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Emma R Andersson

@anderssonlab.bsky.social

629 followers 428 following 85 posts

Assoc Prof at Karolinska Institutet. Dev bio enthusiast, from liver to brain, and Notch to miRs, cell fates and lineages.. www.anderssonlab.com

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Emma R Andersson @anderssonlab.bsky.social · 23/09/2026

Most strikingly, transcriptionally similar valve-mesenchymal cells can have fundamentally different origins: epicardial/mesodermal or neural crest. (disclaimer, endocardium was not targeted with our approach) So, cell state (convergent mesenchyme) does not reveal developmental history.

Three Visium HD spatial deconvolution maps of an E16.5 mouse heart. The left panel shows neural crest-related valve-mesenchymal populations identified in our study and great-artery smooth muscle cells concentrated around the aorta and aortic valve, with little contribution to the mitral valve. The middle panel maps epicardium, epicardium-derived cells and intermediate populations identified as clonally related, along a spatial route from the heart surface toward the valves. The right panel shows more differentiated mesoderm-related valve populations concentrated within the developing valve region.

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Emma R Andersson @anderssonlab.bsky.social · 23/09/2026

In heart, atrial and ventricular cardiomyocyte lineages are strongly segregated by E7.5. Yet left–right ventricular identities remain embedded within a more plastic continuum of ventricular competence.

Hierarchically clustered heatmap of clonal-coupling correlations among fetal heart cell populations. Red indicates positive and blue negative correlation. The analysis separates ventricular cardiomyocyte clones from epicardium-related mesenchymal clones, with strong positive correlations within each compartment and negative correlations between them. Epicardium-related cells form three distinct clonal lineages, while atrial cardiomyocytes (aCM) and several valve, vascular and non-cardiac populations form separate branches.

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Emma R Andersson @anderssonlab.bsky.social · 23/09/2026

We next barcoded mesoderm and analyzed heart development with single cell lineage tracing and VisiumHD to again annotate all the new cell types with high confidence.

Experimental workflow for fetal heart lineage tracing. At E7.5, a lentiviral barcode library was injected into the exocoelomic cavity. At E16.5, four barcoded hearts were collected and tdTomato-positive, barcode-positive cells were isolated for 10x Chromium single-cell RNA sequencing, alongside two non-injected hearts. Visium HD spatial transcriptomics of two control hearts enabled spatially informed cell annotation, followed by barcode-based clonal analyses.

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Emma R Andersson @anderssonlab.bsky.social · 23/09/2026

In liver, mesothelium is not a uniform progenitor pool. Spatially distinct mesothelial subsets are already lineage-biased toward stellate cells versus fibroblast and mural-cell fates - revealing multiple routes to liver mesenchymal diversity.

Hierarchically clustered heatmap of clonal-coupling correlations among fetal liver cell populations. Red indicates positive and blue negative correlation. Distinct modules separate mesothelial-related populations, including hepatic stellate cells, from fibroblast/mural populations and from hepatoblast, endothelial, erythroid and other blood lineages. The strongest within-module correlations reveal lineage-biased relationships among liver mesenchymal populations.

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Emma R Andersson @anderssonlab.bsky.social · 23/09/2026

So we barcoded mesoderm at E7.5, and analyzed liver development at E16.5 with single cell lineage tracing and VisiumHD to annotate the many new cell types/states in a spatially aware manner, with high confidence.

Experimental workflow for fetal liver lineage tracing. At E7.5, a lentiviral barcode library was injected into the exocoelomic cavity. At E16.5, four barcoded livers were collected and tdTomato-positive, barcode-positive cells were isolated for 10x Chromium single-cell RNA sequencing, alongside three non-injected livers. Visium HD spatial transcriptomics of two control livers enabled spatially informed cell annotation, followed by barcode-based clonal analyses.

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Emma R Andersson @anderssonlab.bsky.social · 23/09/2026

That old image revealed an opportunity hiding in plain sight: an accessible route to developing mesoderm. We used it to deliver lentiviral reporters and barcodes at E7.5: a scalable, Cre-independent method to manipulate and lineage-trace mammalian mesoderm in utero.

Two UMAP plots of 242,486 single cells from whole E9.5 and E10.5 mouse embryos. The left plot identifies 18 populations spanning ectodermal, neural crest, mesodermal, endothelial, hematopoietic and epithelial lineages. The right plot shows tdTomato-positive cells following E7.5 exocoelomic-cavity injection, comprising 92.8% of recovered cells and strongly enriching mesodermal populations, particularly limb, pharyngeal-arch and splanchnic lateral-plate mesoderm derivatives. Colored cells represent 6,312 E9.5 cells from 10 embryos and 55,830 E10.5 cells from five embryos.

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Emma R Andersson @anderssonlab.bsky.social · 23/09/2026

Sometimes a new technology begins with a 60-year-old anatomical drawing. A 1966 image from Biology of the Laboratory Mouse showed a crucial detail: the extraembryonic exocoelomic cavity is continuous with the embryo’s coelomic cavity.

Figure 12-18, Snell and Stevens, Biology of the Laboratory Mouse, 2nd ed., 1966; digitized by Mouse Genome Informatics, The Jackson Laboratory. Black and white drawing of cross-section of E8 mouse embryo.

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Emma R Andersson @anderssonlab.bsky.social · 23/09/2026

🧬 Preprint! 🧵 Our goal is to genetically manipulate every embryonic germ layer to enable high throughput in vivo studies. We previously showed mouse ectoderm can be targeted by amniotic injection, enabling cell-specific manipulation, lineage tracing, and knockouts. But how to reach mesoderm?

Schematic of method developed and application. At embryonic day 7.5, a lentiviral library carrying unique 30-nucleotide barcodes and a fluorescent reporter is injected into the mouse exocoelomic cavity. An E8 embryo cross-section shows that this cavity is continuous with the intraembryonic coelomic cavity, allowing the virus to reach and barcode mesodermal progenitors, including lateral plate and paraxial mesoderm.

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Emma R Andersson @anderssonlab.bsky.social · 15/11/2025

😂 Ditto! Despite my track record in agriculture… (Dear reader: she does not have a track record in agriculture…)

Screenshot of an email that reads “Dear Emma R. Andersson,
Cureus Journals, a part of Springer Nature, will be launching its fourth open access journal—Cureus Journal of Agriculture and Food Science (CJAF)— in December 2025.

I would like to take this opportunity to invite you to apply for a position on our esteemed Editorial Board as an Associate Editor (AE) for CJAF.

Your expertise in agriculture and food science is highly regarded, and your research contributions have significantly advanced the field. “

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Emma R Andersson @anderssonlab.bsky.social · 15/08/2025

If we lose our inner ear hair cells, we lose our hearing.. but reptiles can repair their sensory organs 🐊🤩 Tune in to Vetenskapspodden on Swedish radio P1, Sun 07:03, Mon 18:33, or bit.ly/4oCDHzP from Sunday, to hear me & Helge Rask-Andersen discuss crocodiles & regeneration with Lena Nordlund!

Portrait photo of me (Emma R Andersson, Associate Professor at Karolinska Institutet), Helge Rask-Andersen (Professor Emeritus at Uppsala University), and Lena Nordlund (journalist, host of Vetenskapspodden, and originally a chemist!)

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Emma R Andersson @anderssonlab.bsky.social · 04/04/2025

We've previously shown that the approach can achieve conditional perturbations by driving expression with mini-promoters, and can recapitulate existing knockout mice with shRNA. We called this iteration "NEPTUNE" for "neural plate targeting with in utero nano-injection": doi.org/10.1016/j.cr...

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Emma R Andersson @anderssonlab.bsky.social · 20/01/2025

Want to delve deep into liver and pancreas biology in a beautiful setting? Join us April 1–4 at the EMBO Workshop in the beautiful coastal town of Sant Feliu de Guíxols (Girona), Spain! Organized w/ Ines Cebola, @jorge-ferrer.bsky.social @heikolickert.bsky.social & Ludovic Vallier. bit.ly/4g8zajj

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