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Application of tissue-engineered bones (TEBs) is hindered by challenges associated with incorporated viable cells. Previously, we employed freeze-drying techniques on TEBs to devitalize mesenchymal stem cells (MSCs) while preserving functional proteins, yielding functional proteins-based TEBs (FP-TEBs). Here, we aimed to elucidate their in vivo angiogenic and osteogenic capabilities and the mechanisms. qPCR arrays were employed to evaluate chemokines and receptors governing EC migration. Identified C-X-C chemokine receptors (CXCRs) were substantiated using shRNAs, and the pivotal role of CXCR2 was validated via conditional knockout mice. Finally, signaling molecules downstream of CXCR2 were identified. Additionally, Src, MAP4K4, and p38 MAPK were identified indispensable for CXCR2 function. Further investigations revealed that regulation of p38 MAPK by Src was mediated by MAP4K4. In conclusion, FP-TEBs promoted EC migration, angiogenesis, and osteogenesis via the CXCR2-Src-Map4k4-p38 MAPK axis. [ABSTRACT FROM AUTHOR]

Homing of mesenchymal stem cells (MSCs) to the defect site is indispensable for bone repair. Local endothelial cells (ECs) can recruit MSCs; however, the mechanism remains unclear, especially in the context of the inflammatory microenvironment. This study was aimed to investigate the role of ECs in MSCs migration during the inflammatory phase of bone repair. The inflammatory microenvironment was mimicked in vitro via adding a cytokine set (IL-1β, IL-6, and TNF-α) to the culture medium of ECs. The production of PDGF-BB from ECs was measured by ELISA. Transwell and wound healing assays were employed to assess MSCs migration toward ECs and evaluate the implication of PDGF-BB/PDGFRβ. A series of shRNA and pathway inhibitors were used to screen signal molecules downstream of PDGF-BB/PDGFRβ. Then, mouse models of femoral defects were fabricated and DBM scaffolds were implanted. GFP+ MSCs were injected via tail vein, and the relevance of PDGF-BB/PDGFRβ, as well as screened signal molecules, in cell homing was further verified during the early phase of bone repair. In the mimicked inflammatory microenvironment, MSCs migration toward ECs was significantly promoted, which could be abrogated by pdgfrb knockout in MSCs. Inhibition of Src or Akt led to negative effects analogous to pdgfrb knockout. Blockade of JNK, MEK, and p38 MAPK had no impact. Meanwhile, the secretion of PDGF-BB from ECs was evidently motivated by the inflammatory microenvironment. Adding recombinant PDGF-BB protein to the culture medium of ECs phenocopied the inflammatory microenvironment with regard to attracting MSCs, which was abolished by pdgfb, src, or akt in MSCs. Moreover, pdgfb knockout suppressed the expression and phosphorylation of Src and Akt in migrating MSCs. Src knockout impaired Akt expression but not vice versa. In vivo, reduced infiltration of CD31+ ECs was correlated with diminished PDGF-BB in local defect sites, and silencing pdgfb, src, or akt in MSCs markedly hampered cell homing. Together, these findings suggest that in the inflammatory microenvironment, MSCs migrate toward ECs via PDGF-BB/PDGFRβ and the downstream Src-Akt signal pathway. [ABSTRACT FROM AUTHOR]

The treatment of bone defects has always been a challenge for orthopedic surgeons. The development of tissue engineering technology provides a novel method for repairing bone defects and has been used in animal experiments and clinical trials. However, there are few clinical studies on comparing the long-term outcomes of tissue-engineered bones (TEBs) and other bone grafts in treating bone defects, and the long-term efficiency of TEBs remains controversial. Therefore, a study designed by us was aimed to compare the long-term efficacy and safety of individual tissue-engineered bones (iTEBs) and allogeneic bone granules (ABGs) in treating bone defects caused by curettage of benign bone tumors and tumor-like lesions. From September 2003 to November 2009, 48 patients who received tumor curettage and bone grafting were analyzed with a mean follow-up of 122 mo (range 60 to 173 mo). Based on implant style, patients were divided into groups of iTEBs (n = 23) and ABGs (n = 25). Postoperatively, the healing time, healing quality, incidence of complications, and functional scores were compared between the two groups. The Musculoskeletal Tumor Society functional evaluation system and Activities of Daily Living Scale scores were significantly improved in both groups with no significant difference. The average healing time of ABGs was longer than that of iTEBs (P < 0.05). At the final follow-up, iTEBs had a better performance in the bone healing quality evaluated by modified Neer classification (P < 0.05). In the group of iTEBs, the complication and reoperation rate was lower than that in the group of ABGs, with no tumorigenesis or immune rejection observed. In summary, for treating bone defects caused by tumor curettage, iTEBs were safe, effective, and tagged with more rapid healing speed, better healing outcome, and lower complication and reoperation rate, in comparison with ABGs. [ABSTRACT FROM AUTHOR]

Background and Aims. Host-derived cells play crucial roles in the regeneration process of tissue-engineered constructs (TECs) during the treatment of large segmental bone defects (LSBDs). However, their identity, source, and cell recruitment mechanisms remain elusive. Methods. A complex model was created using mice by combining methods of GFP+ bone marrow transplantation (GFP-BMT), parabiosis (GFP+-BMT and wild-type mice), and femoral LSBD, followed by implantation of TECs or DBM scaffolds. Postoperatively, the migration of host BM cells was detected by animal imaging and immunofluorescent staining. Bone repair was evaluated by micro-CT. Signaling pathway repressors including AMD3100 and SP600125 associated with the migration of BM CD44+ cells were further investigated. In vitro, transwell migration and western-blotting assays were performed to verify the related signaling pathway. In vivo, the importance of the SDF-1/CXCR4-JNK pathway was validated by ELISA, fluorescence-activated cell sorting (FACS), immunofluorescent staining, and RT-PCR. Results. First, we found that host cells recruited to facilitate TEC-mediated bone repair were derived from bone marrow and most of them express CD44, indicating the significance of CD44 in the migration of bone marrow cells towards donor MSCs. Then, the predominant roles of SDF-1/CXCR4 and downstream JNK in the migration of BM CD44+ cells towards TECs were demonstrated. Conclusion. Together, we demonstrated that during bone repair promoted by TECs, BM-derived CD44+ cells were essential and their migration towards TECs could be regulated by the SDF-1/CXCR4-JNK signaling pathway. [ABSTRACT FROM AUTHOR]

Bone repair involves bone resorption through osteoclastogenesis and the stimulation of neovascularization and osteogenesis by endothelial progenitor cells (EPCs). However, the role of EPCs in osteoclastogenesis is unclear. In this study, we assess the effects of EPC‐derived exosomes on the migration and osteoclastic differentiation of primary mouse bone marrow‐derived macrophages (BMMs) in vitro using immunofluorescence, western blotting, RT‐PCR and Transwell assays. We also evaluated the effects of EPC‐derived exosomes on the homing and osteoclastic differentiation of transplanted BMMs in a mouse bone fracture model in vivo. We found that EPCs cultured with BMMs secreted exosomes into the medium and, compared with EPCs, exosomes had a higher expression level of LncRNA‐MALAT1. We confirmed that LncRNA‐MALAT1 directly binds to miR‐124 to negatively control miR‐124 activity. Moreover, overexpression of miR‐124 could reverse the migration and osteoclastic differentiation of BMMs induced by EPC‐derived exosomes. A dual‐luciferase reporter assay indicated that the integrin ITGB1 is the target of miR‐124. Mice treated with EPC‐derived exosome‐BMM co‐transplantations exhibited increased neovascularization at the fracture site and enhanced fracture healing compared with those treated with BMMs alone. Overall, our results suggest that EPC‐derived exosomes can promote bone repair by enhancing recruitment and differentiation of osteoclast precursors through LncRNA‐MALAT1. [ABSTRACT FROM AUTHOR]

Nitrogen‐containing bisphosphonates including alendronate (ALN) are the current first line antiresorptive drug in treating osteoporosis. In our study, we found that ALN administration impaired the secretion of platelet derived growth factor‐BB (PDGF‐BB), the most important angiogenic cytokines produced by preosteoclast (POC), in both sham and ovariectomized (OVX) mice. To further understand this phenomenon, we induced bone marrow macrophages (BMMs) to POCs in vitro and detected the effects of ALN particularly in POCs. The proapoptotic effect of ALN in POCs was confirmed by flow cytometry. On the molecular level, we found that farnesyl diphosphate synthase (FDPS) inhibition of ALN led to peroxisomal dysfunction and up regulation of cytoprotective protein glucose‐regulated protein (GRP) 78. Peroxisomal dysfunction further induced endoplasmic reticulum (ER) stress in POCs and finally resulted in cell apoptosis marked by reduced expression of B‐cell lymphoma 2 (Bcl‐2) and increased expressions of CCAAT/enhancer binding protein homologous protein (CHOP), Bcl2 associated X (Bax), and cleaved caspase‐3. We concluded that ALN has no selectivity in inhibiting POC and mature osteoclast. For POCs, ALN inhibition of FDPS leads to peroxisomal dysfunction, which further mediates ER stress and finally causes cell apoptosis. Considering that decreased angiogenesis is also an important issue in treating osteoporosis, how to preserve pro‐angiogenic POCs while depleting mature osteoclasts is a problem worthy to be solved. [ABSTRACT FROM AUTHOR]

Background/Aims: Tissue engineering bone transplantation with bone marrow mesenchymal stem cells (BMSCs) is an effective technology to treat massive bone loss, while molecular regulation of the bone regeneration processes remains poorly understood. Here, we aimed to assess the role of interleukin-8 (IL-8) in the recruitment of host cells by seeded BMSCs and in the bone regeneration. Methods: A transwell assay was performed to examine the role of IL-8/CXCR1/CXCR2/PI3k/Akt on the migration potential of hBMSCs. The in vitro chondrogenic differentiation of hBMSCs was assessed by examination of 2 chondrogenic markers, Sox9 and type 2 collagen (COL2). mBMSCs were used in tissue engineered bone (TEB) with/without IL-8 implanted into bone defect area with CXCR2 or Akt inhibitors. Density and Masson staining of the regenerated bone were assessed. The chondrogenesis was assessed by expression levels of associated proteins, Sox9 and COL2, by RT-qPCR and by immunohistochemistry. Results: IL-8 may trigger in vitro migration of hBMSCs via CXCR2-mediated PI3k/Akt signaling pathway. IL-8 enhances osteogenesis in the TEB-implanted bone defect in mice. IL-8 induces chondrogenic differentiation of hBMSCs via CXCR2-mediated PI3k/Akt signaling pathway in vitro and in vivo. Conclusions: IL-8 enhances therapeutic effects of MSCs on bone regeneration via CXCR2-mediated PI3k/Akt signaling pathway. [ABSTRACT FROM AUTHOR]

ABSTRACT Tissue-engineered constructs (TECs) seeded with mesenchymal stem cells (MSCs) represent a therapy for large bone defects. However, massive cell death in TECs in the early postimplantation period prompted us to investigate the osteoinductive mechanism of TECs. Previous studies demonstrated that stem cell extracts retained equivalent levels of bioactive proteins and exhibited an osteoinductive nature similar to that of intact cells. These data led us to hypothesize that despite the massive cell death in TECs, devitalized MSC-derived proteins remain on the scaffolds and are released to improve cell function. Here, TECs were prepared using demineralized bone matrix seeded with human umbilical cord Wharton's jelly-derived MSCs (hWJMSCs), and the cells seeded in TECs were devitalized by lyophilizing the TECs. Scanning electron microscopy, BCA protein assays, quantitative cytokine array analysis and immunofluorescent staining indicated that approximately 3 mg/cm3 of total protein and 49 types of cytokines derived from hWJMSCs were preserved in the lyophilized TECs (LTECs). The sustainable release of total protein and cytokines from LTECs lasted for more than 2 weeks. The released protein improved the osteogenic behavior of and gene expression in MSCs. Furthermore, the lyophilized hWJMSC-derived proteins had immunoregulatory properties similar to those of live MSCs in mixed lymphocyte reactions. Collectively, we present a novel perspective on the osteoinductive mechanism of TECs and introduce LTECs as new systems for delivering multiple cytokines to enhance MSC behavior. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:386-394, 2016. [ABSTRACT FROM AUTHOR]

Purpose: This study focuses on nanoscale self-assembly peptides (SAP) modified demineralized bone matrix (DBM) which provided a more effective osteogenesis and regeneration for critically-sized femur defects in goats using the selective cell retention (SCR) strategy. Methods: RADA16-I peptide was used to modify DBM and formed a composite scaffold (SAP/DBM). The morphological change and dynamic expression of osteogenic genes of mesenchymal stem cells (MSCs) derived from marrow in SAP/DBM was observed. The cells and factors in bone marrow were enriched into SAP/DBM by technology of selective cells retension (SCR). The construct was transplanted into 20-mm femur defects in goats and their osteogenesis was evaluated. Results: The SAP/DBM scaffold formed a three-dimensional interweaving nanofiber in pores of DBM. MSCs exhibited better morphology in SAP/DBM than that in only DBM, and the levels of expression of ALP ,OCN and Runx2 gene in SAP/DBM samples was significantly higher than that of DBM at 14 days in vitro ( P < 0.05). Compared with marrow-enriched DBM, the volume of newly formed bone from marrow-enriched SAP/DBM is higher in goats ( P < 0.05). Conclusion: Our study may not only have a significant impact on the construction method of tissue engineering but also provide a viable, simple and effective method for clinical bone construction. [ABSTRACT FROM AUTHOR]

To date, various types of cells for seeding regenerative scaffolds have been used for bone tissue engineering. Among seed cells, the mesenchymal stem cells derived from human umbilical cord Wharton’s jelly (hUCMSCs) represent a promising candidate and hold potential for bone tissue engineering due to the the lack of ethical controversies, accessibility, sourced by non-invasive procedures for donors, a reduced risk of contamination, osteogenic differentiation capacities, and higher immunomodulatory capacity. However, the current culture methods are somewhat complicated and inefficient and often fail to make the best use of the umbilical cord (UC) tissues. Moreover, these culture processes cannot be performed on a large scale and under strict quality control. As a result, only a small quantity of cells can be harvested using the current culture methods. To solve these problems, we designed and evaluated an UC Wharton’s jelly repeated culture device. Using this device, hUCMSCs were obtained from the repeated cultures and their quantities and biological characteristics were compared. We found that using our culture device, which retained all tissue blocks on the bottom of the dish, the total number of obtained cells increased 15–20 times, and the time required for the primary passage was reduced. Moreover, cells harvested from the repeated cultures exhibited no significant difference in their immunophenotype, potential for multilineage differentiation, or proliferative, osteoinductive capacities, and final osteogenesis. The application of the repeated culture frame (RCF) not only made full use of the Wharton’s jelly but also simplified and specified the culture process, and thus, the culture efficiency was significantly improved. In summary, abundant hUCMSCs of dependable quality can be acquired using the RCF. [ABSTRACT FROM AUTHOR]

Background/Aims: Human bone-marrow mesenchymal stem cells (hBMSCs) are widely transplanted into inflammatory microenvironment to accelerate tissue regeneration. Transplanted hBMSCs recruit host hBMSCs through a poorly understood mechanism. This study was aimed to determine whether and how inflammatory microenvironment influenced the host-hBMSCs-recruiting capability of transplanted hBMSCs. Methods: Pro-inflammatory factors, including IL-1β, IL-6 and TNF-α, were utilized to mimic inflammatory microenvironment. hBMSCs were cultured and conditioned media (CM) were collected. The effects of inflammatory microenvironment on the host-hBMSCs-recruiting capability of cultured hBMSCs were revealed by transwell migration assays. Employing semi-quantitative and quantitative cytokine antibody assays, we examined the secretory profile of cultured hBMSCs. Results: CM from cultured hBMSCs exerted excellent host-hBMSCs-recruiting capability, which was significantly promoted by exposure to inflammatory microenvironment. Within inflammatory microenvironment, hBMSCs secreted more chemokines related to cell migration. Finally, 21 cytokines were verified as potential factors accounting for the enhanced host-hBMSCs-recruiting capability of cultured hBMSCs exposed to inflammatory microenvironment. Conclusion: These results strongly suggested that in clinic, inflammatory microenvironment might promote the host-hBMSCs-recruiting capacity of transplanted hBMSCs by increasing chemokines secretion. Modulation of such characteristics of hBMSCs might provide novel therapeutic ideas in the context of hBMSCs. © 2014 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

The antitumor effects of curcumin have attracted widespread attention worldwide. One of its major functions is to induce the apoptosis of tumor cells, but the antitumor mechanism is currently unclear. In the present study, we found that cell mortality and curcumin concentration were dose dependent. Curcumin of low concentrations (10 μΜ) could reduce the level of reactive oxygen species (ROS) in tumor cells, while curcumin of high concentrations (80 μΜ) was able to significantly increase the content of ROS. In addition, Western blotting detection suggested that curcumin of high concentrations can induce the release of Cyto-C and the activation of Caspase-3, and that ROS scavenger NAC apparently inhibits apoptosis protein release and activation, consequently slowing the curcumin-induced apoptosis. Taken together, curcumin further activates the mitochondrial apoptotic pathway by inducing cells to generate ROS and ultimately promotes the apoptosis of tumor cells. [ABSTRACT FROM AUTHOR]

CD4++ T helper (Th) cells act as important regulators of the mammalian adaptive immune response. CD4++ Th cells were originally characterized as either Th1 or Th2 types, based on the cytokines they produce. Over the past two decades, however, we have attained a much more detailed understanding of CD4++ T-cell differentiation, functions, and gene expression profiles, which led to the identification of additional types, such as the Th17 and induced regulatory T cells. Recently, researchers have characterized yet another novel and distinct population that exists among these immune-modulatory cells. The ''Th9'' cells were first identified as a Th2 subpopulation that produced exceptionally large quantities of the Th2-specific cytokine interleukin 9. However, experimental analysis revealed that Th9 cells had divergent regulatory capabilities and were critically involved in different immune processes. In particular, we now know that Th9 acts as a major contributor to the onset and progression of allergies, especially asthma. Here, we will review the heterogeneity and biology of CD4++ Th cells and summarize the characteristics known to date of interleukin 9 and Th9 cells to build a framework for better understanding of their roles in disease processes, especially in allergy-induced asthma. [ABSTRACT FROM AUTHOR]

Tissue-engineered bones (TEB) are a promising strategy for treating large segmental bone defects. However, the application of TEB is greatly limited by technical and logistical issues caused by the viable cells used. The aim of the present study was to devise novel TEB, termed functional TEB (fTEB) using devitalized mesenchymal stem cells (MSCs) with the functional proteins retained. TEB were fabricated by seeding MSCs on demineralized bone matrix (DBM) scaffolds. fTEB were prepared with deep hyperthermia treatment. Total proteins were extracted from fTEB and conditioned media (CM) were prepared. The effects of fTEB-CM on the proliferation, differentiation and migration of host MSCs were assessed. Following lyophilization, the majority of the MSCs were devitalized, but the proteins within the TEB were retained in fTEB. Similar to TEB, fTEB outperformed the DBM in inducing migration, proliferation and osteogenic differentiation in MSCs. The abundance of cytokines in fTEB was also determined. fTEB were shown to be a promising alternative to TEB. Thus, they might serve as off-the-shelf tissue engineering products, meeting the high demands for bone substitutes in the clinical setting. [ABSTRACT FROM AUTHOR]

Carbon starvation is the current leading hypothesis of plant mortality mechanisms under drought stress; recently, it is also used to explain tree die-off in plant diseases. However, the molecular biology of the carbon starvation pathway is unclear. Here, using a punch inoculation system, we conducted transcriptome and physiological assays to investigate pathogen response in poplar stems at the early stages of Botryosphaeria and Valsa canker diseases. Transcriptome assays showed that the majority of differentially expressed genes (DEGs) in stem phloem and xylem, such as genes involved in carbon metabolism and transportation, aquaporin genes (in xylem) and genes related to the biosynthesis of secondary metabolites and the phenylpropanoid pathway (related to lignin synthesis), were downregulated at 7 days after inoculation (DAI). Results also showed that the expression of the majority of disease-resistance genes upregulated in poplar stems, which may be connected with the downregulation expression of the majority of WRKY family genes. Physiological assays showed that transpiration rate decreased but WUE (water use efficiency) increased the 3 and 7 DAI, while the net photosynthetic rate decreased at 11 DAI in Botryosphaeria infected poplars (ANOVA, P < 0.05). The NSC (non-structural carbohydrates) content assays showed that the soluble sugar content of stem phloem samples increased at 3, 7, and 11 DAI that might due to the impede of pathogen infection. However, soluble sugar content of stem xylem and root samples decreased at 11 DAI; in contrast, the starch content unchanged. Therefore, results revealed a chronological order of carbon related molecular and physiological performance: declination of genes involved in carbon and starch metabolism first (at least at 7 DAI), declination of assimilation and carbon reserve (at 11 DAI) second. Results implied a potential mechanism that affects the host carbon reserve, by directly inhibiting the expression of genes involved in carbon metabolism and transport. [ABSTRACT FROM AUTHOR]