Plexin D1 negatively regulates zebrafish lymphatic development

The phospholipid composition of artificial lipid droplets enhances their deliverability and facilitates a broad Biodistribution in vivo and in vitro

Artificial lipid droplets (aLDs) provide a useful tool to explore the multiple functionalities of intracellular lipid droplets (LDs). In this study we explored the dynamics and potential multidisciplinary applications of these lipid particles. We have optimised construction of fluorescently labelled aLDs to allow their tracking in various in vitro and in vivo models. Modifying the phospholipid membrane of aLDs achieved enhanced delivery efficiency to a broad range of cells with various origins leading to a wide biodistribution of aLDs to organ systems in both mice and zebrafish models. The broad targeting and stability of this new generation of aLDs holds promise to now utilise aLDs as a novel delivery system as well as offering a toolset for further investigation on intracellular LD dynamics and function. STATEMENT OF SIGNIFICANCE: Artificial lipid droplets (aLDs) are a novel nanoparticle tool for biomedical research, consisting of a phospholipid monolayer with a neutral core interior. They offer new opportunities for the delivery of lipids and proteins in vivo; however, the ability of aLD lipid composition to drive enhanced cellular delivery remains unexplored. Here, we demonstrate that enhancing aLD phospholipid complexity significantly increases in vitro cellular delivery across multiple cell types and offers broad organ biodistribution, including delivery to the brain, in both mice and zebrafish. These findings highlight aLDs as potential vehicles in both basic biological studies and therapeutic interventions. Additionally, increasing the complexity of phospholipids into alternate nanoparticles such as LNPs may enhance organ biodistribution, thus opening the field up to new opportunities for cargo to reach previously undeliverable areas.

Lymphatic System Development and Function

PURPOSE OF REVIEW

This review delves into recent advancements in understanding generalized and organ-specific lymphatic development. It emphasizes the distinct characteristics and critical anomalies that can impair lymphatic function. By exploring developmental mechanisms, the review seeks to illuminate the profound impact of lymphatic malformations on overall health and disease progression.

RECENT FINDINGS

The introduction of genome sequencing, single-cell transcriptomic analysis, and advanced imaging technologies has significantly enhanced our ability to identify and characterize developmental defects within the lymphatic system. As a result, a wide range of lymphatic anomalies have been uncovered, spanning from congenital abnormalities present at birth to conditions that can become life-threatening in adulthood. Additionally, recent research highlights the heterogeneity of lymphatics, revealing organ-specific developmental pathways, unique molecular markers, and specialized physiological functions specific to each organ. A deeper understanding of the unique characteristics of lymphatic cell populations in an organ-specific context is essential for guiding future research into lymphatic disease processes. An integrated approach to translational research could revolutionize personalized medicine, where treatments are precisely tailored to individual lymphatic profiles, enhancing effectiveness and minimizing side effects.

Plxnd1-mediated mechanosensing of blood flow controls the caliber of the Dorsal Aorta via the transcription factor Klf2

The cardiovascular system generates and responds to mechanical forces. The heartbeat pumps blood through a network of vascular tubes, which adjust their caliber in response to the hemodynamic environment. However, how endothelial cells in the developing vascular system integrate inputs from circulatory forces into signaling pathways to define vessel caliber is poorly understood. Using vertebrate embryos and in vitro-assembled microvascular networks of human endothelial cells as models, flow and genetic manipulations, and custom software, we reveal that Plexin-D1, an endothelial Semaphorin receptor critical for angiogenic guidance, employs its mechanosensing activity to serve as a crucial positive regulator of the Dorsal Aorta's (DA) caliber. We also uncover that the flow-responsive transcription factor KLF2 acts as a paramount mechanosensitive effector of Plexin-D1 that enlarges endothelial cells to widen the vessel. These findings illuminate the molecular and cellular mechanisms orchestrating the interplay between cardiovascular development and hemodynamic forces.

Lymphatic vessel: origin, heterogeneity, biological functions, and therapeutic targets

Lymphatic vessels, comprising the secondary circulatory system in human body, play a multifaceted role in maintaining homeostasis among various tissues and organs. They are tasked with a serious of responsibilities, including the regulation of lymph absorption and transport, the orchestration of immune surveillance and responses. Lymphatic vessel development undergoes a series of sophisticated regulatory signaling pathways governing heterogeneous-origin cell populations stepwise to assemble into the highly specialized lymphatic vessel networks. Lymphangiogenesis, as defined by new lymphatic vessels sprouting from preexisting lymphatic vessels/embryonic veins, is the main developmental mechanism underlying the formation and expansion of lymphatic vessel networks in an embryo. However, abnormal lymphangiogenesis could be observed in many pathological conditions and has a close relationship with the development and progression of various diseases. Mechanistic studies have revealed a set of lymphangiogenic factors and cascades that may serve as the potential targets for regulating abnormal lymphangiogenesis, to further modulate the progression of diseases. Actually, an increasing number of clinical trials have demonstrated the promising interventions and showed the feasibility of currently available treatments for future clinical translation. Targeting lymphangiogenic promoters or inhibitors not only directly regulates abnormal lymphangiogenesis, but improves the efficacy of diverse treatments. In conclusion, we present a comprehensive overview of lymphatic vessel development and physiological functions, and describe the critical involvement of abnormal lymphangiogenesis in multiple diseases. Moreover, we summarize the targeting therapeutic values of abnormal lymphangiogenesis, providing novel perspectives for treatment strategy of multiple human diseases.