Interferon Gamma Inhibits Adipogenesis in vitro and Prevents Marrow Fat Infiltration in Oophorectomized Mice

Authors

Christopher Vidal, Sandra Bermeo, Wei Li, Dao Chao Huang, Richard Kremer, Gustavo Duque

Abstract

Interferon gamma (IFNγ) has been reported to induce osteoblastogenesis from mesenchymal stem cells (MSC) both in vitro and in vivo. With ageing, adipocytes outnumber osteoblasts within the bone microenvironment leading to a decrease in bone formation. Since both osteoblasts and adipocytes are of mesenchymal origin we hypothesized that IFNγ treatment might negatively affect adipogenesis while stimulates osteoblastogenesis in human MSC. To test this hypothesis, human MSC were induced to differentiate into adipocytes in the presence or absence of osteogenic doses of IFNγ (1, 10, 100 ng/ml). IFNγ-treated MSC showed a decrease in adipocyte differentiation and lipid deposition as compared with vehicle-treated controls. Additionally, adipogenic markers were significantly decreased by IFNγ treatment at the same doses that have been reported to have a strong osteogenic effect in vitro. Furthermore, DNA binding of PPARγ was significantly lower in IFNγ-treated differentiating MSC. Subsequently, ovariectomized C57BL6 mice were treated with osteogenic doses of IFNγ three times a week for 6 weeks. In distal femur, treated mice showed significantly higher hematopoiesis concomitant with lower levels of fat volume/total volume, adipocyte number and expression of adipogenic markers as compared with the vehicle-treated mice. Together, these findings demonstrate that, at osteogenic doses, IFNγ also acts as an inhibitor of adipogenesis in vitro and prevents marrow fat infiltration while favors hematopoiesis in ovariectomized mice.

Link to Article

http://dx.doi.org/10.1002/stem.1063

Histological results after maxillary sinus augmentation with Straumann® BoneCeramic, Bio-Oss®, Puros®, and autologous bone. A randomized controlled clinical trial

Author

Christian Martin Schmitt, Hendrik Doering, Thomas Schmidt, Rainer Lutz, Friedrich Wilhelm Neukam, Karl Andreas Schlegel

Abstract

This investigation focused on a comparison of clinical and histological characteristics after sinus floor augmentation with biphasic calcium phosphate (BCP, Straumann BoneCeramic®), anorganic bovine bone (ABB, Geistlich Bio-Oss®), mineralized cancellous bone allograft (MCBA, Zimmer Puros®), or autologous bone (AB). Thirty consecutive patients with a posterior edentulous maxillary situation and a vertical bone height less than or equal to 4 mm were included in this study. A two-stage procedure was carried out. After augmentation of the maxillary sinus with ABB, BCP, MCBA, or AB followed by a healing period of 5 months, biopsies were taken with simultaneous implant placement. The samples were analyzed using microradiography and histology. Ninety-four implants were placed in the augmented positions and 53 bone biopsies were taken and evaluated. The bone volume fraction of newly formed bone was measured as 30.28 ± 2.16% for BCP, 24.9 ± 5.67% for ABB, 41.74 ± 2.1% for AB, and 35.41 ± 2.78% for MCBA with significant increases in bone volume of AB vs. BCP and ABB, and MCBA vs. ABB samples. Significantly different residual bone substitute material was measured as 15.8 ± 2.1% in the BCP group and 21.36 ± 4.83% in the ABB group. As it provides the highest rate of de novo bone formation, AB can be considered to remain the gold standard in sinus floor augmentation. All tested control materials showed comparable results and are suitable for maxillary sinus augmentation.

Link to Article

http://dx.doi.org/10.1111/j.1600-0501.2012.02431.x

Activation of β-Catenin Signaling in Androgen Receptor–Negative Prostate Cancer Cells

Authors

Xinhai Wan, Jie Liu, Jing-Fang Lu, Vassiliki Tzelepi, Jun Yang, Michael W. Starbuck, Lixia Diao, Jing Wang, Eleni Efstathiou, Elba S. Vazquez, Patricia Troncoso, Sankar N. Maity, and Nora M. Navone

Abstract

To study Wnt/β-catenin in castrate-resistant prostate cancer (CRPC) and understand its function independently of the β-catenin–androgen receptor (AR) interaction. We carried out β-catenin immunocytochemical analysis, evaluated TOP-flash reporter activity (a reporter of β-catenin–mediated transcription), and sequenced the β-catenin gene in MDA prostate cancer 118a, MDA prostate cancer 118b, MDA prostate cancer 2b, and PC-3 prostate cancer cells. We knocked down β-catenin in AR-negative MDA prostate cancer 118b cells and carried out comparative gene-array analysis. We also immunohistochemically analyzed β-catenin and AR in 27 bone metastases of human CRPCs. β-Catenin nuclear accumulation and TOP-flash reporter activity were high in MDA prostate cancer 118b but not in MDA prostate cancer 2b or PC-3 cells. MDA prostate cancer 118a and MDA prostate cancer 118b cells carry a mutated β-catenin at codon 32 (D32G). Ten genes were expressed differently (false discovery rate, 0.05) in MDA prostate cancer 118b cells with downregulated β-catenin. One such gene, hyaluronan synthase 2 (HAS2), synthesizes hyaluronan, a core component of the extracellular matrix. We confirmed HAS2 upregulation in PC-3 cells transfected with D32G-mutant β-catenin. Finally, we found nuclear localization of β-catenin in 10 of 27 human tissue specimens; this localization was inversely associated with AR expression (P = 0.056, Fisher's exact test), suggesting that reduced AR expression enables Wnt/β-catenin signaling. We identified a previously unknown downstream target of β-catenin, HAS2, in prostate cancer, and found that high β-catenin nuclear localization and low or no AR expression may define a subpopulation of men with bone metastatic prostate cancer. These findings may guide physicians in managing these patients.

Link to Article

http://dx.doi.org/10.1158/1078-0432.CCR-11-2521

IRE1α activation protects mice against acetaminophen-induced hepatotoxicity

Authors

Kyu Yeon Hur, Jae-Seon So, Vera Ruda, Maria Frank-Kamenetsky, Kevin Fitzgerald, Victor Koteliansky, Takao Iwawaki, Laurie H. Glimcher, and Ann-Hwee Lee

Abstract

The mammalian stress sensor IRE1α plays a central role in the unfolded protein, or endoplasmic reticulum (ER), stress response by activating its downstream transcription factor XBP1 via an unconventional splicing mechanism. IRE1α can also induce the degradation of a subset of mRNAs in a process termed regulated IRE1-dependent decay (RIDD). Although diverse mRNA species can be degraded by IRE1α in vitro, the pathophysiological functions of RIDD are only beginning to be explored. Acetaminophen (APAP) overdose is the most frequent cause of acute liver failure in young adults in the United States and is primarily caused by CYP1A2-, CYP2E1-, and CYP3A4-driven conversion of APAP into hepatotoxic metabolites. We demonstrate here that genetic ablation of XBP1 results in constitutive IRE1α activation in the liver, leading to RIDD of Cyp1a2 and Cyp2e1 mRNAs, reduced JNK activation, and protection of mice from APAP-induced hepatotoxicity. A pharmacological ER stress inducer that activated IRE1α suppressed the expression of Cyp1a2 and Cyp2e1 in WT, but not IRE1α-deficient mouse liver, indicating the essential role of IRE1α in the down-regulation of these mRNAs upon ER stress. Our study reveals an unexpected function of RIDD in drug metabolism.

Link to Article

http://dx.doi.org/10.1084/jem.20111298

Osteo-regenerative potential of ovarian granulosa cells: An in vitro and in vivo study

Authors

M. Mattiolia, A. Gloriaa, M. Turriania, P. Berardinellia, V. Russoa, D. Nardinocchia, V. Curinia, M. Barattab, E. Martignanib, B. Barboni

Abstract

Granulosa cells (GC) express stemness markers and can differentiate into cell types not present within the follicles. Given that follicles at different stages of development populate the ovary, we undertook this research in the pig model to identify the stage of follicle, growing or luteinizing, from which GC with the best regenerative potential can be retrieved. Growing follicles were isolated from prepubertal gilts 50 h after equine chorionic gonadotropin (eCG) (1,200 IU) administration. Luteinizing follicles were obtained from prepubertal gilts treated with eCG (1,200 IU) followed, 60 h later, by hCG (500 IU). The follicles were isolated 30 h after hCG. The GC isolated from growing (GGC) and from luteinizing (LGC) follicles were expanded in vitro for three passages and exposed to osteogenic medium to trigger differentiation. The GC incorporated in PLGA scaffolds were cultured in osteogenic medium for 2 wks and then implanted subcutaneously in the dorsal region of SCID mice to assess their osteogenic potential in vivo. In addition to the typical granulosa cells characteristics (inhibin, progesterone and estrogen production and FSH receptors), GGC and LGC showed a diffused expression of the stemness markers Sox2, Nanog and TERT immediately after isolation. Expansion caused in both cell types a rapid disappearance of granulosa cell characters while it did not modify stemness marker expression. Osteogenic medium induced a marked extracellular matrix mineralization and alkaline phosphatase activation in LGC, clearly detectable after two wks, while the process was much lighter in GGC, where it became evident after 3 wks. Osteocalcin and Runx2 expressions were upregulated and stemness markers downregulated by osteogenic medium. The GC loaded implants, retrieved 8 wks after transplantation, had viable GC surrounding the several nodules of calcifications recorded. Similar effects were induced by GGC and LGC while calcification nodules were not recorded when scaffolds without cells were implanted. These data confirm that GC, expanded in vitro undergo progressive de-differentiation retaining their plasticity and demonstrate that both GGC and LGC have osteogenic potential, luteinizing cells being more efficient. Transplanted in SCID mice, GC participate in new bone formation, thus confirming their therapeutic potential.

Link to Article

http://dx.doi.org/10.1016/j.theriogenology.2011.11.008

Bisphosphonate Binding Affinity Affects Drug Distribution in Both Intracortical and Trabecular Bone of Rabbits

Authors

John Turek, F. Hal Ebetino, Mark W. Lundy, Shuting Sun, Boris A. Kashemirov, Charles E. McKenna, Maxime A. Gallant, Lilian I. Plotkin, Teresita Bellido and Xuchen Duan, et al.

Abstract

Differences in the binding affinities of bisphosphonates for bone mineral have been proposed to determine their localizations and duration of action within bone. The main objective of this study was to test the hypothesis that mineral binding affinity affects bisphosphonate distribution at the basic multicellular unit (BMU) level within both cortical and cancellous bone. To accomplish this objective, skeletally mature female rabbits (n = 8) were injected simultaneously with both low- and high-affinity bisphosphonate analogs bound to different fluorophores. Skeletal distribution was assessed in the rib, tibia, and vertebra using confocal microscopy. The staining intensity ratio between osteocytes contained within the cement line of newly formed rib osteons or within the reversal line of hemiosteons in vertebral trabeculae compared to osteocytes outside the cement/reversal line was greater for the high-affinity compared to the low-affinity compound. This indicates that the low-affinity compound distributes more equally across the cement/reversal line compared to a high-affinity compound, which concentrates mostly near surfaces. These data, from an animal model that undergoes intracortical remodeling similar to humans, demonstrate that the affinity of bisphosphonates for the bone determines the reach of the drugs in both cortical and cancellous bone.

Link to Article

http://dx.doi.org/10.1007/s00223-012-9570-0