Cell Proliferation

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.

Retinal organoids (ROs) model human retinogenesis but remain avascular and lack immune components, limiting their utility for studying vascular retinopathies. We generated vascular organoids (VOrs) from human pluripotent stem cells and evaluated their integration into developing ROs. Dissociated VOr cells (day 12 or day 30) were seeded onto 2D retinal neuroepithelium before 3D transition, followed by long-term culture to day 210. VOr derived cells migrated into ROs and transiently persisted. V30 ROs preserved retinal lamination, major neuronal subtypes and light evoked retinal ganglion cell responses comparable to non vascularised controls, whereas media-only ROs cultured in proangiogenic conditions showed structural disorganisation and reduced neuronal survival. Single-cell RNA sequencing revealed an endogenous, inflammatory endothelial-like population with partial endothelial-to-mesenchymal features and a perivascular fibroblast-like cluster in pro-angiogenic media only RO controls. The endothelial-like cell cluster was significantly enriched for genes upregulated in human retinal endothelial cells exposed to high glucose, indicating a diabetic retinopathy like transcriptional state. Microglia like and border associated macrophage populations were present across all conditions, with developmental shifts in morphology and marker expression. Our findings define conditions under which vascular cells can be incorporated into human ROs without disrupting retinal architecture, while uncovering an intrinsic capacity for inflammatory endothelial activation that partially recapitulates diabetic retinopathy. This work advances the engineering of vascularised, immunocompetent retinal models and highlights endogenous vascular immune programmes that must be considered when modelling retinal disease in vitro.

Chemobrain, characterized by cognitive dysfunction, has emerged as a significant health concern following cancer treatment. Doxorubicin, an FDA-approved chemotherapeutic agent, is widely used to treat various cancers. However, its adverse effects raise concerns regarding toxicity in non-cancerous cell types. Microglia, the resident immune cells of the brain, play a central role in maintaining neural homeostasis. Despite this, the mechanisms by which microglia become dysfunctional following doxorubicin exposure remain poorly understood. Understanding the transcriptomic alterations induced by doxorubicin in microglia could provide critical insights into mechanisms underlying its neurotoxic effects. In this study, the transcriptomic response of human microglia to doxorubicin using mRNA sequencing combined with bioinformatic analysis was investigated. Exposure to doxorubicin significantly altered microglial morphology, promoting a shift toward a process-bearing phenotype in human HMC3 cells. This phenotypic change was accompanied by elevated levels of DNA damage and was associated with the induction of cellular senescence. At the gene regulation level, the Illumina-based transcriptomic analysis provided 25,834 gene expression profiling in which 5,669 were differentially expressed. The future analyses revealed that 3,431 (upregulated) and 2,238 (downregulated) were differentially expressed under the treatment of doxorubicin. Genes associated with the p53 signaling pathway and inflammatory responses were upregulated, whereas genes involved in translation, DNA replication, and cell-cycle progression were downregulated. This transcriptional dysregulation was accompanied by differential expression of key transcription factors. This study provides transcriptomic evidence elucidating the genotoxic response to doxorubicin in microglial cells, offering mechanistic insights into chemobrain and highlighting key molecular pathways as potential targets for therapeutic intervention.

Myocardin (MYOCD) is the principal trigger-switch for vascular smooth muscle cell (VSMC) growth arrest and the cyto-contractile program of differentiation. While much is known about MYOCD-dependent VSMC differentiation, limited information exists as to its transcriptional regulation. Here, we report moderate mRNA expression of Myeloid Ecotropic viral Integration Site 1 (MEIS1) in both human and mouse VSMCs. MEIS1 mRNA is reduced in parallel with myocardin mRNA and protein under conditions of VSMC de-differentiation. Loss- and gain-of-Meis1 expression studies in cultured human VSMCs and the mouse carotid artery support MEIS1 as an activator of myocardin and VSMC differentiation. CRISPR-mediated knockout of the endogenous Meis1 gene in vitro and elicited lower levels of VSMC contractile markers and an increase in growth rate. Similarly, Femoral artery wire injury, in mice lacking Meis1 showed and increased of neointima formation. Mechanistically, we identified a conserved MEIS1 response element in the proximal promoter of myocardin, that appears to contribute to the promoter activity, suggesting a potential regulatory interaction. These results suggest a previously unrecognized role for the homeodomain protein MEIS1 in the activation of myocardin and the quiescent, VSMC differentiated state.

Background: Endometriosis is an estrogen-driven, inflammatory disorder affecting ~10% of menstruators, causing severe pain. Current treatments that reduce estrogen or inflammation have inconsistent efficacy and poor tolerability. Therapies identified via drug-repositioning methods, which target patient-specific pathways, offer a promising alternative. Simvastatin and primaquine were identified as potential treatments, strongly reversing endometriosis-associated gene expression pathways, and behavioral testing in an animal model showed that these drugs diminish endometriosis-associated pain. This paper examines their effects in human assembloids to provide proof-of-concept validation and insights into their mechanisms of action relevant to endometriosis. Methods: We established human endometrial assembloids using immortalized epithelial (12Z) and stromal fibroblast (iEc) cell lines, as well as primary tissue from patients. Assembloids were generated in 96-well agarose molds with both cell types. We tested ibuprofen, fenoprofen, primaquine, and simvastatin. Following a 24-hour exposure, assembloids and monolayer cultures were harvested and stranded mRNA-seq libraries were sequenced on an Illumina NovaSeqX Plus System. Results: Gene set enrichment analysis showed key pathway reversals: Primaquine reversed the chemical carcinogenesis ROS pathway in assembloids. Simvastatin reversed cytokine-cytokine receptor interaction in both epithelial and stromal cell lines, and the cytoskeleton in muscle cells pathway in stromal cell lines. Fenoprofen reversed the calcium signaling pathway in stromal cell lines. Conclusion: Simvastatin induced the most significant gene expression changes, notably reversing cytokine-cytokine receptor interactions in both cell lines, mirroring findings from our rat model. Despite the small sample size limitation, these experiments highlight the promise of assembloid models to test therapeutic candidates for endometriosis.

Aims: Mature, contractile vascular smooth muscle cells (vSMC) in muscular blood vessels can de-differentiate into synthetic vSMC, while human pluripotent stem cells (hPSC) differentiate into proliferating, fetal-like vSMC that can be induced to form contractile vSMC. Given the complicated embryonic origins and conflicting views on vSMC heterogeneity, our aim was to establish how closely hPSC-vSMC of a known germ layer lineage and defined phenotype are representative of vSMC obtained from aorta (AoSMC). Methods and Results: We generated paraxial mesoderm (PM)-derived synthetic and contractile vSMC from hPSC lines and performed phenotypic and mechanical comparisons with AoSMC. Synthetic hPSC-vSMC and cultured AoSMC are proliferative, sensitive to contact inhibition and exhibit phenotype switching. Contractile hPSC-vSMC are non-proliferative, capable of phenotype switching and have elevated levels of contractile proteins (CNN1, TAGLN, ACTA2). These contractile proteins also displayed density-dependent, cell-to-cell heterogeneity in both AoSMC and hPSC-vSMC. Single-cell traction force measurements on micropost array detectors (mPADs) yielded comparable forces per micropost in the nN range across cell types. Quantitative 3D force measurements on humanized smooth muscle cell microtissues (SMTs) developed similar forces per cell. Larger forces were generated by MEKi-treated hPSC-vSMC and AoSMC versus controls. Conclusions: We have systematically studied the properties of hPSC-vSMC and performed comprehensive phenotypic and mechanical comparisons with AoSMC. These results demonstrate that synthetic hPSC-vSMC generated in vitro and cultured AoSMC derived from tissues are comparable and mechanically similar, but results with hPSC-vSMC are more reproducible.

Background: Chronic low-grade inflammation and gut microbiota dysbiosis contribute to metabolic syndrome (MS). Huanglian Wendan Decoction (HLWDD) is a defined multi-herbal formulation used in Chinese medicine, but its effects on gut microbiota-associated metabolism and NLRP3 inflammasome signaling remain unclear. Objective: This study evaluated the pharmacological effects and candidate absorbed bioactive constituents of HLWDD in experimental MS. Methods: A high-fat, high-sugar diet-induced rat model of MS was assessed using metabolic, biochemical, histological, molecular, and multi-omics endpoints. Gut metagenomics, untargeted metabolomics of liver and colonic contents, liver transcriptomics, and UPLC-HRMS/MS analysis of serum-absorbed constituents were integrated with network pharmacology and molecular docking. Baicalin was further evaluated in PA-BSA-treated HepG2 cells. Results: HLWDD ameliorated obesity, dyslipidemia, hepatic steatosis, and systemic inflammation and attenuated NLRP3 inflammasome-related signaling. Multi-omics analysis identified nine shared differential metabolites and a strong positive association between Faecalibacterium and butyrate. Thirty-two serum-absorbed constituents were tentatively identified. Baicalin showed favorable predicted interactions with NLRP3 (-5.82 kcal/mol) and CASP1 (-5.41 kcal/mol) and concentration-dependently suppressed NLRP3 inflammasome-related signaling in HepG2 cells; the highest concentration increased intracellular butyrate. Conclusion: HLWDD ameliorated metabolic and inflammatory abnormalities in experimental MS in association with restoration of gut-liver metabolic homeostasis and attenuation of NLRP3 inflammasome signaling. Baicalin emerged as a candidate absorbed bioactive constituent.

Cardiovascular diseases (CVD) are the leading cause of morbidity and mortality worldwide. This clinical burden is predominantly attributable to atherothrombotic events resulting from platelet hyperactivation, a process integral to the pathophysiology of atherosclerosis. Cilostazol (CLZ) is a clinically established phosphodiesterase-IIIA inhibitor with antiplatelet and vasodilatory activity. However, its extremely low aqueous solubility results in dissolution-limited and variable oral absorption, while dose-dependent adverse effects and cardiovascular safety restrictions may constrain its clinical use. Lipid-polymer hybrid nanoparticles (LPHNPs) represent a highly promising drug delivery system to address these biopharmaceutical limitations. However, their interactions with blood components remain poorly understood, with surface charge among the most controversial physicochemical parameters implicated in platelet toxicity. Here, we applied an integrated ex vivo and in silico screening strategy to design LPHNPs based on poly(lactic acid) and poly(ethylene glycol)-modified lipids displaying positive (amine), nominally neutral (methoxy), and negative (carboxyl) surface charges to systematically identify safe boundaries at the nano-human platelet interface and evaluate their suitability as CLZ carriers. Positively charged nanoparticles precipitated immediately during self-assembly due to uncontrolled ionic pairing and were therefore structurally unviable. Neutral nanoparticles maintained a stable size (~113 nm hydrodynamic diameter) but unexpectedly induced spontaneous platelet aggregation, limiting their applicability. In contrast, negatively charged nanoparticles exhibited exceptional colloidal stability (hydrodynamic size of ~120 nm and zeta potential of -48 mV), achieved significant inhibition of ADP-induced platelet aggregation, and adhered to the platelet surface without inducing activation or membrane disruption. Steered molecular dynamics simulations, performed under identical non-equilibrium pulling conditions, showed the highest interfacial resistance to CLZ extraction for the negatively charged model, qualitatively consistent with the sustained CLZ release profile observed in vitro. These findings highlight the importance of precise surface charge tuning in the development of safe cardiovascular nanomedicines based on LPHNPs, emphasizing the need for comprehensive platelet compatibility testing before further biological evaluation.

Background: Pulmonary arterial hypertension (PAH) manifests by pulmonary vascular remodeling, caused by hyper-proliferation and apoptosis resistance of resident PA cells, elevated right ventricular (RV) afterload, and death of RV failure. The goal of this study is to determine the role and mechanisms of action of mitotic spindle-associated microtubule regulator DLG associated protein 5 (DLGAP5) in pulmonary vascular remodeling in PAH. Methods: DLGAP5 expression was assessed in human PAH transcriptomic datasets, PAH patients' lung tissues, pulmonary artery smooth muscle cells (PASMCs), and pulmonary artery adventitial fibroblasts (PAAFs). Loss-of-function, molecular, functional, RNAseq, and network analyses were performed. Smooth muscle (SM)-specific DLGAP5 knockdown using adeno-associated virus serotype 6 (AAV6) in mice with SU5416/hypoxia-induced PH was performed. Results: DLGAP5 was overaccumulated in small muscular PAs, PASMCs, and PAAFs from PAH lungs. siRNA DLGAP5 down-regulated cyclin A2, suppressed hyper-proliferation, increased pro-apoptotic BIM, and induced apoptosis in human PAH PASMCs and PAAFs. DEP domain containing 1 (DEPDC1) was identified and validated as a downstream effector of DLGAP5 in PAH PASMCs responsible for hyper-proliferation and apoptosis resistance of human PAH PASMCs. SM-specific DLGAP5 knockdown with AAV6-enTagln-shDLGAP5 reversed DEPDC1 overaccumulation in small muscular PAs, reduced PA medial thickness, RV systolic pressure, mean PA pressure, and RV hypertrophy in mice with SuHx-induced PH. Conclusions: DLGAP5 supports proliferation and survival of human PAH PASMCs and PAAFs through up-regulation of cyclin A2, DEPDC1, and suppression of BIM, and promotes PA remodeling and PH in mice. DLGAP5 could serve as a potential molecular target to attenuate pulmonary vascular remodeling in PAH.

Female infertility remains a major women's reproductive health challenge, with impaired endometrial receptivity contributing to recurrent implantation failure, early pregnancy loss, and pregnancy complications. Mechanistic studies of human early pregnancy are limited by the lack of physiologically relevant models, and existing in vitro endometrial models rely on exogenous hormone treatment and do not recapitulate the dynamic ovarian control of endometrial growth and differentiation. Here, as a proof of concept, we developed a 3D in vitro ovarian follicle-endometrial organoid co-culture model. Immature murine follicles were cultured in vitro to obtain preovulatory follicles, followed by human chorionic gonadotropin (hCG) stimulation to induce ovulation and luteinization. Luteinized follicles were co-cultured with human endometrial stroma organoids for 6 days. The results showed that luteinized follicles generated a dynamic endocrine environment characterized by progressively increasing progesterone levels and declining estradiol levels. Follicle co-culture induced morphological differentiation and expression of decidualization markers in human endo-organoids. Transcriptomic analysis revealed strong genome-wide concordance between follicle co-culture and conventional decidualization induction using estradiol/progesterone/cAMP (EPC), with significant enrichment of decidualization-associated genes and pathways under both conditions. Nevertheless, the two conditions also exhibited distinct transcriptional states, with EPC preferentially enriched for more mature decidualization-associated programs, whereas luteinized follicle co-culture retained features of the early stage of decidualization. Functional perturbation testing revealed that the progesterone receptor (PR) antagonist RU486 attenuated co-culture-induced endometrial decidualization. Together, these results establish a new in vitro new approach methodology (NAM) that recapitulates ovarian control of endometrial decidualization. This platform provides a human-relevant NAM model to investigate the physiology and pathophysiology of endometrial decidualization, and to evaluate how drugs and environmental chemicals perturb uterine receptivity and early pregnancy.

Minor introns are rare but evolutionarily conserved introns in the human genome. Defects in minor spliceosome components have been reported to cause several human diseases. Mutations in ZRSR2 are frequently observed in myelodysplastic syndrome (MDS) patients. However, the precise molecular mechanism by which these mutations cause a loss of ZRSR2 function in minor intron splicing remain elusive. In this study, we characterized the impact of MDS-causing missense mutations in ZRSR2. Most of the mutant ZRSR2 proteins we tested showed different subnuclear localization pattern from that of wild-type ZRSR2 protein. Co-immunoprecipitation (co-IP) analysis revealed that UHM missense mutations disrupted the interaction between ZRSR2 and SF3B complex. We also demonstrated that ZRSR2 preferentially immunoprecipitated minor spliceosome components over major spliceosome components and it directly interacts with SF3B1. Furthermore, co-IP analysis utilizing a variety of ZRSR2 mutants revealed that mutations in the UHM and Zn2 domains significantly attenuated the interaction with SF3B complex. Finally, UHM and Zn2 mutations markedly disrupted the supporting activity of ZRSR2 for minor intron splicing. Our results indicate that disruption of the physical interaction with SF3B complex is one of the hallmarks of MDS-causing mutations of ZRSR2, which results in aberrant splicing of minor introns.

Microglia, the immune cells of the brain parenchyma, play a pivotal role in neurodevelopment and neuroprotection. Human stem cell-derived microglia-like cells (MGL) offer a valuable, human-relevant system to study microglia in vitro. However, their cell states and intercellular interactions within complex 3-dimensional (3D) tissue contexts in vitro remain underexplored. Here, we analyze the gene expression profiles of MGL generated by two differentiation protocols in conventional 2D cultures. We show that co-culture with neural organoids promotes a more mature, in vivo-like MGL phenotype but this signature is lost during long-term co-culture. By varying media compositions, we modulate 2D MGL states toward more active or more homeostatic identities, which may enhance the similarity to primary microglia identities upon subsequent co-culture. Moreover, forced expression of the microglial lineage regulator SALL1 shifts MGL away from a general myeloid state toward a more defined pre-microglial fate. SALL1 overexpression within a 3D neural organoid environment further amplifies the shift toward a homeostatic developmental microglia population. Collectively, our transcriptomic analysis delineates human MGL states in 2D and 3D contexts, refines existing differentiation protocols toward more authentic MGL, and establishes a framework to investigate the intricate microglia-neural tissue interplay.

Background: Ion channels regulate mammalian sperm function, yet chloride channels have received less attention than their cation counterparts. Herein, we investigated the presence, localization, and function of voltage-gated chloride channels (ClC-1, ClC-2, and ClC-K) and calcium-activated channels (ANO1 and ANO2) during sperm capacitation and the acrosome reaction. Results: Using the pig as an animal model, we localized these channels in different sperm regions: ClC-1 in the equatorial and post-acrosomal regions; ClC-2 in the connecting and principal pieces; ClC-K in the acrosome, connecting, and principal pieces; ANO1 in the principal piece; and ANO2 in the mid-piece and post-acrosomal sheath region. Following this, we addressed the roles of these channels in sperm capacitation and acrosome reaction by blocking them with different inhibitors: 9AC, specific for ClCs; BBR, specific for CaCCs; and NPPB, a broad-spectrum blocker that inhibits ClCs, CaCCs, and other chloride channels. Blocking CaCCs with BBR led to a significant reduction in sperm motility and mitochondrial membrane potential, with effects similar to those of the non-selective inhibitor NPPB or to a combination of BBR and NPPB. Moreover, although none of the three inhibitors affected intracellular calcium levels or acrosomal integrity, a significant reduction in protein tyrosine phosphorylation was observed in sperm treated with the combination of NPPB and BBR. Finally, membrane lipid disorder was increased when ClCs were blocked with 9AC and when sperm were incubated with a combination of BBR and NPPB. Conclusions: Our results suggest that CaCCs play a major role in sperm capacitation compared to ClCs. Further research to address the regulatory mechanisms involved and the potential relationship with other ion channels is warranted.

Animal-derived surface coatings present the gold standard in stem cell culture. However, they come with major drawbacks such as lot-to-lot inconsistency and an ethically problematic production. Approaches to develop synthetic coating alternatives have largely failed to recapitulate biological functions essential to PSC-self renewal and differentiation. In this study, we have investigated the suitability of a fully synthetic, chemically defined extracellular matrix-mimicking coating named BIOINSTRUCT for hiPSC culture. BIOINSTRUCT was employed during maintenance culture of IMR90-4 cells, as well as directed differentiation of HIHCNi008-A, ACTN2-GFP, and UKKI-011-A cells. BIOINSTRUCT preserved hiPSC characteristics over the experimental period of 10 passages similar to Matrigel. Spontaneous differentiation resulted in the formation of ectodermal, mesodermal and endodermal derivatives, confirming the retention of pluripotency. Directed differentiation on BIOINSTRUCT enabled the generation of neuronal, cardiac and pancreatic endocrine cells. Altogether, our data underscore BIOINSTRUCT as a promising alternative to animal-derived extracellular matrix coatings.

Abstract Background: Placental insufficiency (PI), characterized by impaired placental function, is a leading cause of stillbirth. Although rare coding variants are known to cause a subset of stillbirths, their contribution to PI is poorly understood. Methods: We conducted a secondary analysis of stillbirth cases (N=292) of the Stillbirth Collaborative Research Network study with exome sequencing available on postmortem placental or fetal samples. PI was defined by standardized placental pathological lesions (e.g., maternal vascular malperfusion) and prespecified clinical criteria for placental dysfunction. Candidate gene-based rare-variant burden analysis was performed using the Sequence Kernel Association Test-Optimal framework, focusing on evolutionarily constrained developmental and placental-function genes. Primary analysis compared stillbirths with and without placental vascular malperfusion. Similar comparisons by clinical PI and other placental pathological lesions were conducted in secondary analysis. Results: Stillbirths with PI phenotypes demonstrated different patterns of genetic variation than stillbirths without PI. Specifically, we observed nominal differential enrichment of constrained variants in biologically prioritized placental-function genes, regulating extravillous trophoblast invasion and spiral artery remodeling (CTNND2, PHACTR1, SLIT1, VEGFA), placental angiogenesis (IGF2R, TEK), mitochondrial homeostasis (OPA1), and fetal growth (DLK1, GNAS). Secondary analyses on specific placental pathological lesions suggested recurrent enrichment of genes within similar placental developmental pathways. Conclusions: We observed nominal differential enrichment of constrained developmental and placental-function genes in stillbirths with PI compared to stillbirths without PI. The observed genetic signals across PI phenotypes suggest shared biological pathways underlie placental dysfunction. Our findings advance genotype-phenotype characterization and help prioritize candidate pathways for larger collaborative genomic and functional studies to improve stillbirth risk stratification and prevention.

The teleost whole-genome duplication (TGD) contributed to functional diversification of opsins. Some TGD paralogs, including those of parapinopsin (PP), Vertebrate Ancient (VA) opsin, and long wavelength-sensitive (LWS) opsin, show different absorption spectra and/or expression patterns. However, our knowledge of detailed evolutionary processes and mechanisms by which TGD contributed to opsin diversification is still limited. Here, we report that TGD paralogs of parietopsin (PT1 and PT2) are retained in extant species. While most species, including the zebrafish, have only PT1, several characins, including the red piranha (Pygocentrus nattereri), retain both PT1 and PT2. The Mexican tetra (Astyanax mexicanus) and catfishes have only PT2. To assess the degree of functional diversification between PT1 and PT2, we characterized spectral properties and expression patterns. Maximum absorption spectra differ slightly among PTs. Those of red piranha PT1, PT2, Mexican tetra PT2, and Japanese catfish (Silurus asotus) PT2 were located at 517 nm, 528 nm, 517 nm, and ~535 nm, respectively. Fluorescence in situ hybridization showed that (1) piranha PT1 and PT2 are expressed in the same pineal cells, and (2) they are also co-expressed with PP1. Based on these findings, functional diversification of opsins after gene duplication is discussed.

Cationic lipid nanoparticles have demonstrated unique potential for extrahepatic mRNA delivery, particularly enabling selective targeting of the pulmonary endothelium. However, their translational development has been hampered by reports of infusion-related immune reactions and innate immune system activation, most notably transient complement activation. Here, we present a case study illustrating the discovery and translational advancement of a selected cationic LNP into non-human primates (NHPs) for initial pharmacokinetic assessment and evaluation of potential immunostimulatory side effects. We show surface charge dependent organ-selective expression of reporter mRNAs from different LNPs in vivo. An mRNA encoding the Tie2 agonist COMP-Angl, was formulated with LNP002, and respective pharmacokinetic and pharmacodynamic readouts were analyzed in two independent non-human primate studies. Notably, dose-dependent transient complement activation could be abrogated by extending the infusion time. Finally, we identified the blood-borne pharmacodynamic biomarker PDGFB for LNP002/mRNA-76 treatment reflecting activated Tie2-signalling in healthy pulmonary endothelium in vivo supported by single cell sequencing and cluster-alignment of downstream effector genes with the same spatial profile as the delivered mRNA.

CBX1-related syndrome is characterized by developmental delay, hypotonia, autistic features, and mild dysmorphic features. This syndrome is caused by heterozygous missense variants in CBX1, which encodes heterochromatin protein 1 beta (HP1{beta}). These variants are situated within the chromodomain of HP1{beta}, a critical region that mediates the interaction between HP1{beta} and trimethylated H3K9. While a prior study identified three individuals with pathogenic CBX1 variants, the variant and clinical spectrum of CBX1-related syndrome remains largely unknown. Here we report three patients with novel de novo heterozygous variants in CBX1. Patients with CBX1 p.(Leu40Pro) and p.(Cys60Arg) manifested with global developmental delay, while the patient with CBX1 p.(Cys60Gly) primarily exhibited speech delay without concurrent motor developmental delay. All variants reside within chromodomain of the HP1{beta} protein. Interestingly, in vitro cellular assays revealed that CBX1 p.(Cys60Gly) variant showed an intermediate cellular phenotype between the wild type and the CBX1 p.(Leu40Pro) and p.(Cys60Arg) variants, suggesting a possible genotype-phenotype correlation. This report provides further evidence that missense variants within the chromodomain of HP1{beta} cause a syndromic neurodevelopmental disorder, CBX1-related syndrome.

Cellular diversity is required for the proper function of many tissues, including the retina, with its ~130 cell types.1-3 Previous lineage studies suggested that retinal progenitor cells (RPCs) generate cell diversity through biased cell divisions.4-9 However, the extent to which each progenitor cell contributes to diversity, and the overarching rules governing the lineages of the collection of progenitor cells, are unknown. While classic lineage tracing approaches including retroviral labeling4,6,10, dye injection11,12, and time-lapse microscopy13,14 were used to make the foundational insights regarding retinal lineages, they cannot be used to interrogate multigenerational lineages at scale. Here we describe the creation of an evolvable lineage tracing tool, "SCRIBBLE" for Sequential Combinatorial Recorder for Iterative Barcode-Based Lineage Evolution. SCRIBBLE uses prime editor to iteratively edit a barcode sequence while preserving the order of genesis of clonally related progeny. Through a series of rationally designed high-throughput screens and design optimizations, we identified novel sequences that support a high level of barcode editing and information content. Evaluation of SCRIBBLE in embryonic mouse retina recapitulated known lineages in retinal development, demonstrating that SCRIBBLE is capable of high-resolution lineage tracing in a complex tissue.

CC10137 is a first-in-class peripherally restricted 2A-adrenergic receptor (2AAR) agonist with broad-spectrum analgesic efficacy and a favorable safety profile. Systematic exploration of the chemical space surrounding first-in-class leads is important for defining series boundaries and guiding continued optimization, but conventional analogue-by-analogue medicinal chemistry samples only a small fraction of the accessible structural space. Here, we used a scaffold-seeded enumeration strategy to expand the chemical space surrounding CC10137 from four SAR-informed seed compounds comprising CC10137 and three closely related structural variants. Application of predefined medicinal chemistry transformation rules in StarDrop generated a virtual library of 16,601,163 unique structures. Morgan fingerprint-based principal component analysis indicated that the library occupied a highly multidimensional structural space involving variation in scaffold substitution, peripheral functional groups, and side-chain composition. A retrospective comparison set of 43 compounds independently designed and experimentally characterized in the earlier CC10137 program represented only approximately 0.00026% of the 16.6-million-member library, yet all 43 were recovered as exact structural matches. Three compounds selected directly from the virtual library retained 2AAR binding affinity and agonist potency below 25 nM. Five representative compounds further showed significant anti-allodynic effects in the in vivo spared nerve injury model, with inhibition rates ranging from 39.3% to 55.7%. These findings support scaffold-seeded computational enumeration as a practical strategy for systematic chemical-space mapping around a first-in-class lead and for identifying additional pharmacologically active structural regions for further optimization.