Citations

Abstract Bone marrow adipocytes (BMAd) have recently been implicated in accelerating bone metastatic cancers, such as acute myelogenous leukemia and breast cancer. Importantly, bone marrow adipose tissue (BMAT) expands with aging and obesity, two key risk factors in multiple myeloma disease prevalence, suggesting that BMAds may influence and be influenced by myeloma cells in the marrow. Here, we provide evidence that reciprocal interactions and cross-regulation of myeloma cells and BMAds play a role in multiple myeloma pathogenesis and treatment response. Bone marrow biopsies from patients with multiple myeloma revealed significant loss of BMAT with myeloma cell infiltration of the marrow, whereas BMAT was restored after treatment for multiple myeloma. Myeloma cells reduced BMAT in different preclinical murine models of multiple myeloma and in vitro using myeloma cell-adipocyte cocultures. In addition, multiple myeloma cells altered adipocyte gene expression and cytokine secretory profiles, which were also associated with bioenergetic changes and induction of a senescent-like phenotype. In vivo, senescence markers were also increased in the bone marrow of tumor-burdened mice. BMAds, in turn, provided resistance to dexamethasone-induced cell-cycle arrest and apoptosis, illuminating a new possible driver of myeloma cell evolution in a drug-resistant clone. Our findings reveal that bidirectional interactions between BMAds and myeloma cells have significant implications for the pathogenesis and treatment of multiple myeloma. Targeting senescence in the BMAd or other bone marrow cells may represent a novel therapeutic approach for treatment of multiple myeloma. Significance: This study changes the foundational understanding of how cancer cells hijack the bone marrow microenvironment and demonstrates that tumor cells induce senescence and metabolic changes in adipocytes, potentially driving new therapeutic directions.

(1) Background: Arthrofibrosis is a common cause of patient debility and dissatisfaction after total knee arthroplasty (TKA). The diversity of molecular pathways involved in arthrofibrosis disease progression suggest that effective treatments for arthrofibrosis may require a multimodal approach to counter the complex cellular mechanisms that direct disease pathogenesis. In this study, we leveraged RNA-seq data to define genes that are suppressed in arthrofibrosis patients and identified adiponectin (ADIPOQ) as a potential candidate. We hypothesized that signaling pathways activated by ADIPOQ and the cognate receptors ADIPOR1 and ADIPOR2 may prevent fibrosis-related events that contribute to arthrofibrosis. (2) Methods: Therefore, ADIPOR1 and ADIPOR2 were analyzed in a TGFβ1 inducible cell model for human myofibroblastogenesis by both loss- and gain-of-function experiments. (3) Results: Treatment with AdipoRon, which is a small molecule agonist of ADIPOR1 and ADIPOR2, decreased expression of collagens (COL1A1, COL3A1, and COL6A1) and the myofibroblast marker smooth muscle α-actin (ACTA2) at both mRNA and protein levels in basal and TGFβ1-induced cells. (4) Conclusions: Thus, ADIPOR1 and ADIPOR2 represent potential drug targets that may attenuate the pathogenesis of arthrofibrosis by suppressing TGFβ-dependent induction of myofibroblasts. These findings also suggest that AdipoRon therapy may reduce the development of arthrofibrosis by mediating anti-fibrotic effects in joint capsular tissues.

Abstract ObjectiveChondrocyte apoptosis plays a vital role in osteoarthritis (OA) progression. Angelica sinensis polysaccharide (ASP), a traditional Chinese medicine, possesses anti-inflammatory and anti-apoptotic properties in chondrocytes. This study aimed to determine the protective role of ASP on sodium nitroprusside (SNP)-induced chondrocyte apoptosis, and explore the underlying mechanism.MethodHuman primary chondrocytes isolated from articular cartilage of OA patients were treated with SNP alone or in combination with different doses of ASP. Cell viability and apoptosis were assessed, and apoptosis-related proteins including Bcl-2 and Bax were detected. Autophagy levels were evaluated by light chain 3 (LC3)-II immunofluorescence staining, mRFP-GFP-LC3 fluorescence localisation and western blot (LC3II, p62, Beclin-1, Atg5). Meanwhile，activation of ERK 1/2 pathway was determined by western blot. The autophagy inhibitors 3-Methyladenine (3-MA), chloroquine (CQ) and a specific inhibitor of ERK1/2, SCH772984, were used respectively to confirm the autophagic effect of ASP.ResultsThe results showed that SNP-induced chondrocyte apoptosis was significantly rescued by ASP, whereas ASP alone promoted chondrocytes proliferation. The anti-apoptotic effect of ASP was related to the enhanced autophagy and depended on the activation of ERK1/2 pathway.ConclusionASP markedly rescued SNP-induced chondrocyte apoptosis by activating ERK1/2-dependent autophagy in chondrocytes, and it made ASP a potential therapeutic supplementation for OA treatment.

Objective Cartilage formation is stimulated in mixtures of chondrocytes and human adipose–derived mesenchymal stromal cells (MSCs) both in vitro and in vivo. During coculture, human MSCs perish. The goal of this study is to elucidate the mechanism by which adipose tissue–derived MSC cell death occurs in the presence of chondrocytes. Methods Human primary chondrocytes were cocultured with human MSCs derived from 3 donors. The cells were cultured in monoculture or coculture (20% chondrocytes and 80% MSCs) in pellets (200,000 cells/pellet) for 7 days in chondrocyte proliferation media in hypoxia (2% O 2 ). RNA sequencing was performed to assess for differences in gene expression between monocultures or coculture. Immune fluorescence assays were performed to determine the presence of caspase-3, LC3B, and P62. Results RNA sequencing revealed significant upregulation of >90 genes in the 3 cocultures when compared with monocultures. STRING analysis showed interconnections between >50 of these genes. Remarkably, 75% of these genes play a role in cell death pathways such as apoptosis and autophagy. Immunofluorescence shows a clear upregulation of the autophagic machinery with no substantial activation of the apoptotic pathway. Conclusion In cocultures of human MSCs with primary chondrocytes, autophagy is involved in the disappearance of MSCs. We propose that this sacrificial cell death may contribute to the trophic effects of MSCs on cartilage formation.

AbstractThe catalytic subunit of DNA‐dependent protein kinase (DNA‐PKcs) is a pleiotropic enzyme involved in DNA repair, cell cycle control, and transcription regulation. A potential role for DNA‐PKcs in the regulation of osteoblastogenesis remains to be established. We show that pharmacological inhibition of DNA‐PKcs kinase activity or gene silencing of Prkdc (encoding DNA‐PKcs) in murine osteoblastic MC3T3‐E1 cells and human adipose‐derived mesenchymal stromal cells markedly enhanced osteogenesis and the expression of osteoblast differentiation marker genes. Inhibition of DNA‐PKcs inhibited cell cycle progression and increased osteogenesis by significantly enhancing the bone morphogenetic protein 2 response in osteoblasts and other mesenchymal cell types. Importantly, in vivo pharmacological inhibition of the kinase enhanced bone biomechanical properties. Bones from osteoblast‐specific conditional Prkdc‐knockout mice exhibited a similar phenotype of increased stiffness. In conclusion, DNA‐PKcs negatively regulates osteoblast differentiation, and therefore DNA‐PKcs inhibitors may have therapeutic potential for bone regeneration and metabolic bone diseases.

Significance Statement The arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis, but several studies have shown that the primary patency rate at 1 year is approximately 60%. Percutaneous transluminal angioplasty (PTA) is the first line of treatment for AVF stenosis. However, the rate of restenosis after angioplasty is high and the primary patency rate after PTA treatment in AVFs at 6, 12, and 24 months is 61%, 42%, and 35%, respectively. Currently, no durable therapies prolong patency after angioplasty. This paper describes the use of adipose-derived mesenchymal stem cells to reduce stenosis after PTA treatment in a murine AVF model and provides rationale for potential clinical use. Background Percutaneous transluminal angioplasty (PTA) is the first line of treatment for stenosis in the arteriovenous fistula (AVF) created to provide access for hemodialysis, but resenosis still occurs. Transplants of adipose-derived mesenchymal stem cells (AMSCs) labeled with green fluorescent protein (GFP) to the adventitia could reduce pro-inflammatory gene expression, possibly restoring patency in a murine model of PTA for venous stenosis. Methods Partial nephrectomy of male C57BL/6J mice induced CKD. Placement of the AVF was 28 days later and, 14 days after that, PTA of the stenotic outflow vein was performed with delivery of either vehicle control or AMSCs (5×10 5 ) to the adventitia of the vein. Mice were euthanized 3 days later and gene expression for interleukin-1 beta (IL-1 β ) and tumor necrosis factor-alpha TNF- α ) analyzed, and histopathologic analysis performed on day 14 and 28. GFP (+) AMSCs were tracked after transplantation for up to 28 days and Doppler ultrasound performed weekly after AVF creation. Results Gene and protein expression of IL-1 β and TNF- α, fibrosis, proliferation, apoptosis and smooth muscle actin decreased, and the proportions of macrophage types (M2/M1) shifted in a manner consistent with less inflammation in AMSC-transplanted vessels compared to controls. After PTA, AMSC-treated vessels had significantly higher wall shear stress, average peak, and mean velocity, with increased lumen vessel area and decreased neointima/media area ratio compared to the control group. At 28 days after delivery, GFP (+) AMSC were present in the adventitia of the outflow vein. Conclusions AMSC-treated vessels had improved vascular remodeling with decreased proinflammatory gene expression, inflammation, and fibrotic staining compared to untreated vessels.

AbstractScapholunate interosseous ligament tears are a common wrist injury in young and active patients that can lead to suboptimal outcomes after repair. This research aims to assess a multiphasic scaffold using 3D‐printing for reconstruction of the dorsal scapholunate interosseous ligament. The scaffold was surgically implanted in vivo in the position of the native rabbit medial collateral ligament. Two branches of treatment were implemented in the study. In the first group, the rabbits (n = 8) had the knee joint fixed in flexion for 4 weeks using 1.4 mm K‐wires prior to sample harvesting. The second group (n = 8) had the rabbit knee joint immobilized for 4 weeks prior to K‐wire removal and mobilization for an additional 4 weeks prior to sample harvesting. Overall, samples were harvested at 4 weeks post‐surgery (immobilized group) and eight weeks post‐surgery (mobilized group). Mechanical tensile testing (n = 5/group) and histology (n = 3/group) of the constructs were conducted. Tissue integration and maturation were observed resulting in increased mechanical strength of the operated joint at 8 weeks (P < .05). Bone and ligament tissues were regenerated in their respective compartments with structural and mechanical properties approaching those reported for the human dorsal SLIL ligament. Clinical Significance: This proof of concept study has demonstrated that the synthetic multiphasic scaffold was capable of regenerating both bone and ligament while also withstanding the physiological load once implanted in the rabbit knee. The artificial scaffold may provide an alternative to current techniques for reconstruction of scapholunate instability or other ligament injuries in the hand and wrist.

Aims Arthrofibrosis is a relatively common complication after joint injuries and surgery, particularly in the knee. The present study used a previously described and validated rabbit model to assess the biomechanical, histopathological, and molecular effects of the mast cell stabilizer ketotifen on surgically induced knee joint contractures in female rabbits. Methods A group of 12 skeletally mature rabbits were randomly divided into two groups. One group received subcutaneous (SQ) saline, and a second group received SQ ketotifen injections. Biomechanical data were collected at eight, ten, 16, and 24 weeks. At the time of necropsy, posterior capsule tissue was collected for histopathological and gene expression analyses (messenger RNA (mRNA) and protein). Results At the 24-week timepoint, there was a statistically significant increase in passive extension among rabbits treated with ketotifen compared to those treated with saline (p = 0.03). However, no difference in capsular stiffness was detected. Histopathological data failed to demonstrate a decrease in the density of fibrous tissue or a decrease in α-smooth muscle actin (α-SMA) staining with ketotifen treatment. In contrast, tryptase and α-SMA protein expression in the ketotifen group were decreased when compared to saline controls (p = 0.007 and p = 0.01, respectively). Furthermore, there was a significant decrease in α-SMA (ACTA2) gene expression in the ketotifen group compared to the control group (p < 0.001). Conclusion Collectively, these data suggest that ketotifen mitigates the severity of contracture formation in a rabbit model of arthrofibrosis. Cite this article: Bone Joint Res 2020;9(6):302–310.

Abstract Objective Chondrocyte apoptosis plays a vital role in osteoarthritis (OA) progression. Angelica sinensis polysaccharide (ASP), a traditional Chinese medicine, possesses anti-inflammatory and anti-apoptotic properties in chondrocytes. This study aimed to determine the protective role of ASP on sodium nitroprusside (SNP)-induced chondrocyte apoptosis, and explore the underlying mechanism. Method Human primary chondrocytes isolated from articular cartilage of OA patients were treated with SNP alone or in combination with different dose of ASP. Cell viability and apoptosis were assessed, and apoptosis-related proteins including Bcl-2 and Bax were detected. Autophagy levels were evaluated by light chain 3 (LC3)-II immunofluorescence staining, mRFP-GFP-LC3 fluorescence localisation and western blot (LC3II, p62, Beclin-1, Atg5). Meanwhile,activation of ERK 1/2 pathway was determined by western blot. The autophagy inhibitors 3-Methyladenine (3-MA), chloroquine (CQ) and a specific inhibitor of ERK1/2, SCH772984, were used respectively to confirm the autophagic effect of ASP. Results The results showed that SNP-induced chondrocyte apoptosis was significantly rescued by ASP, whereas ASP alone promoted chondrocytes proliferation. The anti-apoptotic effect of ASP was related to the enhanced autophagy and depended on the activation of ERK1/2 pathway.Conclusion ASP markedly rescued SNP-induced chondrocyte apoptosis by activating ERK1/2-dependent autophagy in chondrocytes, and it made ASP a potential therapeutic supplementation for OA treatment.