Multiscale spatial mapping of cell populations across anatomical sites in healthy human skin and basal cell carcinoma

\ua9 2024 National Academy of Sciences. All rights reserved.Our understanding of how human skin cells differ according to anatomical site and tumour formation is limited. To address this, we have created a multiscale spatial atlas of healthy skin and basal cell carcinoma (BCC), incorporating in vivo optical coherence tomography, single-cell RNA sequencing, spatial global transcriptional profiling, and in situ sequencing. Computational spatial deconvolution and projection revealed the localisation of distinct cell populations to specific tissue contexts. Although cell populations were conserved between healthy anatomical sites and in BCC, mesenchymal cell populations including fibroblasts and pericytes retained signatures of developmental origin. Spatial profiling and in silico lineage tracing support a hair follicle origin for BCC and demonstrate that cancer-associated fibroblasts are an expansion of a POSTN+ subpopulation associated with hair follicles in healthy skin. RGS5+ pericytes are also expanded in BCC suggesting a role in vascular remodelling. We propose that the identity of mesenchymal cell populations is regulated by signals emanating from adjacent structures and that these signals are repurposed to promote the expansion of skin cancer stroma. The resource we have created is publicly available in an interactive format for the research community

Incubation Period of the Killdeer

Volume: 46Start Page: 17End Page: 1

Les lysimètres de petite taille : un outil pertinent d'évaluation du transfert des pesticides ?

Small size lysimeters placed under field conditions are compared to field studies for pesticide leaching and fate. Such column apparatus allows easy collection of leachates and use of radiolabeled pesticides. Soil structure can also be preserved as well as when using the usual larger lysimeters. Moreover, the small size permits an increase in the replicate number and to avoid soil sampling variability. Two exemples are provided to evaluate the relevance of those experimental models compared to field monitoring campaigns. / Des lysimètres de petite taille, placés sous conditions naturelles, sont utilisés en parallèle avec des expériences de suivi de transfert d'herbicides au champ. Ce type de dispositif permet une récolte facile des eaux de percolation ainsi que l'utilisation de molécules marquées. Comme pour des lysimètres classiques de grande taille, il est possible de travailler en préservant la structure du sol mais leurs faibles dimensions permettent d'augmenter le nombre de répétitions ainsi que de s'affranchir des problèmes d'échantillonnage. Deux exemples de résultats obtenus sont présentés pour permettre de juger de la validité de ce type de modèle par rapport à des résultats de plein champ

Ex Vivo COL7A1 Correction for Recessive Dystrophic Epidermolysis Bullosa Using CRISPR/Cas9 and Homology-Directed Repair

International audienceRecessive dystrophic epidermolysis bullosa is a rare and severe genetic skin disease resulting in blistering of the skin and mucosa. Recessive dystrophic epidermolysis bullosa (RDEB) is caused by a wide variety of mutations in COL7A1-encoding type VII collagen, which is essential for dermal-epidermal adhesion. Here we demonstrate the feasibility of ex vivo COL7A1 editing in primary RDEB cells and in grafted 3D skin equivalents through CRISPR/Cas9-mediated homology-directed repair. We designed five guide RNAs to correct a RDEB causative null mutation in exon 2 (c.189delG; p.Leu64Trpfs*40). Among the site-specific guide RNAs tested, one showed significant cleavage activity in primary RDEB keratinocytes and in fibroblasts when delivered as integration-deficient lentivirus. Genetic correction was detected in transduced keratinocytes and fibroblasts by allele-specific highly sensitive TaqMan-droplet digital PCR (ddPCR), resulting in 11% and 15.7% of corrected COL7A1 mRNA expression, respectively, without antibiotic selection. Grafting of genetically corrected 3D skin equivalents onto nude mice showed up to 26% re-expression and normal localization of type VII collagen as well as anchoring fibril formation at the dermal-epidermal junction. Our study provides evidence that precise genome editing in primary RDEB cells is a relevant strategy to genetically correct COL7A1 mutations for the development of future ex vivo clinical applications

Learning to write effectively: current trends in European research

International audienc