Frontiers in Cell and Developmental Biology

A central question in developmental biology is how spatiotemporal embryo morphological events and cell differentiation are precisely coordinated to eventually develop into a mature organism. Previous research has shown cell positions and asymmetric division stages are related to cell lineage specification since morula stage. However, the detailed spatiotemporal dynamics and histories of embryonic cells and their relations with cell lineage specification remain incompletely understood from the onset of embryo development onward. My study on in-vitro embryos showed that continuous live cell tracking mapped community-like patterns in cell origin and differentiation. Cell positions, cell temporal factors (such as cell division order and cell cycle) and their histories intricately interacted over pre- and peri-implantation stages. These interactions of spatiotemporal cellular activities directed embryo morphological events and asymmetric cell lineage origin and differentiation throughout 2-cell to around 100-cell stage. In conclusion, this study provides comprehensive insights into the cellular spatiotemporal dynamics of cell inheritance and differentiation during pre- and peri-implantation morphological events and cell lineage specification. By longitudinally integrating spatial and temporal parameters relating to early embryogenesis, the findings not only bridge divergent explanations stemmed from different studies in the field but also offers a refined foundation for evaluating embryo potential and improving outcomes in assisted reproductive technologies, stem cell research, and regenerative medicine.

Multiple hypotheses have been formulated to explain differences in tissue repair ability across vertebrates. One hypothesis posits that the accessibility of actively cycling stromal cells within uninjured tissue confers access to a proliferative population in response to tissue damage. This hypothesis further suggests that animals with an indeterminate growth mode possess an actively cycling cell population necessary for growth that can be readily accessed for tissue regeneration. Moreover, the absence of an actively cycling population in connective tissue provides a mechanism that restricts regeneration in animals with determinate growth whose cells are refractory to cell cycle progression and proliferation to produce new tissue for morphogenesis. Here, we explore this paradigm using an EdU-BrdU pulse chase strategy in four different vertebrate species: two with determinate (Acomys dimidiatus and Mus musculus) and two with indeterminate modes of growth (Danio rerio and Ambystoma mexicanum). We find that although indeterminate growers do possess a small population of actively cycling cells, this population does not contribute to regeneration. Moreover, we found that while Acomys does not possess a population of actively cycling stromal cells, cells re-enter the cell cycle de novo in these animals to contribute to regeneration. Furthermore, testing this hypothesis allowed us to ask whether tissue injury could stimulate cell cycle re-entry - a so-called primed state - in cells at distance from the injury site in these four species and we did not find evidence of such priming in stromal or epidermal tissue. HighlightsO_LICell cycle re-entry is a common response to injury in regenerative and non-regenerative vertebrates that is independent of actively cycling stromal cells in uninjured connective tissue C_LIO_LIActively cycling cells do not contribute to regenerative healing in spiny mice, axolotls or zebrafish. C_LIO_LIOur data do not support systemic cell cycle activation in response to injury. C_LI

Genome-edited mice are widely used to elucidate molecular mechanisms in vivo and are an indispensable tool, particularly for studies aimed at clarifying gene function at the organismal level. Currently, there is an increasing demand for mice in which multiple genes are simultaneously modified in order to investigate interactions among multiple genes. Notably, generating conditional multiple-gene knockout mice with temporal and spatial specificity requires extensive crossing between multiple Cre-driver mice and floxed mice, resulting in a prolonged time frame for line establishment. To address this limitation, we developed Transposon-Enhanced Multi-Plex Orchestration Editing (TEMPO-editing), a single-step strategy for generating multiple-gene-edited mice. TEMPO-editing enables simultaneous modification of multiple genes through the integration of transposon, Cre-loxP, and CRISPR/Cas9 systems. Using the DNA transposon piggyBac, we constructed a single cassette harboring gRNAs targeting genes of interest together with a conditionally expressed Cas9 (lsl-Cas9). By injecting this cassette into fertilized eggs of Cre mice, we enabled the generation of temporally and spatially specific genome edited mice in the F0 generation. In this study, we generated double-gene-edited mice targeting Hoxa13 and Hoxd13, which are key regulators of embryonic body patterning and are essential for autopod development. The phenotype observed in these mice was consistent with the incomplete autopod phenotype previously reported in mice generated by crossing Hoxa13 knockout and Hoxd13 knockout mice. These results demonstrate the utility of TEMPO-editing for the generation of multiple-gene-edited mice in the F0 generation. Notably, this study establishes a simplified strategy for producing conditional multi-gene-edited mice, a process that has traditionally required substantial time and labor using conventional methods.

Using a genetic screening approach based on an inducible gene-activating system and cell sorting, Down syndrome critical region 3 (DSCR3) was isolated as a gene whose overexpression increased cell size. Fibroblasts derived from individuals with Down syndrome (DS) exhibit elevated DSCR3 expression at both the mRNA and protein levels, correlating with increased cell volume compared to fibroblasts from healthy donors. Despite a slower proliferation rate, DS fibroblasts demonstrate higher basal and maximal mitochondrial respiration, suggesting enhanced metabolic activity associated with increased cell size. siRNA-mediated knockdown of DSCR3 reduces cell size in both DS and normal fibroblasts, indicating its general role in cell size regulation. As DSCR3 is a component of the retriever complex involved in endosomal cargo recycling, these findings position membrane protein trafficking as a novel module for cell size control.

In mammals, ovarian follicle development is a highly coordinated process that underlies female fertility. Granulosa cells expressing anti-Mullerian hormone (AMH) are widely used as a marker of growing follicles. However, the in vivo roles of granulosa cells in follicular development and female fertility remain unclear. Here, we analyzed AMH-toxin receptor-mediated cell knockout (AMH-TRECK) transgenic (Tg) mice on a NOG background, in which AMH-expressing granulosa cells are specifically depleted by diphtheria toxin (DT). We first found that, after a single DT injection into postnatal AMH-TRECK Tg females, AMH-expressing granulosa cells in primary and secondary follicles exhibited cleaved caspase-3 signals 1 day later and were depleted 4 days later. Second, after repeated DT injections weekly from 1 to 7 weeks of age in AMH-TRECK Tg females, antral follicles and corpora lutea were rarely observed, and the numbers of primordial, primary, and secondary follicles were decreased. Following PMSG and hCG stimulation, repeated DT-injected Tg females exhibited a reduced number of ovulated oocytes with a low proportion of mature oocytes, resulting in reduced IVF rates and fertility. Further, after a cessation of repeated DT treatment, ovarian weight and follicular development recovered: the numbers of primary, secondary, and antral follicles were recovered, whereas the primordial follicle pool remains reduced. We conclude that selective depletion of AMH-expressing granulosa cells in vivo impairs follicular development and fertility. Our model enables assessment of the in vivo effects of granulosa cell depletion and may provide a useful platform for future transplantation-based studies to understand complex follicular dynamics.

Activated leukocyte cell adhesion molecule A (Alcama) plays a role in axonal guidance, cell differentiation, and retinal lamination in a developing retina and was identified as a marker for activated Muller glial cells in adult zebrafish. However, its spatiotemporal localization and its involvement in retina regeneration remains unclear. Here we induced focal photoreceptor damage in zebrafish using laser photocoagulation and examined the expression and localization of Alcama at different time points post lesion. Immunohistochemistry in wild type fish and Tg(kdrl-EGFP) fish showed Alcama localized to the blood retina barrier with increased expression in Muller glial end feet and radial processes in a regenerating retina. To confirm its role in retina regeneration, alcama expression was transiently knocked down using morpholinos in adult fish. Scanning laser ophthalmoscopy, Zpr1 immunostaining and EdU staining showed delayed retina regeneration in alcama knockdown fish, indicating a possible role for Alcama in zebrafish retina regeneration.

Zebrafish bone regeneration is a highly efficient process, enabling the complete restoration of an amputated fin within few weeks. The hallmark of this epimorphic regeneration is the formation of a blastema atop of a bony fin ray. Osteoblasts near the injury site dedifferentiate and migrate off the bone to contribute to the developing blastema. We show that an injury or a blastema alone is not sufficient to trigger off-bone migration of osteoblasts. Surprisingly, we found that blastema cells themselves possess intrinsic migratory properties. Moreover, when multiple injury sites are present, a preferential distal migration could be observed. We conclude that multiple injuries are hierarchical organized, and that injuries with the highest regenerative potential take priority.

Interleukin-15 (IL-15) trans-presentation (TP) by B cells is an important mechanism of T-cell activation; however, the spatial organisation of interleukin-15 receptor (IL-15R) relative to major histocompatibility complex (MHC) molecules on B-cell microvilli remains poorly understood. As microvilli protrude from the B-cell surface and may serve as sites of initial B cell-T-cell contact, the distribution of IL-15R and MHC molecules within these structures may be important during the earliest stages of T-cell recognition and activation. Here, we investigated the spatial association and molecular proximity of IL-15R with MHC class I and class II molecules on B-cell microvilli before immunological synapse formation, using confocal microscopy, stimulated emission depletion (STED) microscopy, stochastic optical reconstruction microscopy (STORM), and fluorescence lifetime imaging microscopy-based Forster resonance energy transfer (FLIM-FRET). Both MHC class I and class II molecules showed significant spatial association with IL-15R; however, the extent of colocalisation decreased as spatial resolution increased. STED microscopy revealed significant colocalisation between IL-15R and MHC class I, whereas STORM did not detect this association. In contrast, IL-15R and MHC class II remained significantly colocalised at both resolutions. FLIM-FRET further demonstrated molecular proximity between IL-15R and both MHC class I and class II molecules, with higher FRET efficiency observed for MHC class II. Collectively, these findings indicate that IL-15R is spatially organised in proximity to both MHC class I and class II molecules on B-cell microvilli before immunological synapse formation. This arrangement at potential sites of initial B-cell-T-cell contact may facilitate the coordination of IL-15 trans-presentation and antigen presentation during the earliest stages of B-cell-T-cell interactions.

Originating at the base of the bilaterian tree of life, the monoaminergic (MOA) system is a pivotal and evolutionarily conserved regulator of animal development and of responses to changing environmental conditions. Investigating the ontogeny of monoaminergic modulation in model systems such as marine bivalve molluscs is therefore particularly relevant, as their life cycle and developmental transitions are strongly influenced by environmental cues. Here, we characterized the spatio-temporal and tissue-specific expression of components of the MOA system during early larval development of the Mediterranean mussel Mytilus galloprovincialis using both time resolved transcriptomics and in situ Hybridization Chain Reaction (HCR). Our results identify serotonin and dopamine as the predominant and interconnected monoaminergic pathways deployed during early mussel development, with receptors, enzymes, and selective transporters broadly expressed across both neuronal and non-neuronal tissues. Notably, the expression of receptors preceding that of the corresponding biosynthetic enzymes indicates early, non-neuronal roles of monoaminergic signalling, supported by their localization in peripheral tissues such as ciliated epithelia. Altogether, These findings support the hypothesis that the MOA system acts as a pervasive and tightly regulated modulator of larval morphogenesis and could therefore play an evolutionary conserved role in mediating development and environmental plasticity in developing bilaterian organisms.

Regenerative capacity varies widely across flatworms (Platyhelminthes). Whereas catenulids, microstomids and planarians can regenerate a complete head de novo, other flatworms cannot. This striking diversity raises a longstanding evolutionary question: does whole-body regeneration represent an ancestral trait that was subsequently lost in multiple lineages, or did it evolve convergently? Addressing this question requires comparative analyses of the molecular mechanisms underlying regeneration across phylogenetically diverse flatworms. Here, we focus on Wnt signaling, a deeply conserved regulator of antero-posterior (A-P) patterning and a central determinant of head-versus-tail identity during planarian regeneration, to establish a mechanistic framework for such comparisons. Although Wnt signaling has been studied extensively in planarians and parasitic neodermatans, its evolution and deployment in other flatworm clades remain poorly characterized. To address this gap, we characterized the complement of Wnt signaling components in two early-diverging flatworm clades, Catenulida and Macrostomorpha, with particular emphasis on expression and function in the catenulid Stenostomum brevipharyngium. Phylogenetic analyses reveal the ancient loss of six Wnt families and one secreted Frizzled-related protein (sFRP) family in the last common ancestor of flatworms, followed by additional lineage-specific gene losses and expansions. Moreover, several Wnt pathway components display markedly divergent expression patterns between catenulids and other flatworms, while functional analyses indicate corresponding differences in their regenerative deployment. Together, our findings reveal a dynamic evolutionary history of the flatworm Wnt signaling toolkit and establish a comparative framework for testing whether the molecular circuitry underlying head regeneration is ancestrally conserved or has evolved independently in distinct flatworm lineages.

RASAL3 acts as a negative regulator of small cellular GTPases in hematopoietic cells. In immune cells, it primarily modulates the RAS/MAPK signaling pathway and affects cellular events including proliferation, differentiation, survival, and migration. Due to its inhibitory role in T cells, RASAL3 may represent a potential modulatory target for improving therapeutic strategies such as cell-based immunotherapy. However, most existing knowledge about RASAL3 function is derived from murine models, and its role in human T-cell signaling remains insufficiently characterized. To address this gap, we systematically investigated the function of RASAL3 in human primary T cells and T-cell line. For this purpose, we employed RASAL3 overexpression, CRISPR/Cas9-mediated deletion, and siRNA-mediated knockdown to thoroughly analyze the effects of RASAL3 on T-cell signaling, proliferation, and migration. Our data demonstrate that RASAL3 modulates primarily CDC42 and RAC1/RAC2 GTPases activity, SAPK/JNK phosphorylation, c-Fos and c-Jun expression, and IL-2 gene promoter activation. In addition, RASAL3 regulates actin polymerization and T-cell migration. Notably, loss of RASAL3 increases Jurkat T cells motility in vivo and potentiates their homing to the spleen. Collectively, these findings identify RASAL3 as an important regulator of human T-cell activation and motility and highlight its application potential for improving CAR-T cell therapy.

Direct experimental analysis of the mammalian oviduct is constrained by limited tissue access and the short lifespan of ex vivo preparations. Extracellular matrix-embedded three-dimensional epithelial organoids provide longer-term in vitro models. However, their inward-facing apical surface and the absence of supporting stromal cells limit physiological studies of the oviduct, including ciliary activity and maternal-embryonic interactions. Here, we provide a step-wise protocol detailing the generation of mouse and human oviductal assembloids in which epithelial cells form an outward-facing (apical-out) layer around a stromal core. Epithelial and stromal cells from adult mouse oviducts or human Fallopian tubes are isolated, expanded separately, and subsequently aggregated in a rotational culture system. The protocol also outlines morphological and immunostaining criteria for confirming cellular organization, whole-mount detection of external cilia, measurement of ciliary beat frequency, and co-culture of mouse assembloids with preimplantation embryos. Mouse and human assembloids retained epithelial and stromal identity and displayed cilia at the accessible outer surface. In a proof-of-concept experiment, embryos co-cultured with the assembloids developed to blastocysts at a rate similar to that of in vivo-derived blastocysts. This reductionist system provides a straightforward and tractable model to investigate oviduct physiology and embryo-maternal communication while allowing direct manipulation and observation of the epithelial interface. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=148 SRC="FIGDIR/small/743297v1_ufig1.gif" ALT="Figure 1"> View larger version (50K): org.highwire.dtl.DTLVardef@1917a7borg.highwire.dtl.DTLVardef@41d7org.highwire.dtl.DTLVardef@e2bf98org.highwire.dtl.DTLVardef@90c9f3_HPS_FORMAT_FIGEXP M_FIG C_FIG SummaryThe protocol for generating mouse and human oviductal assembloids by combining epithelial and stromal cells for studying oviductal function in an in vitro setting.

Hematopoietic stem cells (HSCs) give rise to all blood cell lineages and possess long-term self-renewal potential. HSCs undergo symmetric division for their expansion and asymmetric division to generate one HSCs and one progenitor cells which contribute to production of mature blood cells. The midbody is a structure which is formed in the center of the intercellular bridge during cytokinesis. However, the midbody is either asymmetrically inherited by one daughter cell or symmetrically released after cell division, whether these distinct patterns of midbody inheritance influence HSC fate remain poorly understood. In this study, we designed a fusion protein hmKO2 and MgcRacGAP which is a component of midbody. We then traced the midbody inheritance during cell division and the future cell fates of HSC daughters after division by time-lapse imaging. As a result, we found that the midbody release correlated with the delay of the time to the next division but not to the lineage potential of HSCs, indicating the possibility that midbody remnant plays some roles in cell cycle progression. HighlightHematopoietic stem cells exhibit a low frequency of midbody inheritance. Midbody inheritance does not affect the lineage potential of daughter cells. Midbody loss is associated with delayed entry into the next cell cycle.

Adult zebrafish efficiently regenerate skeletal muscle following different types of injury; however, the molecular programs involved in repair after extensive cryoinjury remain to be comprehensively characterized. Here, we explored the transcriptomic response of adult zebrafish skeletal muscle at 7 days post cryoinjury (dpci), a stage marked by ongoing tissue clearance, progenitor expansion, myogenic differentiation, and nascent myofiber formation, and compared it with phase-matched stab wound injury. Cryoinjury induced a broad transcriptional response, with 5,330 differentially expressed genes. Integrated enrichment and protein-protein interaction analyses revealed that, at 7 dpci, zebrafish skeletal muscle functions as an integrated regenerative system in which immune remodeling, progenitor expansion, myogenic differentiation, extracellular matrix reconstruction, mechanotransduction, biosynthetic adaptation, proteostasis, and intracellular trafficking operate simultaneously. In parallel, mature sarcomeric and oxidative metabolic programs were suppressed, consistent with ongoing tissue reconstruction and structural immaturity. Comparison with stab-wounded skeletal muscle revealed substantial transcriptional conservation, as 612 of 717 stab-wound-responsive genes (85%) were also differentially expressed after cryoinjury. Shared upregulated genes formed coherent functional modules related to proliferation, extracellular matrix organization and signaling, immune regulation, muscle differentiation, and protein processing. Thus, distinct injury modalities converge on a common regenerative program, while cryoinjury elicits a quantitatively broader transcriptional response. These findings support a conserved regenerative architecture of adult zebrafish skeletal muscle repair, in which interconnected biological modules act coordinately, with the breadth of transcriptional engagement reflecting regenerative demand.

Fibroblasts are readily obtained and expanded and may provide an alternative cell source for cultivated seafood if their latent myogenic potential can be accessed. We examined whether transient exposure to 5-azacytidine (AZA), a cytidine analogue known to convert mouse embryonic fibroblasts into myoblasts, elicits a persistent muscle gene program in embryo-derived zebrafish (Danio rerio) Z3 fibroblasts. Cells were exposed to 0, 2.5, 5 or 10 M AZA for 48 h and maintained in drug-free medium for 3 weeks. RNA-seq identified 744 genes that increased and 670 that decreased consistently across the concentration series. Increased genes encompassed myogenic regulators, fusion factors, sarcomeric components and excitation-contraction machinery, whereas decreased genes were enriched for extracellular-matrix and adhesion functions. In a separate six-dose RT-qPCR experiment (0-20 M AZA) with three biological replicates per concentration, all 19 selected muscle genes were significantly increased at 1.25 M, the lowest concentration tested, whereas 9 of 12 extracellular-matrix/fibroblast genes were significantly decreased. Several muscle genes plateaued or declined at higher concentrations, and multinucleated myotubes were not observed. A separate 5-aza-2'-deoxycytidine (decitabine) series showed a comparable muscle-associated response at 0.25 M. These findings indicate that zebrafish fibroblasts retain access to a myogenic-like transcriptional program, and they provide a model for identifying food-compatible approaches to control fish-cell lineage plasticity for cultivated seafood.

Understanding how to maintain and direct spermatogenesis in vitro is central to advancing reproductive biotechnologies in aquaculture species where the ability to generate gametes outside the organism could facilitate selective breeding, genetic modification, and germline preservation. However, current culture systems remain poorly defined in farmed fish species. In Atlantic salmon (Salmo salar), progress has been further limited by the absence of a comprehensive reference atlas of testicular cell types, making it difficult to determine how cells maintained in culture relate to their native counterparts. To address this, we first established a single-cell RNA atlas of the Atlantic salmon testis from freshly isolated tissue, resolving somatic and germ cell populations across all major stages of spermatogenesis. Primary testicular cells were then cultured under distinct conditions designed to promote either proliferation or differentiation for 14 days and subsequently subjected to single-cell RNA sequencing. To assign cell identities in cultured samples, the transcriptional profiles of cultured cells were computationally mapped onto the atlas, allowing direct comparison of cultured and native cell states. This approach revealed pronounced, condition-specific shifts in cellular composition. Proliferation medium supplemented with epidermal growth factors (EGF) and insulin-like growth factor (IGF) enriched spermatogonial populations, indicating preferential support of undifferentiated and actively dividing germ cells. In contrast, basal medium favoured the preferential survival of Sertoli cells in the absence of defined growth cues. A differentiation medium containing hormones that stimulate male gonad development (gonadotropins and androgens) failed to robustly promote meiotic progression. Further, comparative analysis of Sertoli cells across different conditions (in vivo and in vitro) revealed a loss of canonical identity markers and induction of stress-associated transcriptional programs in vitro compared to in vivo, indicating a shift away from specialised somatic function. Together, these findings establish the first single-cell reference atlas of Atlantic salmon testis and provide a framework for evaluating and optimising testis culture systems in salmonids. While early germ cell populations could be maintained and enriched in vitro, progression through later stages of spermatogenesis remained limited, indicating that important biological requirements of the native testicular environment are not yet fully recapitulated under current culture conditions.

Platelets are increasingly recognized as active regulators of tissue repair and liver regeneration beyond their classical roles in hemostasis and thrombosis. Loss of terminal sialic acid from platelet surface glycoproteins, a process known as desialylation, occurs during platelet aging or activation and has been linked to platelet clearance via the asialoglycoprotein receptor (ASGPR) on hepatocytes. However, the mechanisms by which desialylated platelets (D-plts) directly stimulate hepatocyte proliferation remain poorly understood. This study aimed to elucidate the proliferative effects of D-plts on hepatocytes and to identify the underlying signaling mechanisms. D-plts were generated and co-cultured with hepatocyte models exhibiting low or absent levels of asialoglycoprotein receptor 1 (ASGPR1) expression, including HepG2 cells, HuH-7 cells, and human chemically induced liver progenitors. Hepatocyte proliferation was assessed, and the roles of platelet-derived factors and downstream signaling pathways were investigated. Co-culture with D-plts significantly increased hepatocyte proliferation in all three cell models compared with the corresponding controls. Moreover, supernatants derived from stimulated D-plts also significantly enhanced hepatocyte proliferation, suggesting that soluble platelet-derived factors contribute to this effect. Mechanistically, the proliferative effects were mediated predominantly through the ERK1/2 signaling pathway rather than the JAK-STAT pathway in both hepatocytes co-cultured with D-plts and those treated with D-plt-derived supernatants. In conclusion, our findings demonstrate that D-plts directly promote hepatocyte proliferation through an ASGPR-independent pathway, in which ERK1/2 signaling plays a central role. These results highlight a novel mechanism through which platelet desialylation may contribute to liver regeneration. Graphical Abstract(A) Desialylated platelets are readily activated and release increased amounts of EGF, promoting hepatocyte proliferation via the EGF-ERK signaling pathway. (B) Normal platelets show lower reactivity and reduced EGF release than desialylated platelets, resulting in weaker hepatocyte proliferation. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=102 SRC="FIGDIR/small/740293v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@1cbe93borg.highwire.dtl.DTLVardef@3d57c7org.highwire.dtl.DTLVardef@14dd63forg.highwire.dtl.DTLVardef@12cf508_HPS_FORMAT_FIGEXP M_FIG C_FIG

In the developing human placenta, three subtypes of trophoblast cells, cytotrophoblasts (CTBs), extravillous trophoblasts (EVTs), and syncytiotrophoblasts (STBs), mediate critical functions essential for a successful pregnancy. CTBs constitute the stem/progenitor compartment and differentiate into STBs and EVTs within the floating and anchoring villi, respectively. STBs establish the maternal-fetal exchange interface and secrets human chorionic gonadotropin (hCG), a hormone vital for the maintenance of early pregnancy. EVTs anchor the maternal endometrium and invade the uterine tissue to remodel maternal cells, supporting implantation and progression of pregnancy. In this study, we used human trophoblast stem cells (hTSCs) as a model system and performed quantitative, label-free liquid chromatography-tandem Mass Spectrometry (LC-MS/MS) to profile proteome and phosphoproteome in TSC stem state (analogous to undifferentiated CTBs) and following their differentiation to STBs and EVTs. Through a multiomics approach, we integrated our proteomics data with global gene expression profiles to correlate cell-type specific gene and protein expression during human trophoblast development. We also identified global phosphoproteome and analyzed kinases that are specifically active in hTSC stem state, as well as in differentiated STBs and EVTs. We experimentally validated specific kinases, such as BUB1B, PAK6, PKYMT1 and TNIK are essential for maintaining the hTSC stem-state. Additionally, atypical protein kinase C isoforms PKC{zeta} is essential for STB development, while PTK2B, SRC, TRIO and LYN are important for EVT development. Our findings highlight key kinases uniquely required for specific stages of trophoblast development during human placentation and suggest that pharmacological inhibition of these kinases could negatively impact the placentation process during pregnancy.

Living myocardial slices (LMS) are a highly relevant ex vivo model for investigating cardiac physiology and disease, as they preserve the native three-dimensional architecture, cellular diversity, and extracellular matrix of the heart. In addition, LMS enable longitudinal functional and molecular analyses. In this study, we established and compared two LMS culture approaches: an air-liquid interface system and a biomimetic culture system. We further examined how different slicing techniques affect tissue quality and longevity within the biomimetic setup. To develop a fibrosis model, LMS were stimulated with transforming growth factor-beta1 (TGF-beta1) and/or exposed to increased mechanical load. Tissue viability was assessed using LIVE/DEAD staining and the MTT assay, while cytotoxicity was evaluated with the LDH-Glo-TM Cytotoxicity assay. Contractile function was measured, and fibrotic remodelling was analysed using RT-qPCR, ELISA, and immunohistochemistry. Our results demonstrate that LMS cultured in the biomimetic system exhibit superior viability, structural integrity, and functional performance compared with those maintained at the air-liquid interface. Mouse LMS could be stably cultured for up to one week in the biomimetic system. Importantly, sample preparation, particularly the slicing method, had a significant impact on tissue quality and culture duration. While TGF-beta1 stimulation alone did not consistently induce fibrosis, combining TGF-beta1 treatment with increased mechanical load led to more pronounced fibrotic remodelling in LMS. These findings highlight the importance of biomechanical cues in modelling cardiac fibrosis ex vivo and support the biomimetic system as a robust platform for functional and disease-relevant studies.

Microplicae are ridge-like membrane projections that are prominent features of many epithelial surfaces, yet little is known about the principles governing their spatial organisation. Determining whether microplicae represent stochastic membrane folds or biologically organised surface architectures is essential for understanding their formation and functional roles. Here, differential interference contrast images of human buccal epithelial cells were analysed using quantitative image-processing approaches. Ridge networks were segmented and characterised using complementary measurements of characteristic wavelength, including medial-axis and nearest-neighbour Voronoi analyses, together with skeleton-based metrics describing network architecture. Analysis of n=100 buccal epithelial cells sampled from n=10 donors revealed a reproducible sub-micron characteristic wavelength. Mean medial-axis spacing was 0.511 {+/-} 0.042 {micro}m and mean Voronoi nearest-neighbour spacing was 0.588 {+/-} 0.057 {micro}m. Characteristic wavelength exhibited CV of between only 8.26% and 9.67% across the dataset. However, metrics describing network architecture, including ridge density, branching and connectivity, varied by up to 109%. Donor-level analysis reported the same overall trends, with conservation of the characteristic wavelength while network parameters had considerably greater variation. These findings identify a previously unrecognised organising principle of microplical architecture, suggesting that epithelial membrane organisation is regulated through conservation of an intrinsic geometric length scale while network topology remains comparatively free to remodel.