Publications by authors named "Yichi Xu"

38 Publications

An anisotropic nanocomposite hydrogel guides aligned orientation and enhances tenogenesis of human tendon stem/progenitor cells.

Biomater Sci 2021 Feb 12;9(4):1237-1245. Epub 2021 Feb 12.

AO Research Institute Davos, Clavadelerstrasse 8, Davos Platz, Switzerland.

The uniform and aligned arrangement of tendon cells is a marker of tendon tissue morphology and the embodiment of its biological anisotropy. However, most of the hydrogels used for tendon tissue engineering do not present anisotropic structures. In this work, a magnetically-responsive nanocomposite hydrogel composed of collagen type I (COL I) and aligned iron oxide nanoparticles (IOPs) was investigated for potential application in tendon tissue engineering. COL I with a mixture of remotely aligned IOPs (A/IOPs) and human tendon stem/progenitor cells (COL I-A/IOPs-hTSPCs) was prepared and the alignment of IOPs was induced under a remote magnetic field. Following the gelation of COL I, a stable and anisotropic nanocomposite COL I-A/IOPs hydrogel was formed. In addition, hTSPCs embedded in COL I with random IOPs (COL I-R/IOPs-hTSPCs) and in pure COL I (COL I-hTSPCs) were used as control groups. Cell viability, proliferation, morphology, cell row formation, and alignment of IOPs and hTSPCs were evaluated over time. In addition, a comprehensive gene expression profile of 48 different genes, including tendon-related genes and lineage/cross-linking genes, was obtained by implementing designer quantitative RT-PCR plates. The hTSPCs morphology followed the orientation of the anisotropic COL I-A/IOPs hydrogel with increased row formation in comparison to pristine COL I and COL-R/IOPs. Moreover, higher proliferation rate and significant upregulation of tendon gene markers were measured in comparison to hTSPCs cultivated in the COL I-R/IOPs and COL I. Thus, we suggest that providing the cells with aligned focal contact points, namely the aligned IOPs, is sufficient to provoke an immense effect on the formation of aligned cell rows. Taken together, we report a novel strategy for directing stem cell behavior without the use of exogenous growth factors or pre-aligned COL I fibers, and propose that anisotropic nanocomposite hydrogels hold great potential for tendon tissue engineering applications.
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http://dx.doi.org/10.1039/d0bm01127dDOI Listing
February 2021

Potential and recent advances of microcarriers in repairing cartilage defects.

J Orthop Translat 2021 Mar 13;27:101-109. Epub 2021 Jan 13.

Institute of Orthopedics/ Beijing Key Laboratory of Regenerative Medicine in Orthopedics/ Key Laboratory of Musculoskeletal Trauma & War Injuries PLA, Chinese PLA General Hospital, Beijing, 100853, China.

Articular cartilage regeneration is one of the challenges faced by orthopedic surgeons. Microcarrier applications have made great advances in cartilage tissue engineering in recent years and enable cost-effective cell expansion, thus providing permissive microenvironments for cells. In addition, microcarriers can be loaded with proteins, factors, and drugs for cartilage regeneration. Some microcarriers also have the advantages of injectability and targeted delivery. The application of microcarriers with these characteristics can overcome the limitations of traditional methods and provide additional advantages. In terms of the transformation potential, microcarriers have not only many advantages, such as providing sufficient and beneficial cells, factors, drugs, and microenvironments for cartilage regeneration, but also many application characteristics; for example, they can be injected to reduce invasiveness, transplanted after microtissue formation to increase efficiency, or combined with other stents to improve mechanical properties. Therefore, this technology has enormous potential for clinical transformation. In this review, we focus on recent advances in microcarriers for cartilage regeneration. We compare the characteristics of microcarriers with other methods for repairing cartilage defects, provide an overview of the advantages of microcarriers, discuss the potential of microcarrier systems, and present an outlook for future development.

Translational Potential Of This Article: We reviewed the advantages and recent advances of microcarriers for cartilage regeneration. This review could give many scholars a better understanding of microcarriers, which can provide doctors with potential methods for treating patients with cartilage injure.
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http://dx.doi.org/10.1016/j.jot.2020.10.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7810913PMC
March 2021

A single-cell analysis of the molecular lineage of chordate embryogenesis.

Sci Adv 2020 Nov 4;6(45). Epub 2020 Nov 4.

Developmental Biology Program, Sloan Kettering Institute, New York, NY 10065, USA.

Progressive unfolding of gene expression cascades underlies diverse embryonic lineage development. Here, we report a single-cell RNA sequencing analysis of the complete and invariant embryonic cell lineage of the tunicate from fertilization to the onset of gastrulation. We reconstructed a developmental landscape of 47 cell types over eight cell cycles in the wild-type embryo and identified eight fate transformations upon fibroblast growth factor (FGF) inhibition. For most FGF-dependent asymmetric cell divisions, the bipotent mother cell displays the gene signature of the default daughter fate. In convergent differentiation of the two notochord lineages, we identified additional gene pathways parallel to the master regulator / Last, we showed that the defined cell types can be matched to E6.5-E8.5 stage mouse cell types and display conserved expression of limited number of transcription factors. This study provides a high-resolution single-cell dataset to understand chordate early embryogenesis and cell lineage differentiation.
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http://dx.doi.org/10.1126/sciadv.abc4773DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7673699PMC
November 2020

Cadherin preserves cohesion across involuting tissues during neurulation.

Elife 2020 10 8;9. Epub 2020 Oct 8.

Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States.

The internalization of the central nervous system, termed neurulation in vertebrates, is a critical step in embryogenesis. Open questions remain regarding how force propels coordinated tissue movement during the process, and little is known as to how internalization happens in invertebrates. We show that in morphogenesis, apical constriction in the retracting pharynx drives involution of the adjacent neuroectoderm. HMR-1/cadherin mediates this process via inter-tissue attachment, as well as cohesion within the neuroectoderm. Our results demonstrate that HMR-1 is capable of mediating embryo-wide reorganization driven by a centrally located force generator, and indicate a non-canonical use of cadherin on the basal side of an epithelium that may apply to vertebrate neurulation. Additionally, we highlight shared morphology and gene expression in tissues driving involution, which suggests that neuroectoderm involution in is potentially homologous with vertebrate neurulation and thus may help elucidate the evolutionary origin of the brain.
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http://dx.doi.org/10.7554/eLife.58626DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7544503PMC
October 2020

The Prognostic Value of the Chromobox Family in Human Ovarian Cancer.

J Cancer 2020 6;11(17):5198-5209. Epub 2020 Jul 6.

Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.

Ovarian cancer is one of the most lethal gynecologic tumors in women and has a poor prognosis. The purpose of our study was to identify new prognostic markers in ovarian cancer. We examined the prognostic roles of mRNA expression of the chromobox (CBX) family in patients with ovarian cancer utilizing the Kaplan-Meier plotter database. The prognostic values and expression levels of CBX members associated with prognosis were further evaluated using KM plotter in diverse subgroups and immunohistochemistry (IHC) analysis in ovarian carcinoma. The results revealed that elevated CBX1-3 mRNA expression may predict poor overall survival (OS) and progression-free survival (PFS) outcomes in patients with ovarian cancer. Notably, in women with ovarian cancer, increased CBX1 mRNA expression was linked to a short OS in all stages and in the grade II and grade III subgroups. Additionally, CBX2 and CBX3 were strongly related to short OS in stage III+IV patients, and a link between high CBX3 mRNA expression and unfavorable OS in grade II patients was observed. High expression levels of CBX1 and CBX3 were significantly associated with chemotherapy resistance in ovarian cancer patients. IHC staining showed that the CBX1-3 proteins were upregulated in serous ovarian carcinoma tissues compared with normal ovarian tissues. Therefore, our results indicated that CBX1-3 could be attractive biomarkers for predicting poor prognosis of ovarian cancer.
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http://dx.doi.org/10.7150/jca.44475DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7378907PMC
July 2020

Effects of propofol on the development of cancer in humans.

Cell Prolif 2020 Aug 29;53(8):e12867. Epub 2020 Jun 29.

Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.

Cancer is one of most the significant threats to human health worldwide, and the primary method of treating solid tumours is surgery. Propofol, one of the most widely used intravenous anaesthetics in surgery, was found to be involved in many cancer-related pathophysiology processes, mainly including anti-tumour and minor cancer-promoting effects in various types of cancer. An increasing number of studies have identified that propofol plays a role in cancer by regulating the expression of multiple signalling pathways, downstream molecules, microRNAs and long non-coding RNAs. Emerging evidence has indicated that propofol can enhance the anti-tumour effect of chemotherapeutic drugs or some small molecular compounds. Additionally, in vivo animal models have shown that propofol inhibits tumour growth and metastasis. Furthermore, most clinical trials indicate that propofol is associated with better survival outcomes in cancer patients after surgery. Propofol use is encouraged in cancers that appear to have a better prognosis after its use during surgery. We hope that future large and prospective multicenter studies will provide more precise answers to guide the choice of anaesthetics during cancer surgery.
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http://dx.doi.org/10.1111/cpr.12867DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7445405PMC
August 2020

Overexpression and biological function of PRDX6 in human cervical cancer.

J Cancer 2020 10;11(9):2390-2400. Epub 2020 Feb 10.

Department of Obstetrics and Gynecology, the Second Affiliated Hospital of Wenzhou Medical University, Wenzhou 325027, China.

: Our previous study demonstrated that the peroxiredoxin 6 (PRDX6) protein was downregulated in squamous cervical cancer samples after neoadjuvant chemotherapy compared with the expression level before chemotherapy. However, the effect of PRDX6 on the biological behavior of cervical cancer is still uncertain. Thus, the purpose of this study was to explore the functional impacts of PRDX6 gene on the biological behavior of cervical squamous cancer cells. : An immunofluorescence assay was applied to evaluate the expression difference of PRDX6 between cervical cancer tissue and normal cervical tissue samples. A lentivirus was used to upregulate and downregulate PRDX6 expression in SiHa cells. Furthermore, the role of PRDX6 on cell proliferation, apoptosis, migration and invasion was evaluated. Additionally, the effect of PRDX6 on the progression of the cervical cancer was investigated via a xenograft model in BALB/c nude mice that either overexpressed or underexpressed PRDX6. : The expression of PRDX6 was generally increased in cervical cancer tissues. Furthermore, the overexpression of PRDX6 stimulated the proliferation, migration and invasion of cervical squamous cancer cells, and suppressed cell apoptosis. The opposite results were also obtained after successful knockdown of PRDX6. In addition, the overexpression of PRDX6 significantly promoted the growth of cervical carcinoma . : PRDX6 promoted the proliferation, migration and invasion, and inhibited apoptosis in cervical cancer cells, indicating that PRDX6 is an important promoter of cervical cancer tumorigenicity.
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http://dx.doi.org/10.7150/jca.39892DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7066013PMC
February 2020

The Role of Inhaled Anesthetics in Tumorigenesis and Tumor Immunity.

Cancer Manag Res 2020 4;12:1601-1609. Epub 2020 Mar 4.

Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, People's Republic of China.

Inhaled anesthetics are widely used for induction and maintenance of anesthesia during surgery, including isoflurane, sevoflurane, desflurane, haloflurane, nitrous oxide (NO), enflurane and xenon. Nowadays, it is controversial whether inhaled anesthetics may influence the tumor progression, which urges us to describe the roles of different inhaled anesthetics in human cancers. In the review, the relationships among the diverse inhaled anesthetics and patient outcomes, immune response and cancer cell biology were discussed. Moreover, the mechanisms of various inhaled anesthetics in the promotion or inhibition of carcinogenesis were also reviewed. In summary, we concluded that several inhaled anesthetics have different immune functions, clinical outcomes and cancer cell biology, which could contribute to opening new avenues for selecting suitable inhaled anesthetics in cancer surgery.
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http://dx.doi.org/10.2147/CMAR.S244280DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7061426PMC
March 2020

The role of the cancer testis antigen PRAME in tumorigenesis and immunotherapy in human cancer.

Cell Prolif 2020 Mar 5;53(3):e12770. Epub 2020 Feb 5.

Departmant of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.

Preferentially expressed antigen in melanoma (PRAME), which belongs to the cancer/testis antigen (CTA) gene family, plays a pivotal role in multiple cellular processes and immunotherapy response in human cancers. PRAME is highly expressed in different types of cancers and is involved in cell proliferation, apoptosis, differentiation and metastasis as well as the outcomes of patients with cancer. In this review article, we discuss the potential roles and physiological functions of PRAME in various types of cancers. Moreover, this review highlights immunotherapeutic strategies that target PRAME in human malignancies. Therefore, the modulation of PRAME might be useful for the treatment of patients with cancer.
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http://dx.doi.org/10.1111/cpr.12770DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7106952PMC
March 2020

Adult Human Glioblastomas Harbor Radial Glia-like Cells.

Stem Cell Reports 2020 02 30;14(2):338-350. Epub 2020 Jan 30.

Department of Neurosurgery, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA. Electronic address:

Radial glia (RG) cells are the first neural stem cells to appear during embryonic development. Adult human glioblastomas harbor a subpopulation of RG-like cells with typical RG morphology and markers. The cells exhibit the classic and unique mitotic behavior of normal RG in a cell-autonomous manner. Single-cell RNA sequencing analyses of glioblastoma cells reveal transcriptionally dynamic clusters of RG-like cells that share the profiles of normal human fetal radial glia and that reside in quiescent and cycling states. Functional assays show a role for interleukin in triggering exit from dormancy into active cycling, suggesting a role for inflammation in tumor progression. These data are consistent with the possibility of persistence of RG into adulthood and their involvement in tumor initiation or maintenance. They also provide a putative cellular basis for the persistence of normal developmental programs in adult tumors.
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http://dx.doi.org/10.1016/j.stemcr.2020.01.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7014025PMC
February 2020

Up-regulation of peroxiredoxin-1 promotes cell proliferation and metastasis and inhibits apoptosis in cervical cancer.

J Cancer 2020 1;11(5):1170-1181. Epub 2020 Jan 1.

Department of Obstetrics and Gynecology, the Second Affiliated Hospital of Wenzhou Medical University, Wenzhou 325027, China.

To investigate the effect of peroxiredoxin 1 (PRDX1) on the biological behavior of cervical cancer cells and the possible mechanism. The expression of PRDX1 in human cervical cancer tissues and adjacent non-tumor tissues were detected by immunohistochemistry (IHC). Lentivirus containing PRDX1-cDNA or shRNA against PRDX1 was constructed to overexpress or knockdown PRDX1 in SiHa cervical cancer cells. Cell proliferation was tested by CCK-8 and BrdU incorporation assay and cell apoptosis was evaluated by AnnexinV-PE /7AAD assay. Scratch wound and transwell invasion assay were used to test migration and invasion activity after PRDX1 was overexpressed or suppressed. Furthermore, the effect of PRDX1 on cell proliferation and apoptosis was also studied using a xenograft model of nude mice. The expression of PRDX1 protein was significantly up-regulated in the tumor tissues compared with the paired adjacent non-tumor tissues. Meanwhile, PRDX1 overexpression was associated with tumor stage, lymphatic metastasis and differentiation. Overexpression of PRDX1 significantly promoted proliferation and inhibited apoptosis by increasing the expression of Nanog, proliferating cell nuclear antigen (PCNA), B-cell lymphoma-2 (Bcl-2) and downregulating the expression of Bcl2-associated X protein (BAX) in SiHa cervical cancer cells. Moreover, PRDX1 overexpression increased invasion and migration of SiHa cervical cancer cells via up-regulating the expression of Snail and matrix metalloprotein 9 (MMP-9) and down-regulating the expression of E-cadherin. Knockdown of PRDX1 resulted in the opposite results. The role of PRDX1 in promoting SiHa cervical cancer cell proliferation and inhibiting apoptosis has also been confirmed in a mouse xenograft model. PRDX1 promoted cell proliferation, migration, and invasion and suppressed apoptosis of cervical cancer possibly via regulating the expression of related protein.
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http://dx.doi.org/10.7150/jca.37147DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6959069PMC
January 2020

The emerging role of SPOP protein in tumorigenesis and cancer therapy.

Mol Cancer 2020 01 4;19(1). Epub 2020 Jan 4.

Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, No. 109 Xueyuan Xi Road, Wenzhou, 325027, Zhejiang, China.

The nuclear speckle-type pox virus and zinc finger (POZ) protein (SPOP), a representative substrate-recognition subunit of the cullin-RING E3 ligase, has been characterized to play a dual role in tumorigenesis and cancer progression. Numerous studies have determined that SPOP suppresses tumorigenesis in a variety of human malignancies such as prostate, lung, colon, gastric, and liver cancers. However, several studies revealed that SPOP exhibited oncogenic function in kidney cancer, suggesting that SPOP could exert its biological function in a cancer type-specific manner. The role of SPOP in thyroid, cervical, ovarian, bone and neurologic cancers has yet to be determined. In this review article, we describe the structure and regulation of SPOP in human cancer. Moreover, we highlight the critical role of SPOP in tumorigenesis based on three major categories: physiological evidence (animal models), pathological evidence (human cancer specimens) and biochemical evidence (downstream ubiquitin substrates). Furthermore, we note that SPOP could be a promising therapeutic target for cancer treatment.
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http://dx.doi.org/10.1186/s12943-019-1124-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6942384PMC
January 2020

The Effects Of Sevoflurane On The Progression And Cisplatinum Sensitivity Of Cervical Cancer Cells.

Drug Des Devel Ther 2019 18;13:3919-3928. Epub 2019 Nov 18.

Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou 325027, People's Republic of China.

Objective: To investigate the effect of sevoflurane on the progression of cervical cancer cells, and to explore its effect on the cisplatinum (DDP) sensitivity in cervical cancer cells and underlying mechanism.

Methods: Siha and Hela cervical cancer cells were cultured and treated with 3% sevoflurane, 10 μmol/L DDP, or the co-treatment of sevoflurane and DDP, respectively. Cell proliferation was evaluated by the CCK8 assay. Cell apoptosis was assessed by flow cytometry. Cell migration was detected by wound healing assay. The expression of B-cell lymphoma-2 (BCL-2), B-cell lymphoma-2 associated X (BAX), Ezrin, matrix metalloproteinase 2 (MMP2), lung resistance-related protein (LRP), multiple drug resistance protein 1 (MRP1), glutathione-S-transferase-π (GST-π), and P glycoprotein (P-gp) protein was determined by Western blotting.

Results: After treated with sevoflurane, cell proliferation and migration rate in Siha and Hela cells were significantly elevated, while cell apoptosis was decreased. In addition, the expression of migration-related protein Ezrin and MMP2 was increased accordingly, apoptotic-related protein BCL-2 expression was also increased while BAX protein expression was decreased after sevoflurane treatment. The proliferation, migration rate, and apoptosis of Siha and Hela cells in sevoflurane plus DDP group were not significantly different with those in DDP group. There was no significant difference in apoptotic-related protein, migration-related protein, and drug resistance-associated proteins expression between DDP treatment group and combined treatment group.

Conclusion: Sevoflurane promotes the progression but has no effect on the cisplatinum sensitivity in cervical cancer cells.
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http://dx.doi.org/10.2147/DDDT.S219788DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6873969PMC
June 2020

Regulation of F-box proteins by noncoding RNAs in human cancers.

Cancer Lett 2019 12 20;466:61-70. Epub 2019 Sep 20.

Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China; Department of Biochemistry and Molecular Biology, School of Laboratory Medicine, Bengbu Medical College, Bengbu, Anhui, 233030, China; Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA. Electronic address:

F-box proteins (FBPs) are proteins containing an F-box domain and are one of three subunits in SKP1-Cullin1-F-box protein (SCF) E3 ligase complexes. Accumulated evidence has shown that FBP regulates tumorigenesis and the progression of human cancer via ubiquitination and degradation of downstream substrates, which can be oncoproteins or tumor suppressors. Emerging evidence has revealed that noncoding RNAs (ncRNAs) govern the expression of FBP in human cancers. Specifically, microRNAs (miRNAs), long ncRNAs (lncRNAs), and circular RNAs (circRNAs) have been shown to govern FBP expression in malignancies. Therefore, in this review article, we discuss how miRNAs target FBPs and participate in tumorigenesis and tumor progression. Moreover, we briefly highlight the role of lncRNAs and circRNAs in the regulation of FBPs in cancer. Therefore, targeting ncRNAs could be a novel approach to regulate FBPs for anticancer therapy.
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http://dx.doi.org/10.1016/j.canlet.2019.09.008DOI Listing
December 2019

Optimization of electrospray fabrication of stem cell-embedded alginate-gelatin microspheres and their assembly in 3D-printed poly(ε-caprolactone) scaffold for cartilage tissue engineering.

J Orthop Translat 2019 Jul 25;18:128-141. Epub 2019 Jun 25.

AO Research Institute Davos, Clavadelerstrasse 8, 7270 Davos Platz, Switzerland.

Objective: Our study reports the optimization of electrospray human bone marrow stromal cell (hBMSCs)-embedded alginate-gelatin (Alg-Gel, same as following) microspheres for the purpose of their assembly in 3D-printed poly(ε-caprolactone) (PCL) scaffold for the fabrication of a mechanically stable and biological supportive tissue engineering cartilage construct.

Methods: The fabrication of the Alg-Gel microspheres using an electrospray technique was optimized in terms of polydispersity, yield of microspheres and circularity and varying fabrication conditions. PCL scaffolds were designed and printed by melt extrusion. Then, four groups were set: Alg-hBMSC microspheres cultured in the 2D well plate (Alg-hBMSCs+2D) group, Alg-Gel-hBMSC microspheres cultured in the 2D well plate (Alg-Gel-hBMSCs+2D) group, Alg-Gel-hBMSC microspheres embedded in PCL scaffold cultured in the 2D well plate (Alg-Gel-hBMSCs+2D) group and Alg-Gel-hBMSCs microspheres cultured in the 3D bioreactor (Alg-Gel-hBMSCs+3D) group. Cell viability, proliferation and chondrogenic differentiation were evaluated, and mechanical test was performed.

Results: Nonaggregated, low polydispersity and almost spherical microspheres of average diameter of 200-300 μm were produced with alginate 1.5 w: v%, gelatin (Type B) concentration of 0.5 w: v % and CaCl coagulating bath concentration of 3.0 w: v %, using 30G needle size and 8 kV and 0.6 bar voltage and air pressure, respectively. Alginate with gelatin hydrogel improved viability and promoted hBMSC proliferation better than alginate microspheres. Interestingly, hBMSCs embedded in microspheres assembled in 3D-printed PCL scaffold and cultured in a 3D bioreactor were more proliferative in comparison to the previous two groups (p < 0.05). Similarly, the GAG content, GAG/DNA ratio as well as Coll 2 and Aggr gene expression were increased in the last two groups.

Conclusion: Optimization of hBMSC-embedded Alg-Gel microspheres produced by electrospray has been performed. The Alg-Gel composition selected allows conservation of hBMSC viability and supports proliferation and matrix deposition. The possibility to seed and assemble microspheres in designed 3D-printed PCL scaffolds for the fabrication of a mechanically stable and biological supportive tissue engineering cartilage construct was demonstrated.

Translational Potential Of This Article: We optimize and demonstrate that electrospray microsphere fabrication is a cytocompatible and facile process to produce the hBMSC-embedded microsize tissue-like particles that can easily be assembled into a stable construct. This finding could have application in the development of mechanically competent stem cell-based tissue engineering of cartilage regeneration.
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http://dx.doi.org/10.1016/j.jot.2019.05.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6718928PMC
July 2019

Human amnion mesenchymal stem cells attenuate atherosclerosis by modulating macrophage function to reduce immune response.

Int J Mol Med 2019 Oct 23;44(4):1425-1435. Epub 2019 Jul 23.

Department of Geriatric Cardiology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China.

Mesenchymal stem cells (MSCs) show immunosuppressive activities and alleviate atherosclerosis (AS) formation in apolipoprotein E‑knockout (apoE‑KO) mice. Human amnion mesenchymal stem cells (hAMSCs), a particular population of mesenchymal stem cells, have been shown to have immunomodulatory abilities. The present study investigated the effects of hAMSCs treatment on early atherosclerotic plaque formation and the progression of established lesion in apoE‑KO mice. In total, 36 mice were fed with a high‑fat diet. Mice were subjected to hAMSCs‑injection treatment simultaneously with high‑fat diet (early treatment) or after 8 weeks of high‑fat diet (delayed treatment). In each treatment, mice were divided into three groups: i) hAMSCs group with hAMSCs treatment; ii) PBS group injected with PBS; and iii) control group without injection. Histological results showed that the plaque area in the aortic arch of mice was significantly reduced after hAMSCs treatment in the early and delayed treatment groups. In addition, immunohistochemical analysis suggested that the accumulation of macrophages was significantly decreased after hAMSCs treatment. Similarly, the release of the pro‑inflammatory cytokine tumor necrosis factor‑α was also decreased, whereas the release of the anti‑inflammatory cytokine interleukin‑10 was increased. In addition, hAMSCs treatment suppressed the phosphorylation of p65 and inhibitor of κB‑α, suggesting that NF‑κB pathway was involved in the hAMSCs‑mediated suppression of immune response. In conclusion, hAMSCs treatment was effective in reducing immune response, which is the one of the major causes of AS, eventually leading to a significant reduction in size of atherosclerotic lesions.
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http://dx.doi.org/10.3892/ijmm.2019.4286DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6713407PMC
October 2019

The IRE1 endoplasmic reticulum stress sensor activates natural killer cell immunity in part by regulating c-Myc.

Nat Immunol 2019 07 13;20(7):865-878. Epub 2019 May 13.

Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, USA.

Natural killer (NK) cells are critical mediators of host immunity to pathogens. Here, we demonstrate that the endoplasmic reticulum stress sensor inositol-requiring enzyme 1 (IRE1α) and its substrate transcription factor X-box-binding protein 1 (XBP1) drive NK cell responses against viral infection and tumors in vivo. IRE1α-XBP1 were essential for expansion of activated mouse and human NK cells and are situated downstream of the mammalian target of rapamycin signaling pathway. Transcriptome and chromatin immunoprecipitation analysis revealed c-Myc as a new and direct downstream target of XBP1 for regulation of NK cell proliferation. Genetic ablation or pharmaceutical blockade of IRE1α downregulated c-Myc, and NK cells with c-Myc haploinsufficency phenocopied IRE1α-XBP1 deficiency. c-Myc overexpression largely rescued the proliferation defect in IRE1α NK cells. Like c-Myc, IRE1α-XBP1 also promotes oxidative phosphorylation in NK cells. Overall, our study identifies a IRE1α-XBP1-cMyc axis in NK cell immunity, providing insight into host protection against infection and cancer.
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http://dx.doi.org/10.1038/s41590-019-0388-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6588410PMC
July 2019

Diagnosis and treatment of traumatic vascular injury of limbs in military and emergency medicine: A systematic review.

Medicine (Baltimore) 2019 May;98(18):e15406

Institute of Orthopedics, Chinese PLA General Hospital, Beijing Key Laboratory (No BZ0128), Beijing Key Lab of Regenerative Medicine in Orthopedics, Key Laboratory of Musculoskeletal Trauma and War Injuries, PLA, Beijing, China.

Background: Traumatic vascular injury is caused by explosions and projectiles (bullets and shrapnel); it may affect the arteries and veins of the limbs, and is common in wartime, triggering bleeding, and ischemia. The increasing use of high-energy weapons in modern warfare is associated with severe vascular injuries.

Methods: To summarize the current evidence of diagnosis and treatment for traumatic vascular injury of limbs, for saving limbs and lives, and put forward some new insights, we comprehensively consulted literatures and analyzed progress in injury diagnosis and wound treatment, summarized the advanced treatments now available, especially in wartime, and explored the principal factors in play in an effort to optimize clinical outcomes.

Results: Extremity vascular trauma poses several difficult dilemmas in diagnosis and treatment. The increasing use of high-energy weapons in modern warfare is associated with severe vascular injuries. Any delay in treatment may lead to loss of limbs or death. The development of diagnose and treat vascular injury of extremities are the clinical significance to the tip of military medicine, such as the use of fast, cheap, low invasive diagnostic methods, repairing severe vascular injury as soon as possible, using related technologies actively (fasciotomy, etc).

Conclusion: We point out the frontier of the diagnosis and treatment of traumatic vascular injury, also with a new model of wartime injury treatment in American (forward surgical teams and combat support hospitals), French military surgeons regarding management of war-related vascular wounds and Chinese military ("3 districts and 7 grades" model). Many issues remain to be resolved by further experience and investigation.
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http://dx.doi.org/10.1097/MD.0000000000015406DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6504268PMC
May 2019

Cellular structure image classification with small targeted training samples.

IEEE Access 2019 9;7:148967-148974. Epub 2019 Sep 9.

Developmental Biology Program, Sloan Kettering Institute, New York, NY 10065, USA.

Cell shapes provide crucial biological information on complex tissues. Different cell types often have distinct cell shapes, and collective shape changes usually indicate morphogenetic events and mechanisms. The identification and detection of collective cell shape changes in an extensive collection of 3D time-lapse images of complex tissues is an important step in assaying such mechanisms but is a tedious and time-consuming task. Machine learning provides new opportunities to automatically detect cell shape changes. However, it is challenging to generate sufficient training samples for pattern identification through deep learning because of a limited amount of images and annotations. We present a deep learning approach with minimal well-annotated training samples and apply it to identify multicellular rosettes from 3D live images of the embryo with fluorescently labeled cell membranes. Our strategy is to combine two approaches, namely, feature transfer and generative adversarial networks (GANs), to boost image classification with small training samples. Specifically, we use a GAN framework and conduct an unsupervised training to capture the general characteristics of cell membrane images with 11,250 unlabelled images. We then transfer the structure of the GAN discriminator into a new Alex-style neural network for further learning with several dozen labeled samples. Our experiments showed that with 10-15 well-labeled rosette images and 30-40 randomly selected nonrosette images our approach can identify rosettes with more than 80% accuracy and capture more than 90% of the model accuracy achieved with a training data et that is five times larger. We also established a public benchmark dataset for rosette detection. This GAN-based transfer approach can be applied to the study of other cellular structures with minimal training samples.
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http://dx.doi.org/10.1109/access.2019.2940161DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7442139PMC
September 2019

Functional tissue-engineered microtissue derived from cartilage extracellular matrix for articular cartilage regeneration.

Acta Biomater 2018 09 18;77:127-141. Epub 2018 Jul 18.

Institute of Orthopaedics, Chinese PLA General Hospital, Beijing Key Lab of Regenerative Medicine in Orthopaedics, Key Laboratory of Musculoskeletal Trauma & War Injuries, PLA, No. 28 Fuxing Road, Beijing 100853, PR China. Electronic address:

We developed a promising cell carrier prepared from articular cartilage slices, designated cartilage extracellular matrix (ECM)-derived particles (CEDPs), through processes involving physical pulverization, size screening, and chemical decellularization. Rabbit articular chondrocytes (ACs) or adipose-derived stem cells (ASCs) rapidly attached to the surface of the CEDPs and proliferated with high cell viability under microgravity (MG) condition in a rotary cell culture system (RCCS) or static condition. Gene profiling results demonstrated that ACs expanded on CEDPs exhibited significantly enhanced chondrogenic phenotypes compared with monolayer culture, and that ASCs differentiated into a chondrogenic phenotype without the use of exogenous growth factors. Moreover, MG culture conditions in a RCCS bioreactor were superior to static culture conditions in terms of maintaining the chondrogenic phenotype of ACs and inducing ACS chondrogenesis. With prolonged expansion, functional microtissue aggregates of AC- or ASC-laden CEDPs were formed. Further, AC- or ASC-based microtissues were directly implanted in vivo to repair articular osteochondral defects in a rabbit model. Histological results, biomechanical evaluations, and radiographic assessments indicated that AC- and ASC-based microtissues displayed equal levels of superior hyaline cartilage repair, whereas the other two treatment groups, in which osteochondral defects were treated with CEDPs alone or fibrin glue, exhibited primarily fibrous tissue repair. These findings provide an alternative method for cell culture and stem cell differentiation and a promising strategy for constructing tissue-engineered cartilage microtissues for cartilage regeneration.

Statement Of Significance: Despite the remarkable progress in cartilage tissue engineering, cartilage repair still remains elusive. In the present study, we developed a cell carrier, namely cartilage extracellular matrix-derived particles (CEDPs), for cell proliferation of articular chondrocytes (ACs) and adipose-derived stem cells (ASCs), which improved the maintenance of chondrogenic phenotype of ACs, and induced chondrogenesis of ASCs. Moreover, the functional microtissue aggregates of AC- or ASC-laden CEDPs induced equal levels of superior hyaline cartilage repair in a rabbit model. Therefore, our study demonstrated an alternative method for chondrocyte culture and stem cell differentiation, and a promising strategy for constructing tissue-engineered cartilage microtissues for in vivo articular cartilage repair and regeneration.
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http://dx.doi.org/10.1016/j.actbio.2018.07.031DOI Listing
September 2018

Deep reinforcement learning of cell movement in the early stage of C.elegans embryogenesis.

Bioinformatics 2018 09;34(18):3169-3177

Developmental Biology Program, Sloan-Kettering Institute, New York, NY, USA.

Motivation: Cell movement in the early phase of Caenorhabditis elegans development is regulated by a highly complex process in which a set of rules and connections are formulated at distinct scales. Previous efforts have demonstrated that agent-based, multi-scale modeling systems can integrate physical and biological rules and provide new avenues to study developmental systems. However, the application of these systems to model cell movement is still challenging and requires a comprehensive understanding of regulatory networks at the right scales. Recent developments in deep learning and reinforcement learning provide an unprecedented opportunity to explore cell movement using 3D time-lapse microscopy images.

Results: We present a deep reinforcement learning approach within an agent-based modeling system to characterize cell movement in the embryonic development of C.elegans. Our modeling system captures the complexity of cell movement patterns in the embryo and overcomes the local optimization problem encountered by traditional rule-based, agent-based modeling that uses greedy algorithms. We tested our model with two real developmental processes: the anterior movement of the Cpaaa cell via intercalation and the rearrangement of the superficial left-right asymmetry. In the first case, the model results suggested that Cpaaa's intercalation is an active directional cell movement caused by the continuous effects from a longer distance (farther than the length of two adjacent cells), as opposed to a passive movement caused by neighbor cell movements. In the second case, a leader-follower mechanism well explained the collective cell movement pattern in the asymmetry rearrangement. These results showed that our approach to introduce deep reinforcement learning into agent-based modeling can test regulatory mechanisms by exploring cell migration paths in a reverse engineering perspective. This model opens new doors to explore the large datasets generated by live imaging.

Availability And Implementation: Source code is available at https://github.com/zwang84/drl4cellmovement.

Supplementary Information: Supplementary data are available at Bioinformatics online.
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http://dx.doi.org/10.1093/bioinformatics/bty323DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6137980PMC
September 2018

Quantifying the degradation of degradable implants and bone formation in the femoral condyle using micro-CT 3D reconstruction.

Exp Ther Med 2018 Jan 30;15(1):93-102. Epub 2017 Oct 30.

Institute of Orthopedics, Chinese PLA General Hospital, Beijing 100853, P.R. China.

Degradation limits the application of magnesium alloys, and evaluation methods for non-traumatic quantification of implant degradation and bone formation are imperfect. In the present study, a micro-arc-oxidized AZ31 magnesium alloy was used to evaluate the degradation of implants and new bone formation in 60 male New Zealand white rabbits. Degradation was monitored by weighing the implants prior to and following implantation, and by performing micro-computed tomography (CT) scans and histological analysis after 1, 4, 12, 24, 36, and 48 weeks of implantation. The results indicated that the implants underwent slow degradation in the first 4 weeks, with negligible degradation in the first week, followed by significantly increased degradation during weeks 12-24 (P<0.05), and continued degradation until the end of the 48-week experimental period. The magnesium content decreased as the implant degraded (P<0.05); however, the density of the material exhibited almost no change. Micro-CT results also demonstrated that pin volume, pin mineral density, mean 'pin thickness', bone surface/bone volume and trabecular separation decreased over time (P<0.05), and that the pin surface area/pin volume, bone volume fraction, trabecular thickness, trabecular number and tissue mineral density increased over time (P<0.05), indicating that the number of bones and density of new bone increased as magnesium degraded. These results support the positive effect of magnesium on osteogenesis. However, from the maximum inner diameter of the new bone loop and diameter of the pin in the same position, the magnesium alloy was not capable of creating sufficient bridges between the bones and biomaterials when there were preexisting gaps. Histological analyses indicated that there were no inflammatory responses around the implants. The results of the present study indicate that a micro-arc-oxidized AZ31 magnesium alloy is safe and efficiently degraded. Furthermore, the novel bone formation increased as the implant degraded. The findings concluded that micro-CT, which is useful for providing non-traumatic, , quantitative and precise data, has great value for exploring the degradation of implants and novel bone formation.
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http://dx.doi.org/10.3892/etm.2017.5389DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5766073PMC
January 2018

Mediator MED23 Links Pigmentation and DNA Repair through the Transcription Factor MITF.

Cell Rep 2017 Aug;20(8):1794-1804

State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China; School of Life Science and Technology, ShanghaiTech University, 100 Haike Road, Shanghai 201210, China. Electronic address:

DNA repair is related to many physiological and pathological processes, including pigmentation. Little is known about the role of the transcriptional cofactor Mediator complex in DNA repair and pigmentation. Here, we demonstrate that Mediator MED23 plays an important role in coupling UV-induced DNA repair to pigmentation. The loss of Med23 specifically impairs the pigmentation process in melanocyte-lineage cells and in zebrafish. Med23 deficiency leads to enhanced nucleotide excision repair (NER) and less DNA damage following UV radiation because of the enhanced expression and recruitment of NER factors to chromatin for genomic stability. Integrative analyses of melanoma cells reveal that MED23 controls the expression of a melanocyte master regulator, Mitf, by modulating its distal enhancer activity, leading to opposing effects on pigmentation and DNA repair. Collectively, the Mediator MED23/MITF axis connects DNA repair to pigmentation, thus providing molecular insights into the DNA damage response and skin-related diseases.
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http://dx.doi.org/10.1016/j.celrep.2017.07.056DOI Listing
August 2017

A class of circadian long non-coding RNAs mark enhancers modulating long-range circadian gene regulation.

Nucleic Acids Res 2017 Jun;45(10):5720-5738

Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.

Circadian rhythm exerts its influence on animal physiology and behavior by regulating gene expression at various levels. Here we systematically explored circadian long non-coding RNAs (lncRNAs) in mouse liver and examined their circadian regulation. We found that a significant proportion of circadian lncRNAs are expressed at enhancer regions, mostly bound by two key circadian transcription factors, BMAL1 and REV-ERBα. These circadian lncRNAs showed similar circadian phases with their nearby genes. The extent of their nuclear localization is higher than protein coding genes but less than enhancer RNAs. The association between enhancer and circadian lncRNAs is also observed in tissues other than liver. Comparative analysis between mouse and rat circadian liver transcriptomes showed that circadian transcription at lncRNA loci tends to be conserved despite of low sequence conservation of lncRNAs. One such circadian lncRNA termed lnc-Crot led us to identify a super-enhancer region interacting with a cluster of genes involved in circadian regulation of metabolism through long-range interactions. Further experiments showed that lnc-Crot locus has enhancer function independent of lnc-Crot's transcription. Our results suggest that the enhancer-associated circadian lncRNAs mark the genomic loci modulating long-range circadian gene regulation and shed new lights on the evolutionary origin of lncRNAs.
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http://dx.doi.org/10.1093/nar/gkx156DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5449593PMC
June 2017

AMECM/DCB scaffold prompts successful total meniscus reconstruction in a rabbit total meniscectomy model.

Biomaterials 2016 12 28;111:13-26. Epub 2016 Sep 28.

Key Lab of Musculoskeletal Trauma&War Injuries, PLA, Beijing Key Lab of Regenerative Medicine in Orthopedics, Chinese PLA General Hospital, Beijing, 100853, China. Electronic address:

Tissue-engineered meniscus regeneration is a very promising treatment strategy for meniscus lesions. However, generating the scaffold presents a huge challenge for meniscus engineering as this has to meet particular biomechanical and biocompatibility requirements. In this study, we utilized acellular meniscus extracellular matrix (AMECM) and demineralized cancellous bone (DCB) to construct three different types of three-dimensional porous meniscus scaffold: AMECM, DCB, and AMECM/DCB, respectively. We tested the scaffolds' physicochemical characteristics and observed their interactions with meniscus fibrochondrocytes to evaluate their cytocompatibility. We implanted the three different types of scaffold into the medial knee menisci of New Zealand rabbits that had undergone total meniscectomy; negative control rabbits received no implants. The reconstructed menisci and corresponding femoral condyle and tibial plateau cartilage were all evaluated at 3 and 6 months (n = 8). The in vitro study demonstrated that the AMECM/DCB scaffold had the most suitable biomechanical properties, as this produced the greatest compressive and tensile strength scores. The AMECM/DCB and AMECM scaffolds facilitated fibrochondrocyte proliferation and the secretion of collagen and glycosaminoglycans (GAGs) more effectively than did the DCB scaffold. The in vivo experiments demonstrated that both the AMECM/DCB and DCB groups had generated neomeniscus at both 3 and 6 months post-implantation, but there was no obvious meniscus regeneration in the AMECM or control groups, so the neomeniscus analysis could not perform on AMECM and control group. At both 3 and 6 months, histological scores were better for regenerated menisci in the AMECM/DCB than in the DCB group, and significantly better for articular cartilage in the AMECM/DCB group compared with the other three groups. Knee MRI scores (Whole-Organ Magnetic Resonance Imaging Scores (WORMS)) were better in the AMECM/DCB group than in the other three groups at both 3 and 6 months. At both 3 and 6 months, RT-PCR demonstrated that aggrecan, Sox9, and collagen II content was significantly higher, and mechanical testing demonstrated greater tensile strength, in the AMECM/DCB group neomenisci compared with the DCB group.
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http://dx.doi.org/10.1016/j.biomaterials.2016.09.017DOI Listing
December 2016

[In vivo degradation of magnesium alloys and poly (lactic-co-glycolic acid) and degradation evaluation of magnesium alloys using micro-ct].

Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi 2016 Jul;30(7):885-891

Institute of Orthopedics, Beijing Key Laboratory, Key Laboratory of Musculoskeletal Trauma & War Injuries of PLA, General Hospital of Chinese PLA, Beijing, 100853, P. R. China.

Objective: ?To explore the degradation of AZ31 magnesium alloy and poly (lactic-co-glycolic acid) (PLGA) in the femoral condyle, and then evaluate the laws of degradation of AZ31 magnesium alloy by Micro-CT images and data.

Methods: ?Forty 3-month-old male New Zealand white rabbits (weighing, 2.5 kg) were randomly divided into 4 groups, 10 rabbits each group. Forty micro-arc-oxidized AZ31 magnesium alloy pins and 40 PLGA pins were implanted into the right and left femoral condyle, respectively. Micro-CT images and data analysis were used to evaluate the degradation at 4, 8, 12, and 16 weeks after operation (n=10). Degradation was evaluated by weight difference between pre-and post-implantation. The inflammatory response was observed around the implants by HE staining. The weight loss of magnesium alloy and Micro-CT results were compared.

Results: ?The Micro-CT images showed that PLGA pins had gray low signal, which was similar to the soft tissue around. At 4 weeks after operation, no signs of degradation were observed, and there were little corrosion pitting on the magnesium alloy. At 8 weeks, corrosion pitting gradually expanded, the boundary between the longitudinal axis and the cross section became blurred; at 16 weeks, corrosion pitting became bigger, and the boundary was discontinuous. Micro-CT quantitative analysis showed that the volume fraction of magnesium pins decreased slowly at 4 and 8 weeks; it was significantly lower at 12 and 16 weeks than 4 and 8 weeks (P<0.05). The magnesium cylinder mineral density continuously decreased during the study period, it had a rapidly speed from 12 to 16 weeks (P<0.05). However, the magnesium CT image density showed a slight change (P>0.05). The surface-to-volume ratio of the pins constantly increased, and the ratio was significantly larger at 12 and 16 weeks than 4 and 8 weeks, and at 16 weeks than 12 weeks (P<0.05). There was more and more corrosion pitting on the surface with time, which resulted in a decrease in the radius that mean trabecular thickness gradually decreased, showing significant difference between different time points after 8 weeks (P<0.05). The weight loss detection showed that the degradation of magnesium pin and PLGA gradually increased with time (P<0.05), and the degradation rate of magnesium pin was significantly lower than that of PLGA at 8-12 weeks (P<0.05), but the degradation rate of magnesium pin was higher than that of PLGA at 16 weeks. At each time point, the weight loss of magnesium alloy was similar to that by Micro-CT, but mass fraction was lower than volume fraction and had significant differences at 8, 12, and 16 weeks (P<0.05). HE staining revealed that slight inflammatory response was observed around the magnesium pins at 4 weeks, and inflammatory reaction gradually reduced with time and disappeared at 16 weeks, but no inflammatory reaction was seen around PLGA.

Conclusions: ?Micro-CT has the advantages of non-trauma, in vivo detection, quantitative analysis, and precise data in evaluating the degradation of AZ31 magnesium alloy. Regarding the degradation of the magnesium alloy and PLGA in vivo, the degradation rate is slow in the early stage, and then increases with time. The degradation of PLGA is faster and earlier but it is then overtaken by AZ31 magnesium alloy at 16 weeks. During the degradation, the density of the magnesium has almost no change. The biomaterials can not firmly attach to the surrounding tissues due to inadequate holding forces.
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http://dx.doi.org/10.7507/1002-1892.20160179DOI Listing
July 2016

Long-Range Chromosome Interactions Mediated by Cohesin Shape Circadian Gene Expression.

PLoS Genet 2016 05 2;12(5):e1005992. Epub 2016 May 2.

CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.

Mammalian circadian rhythm is established by the negative feedback loops consisting of a set of clock genes, which lead to the circadian expression of thousands of downstream genes in vivo. As genome-wide transcription is organized under the high-order chromosome structure, it is largely uncharted how circadian gene expression is influenced by chromosome architecture. We focus on the function of chromatin structure proteins cohesin as well as CTCF (CCCTC-binding factor) in circadian rhythm. Using circular chromosome conformation capture sequencing, we systematically examined the interacting loci of a Bmal1-bound super-enhancer upstream of a clock gene Nr1d1 in mouse liver. These interactions are largely stable in the circadian cycle and cohesin binding sites are enriched in the interactome. Global analysis showed that cohesin-CTCF co-binding sites tend to insulate the phases of circadian oscillating genes while cohesin-non-CTCF sites are associated with high circadian rhythmicity of transcription. A model integrating the effects of cohesin and CTCF markedly improved the mechanistic understanding of circadian gene expression. Further experiments in cohesin knockout cells demonstrated that cohesin is required at least in part for driving the circadian gene expression by facilitating the enhancer-promoter looping. This study provided a novel insight into the relationship between circadian transcriptome and the high-order chromosome structure.
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http://dx.doi.org/10.1371/journal.pgen.1005992DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4852938PMC
May 2016

Mediator MED23 cooperates with RUNX2 to drive osteoblast differentiation and bone development.

Nat Commun 2016 Apr 1;7:11149. Epub 2016 Apr 1.

State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China.

How lineage specifiers are regulated during development is an outstanding question, and the molecular regulation of osteogenic factor RUNX2 remains to be fully understood. Here we report that the Mediator subunit MED23 cooperates with RUNX2 to regulate osteoblast differentiation and bone development. Med23 deletion in mesenchymal stem cells or osteoblast precursors results in multiple bone defects similar to those observed in Runx2(+/-) mice. In vitro, Med23-deficient progenitor cells are refractory to osteoblast differentiation, and Med23 deficiency reduces Runx2-target gene activity without changing Runx2 expression. Mechanistically, MED23 binds to RUNX2 and modulates its transcriptional activity. Moreover, Med23 deficiency in osteoprogenitor cells exacerbates the skeletal abnormalities observed in Runx2(+/-) mice. Collectively, our results establish a genetic and physical interaction between RUNX2 and MED23, suggesting that MED23 constitutes a molecular node in the regulatory network of anabolic bone formation and related diseases.
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http://dx.doi.org/10.1038/ncomms11149DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4821994PMC
April 2016

Induction of mesenchymal stem cell chondrogenic differentiation and functional cartilage microtissue formation for in vivo cartilage regeneration by cartilage extracellular matrix-derived particles.

Acta Biomater 2016 Mar 21;33:96-109. Epub 2016 Jan 21.

Institute of Orthopedics, Chinese PLA General Hospital, 28th Fuxing Road, Beijing 100850, PR China.

Unlabelled: We propose a method of preparing a novel cell carrier derived from natural cartilage extracellular matrix (ECM), designated cartilage ECM-derived particles (CEDPs). Through a series of processes involving pulverization, sieving, and decellularization, fresh cartilage was made into CEDPs with a median diameter of 263 ± 48 μm. Under microgravity culture conditions in a rotary cell culture system (RCCS), bone marrow stromal cells (BMSCs) can proliferate rapidly on the surface of CEDPs with high viability. Histological evaluation and gene expression analysis indicated that BMSCs were differentiated into mature chondrocytes after 21 days of culture without the use of exogenous growth factors. Functional cartilage microtissue aggregates of BMSC-laden CEDPs formed as time in culture increased. Further, the microtissue aggregates were directly implanted into trochlear cartilage defects in a rat model (CEDP+MSC group). Gait analysis and histological results indicated that the CEDP+MSC group obtained better and more rapid joint function recovery and superior cartilage repair compared to the control groups, in which defects were treated with CEDPs alone or only fibrin glue, at both 6 and 12 weeks after surgery. In conclusion, the innovative cell carrier derived from cartilage ECM could promote chondrogenic differentiation of BMSCs, and the direct use of functional cartilage microtissue facilitated cartilage regeneration. This strategy for cell culture, stem cell differentiation and one-step surgery using cartilage microtissue for cartilage repair provides novel prospects for cartilage tissue engineering and may have further broad clinical applications.

Statement Of Significance: We proposed a method to prepare a novel cell carrier derived from natural cartilage ECM, termed cartilage ECM-derived particles (CEDPs), which can support proliferation of MSCs and facilitate their chondrogenic differentiation. Further, the direct use of functional cartilage microtissue of MSC-laden CEDP aggregates for cartilage repair in vivo induced hyaline-like articular cartilage repair. This strategy for cell culture, stem cell differentiation and the one-step surgery for cartilage repair provide novel prospects for cartilage tissue engineering and may have further broad clinical applications.
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http://dx.doi.org/10.1016/j.actbio.2016.01.024DOI Listing
March 2016