. The data were obtained from 182 published articles, published between 1973 and 2017, and 17 unpublished datasets. Amalgamating data into a single global database will assist researchers in investigating and answering a wide variety of pressing questions, for example, jointly assessing aboveground and belowground biodiversity distributions and drivers of biodiversity change

Secretion of SDF-1α by bone marrow-derived stromal cells enhances skin wound healing of C57BL/6 mice exposed to ionizing radiation

Patients treated for cancer therapy using ionizing radiation (IR) have delayed tissue repair and regeneration. The mechanisms mediating these defects remain largely unknown at present, thus limiting the development of therapeutic approaches. Using a wound healing model, we here investigate the mechanisms by which IR exposure limits skin regeneration. Our data show that induction of the stromal cell-derived growth factor 1α (SDF-1α) is severely impaired in the wounded skin of irradiated, compared to non-irradiated, mice. Hence, we evaluated the potential of bone marrow-derived multipotent stromal cells (MSCs), which secrete high levels of SDF-1α, to improve skin regeneration in irradiated mice. Injection of MSCs into the wound margin led to remarkable enhancement of skin healing in mice exposed to IR. Injection of irradiated MSCs into the wound periphery of non-irradiated mice delayed wound closure, also suggesting an important role for the stromal microenvironment in skin repair. The beneficial actions of MSCs were mainly paracrine, as the cells did not differentiate into keratinocytes. Specific knockdown of SDF-1α expression led to drastically reduced efficiency of MSCs in improving wound closure, indicating that SDF-1α secretion by MSCs is largely responsible for their beneficial action. We also found that one mechanism by which SDF-1α enhances wound closure likely involves increased skin vascularization. Our findings collectively indicate that SDF-1α is an important deregulated cytokine in irradiated wounded skin, and that the decline in tissue regeneration potential following IR can be reversed, given adequate microenvironmental suppor

Abrogation of osteogenic differentiation potential following irradiation is limited to stromal progenitor cells.

<p>(<b>A</b>) MSC and osteoblasts (OB–SC) were exposed (IR) or not (CTRL) to 10 Gy IR and one week later placed in osteogenic differentiation media for 14 to 21 days. Representative photographs showing mineralization nodules accumulation stained with Alizarin Red S is shown for each population. Scale bar: 2mm. Phase contrast photograph showing the presence of senescent MSC in absence of mineralization is also shown. (<b>B</b>) Quantification of mineralization was determined by the extraction of Alizarin Red S and detection by spectrophotometry. (<b>C</b> and <b>D</b>) Expression of Runx2 and Osx was determined by quantitative real-time PCR using RNA extracted from control and IR-induced senescent MSC and OB–SC populations cultured or not in osteogenic differentiation media. Mean ± standard error; *: <i>p</i> value < 0.05.</p

IR-induced senescent MSC failed to generate bone in vivo.

<p>(<b>A</b>) Schematic of the experiment. Control or IR-induced senescent MSC were mixed with HA/TCP particles along with collagen and injected subcutaneously to the flank of mice. 10 weeks post injection, implants were retrieved from the animals, embedded in plastic, sectioned and stained with Goldner’s trichrome to detect bone formation. (B) Representative images from n= 6 implants per group showing mineralization (Goldner’s trichrome in green) from control or IR-induced senescent MSC. Implants were counterstained with hematoxylin eosin. Scale bar: 300µm.</p

Loss of osteogenic but not adipogenic potential in senescent MSC is p53 dependent.

<p>(<b>A</b>) MSC derived from p53 knockout mice (MSC-p53KO) were exposed (IR) or not (CTRL) to 10 Gy IR and one week later stained for the expression of SAβ-gal activity. (<b>B</b>) The proliferation capacity of MSC-p53KO was determined using a CFU assay one week post-exposure or not to IR. (<b>C</b>) One week post exposure or not to IR, MSC-p53KO were placed in adipogenic differentiation media for 7 to 14 days. Representative photographs showing lipid accumulation stained with Oil Red O is shown. Scale bar: 200µm. (<b>D</b>) Quantification of lipid accumulation has determined by the extraction of Oil Red O staining and detection by spectrophotometry. (<b>E</b>) Expression of PPARγ was determined by quantitative real-time PCR using RNA extracted from control and IR-induced senescent MSC-p53KO cultured in adipogenic differentiation media. (<b>F</b>) One week post exposure or not to IR, MSC-p53KO were placed in osteogenic differentiation media for 14 to 21 days. Representative photographs showing mineralization nodules accumulation stained with Alizarin Red S is shown. (<b>G</b>) Quantification of mineralization was determined by the extraction of Alizarin Red S staining and detection by spectrophotometry. (<b>H</b>) Expression of Runx2 and Osx was determined by quantitative real-time PCR using RNA extracted from control and IR-induced senescent MSC-p53KO populations placed in osteogenic differentiation media. Mean ± standard error of at least 3 individual experiments is shown; *: <i>p</i> value < 0.05.</p

Targeted Gene Addition of Microdystrophin in Mice Skeletal Muscle via Human Myoblast Transplantation

Zinc finger nucleases (ZFN) can facilitate targeted gene addition to the genome while minimizing the risks of insertional mutagenesis. Here, we used a previously characterized ZFN pair targeting the chemokine (C-C motif) receptor 5 (CCR5) locus to introduce, as a proof of concept, the enhanced green fluorescent protein (eGFP) or the microdystrophin genes into human myoblasts. Using integrase-defective lentiviral vectors (IDLVs) and chimeric adenoviral vectors to transiently deliver template DNA and ZFN respectively, we achieved up to 40% targeted gene addition in human myoblasts. When the O6-methylguanine-DNA methyltransferaseP140K gene was co-introduced with eGFP, the frequency of cells with targeted integration could be increased to over 90% after drug selection. Importantly, gene-targeted myoblasts retained their mitogenic activity and potential to form myotubes both in vitro and in vivo when injected into the tibialis anterior of immune-deficient mice. Altogether, our results could lead to the development of improved cell therapy transplantation protocols for muscular diseases