Modulation of osteogenic properties of biodegradable polymer/extracellular matrix scaffolds generated with a flow perfusion bioreactor

In this study, composite scaffolds consisting of both synthetic and natural components with controllable properties were generated by incorporating mineralized extracellular matrix (ECM) and electrospun poly(ε-caprolactone) (PCL) microfiber scaffolds. Mesenchymal stem cells (MSCs) were cultured on PCL scaffolds under flow perfusion conditions with culture medium supplemented with dexamethasone to investigate the effect of culture duration on mineralized extracellular matrix deposition. MSCs differentiated down the osteogenic lineage and produced extracellular matrix with different compositions of mineral, collagen, and glycosaminoglycan with distinct morphologies at various stages of osteogenesis. To determine whether the presence and maturity of mineralized extracellular matrix influences osteogenic differentiation in vitro, PCL/ECM constructs were decellularized to yield PCL/ECM composite scaffolds that were subsequently seeded with MSCs and cultured in the absence of dexamethasone. The presence of mineralized matrix reduced cellular proliferation while stimulating alkaline phosphatase activity with increasing amounts of calcium deposition over time. PCL/ECM composite scaffolds containing the most mature mineralized matrix resulted in the most rapid increase and highest levels of alkaline phosphatase activity and calcium deposition compared to all other scaffold groups. Therefore, we demonstrate that mineralized extracellular matrix generated under controlled flow perfusion conditions can impart osteogenic properties to an osteoconductive polymer scaffold, and that the maturity of this matrix influences osteogenic differentiation in vitro, even in the absence of dexamethasone.     

Prenatal diagnosis using array-CGH: A French experience

Array-CGH or Chromosomal Microarray Analysis (CMA) is increasingly used in prenatal diagnosis throughout the world. However, routine practices are very different among centers and countries, regarding CMA indications, design and resolution of microarrays, notification and interpretation of Copy Number Alterations (CNA). We present our data and experience from our Fetal Medicine Center on 224 prospective prenatal diagnoses. Our approach is practical, and aims to propose a strategy to offer Chromosomal Microarray Analysis (CMA) to selected fetuses and to help to interpret CNA. We hope that this publication could encourage development of CMA in centers that have not started yet this activity in prenatal routine, and could contribute to edict guidelines in this field.     

Epithelial TLR4 Signaling Activates DUOX2 to Induce Microbiota-Driven Tumorigenesis

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Skeletal characteristics associated with homozygous and heterozygous WNT1 mutations

Recent reports have shown that homozygous or compound heterozygous mutations in WNT1 can give rise to severe bone fragility resembling osteogenesis imperfecta, whereas heterozygous WNT1 mutations have been found in adults with dominant early-onset osteoporosis. Here we assessed the effects of WNT1 mutations in four children with recessive severe bone fragility and in heterozygous family members. In vitro studies using the Topflash luciferase reporter system showed that two WNT1 missense mutations that were observed in these families, p.Cys143Phe and p.Val355Phe, decreased the ability of WNT1 to stimulate WNT signaling by > 90%. Analyses of iliac bone samples revealed no major abnormalities in bone mineralization density distribution, an indicator of material bone properties, whereas a shift towards higher bone mineralization density is characteristic of classical osteogenesis imperfecta caused by mutations in COL1A1/COL1A2. Intravenous bisphosphonate treatment of four children with homozygous or compound heterozygous WNT1 mutations was associated with increasing lumbar spine areal bone mineral density z-scores, as measured by dual energy X-ray absorptiometry, but the effect was smaller than what had previously been reported for children with classical osteogenesis imperfecta. Family members with heterozygous WNT1 mutation tended to have low bone mass. Three of these heterozygous individuals had radiographic signs of vertebral fractures. These observations suggest that more effective treatment approaches are needed for children with recessive WNT1-related bone fragility and that a systematic work-up for osteoporosis is warranted for WNT1 mutation carriers in these families.     

T cell repertoire in DQ5-positive MuSK-positive myasthenia gravis patients

Myasthenia gravis (MG) is a prototypical antibody-mediated disease characterized by muscle weakness and fatigability. Serum antibodies to the acetylcholine receptor and muscle-specific tyrosine kinase receptor (MuSK) are found in about 85% and 8% of patients respectively. We have previously shown that more than 70% of MG patients with MuSK antibodies share the HLA DQ5 allele. The aim of the present study was to analyze the T cell receptor (TCR) repertoire specific for recombinant human MuSK protein. We used the CDR3 TRBV-TRBJ spectratyping (immunoscope) to analyze the T cell response to MuSK from 13 DQ5+ MuSK-MG patients and from 7 controls (six DQ5+ MuSK negative subjects and one DQ5− DQ3+ MuSK positive patient). DQ5+ MuSK-MG patients but not controls used a restricted set of TCR VJ rearrangements in response to MuSK stimulation. One semiprivate (TRBV29-TRBJ2.5) rearrangement was found in 5/13 patients, while 4 other semiprivate (one in TRBV28-TRBJ2.1 and in TRBV3-TRBJ1.2, and two in TRBV28-TRBJ1.2) rearrangements were differently shared by 4/13 patients each and were absent in controls. When we sequenced the TRBV29-TRBJ2.5 rearrangement, we obtained 26 different sequences of the expected 130 bp length from 117 samples of the 5 positive patients: two common motifs GXGQET/TEHQET were shared in 4 patients as semiprivate motifs. Thus, the MuSK-specific T-cell response appears to be restricted in DQ5+ MuSK-MG patients, with a semiprivate repertoire including a common motif of TRBV29. This oligoclonal restriction of T cells will allow the identification of immunodominant epitopes in the antigen, providing therefore new tools for diagnosis and targeted therapy.