Biology subjects

Zlokovic, B. V.

Publications and source records attributed to Zlokovic, B. V..

6 recordsLinked to original sources

bioRxiv2024

Neuronally differentiated endothelial cell subtype regulates organ blood flow and immune balance

Vascular endothelial cells (ECs) perform key pleiotropic functions to maintain body homeostasis via the regulation of organ blood flow, vascular permeability, tissue growth and inflammation, and angiogenesis. Recent transcriptomic studies uncovered many EC subtypes across organs; however their specific functions are incompletely understood. Here we identified and characterized a novel, minority subtype of scattered ECs with a well-defined arteriovenous zonal localization exclusively in small resistance (strain) arterioles, and with the highest density in the brain>retina>kidney. Due to their expression of both endothelial and neuron-like functional and gene transcriptomic signatures, they were termed neuro-endothelial cells (NECs). High resolution single-cell transcriptome analysis of mouse brain and kidney ECs identified neuronal nitric oxide synthase (Nos1) and cytokine-like 1 (Cytl1) as top NEC biomarkers. Intravital multiphoton imaging of optogenetic mouse models with NEC gain/loss-of-function revealed NEC and Nos1-dependent vasodilation/vasoconstriction of intact brain and kidney arterioles and elevation/reduction in blood flow. Silencing NEC Nos1 and Cytl1 gene expression in vivo caused marked segmental arteriolar vasoconstrictions, reductions in vascular density and organ blood flow, increased vascular permeability and immune cell homing. Cytl1 administration triggered vasodilation and increased blood flow acutely, and increased capillary density and clonal EC remodeling chronically. NECs play major vasodilatory, angiogenic and anti-inflammatory functions that may be therapeutically targeted for vascular and inflammatory diseases.

physiology↗

bioRxiv2024

A molecular brain atlas reveals cellular shifts during the repair phase of stroke

Ischemic stroke triggers a cascade of pathological events that affect multiple cell types and often lead to incomplete functional recovery. Despite advances in single-cell technologies, the molecular and cellular responses that contribute to long-term post-stroke impairment remain poorly understood. To gain better insight into the underlying mechanisms, we generated a single-cell transcriptomic atlas from distinct brain regions using a mouse model of permanent focal ischemia at one month post-injury. Our findings reveal cell- and region-specific changes within the stroke-injured and peri-infarct brain tissue. For instance, GABAergic and glutamatergic neurons exhibited upregulated genes in signaling pathways involved in axon guidance and synaptic plasticity, and downregulated pathways associated with aerobic metabolism. Using cell-cell communication analysis, we identified increased strength in predicted interactions within stroke tissue among both neural and non-neural cells via signaling pathways such as those involving collagen, protein tyrosine phosphatase receptor, neuronal growth regulator, laminin, and several cell adhesion molecules. Furthermore, we found a strong correlation between mouse transcriptome responses after stroke and those observed in human nonfatal brain stroke lesions. Common molecular features were linked to inflammatory responses, extracellular matrix organization, and angiogenesis. Our findings provide a detailed resource for advancing our molecular understanding of stroke pathology and for discovering therapeutic targets in the repair phase of stroke recovery.

neuroscience↗

bioRxiv2024

Human iPSC-derived cell grafts promote functional recovery by molecular interaction with stroke-injured brain

Stroke is a leading cause of disability and death due to the brains limited ability to regenerate damaged neural circuits. To date, stroke patients have only few therapeutic options and are often left with considerable disabilities. Induced pluripotent stem cell (iPSC)-based therapies are emerging as a promising therapeutic approach for stroke recovery. In this study, we demonstrate that local transplantation of iPSC-derived neural progenitor cells (NPCs) improves long-term brain tissue repair responses and reduces neurological deficits after cerebral ischemia in mice. Using in vivo bioluminescence imaging and post-mortem histology, we show long-term graft survival over the course of five weeks and preferential graft differentiation into mature neurons without signs of pluripotent residuals. Transplantation of NPCs led to a set of brain tissue repair responses including increased vascular sprouting and repair, improved blood-brain barrier integrity, reduced microglial activation, and increased neurogenesis compared to littermate control animals receiving sham transplantation. Employing deep learning-assisted behavior analysis, we found that NPC-treated mice displayed improved gait performance and complete fine-motor recovery in the horizontal ladder rung walk, five weeks post-injury. To dissect the molecular graft composition and identify graft-host interactions, single nucleus profiling of the cell transplants and host stroke tissue was performed. We identified graft differentiation preferentially towards neurons with GABAergic and glutamatergic phenotypes in similar proportions, with the remaining cells acquiring astrocyte and NPC-like phenotypes. Interaction between graft and host transcriptome indicated that GABAergic cell grafts were primarily involved in graft-host communication through the regeneration-associated neurexin (NRXN), neuregulin (NRG), neural cell adhesion molecule (NCAM) and SLIT signalling pathways. In conclusion, our study reveals that transplanted iPSC-derived NPCs primarily differentiate into GABAergic neurons contributing to long-term recovery and further delineates the regenerative interactions between the graft and the stroke-injured host tissue.

neuroscience↗

bioRxiv2023

Integrative mapping of spatial transcriptomic and amyloid pathology in Alzheimer's disease at single-cell resolution

Alzheimers disease (AD) is a complex neurodegenerative disorder that affects millions of people worldwide. Despite decades of research, the underlying molecular and cellular changes of AD remain unresolved, especially in terms of the spatial structure of gene expression changes that correlates with pathology, e.g. amyloid beta (A-beta) plaques. Recent advances in imaging-or sequencing-based single-cell spatial transcriptomics have allowed a systematic dissection of molecular and cell architectures in the brain and other tissues. In this study, we employed the recently developed Stereo-seq technology to spatially profile the whole-genome transcriptomics in the 5xFAD mouse model and established the methodology to analyze the specific neuronal transcriptomic changes spatially correlated with amyloid pathology at single cell resolution. More specifically, we developed a pipeline for integrative image- and non-image-based cell segmentation, VoxelMorph-based non-linear alignment, and Unet-based object detection to achieve reliable transcriptomics analysis at the single-cell resolution, and investigated the spatial relationship between diverse neuronal clusters and A-beta depositions. This work has demonstrated the potential of using the Stereo-seq technology as a powerful tool to investigate AD and other complex neurological disorders.

neuroscience↗

bioRxiv2021

Neuron-like function of the nephron central command

Interoceptive neurons that sense and regulate our internal milieu have been identified in several organs except in the kidney cortex despite its major importance in maintaining body homeostasis. Here we report that the chief kidney cell type of the macula densa (MD) forms coordinated neural networks in each nephron that resemble peripheral ganglia. A combined in vivo single-cell 4D physiology (sc4DP) and scRNA sequencing approach identified the MD mechanisms of neuronal differentiation, heterogeneity (pacemaker MD cells), sensing of the local and systemic environment via multi-organ crosstalk, and regulation of organ functions by acting as the nephron central command. Consistent with their neuron-like nature, MD cells express the molecular fingerprint of neurodegeneration. Here we put forth the single-cell MD model and concept of local neural networks that control organ and body functions via interoception in normal physiological state and use an integrated mechanism of neurodegeneration in disease.

physiology↗

bioRxiv2018

Balancing dynamic tradeoffs to drive cellular reprogramming

Although cellular reprogramming continues to generate new cell types, reprogramming remains a rare cellular event. The molecular mechanisms that limit reprogramming, particularly to somatic lineages, remain unclear. By examining fibroblast-to-motor neuron conversion, we identify a previously unappreciated dynamic between transcription and replication that determines reprogramming competency. Transcription factor overexpression forces most cells into states that are refractory to reprogramming and are characterized by either hypertranscription with little cell division, or hyperproliferation with low transcription. We identify genetic and chemical factors that dramatically increase the number of cells capable of both hypertranscription and hyperproliferation. Hypertranscribing, hyperproliferating cells reprogram at 100-fold higher, near-deterministic rates. We demonstrate that elevated topoisomerase expression endows cells with privileged reprogramming capacity, suggesting that biophysical constraints limit cellular reprogramming to rare events.

cell biology↗