Expanded equine cumulus–oocyte complexes exhibit higher meiotic competence and lower glucose consumption than compact cumulus–oocyte complexes

Equine cumulus–oocyte complexes (COCs) are classified as compact (cCOC) or expanded (eCOC) and vary in their meiotic competence. This difference could be related to divergent glucose metabolism. To test this hypothesis in the present study, eCOCs, cCOCs and expanded or compact mural granulosa cells (EC and CC respectively) were matured in vitro for 30 h, at which time maturation rate, glucose metabolism and the expression of genes involved in glucose transport, glycolysis, apoptosis and meiotic competence were determined. There were significant differences between eCOCs and cCOCs in maturation rate (50% vs 21.7% (n = 192 and 46) respectively; P < 0.001), as well as mean (± s.e.m.) glucose consumption (1.8 ± 0.5 vs 27.9 ± 5.9 nmol per COC respectively) and pyruvate (0.09 ± 0.01 vs 2.4 ± 0.8 nmol per COC respectively) and lactate (4.7 ± 1.3 vs 64.1 ± 20.6 nmol per COC respectively; P < 0.05 for all) production. Glucose consumption in EC and CC did not differ significantly. Expression of hyaluronan-binding protein (tumour necrosis factor alpha induced protein 6; TNFAIP6) was increased in eCOCs and EC, and solute carrier family 2 member 1 (SLC2A1) expression was increased in eCOCs, but there were no differences in the expression of glycolysis-related enzymes and solute carrier family 2 member 3 (SLC2A3) between the COC or mural granulosa cell types. The findings of the present study demonstrate that metabolic and genomic differences exist between eCOCs and cCOCs and mural granulosa cells in the horse.

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In vitro differentiation of CD34+ hematopoietic progenitor cells toward distinct dendritic cell subsets of the birbeck granule and MIIC- positive Langerhans cell and the interdigitating dendritic cell type

Blood ◽

10.1182/blood.v88.7.2541.bloodjournal8872541 ◽

1996 ◽

Vol 88 (7) ◽

pp. 2541-2548 ◽

Cited By ~ 56

Author(s):

B Herbst ◽

G Kohler ◽

A Mackensen ◽

H Veelken ◽

P Kulmburg ◽

...

Keyword(s):

Dendritic Cell ◽

Progenitor Cells ◽

Mhc Class Ii ◽

Cell Function ◽

Fluorescein Isothiocyanate ◽

Cell Types ◽

Birbeck Granule ◽

Hematopoietic Growth Factors ◽

Necrosis Factor Alpha

We have demonstrated recently that Birbeck granule-positive Langerhans cells (LC) can be derived from CD34+ peripheral blood progenitor cells in the presence of a seven-cytokine cocktail (CC7–7). Here, we show that the sequential use of early-acting hematopoietic growth factors, stem cell factor, interleukin (IL)-3, and IL-6, followed on day 8 by differentiation in the two-factor combination IL-4 plus granulocytemacrophage colony-stimulating factor (GM-CSF) (CC4GM) is more efficient and allows the cells to be arrested in the LC stage for more than 1 week while continuous maturation occurs in CC7–7. Maturation of LC to interdigitating dendritic cells (DC) could specifically be induced within 60 hours by addition of tumor necrosis factor-alpha (20 ng/mL) or lipopolysaccharide (100 ng/mL). Using LC that had been enriched to greater than 90% CD1a+ cells by an immunoaffinity column, we were able to define clear-cut differences between LC and DC that corroborate data of the respective cells derived from epithelial borders (LC) or from lymph nodes (LN) and spleen (DC). Thus, molecules and functions involved in antigen (AG) uptake and processing were highly expressed in LC, while those involved in AG presentation were at maximum in DC. LC were CD1a+2 DR+2, CD23+, CD36+, CD80-, CD86-, and CD25-, while DC were CD1a+/- DR+3, CD23-, CD36-, CD80+, CD86+2, and CD25+, CD40 and CD32 were moderately expressed and nearly unchanged on maturation, in contrast to monocyte-derived DC. Macropinocytosis of fluorescein isothiocyanate-dextran was dominant in LC, as were multilamellar major histocompatibility complex (MHC) class II compartments (MIICs), which were detected by electron microscopy. The functional dichotomy of these cell types was finally supported by testing the AG-presenting cell function for tetanus toxoid to primed autologous T-cell lines, which was optimal when cells were loaded with AG as LC and subsequently induced to become DC.

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HSP27 Is a Ubiquitin-Binding Protein Involved in I-κBα Proteasomal Degradation

Molecular and Cellular Biology ◽

10.1128/mcb.23.16.5790-5802.2003 ◽

2003 ◽

Vol 23 (16) ◽

pp. 5790-5802 ◽

Cited By ~ 225

Author(s):

Arnaud Parcellier ◽

Elise Schmitt ◽

Sandeep Gurbuxani ◽

Daphné Seigneurin-Berny ◽

Alena Pance ◽

...

Keyword(s):

Direct Interaction ◽

Cell Types ◽

26S Proteasome ◽

Necrosis Factor Alpha ◽

Polyubiquitin Chains ◽

Ubiquitinated Proteins ◽

Activation Of Transcription ◽

Ubiquitin Proteasome

ABSTRACT HSP27 is an ATP-independent chaperone that confers protection against apoptosis through various mechanisms, including a direct interaction with cytochrome c. Here we show that HSP27 overexpression in various cell types enhances the degradation of ubiquitinated proteins by the 26S proteasome in response to stressful stimuli, such as etoposide or tumor necrosis factor alpha (TNF-α). We demonstrate that HSP27 binds to polyubiquitin chains and to the 26S proteasome in vitro and in vivo. The ubiquitin-proteasome pathway is involved in the activation of transcription factor NF-κB by degrading its main inhibitor, I-κBα. HSP27 overexpression increases NF-κB nuclear relocalization, DNA binding, and transcriptional activity induced by etoposide, ΤNF-α, and interleukin 1β. HSP27 does not affect I-κBα phosphorylation but enhances the degradation of phosphorylated I-κBα by the proteasome. The interaction of HSP27 with the 26S proteasome is required to activate the proteasome and the degradation of phosphorylated I-κBα. A protein complex that includes HSP27, phosphorylated I-κBα, and the 26S proteasome is formed. Based on these observations, we propose that HSP27, under stress conditions, favors the degradation of ubiquitinated proteins, such as phosphorylated I-κBα. This novel function of HSP27 would account for its antiapoptotic properties through the enhancement of NF-κB activity.

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miR-375 mediates CRH signaling pathway in inhibiting E2 synthesis in porcine ovary

Reproduction ◽

10.1530/rep-16-0323 ◽

2017 ◽

Vol 153 (1) ◽

pp. 63-73 ◽

Cited By ~ 13

Author(s):

Chulin Yu ◽

Meiling Li ◽

Yue Wang ◽

Ying Liu ◽

Chengzhi Yan ◽

...

Keyword(s):

Signaling Pathway ◽

Granulosa Cells ◽

Reproductive System ◽

Follicular Development ◽

Cell Types ◽

Signaling System ◽

Key Factor ◽

The Relationship

The corticotropin-releasing hormone (CRH) signaling system is involved in numbers of stress-related physiological and pathological responses, including its inhibiting effects on estradiol (E2) synthesis and follicular development in the ovary. In addition, there are reports that microRNAs (miRNAs) can control the function of animal reproductive system. The aim of present study was to investigate the functions of miR-375 and the relationship between miR-375 and CRH signaling molecules in the porcine ovary. First, our common PCR results show that miR-375 and the CRH receptor 1 (CRHR1) are expressed in porcine ovary, whereas CRH receptor 2 (CRHR2) is not detected. We further have located the cell types of miR-375 and CRHR1 by in situ hybridization (ISH), and the results show that miR-375 is located only in the granulosa cells, whereas CRHR1 is positive in all of granulosa cells and oocytes, inferring that miR-375 and CRHR1 are co-localized in granulosa cells. Second, we show that overexpression of miR-375 in cultured granulosa cells suppresses the E2 production, whereas miR-375 knockdown demonstrates the opposite result. Besides, our in vitro results demonstrate that miR-375 mediates the signaling pathway of CRH inhibiting E2 synthesis. Finally, our data show that the action of miR-375 is accomplished by directly binding to the 3′UTR of specificity protein1 (SP1) mRNA to decrease the SP1 protein level. Thus, we conclude that miR-375 is a key factor in regulating E2 synthesis by mediating the CRH signaling pathway.

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Alpha/Beta Interferon Protects Adult Mice from Fatal Sindbis Virus Infection and Is an Important Determinant of Cell and Tissue Tropism

Journal of Virology ◽

10.1128/jvi.74.7.3366-3378.2000 ◽

2000 ◽

Vol 74 (7) ◽

pp. 3366-3378 ◽

Cited By ~ 172

Author(s):

Kate D. Ryman ◽

William B. Klimstra ◽

Khuong B. Nguyen ◽

Christine A. Biron ◽

Robert E. Johnston

Keyword(s):

Virus Replication ◽

Sindbis Virus ◽

High Titer ◽

Cell Types ◽

Interleukin 12 ◽

Tissue Tropism ◽

Necrosis Factor Alpha ◽

Beta Interferon ◽

Alpha Beta

ABSTRACT Infection of adult 129 Sv/Ev mice with consensus Sindbis virus strain TR339 is subclinical due to an inherent restriction in early virus replication and viremic dissemination. By comparing the pathogenesis of TR339 in 129 Sv/Ev mice and alpha/beta interferon receptor null (IFN-α/βR−/−) mice, we have assessed the contribution of IFN-α/β in restricting virus replication and spread and in determining cell and tissue tropism. In adult 129 Sv/Ev mice, subcutaneous inoculation with 100 PFU of TR339 led to extremely low-level virus replication and viremia, with clearance under way by 96 h postinoculation (p.i.). In striking contrast, adult IFN-α/βR−/− mice inoculated subcutaneously with 100 PFU of TR339 succumbed to the infection within 84 h. By 24 h p.i. a high-titer serum viremia had seeded infectious virus systemically, coincident with the systemic induction of the proinflammatory cytokines interleukin-12 (IL-12) p40, IFN-γ, tumor necrosis factor alpha, and IL-6. Replicating virus was located in macrophage-dendritic cell (DC)-like cells at 24 h p.i. in the draining lymph node and in the splenic marginal zone. By 72 h p.i. virus replication was widespread in macrophage-DC-like cells in the spleen, liver, lung, thymus, and kidney and in fibroblast-connective tissue and periosteum, with sporadic neuroinvasion. IFN-α/β-mediated restriction of TR339 infection was mimicked in vitro in peritoneal exudate cells from 129 Sv/Ev versus IFN-α/βR−/− mice. Thus, IFN-α/β protects the normal adult host from viral infection by rapidly conferring an antiviral state on otherwise permissive cell types, both locally and systemically. Ablation of the IFN-α/β system alters the apparent cell and tissue tropism of the virus and renders macrophage-DC-lineage cells permissive to infection.

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Steviol Represses Glucose Metabolism and Translation Initiation in Pancreatic Cancer Cells

Biomedicines ◽

10.3390/biomedicines9121814 ◽

2021 ◽

Vol 9 (12) ◽

pp. 1814

Author(s):

Sonam Kumari ◽

Mohammed Sikander ◽

Shabnam Malik ◽

Manish K. Tripathi ◽

Bilal B. Hafeez ◽

...

Keyword(s):

Pancreatic Cancer ◽

Glucose Metabolism ◽

Cancer Cells ◽

Translation Initiation ◽

Lactate Production ◽

Glucose Consumption ◽

Human Pancreatic Cancer ◽

Functional Assay ◽

Pancreatic Cancer Cells

Pancreatic cancer has the worst prognosis and lowest survival rate among all cancers. Pancreatic cancer cells are highly metabolically active and typically reprogrammed for aberrant glucose metabolism; thus they respond poorly to therapeutic modalities. It is highly imperative to understand mechanisms that are responsible for high glucose metabolism and identify natural/synthetic agents that can repress glucose metabolic machinery in pancreatic cancer cells, to improve the therapeutic outcomes/management of pancreatic cancer patients. We have identified a glycoside, steviol that effectively represses glucose consumption in pancreatic cancer cells via the inhibition of the translation initiation machinery of the molecular components. Herein, we report that steviol effectively inhibits the glucose uptake and lactate production in pancreatic cancer cells (AsPC1 and HPAF-II). The growth, colonization, and invasion characteristics of pancreatic cancer cells were also determined by in vitro functional assay. Steviol treatment also inhibited the tumorigenic and metastatic potential of human pancreatic cancer cells by inducing apoptosis and cell cycle arrest in the G1/M phase. The metabolic shift by steviol was mediated through the repression of the phosphorylation of mTOR and translation initiation proteins (4E-BP1, eIF4e, eIF4B, and eIF4G). Overall, the results of this study suggest that steviol can effectively suppress the glucose metabolism and translation initiation in pancreatic cancer cells to mitigate their aggressiveness. This study might help in the design of newer combination therapeutic strategies for pancreatic cancer treatment.

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Borrelia burgdorferiSpirochetes Induce Mast Cell Activation and Cytokine Release

Infection and Immunity ◽

10.1128/iai.67.3.1107-1115.1999 ◽

1999 ◽

Vol 67 (3) ◽

pp. 1107-1115 ◽

Cited By ~ 22

Author(s):

Jeffrey Talkington ◽

Steven P. Nickell

Keyword(s):

Mast Cell ◽

Mast Cells ◽

Cell Activation ◽

Cell Types ◽

Host Cells ◽

Mast Cell Activation ◽

Cytokine Release ◽

Necrosis Factor Alpha ◽

Tnf Α

ABSTRACT The Lyme disease spirochete, Borrelia burgdorferi, is introduced into human hosts via tick bites. Among the cell types present in the skin which may initially contact spirochetes are mast cells. Since spirochetes are known to activate a variety of cell types in vitro, we tested whether B. burgdorferi spirochetes could activate mast cells. We report here that freshly isolated rat peritoneal mast cells or mouse MC/9 mast cells cultured in vitro with live or freeze-thawed B. burgdorferi spirochetes undergo low but detectable degranulation, as measured by [5-3H] hydroxytryptamine release, and they synthesize and secrete the proinflammatory cytokine tumor necrosis factor alpha (TNF-α). In contrast to findings in previous studies, where B. burgdorferi-associated activity was shown to be dependent upon protein lipidation, mast cell TNF-α release was not induced by either lipidated or unlipidated recombinant OspA. This activity was additionally shown to be protease sensitive and surface expressed. Finally, comparisons of TNF-α-inducing activity in known low-, intermediate-, and high-passage B. burgdorferi B31 isolates demonstrated passage-dependent loss of activity, indicating that the activity is probably plasmid encoded. These findings document the presence in low-passage B. burgdorferi spirochetes of a novel lipidation-independent activity capable of inducing cytokine release from host cells.

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Insulin regulation of solute carrier family 2 member 1 (glucose transporter 1) expression and glucose uptake in decidualizing human endometrial stromal cells: an in vitro study

Reproductive Biology and Endocrinology ◽

10.1186/s12958-020-00674-0 ◽

2020 ◽

Vol 18 (1) ◽

Author(s):

Ivika Jakson ◽

Dorina Ujvari ◽

Sebastian Brusell Gidlöf ◽

Angelica Lindén Hirschberg

Keyword(s):

Glucose Uptake ◽

Stromal Cells ◽

Glucose Transporter ◽

Mrna Levels ◽

Solute Carrier Family ◽

Endometrial Stromal Cells ◽

Glucose Transporter 1 ◽

Protein Levels ◽

Solute Carrier

Abstract Background Solute carrier family 2 member 1 (SLC2A1; previously known as glucose transporter 1), is the most abundant glucose transporter in human endometrium and is up-regulated during decidualization, whereas high insulin may have a negative impact on this process. The present study aimed to investigate the effect of insulin on the expression of SLC2A1 and glucose uptake in decidualizing human endometrial stromal cells. Methods We induced in vitro decidualization of endometrial stromal cells obtained from regularly menstruating healthy non-obese women. The cells were treated with increasing concentrations of insulin, and the involvement of the transcription factor forkhead box O1 (FOXO1) was evaluated using a FOXO1 inhibitor. SLC2A1 mRNA levels were measured by Real-Time PCR and protein levels were evaluated by immunocytochemistry. Glucose uptake was estimated by an assay quantifying the cellular uptake of radioactive glucose. One-way ANOVA, Dunnett’s multiple comparisons test and paired t-test were used to determine the statistical significance of the results. Results We found that insulin dose-dependently decreased SLC2A1 mRNA levels and decreased protein levels of SLC2A1 in decidualizing human endometrial stromal cells. Transcriptional inactivation of FOXO1 seems to explain at least partly the down-regulation of SLC2A1 by insulin. Glucose uptake increased upon decidualization, whereas insulin treatment resulted in a slight inhibition of the glucose uptake, although not significant for all insulin concentrations. Conclusions These results indicate an impairment of decidualization by high concentrations of insulin. Future studies will determine the clinical significance of our results for endometrial function and decidualization in women with insulin resistance and hyperinsulinemia.

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43 WARMING TEMPERATURE AFFECTS THE VIABILITY AND MEIOTIC COMPETENCE OF IMMATURE PORCINE OOCYTES VITRIFIED IN A CHEMICALLY DEFINED SOLUTION

Reproduction Fertility and Development ◽

10.1071/rdv26n1ab43 ◽

2014 ◽

Vol 26 (1) ◽

pp. 135

Author(s):

D. Takahashi ◽

H. Funahashi

Keyword(s):

In Vitro Maturation ◽

Fluorescent Microscopy ◽

Dibutyryl Cyclic Amp ◽

Nuclear Maturation ◽

Porcine Oocyte ◽

Different Temperatures ◽

Maturation Rate ◽

Post Hoc ◽

Meiotic Competence

The aim of this study was to examine the viability and meiotic competence of porcine oocytes when immature porcine cumulus-oocyte complexes (COC) were pretreated for vitrification at different temperatures (25 and 39°C), vitrified in a chemically defined solution, and warmed at different temperatures (39 and 60°C). Cumulus-oocyte complexes were aspirated from middle-size follicles (3–6 mm in diameter) of abattoir-derived porcine ovaries. After collection, the COC were pretreated with cryoprotectants at different temperatures (25 and 39°C) and vitrified in a serum-free chemically defined solution containing 0.6 mg mL–1 of hydroxypropyl cellulose, basically according to a commercial protocol (Cryotop, Kitazato BioPharma Co. Ltd., Fuji, Japan). The vitrified COC were warmed in 1 M trehalose solution at 39 for 60 s or at 60°C for 30 s. The COC were cultured for in vitro maturation (IVM) in modified porcine oocyte medium (POM) supplemented with 50 μM β-mercaptoethanol, 10 IU mL–1 of eCG, 10 IU mL–1 of hCG, and 1 mM dibutyryl cyclic AMP (dbcAMP) for 20 h and then in the fresh medium without hormonal supplements and dbcAMP for another 24 h. Viability of COC was evaluated under fluorescent microscopy after stain with fluorescein diacetate and propidium iodide. Nuclear maturation of the oocytes was evaluated after 44 h of IVM. Statistical analyses of results from 5 replicated trials were performed by ANOVA with a Bonferroni/Dunn post-hoc test (significance, P < 0.05). Although viabilities of vitrified oocytes after 44 h of IVM [6.0% (9/149) to 37.8% (59/155)] were significantly lower than fresh controls [98.8% (158/160)], the viabilities of vitrified oocytes warmed at 60°C [32.0% (49/160) to 37.8% (59/155)] were significantly higher than those warmed at 39°C [6.0% (9/149) to 10.0% (16/160)]. Maturation rates in vitrified oocytes [2.7% (4/149) to 19.8% (31/155)] were also significantly lower than fresh controls [74.8% (120/160)]. Regardless of temperature during pretreatment for vitrification (25 and 39°C), maturation rate of the oocytes warmed at 60°C after vitrification [16.4% (25/154) to 19.8% (31/155)] was significantly higher than that warmed at 39°C [3.1% (5/160) to 2.7% (4/149)]. In conclusion, these results demonstrate that warming at 60°C for 30 s maintains the viability and meiotic competence of immature porcine COC.

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152 POST-HATCHING EMBRYO DEVELOPMENT IN VITRO UNTIL DAY 15 IN AGAR GEL DILUTED IN PBS OR IN MilliQ WATER

Reproduction Fertility and Development ◽

10.1071/rdv22n1ab152 ◽

2010 ◽

Vol 22 (1) ◽

pp. 234

Author(s):

G. M. Machado ◽

E. S. Caixeta ◽

M. M. Franco ◽

R. Rumpf ◽

M. A. N. Dode

Keyword(s):

Gene Expression ◽

Embryo Development ◽

Solute Carrier Family ◽

Final Size ◽

Agar Gel ◽

Interferon Tau ◽

Developmental Potential ◽

Solute Carrier ◽

Chi Square Analysis

Post-hatching (PH) in vitro embryo culture is a procedure that allows the establishment of more accurate tools for evaluating embryo developmental potential. An important step in the PH system is the tunnels preparation, since they will hold the developing embryo in advanced stages during culture. However, if the diluent used to dissolve agarose for tunnels preparation can influence the diffusion of nutrients from culture medium to the gel compromising embryo development, is not known. The aim of this study was to compare developmental kinetics and gene expression of Day 15 embryos cultured in the PHD system using PBS and MilliQ water to dilute the agar gel used for tunnels construction. Bovine oocytes obtained from slaughterhouse ovaries were matured, fertilized, and cultured in vitro for 8 days in SOFaaci with 5% fetal bovine serum (FBS) at 39°C in 5% CO2 in air. On Day 9, PHD (Brandão et al. 2004 Biol. Reprod. 71, 2048-2055) medium was added in culture droplets and on Day 11 embryos were measured. Only morphologically normal with ≥0.5 mm of diameter Day 11 blastocysts were placed individually in the tunnels. The tunnels were produced using agar gel 2.4% diluted either in PBS or MilliQ water, supplemented with 10% FBS. Morphology and length of embryos were evaluated on Day 11, Day 12.5, Day 14, and Day 15. Elongated embryos in Day 15 were used for extraction of total RNA using Trizol Reagent to verify gene expression by qPCR. A total of 4 pools containing 3 Day 15 embryos in each pool were used to evaluate the expression of genes involved in glucose metabolism [glucose-6-phosphate dehydrogenase (G6PDH), solute carrier family 2 member 1 (SLC2A1), solute carrier family 2 member 3 (SLC2A3), phosphoglycerate kinase 1 (PGK1)], placenta development [placenta-specific 8 (PLAC8), keratin proteins 8 (KRT8)], heat stress [heat shock transcription factors 1(HSF1)], and maternal recognition of pregnancy [interferon tau (IFNT)]. Embryo growth and gene expression data were examined by the t-test for parametric or Mann-Whitney for non-parametric (P < 0.05). From a total of 2,933 oocytes used, 1,216 (41%) reached the blastocyst stage on Day 8 and of those 72% hatched on Day 9 (n = 873). On Day 11, 39.5% (345/873) of the hatched blastocysts had diameter ≥0.5 mm and 286 were loaded into the MilliQ water (154) and PBS tunnels (132). No difference was observed in the proportion of elongated embryos between PBS (54%, n = 71) and MilliQ water treatment (42%, n = 65) by chi-square analysis. Final size at Day 15 as well as increase in length of the embryos between Days 11 and 15 were similar in PBS (2.37 ± 0.13 mm; 1.68 ± 0.13 mm) and MilliQ water tunnels (3.03 ± 0.23 mm; 2.33 ± 0.22 mm). Regarding gene expression analysis, only SLC2A1 had a tendency (P = 0.08) to be higher expressed in embryos cultured in PBS tunnels. The results suggested that water can be use to construct agar gel tunnels for the PHD system without interfering in embryo developmental kinetics until Day 15 of culture. Embrapa, CNPq, CAPES.

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Modeling Sympathetic Hyperactivity in Alzheimer’s Related Bone Loss

Journal of Alzheimer s Disease ◽

10.3233/jad-215007 ◽

2021 ◽

pp. 1-12

Author(s):

Robert A. Culibrk ◽

Ahmad S. Arabiyat ◽

Carisa A. DeKalb ◽

Mariah S. Hahn

Keyword(s):

Bone Loss ◽

Sympathetic Neurons ◽

Cell Types ◽

Collagen Type I ◽

Type I ◽

Mineral Density ◽

Necrosis Factor Alpha ◽

Glycol Diacrylate ◽

Tnf Α

Background: A significant subset of patients with Alzheimer’s disease (AD) exhibit low bone mineral density and are therefore more fracture-prone, relative to their similarly aged neurotypical counterparts. In addition to chronic immune hyperactivity, behavioral dysregulation of effector peripheral sympathetic neurons—which densely innervate bone and potently modulate bone remodeling—is implicated in this pathological bone reformation. Objective: Thus, there exists a pressing need for a robust in vitro model which allows interrogation of the paracrine interactions between the putative mediators of AD-related osteopenia: sympathetic neurons (SNs) and mesenchymal stem cells (MSCs). Methods: Toward this end, activated SN-like PC12 cells and bone marrow derived MSCs were cultured in poly(ethylene glycol) diacrylate (PEGDA) hydrogels in the presence or absence of the AD-relevant inflammatory cytokine tumor necrosis factor alpha (TNF-α) under mono- and co-culture conditions. Results: PC12s and MSCs exposed separately to TNF-α displayed increased expression of pro-inflammatory mediators and decreased osteopontin (OPN), respectively. These data indicate that TNF-α was capable of inducing a dysregulated state in both cell types consistent with AD. Co-culture of TNF-α-activated PC12s and MSCs further exacerbated pathological behaviors in both cell types. Specifically, PC12s displayed increased secretion of interleukin 6 relative to TNF-α stimulated monoculture controls. Similarly, MSCs demonstrated a further reduction in osteogenic capacity relative to TNF-α stimulated monoculture controls, as illustrated by a significant decrease in OPN and collagen type I alpha I chain. Conclusion: Taken together, these data may indicate that dysregulated sympathetic activity may contribute to AD-related bone loss.

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