Biology subjects

Darrigrand, J.-F.

Publications and source records attributed to Darrigrand, J.-F..

5 recordsLinked to original sources

bioRxiv2025

Spatially organized cellular communities shape functional tissue architecture in the pancreas

Organ function depends on the precise spatial organization of cells across multiple scales, from individual cells to cellular communities that form specialized local niches and, ultimately, complex higher-order structures. While the identities of individual cell are increasingly well-defined, our understanding of how these diverse cell types are spatially distributed and communicate remains incomplete. In this study, we combine single-cell and spatial transcriptomic analyses to map pancreatic cell populations across space and time, from embryonic development to adult homeostasis in mice. Using these comprehensive maps, we systematically resolve spatial heterogeneity among pancreatic cell types and uncover basic tissue niches, which emerge as epithelial-mesenchymal units. We further characterize these niches functionally in both mouse and human models. We demonstrate that the mesenchymal lineage initially diversifies into various subtypes with specialized supportive roles during embryonic development. However, this complexity gradually diminishes over time, ultimately converging into a limited number of fibroblast sub-types in adult tissue. Our findings shed light on how different progenitor lineages co-develop and organize into structured communities that establish a mature, functional pancreas. This foundational framework could inform strategies for in vitro organogenesis and tissue-engineering in the context of pancreatic diseases.

developmental biology↗

bioRxiv2024

Generation of human iPSC-derived pancreatic organoids to study pancreas development and disease

The pancreas has vital endocrine and exocrine functions that can be affected by life-threatening diseases such as diabetes and pancreatic cancer. While animal models have been essential for understanding pancreatic development and disease, they are limited by their low-throughput and major species-specific molecular and physiological differences. Generating 3D in vitro models, such as organoids, that are physiologically relevant is thus primordial for investigating pancreatic development and disease in the human context. However, producing human stem cell-derived pancreatic organoids with proper branched architecture and correct patterning of cell domains has remained challenging. Here, we successfully developed a protocol that efficiently and reproducibly generates such organoids from human induced pluripotent stem cells (hiPSCs) by optimising organoid culture format and media. Our differentiation protocol promotes acinar cell differentiation and generates organoids with branches patterned into central trunk and peripheral tip domains, without relying on animal-derived matrices for organoid culture. This platform opens the door to high-throughput investigations of human pancreas development in a system recapitulating the most important aspects of pancreatic tissue architecture. Lastly, we anticipate that this system will contribute to the partial replacement of animal models used to investigate diseases such as pancreatic cancer.

developmental biology↗

bioRxiv2023

Multi-scale spatial mapping of cell populations across anatomical sites in healthy human skin and basal cell carcinoma

Our understanding of how human skin cells differ according to anatomical site and tumour formation is limited. To address this we have created a multi-scale 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. Significance statementSingle cells RNA sequencing has revolutionised cell biology, enabling high resolution analysis of cell types and states within human tissues. Here, we report a comprehensive spatial atlas of adult human skin across different anatomical sites and basal cell carcinoma (BCC) - the most common form of skin cancer - encompassing in vivo optical coherence tomography, single cell RNA sequencing, global spatial transcriptomic profiling and in situ sequencing. In combination these modalities have allowed us to assemble a comprehensive nuclear-resolution atlas of cellular identity in health and disease.

cell biology↗

bioRxiv2023

Acinar-ductal cell rearrangement drives pancreas branching morphogenesis in an IGF/PI3K-dependent manner

During organ formation, progenitor cells need to acquire the diversity of cell identities found in the organ as well as organize themselves into distinct structural units. How these processes are coordinated, and how tissue architecture(s) are preserved despite the dramatic cell rearrangements occurring in developing organs remain unclear. Here, we identified cellular rearrangements between acinar and ductal progenitors as a mechanism to drive branching morphogenesis in the pancreas while preserving the integrity of the acinar-ductal functional unit. Using ex vivo and in vivo mouse models, we found that pancreatic ductal cells form clefts by protruding and pulling on the acinar basement membrane, which lead to acini splitting. Newly formed acini remain connected to bifurcated branches generated by ductal cell rearrangement. IGF/PI3K pathway regulates this process by controlling ductal cell fluidity. If components of the pathway are genetically or chemically dysregulated, ductal cell fluidity prevents branching and affects pancreatic cell fates. Hence, our results explain how acinar multiplication and branch bifurcation are synchronized during pancreas organogenesis.

developmental biology↗

bioRxiv2021

Development of a 3D atlas of the embryonic pancreas for topological and quantitative analysis of heterologous cell interactions

Generating comprehensive image maps, while preserving spatial 3D context, is essential to quantitatively assess and locate specific cellular features and cell-cell interactions during organ development. Despite the recent advances in 3D imaging approaches, our current knowledge of the spatial organization of distinct cell types in the embryonic pancreatic tissue is still largely based on 2D histological sections. Here, we present a light-sheet fluorescence microscopy approach to image the pancreas in 3D and map tissue interactions at key development time points in the mouse embryo. We used transgenic mouse models and antibodies to visualize the three main cellular components within the developing pancreas, including epithelial, mesenchymal and endothelial cell populations. We demonstrated the utility of the approach by providing volumetric data, 3D distribution of distinct progenitor populations and quantification of relative cellular abundance within the tissue. Lastly, our image data were combined in an open source online repository (referred to as Pancreas Embryonic Cell Atlas). This image dataset will serve the scientific community by enabling further investigation on pancreas organogenesis but also for devising strategies for the in vitro generation of transplantable pancreatic tissue for regenerative therapies.

developmental biology↗