Paris Descartes University

About: Paris Descartes University is a government organization based out in Paris, France. It is known for research contribution in the topics: Population & Transplantation. The organization has 20987 authors who have published 37456 publications receiving 1206222 citations. The organization is also known as: Université Paris V-Descartes & Université de Paris V.

Periosteum contains skeletal stem cells with high bone regenerative potential controlled by Periostin

Abstract: Bone regeneration relies on the activation of skeletal stem cells (SSCs) that still remain poorly characterized. Here, we show that periosteum contains SSCs with high bone regenerative potential compared to bone marrow stromal cells/skeletal stem cells (BMSCs) in mice. Although periosteal cells (PCs) and BMSCs are derived from a common embryonic mesenchymal lineage, postnatally PCs exhibit greater clonogenicity, growth and differentiation capacity than BMSCs. During bone repair, PCs can efficiently contribute to cartilage and bone, and integrate long-term after transplantation. Molecular profiling uncovers genes encoding Periostin and other extracellular matrix molecules associated with the enhanced response to injury of PCs. Periostin gene deletion impairs PC functions and fracture consolidation. Periostin-deficient periosteum cannot reconstitute a pool of PCs after injury demonstrating the presence of SSCs within periosteum and the requirement of Periostin in maintaining this pool. Overall our results highlight the importance of analyzing periosteum and PCs to understand bone phenotypes.

ABC transporters, cytochromes P450 and their main transcription factors: expression at the human blood-brain barrier.

Abstract: We have established the expression patterns of the genes encoding ATP-binding cassette (ABC) transporters and cytochromes P450 (CYPs) at the adult human blood–brain barrier (BBB) using isolated brain microvessels and cortex biopsies from patients with epilepsia or glioma. Microves synaptophysin (neurons) and neuron-glial antigen 2 (NG2) (pericytes). ABCG2 [breast cancer resistance protein (BCRP)] and ABCB1 (MDR1) were the main ABC transporter genes expressed in microvessels, with 20 times more ABCG2 and 25 times more ABCB1 in microvessels than in the cortex. The CYP1B1 isoform represented over 80% of all the CYPs genes detected in microvessels. There were 14 times more CYP1B1 in microvessels than in the cortex, showing that CYP1B1 is mainly expressed at the BBB. p-glycoprotein (ABCB1), BCRP (ABCG2) and CYP1B1 proteins were found in microvessels by western blotting. The expression of genes encoding three transcription factors [pregnane xenobiotic receptor (PXR), constitutive androstane receptor (CAR), aryl hydrocarbon receptor (AhR)] was also investigated. The AhR gene, involved in the regulation of CYP1B1 expression, was highly expressed in brain microvessels, whereas PXR and CAR genes were almost undetected. This detailed pattern of ABC and CYPs gene expression at the human BBB provides useful information for understanding how their substrates enter the brain.