Biology subjects

Carlier, A.

Publications and source records attributed to Carlier, A..

23 records · Page 2Linked to original sources

bioRxiv2020

Expanding Biomaterial Surface Topographical Design Space through Natural Surface Reproduction

Surface topography guides cell behavior and is a tool to endow biomaterials with bioactive properties. The large number of possible designs makes it challenging to find the optimal surface structure to induce a specific cell response. The TopoChip platform is currently the largest collection of topographies with 2176 in silico designed micro-topographies. Still, it is exploring only a small part of the design space due to the boundary conditions of the design algorithm and the surface engineering strategy. Inspired by the diversity of natural surfaces, we assessed to what extend we could expand the topographical design space and consequently the resulting cellular responses using natural surfaces. To this end, we replicated twenty-six plant and insect surfaces in polystyrene and quantified their surface properties using white light interferometry, image analysis and principle component analysis. Next, we quantified mesenchymal stem cell morphology and the pattern of Pseudomonas aeruginosa colonization and compared it to previous data from TopoChip screens. Our data show that natural surfaces extended the TopoChip design space. Moreover, the natural surfaces induced MSC morphologies and bacterial attachment patterns not previously observed on the TopoChip. In the future, we will train our design algorithms with the results obtained by natural surface imprint experiments to further explore the design space and bio-active properties of surface topography.

cell biology↗

bioRxiv2020

On the correlation between material-induced cell shape and phenotypical response of human mesenchymal stem cells

Learning rules by which cell shape impacts cell function would enable control of cell physiology and fate in medical applications, particularly, on the interface of cells and material of the implants. We defined the phenotypic response of human bone marrow-derived mesenchymal stem cells (hMSCs) to 2176 randomly generated surface topographies by probing basic functions such as migration, proliferation, protein synthesis, apoptosis, and differentiation using quantitative image analysis. Clustering the surfaces into 28 archetypical cell shapes, we found a very strict correlation between cell shape and physiological response and selected seven cell shapes to describe the molecular mechanism leading to phenotypic diversity. Transcriptomics analysis revealed a tight link between cell shape, molecular signatures, and phenotype. For instance, proliferation is strongly reduced in cells with limited spreading, resulting in down-regulation of genes involved in the G2/M cycle and subsequent quiescence, whereas cells with large filopodia are related to activation of early response genes and inhibition of the osteogenic process. Thus, we have started to unravel the open question of how cell function follows cell shape. This will allow designing implants that can actively regulate cellular, molecular signalling through cell shape. Here we are proposing an approach to tackle this question.

bioinformatics↗

bioRxiv2020

Surface topography is a context-dependent activator of TGF-β signaling in mesenchymal stem cells

We previously found that surface topographies induce the expression of the Scxa gene, encoding Scleraxis in tenocytes. Because Scxa is a TGF-{beta} responsive gene, we investigated the link between mechanotransduction and TGF-{beta} signaling. We discovered that mesenchymal stem cells exposed to both micro-topographies and TGF-{beta}2 display synergistic induction of SMAD phosphorylation and transcription of the TGF-{beta} target genes SCXA, a-SMA, and SOX9. Pharmacological perturbations revealed that Rho/ROCK/SRF signaling is required for this synergistic response. We further found an activation of the early response genes SRF and EGR1 during the early adaptation phase on micro-topographies, which coincided with higher expression of the TGF-{beta} type-II receptor gene. Of interest, PKC activators Prostratin and Ingenol-3, known for inducing actin reorganization and activation of serum response elements, were able to mimic the topography-induced TGF-{beta} response. These findings provide novel insights into the convergence of mechanobiology and TGF-{beta} signaling, which can lead to improved culture protocols and therapeutic applications.

cell biology↗

bioRxiv2019

Early steps in the evolution of vertical transmission revealed by a plant-bacterium symbiosis

Various plant species establish intimate symbioses with bacteria within their aerial organs. The bacteria are contained within nodules or glands often present in distinctive patterns on the leaves in what is commonly referred to as leaf nodule symbiosis. We describe here a highly specific symbiosis between a wild yam species from Madagascar, Dioscorea sansibarensis and bacteria of the species Orrella dioscoreae. Using whole genome sequencing of plastid and bacteria from wild-collected samples, we show phylogenetic patterns consistent with a vertical transmission of the symbionts. Unique among leaf nodule symbioses, the bacteria can be cultured and are amenable to comparative transcriptomics and phenotypic characterization, revealing a potential role in complementing the hosts arsenal of secondary metabolites. We propose a very recent acquisition of the vertical mode of transmission in this symbiosis which, together with a large effective populations size explain the cultivability and remarkable lack of genome reductive evolution in O. dioscoreae. We leverage these unique features to reveal pathways and functions under positive selection in these specialized endophytes, highlighting the mechanisms enabling a permanent association in the phyllosphere.

microbiology↗

bioRxiv2018

An interdisciplinary study around the reliquary of the late cardinal Jacques de Vitry

The reliquary of Jacques de Vitry, a prominent clergyman and theologian in the early 13th century, has experienced several transfers over the last centuries, which seriously question the attribution of the remains to the late Cardinal. Uncertainty about the year of his birth poses an additional question regarding his age at death in 1240. The reliquary, located in the Saint Marie dOigines church, Belgium, was reopened in 2015 for an interdisciplinary study around his relics as well as the Treasure of Oignies, a remarkable cultural heritage notably built from Jacques de Vitrys donation. Anthropological, isotopic and genetic analyses were performed independently on the remains found in the reliquary. Results of the analyses provided evidence that the likelihood that these remains are those of Jacques de Vitry is very high: the remains belong to the same human male individual and the historical tradition about his age is confirmed. In addition, a separate relic (left tibia) was analysed and found to match with the remains of the reliquary (right tibia). The unique Jacques de Vitrys mitre, made of parchment, was sampled non-destructively and the extracted parchment collagen was analysed by a proteomic method in order to determine the animal species. The results showed that, surprisingly, not all parts of the mitre were made from the same species. All together, these findings are expected to fertilize knowledge carried by historical tradition around the relics of Jacques de Vitry and his related cultural heritage.

genetics↗