The study of stem cell and neuro-vascular development

National Heart, Lung, And Blood Institute

Investigators

Linked publications, trials & patents

Abstract

1) Imaging neuro-vascular dysfunction in development: EC-specific VHL deletion disrupts vascular patterning via ectopic activation of HIF-CXCR4 axis. The VHL protein regulates oxygen sensing by targeting hypoxia-inducible factors (HIFs) for degradation under normal oxygen levels. VHL mutations promote tumor vascularization via HIF activation and upregulation of HIF-target angiogenesis genes, such as VEGF-A, in non-endothelial cells (ECs) across various organs. This process influences neighboring ECs and triggers abnormal angiogenesis. However, it remains unclear whether VHL mutations in ECs themselves directly contribute to abnormal angiogenesis. To address this question, we utilized a well-characterized skin vasculature model to investigate vascular development in mice with an EC-specific VHL deletion. We found that the deletion of VHL in ECs resulted in disorganized vascular networks and caused embryonic lethality. Mechanistically, the loss of VHL led to HIF stabilization and ectopic activation of the chemokine receptor CXCR4 for CXCL12 in ECs. Pharmacological inhibition of CXCR4 with AMD3100 partially rescued the observed vascular abnormalities. Supporting these findings, an analysis of publicly available single-cell RNA sequencing data from VHL syndrome patients confirmed the upregulation of CXCR4 expression in ECs from these patients. Overall, these results suggest that EC-specific VHL mutations drive abnormal angiogenesis via the HIF-CXCR4 axis (Li et al. Revision Submitted). 2) Imaging neuro-vascular dysfunction in development: VSMC-specific Ngf deletion disrupts sympathetic innervation of blood vessels. Sympathetic axons innervate not only blood vessels but also a wide array of target tissues. Our comprehensive whole-mount imaging of the embryonic skin with deep learning-based image processing revealed that after the co-branching of sensory nerves and blood vessels is established, sympathetic axons invade the skin alongside these sensory nerves and extend their branches towards large-diameter blood vessels covered by VSMCs (Li et al. PMID: 38639409; Rehman et al. PMID: 39107416). Furthermore, VSMC-specific Ngf deletion leads to a significant reduction in the collateral branching of sympathetic axons innervating VSMC-covered large-diameter blood vessels (Li et al. PMID: 38639409). These findings suggest that VSMC-derived NGF acts as an inductive signal for the collateral branching of sympathetic axons innervating large-diameter blood vessels in embryonic skin. 3) Neuro-vascular dysfunctions that cause pain sensation and increased vascular permeability in the skin of a DIO mouse model. Obesity often leads to vascular abnormalities and sensory nerve dysfunction known as neuropathy. Our studies in mouse models of DIO revealed notable changes in the skin superficial capillary plexus of the skin, where we observed capillary hyperpermeability. Simultaneously, we observed that peripheral sensory nerves in the skin epidermis of DIO mice showed an exaggerated response to pain stimuli. At the molecular level, epidermal keratinocytes in the skin of DIO mice produce nerve growth factor (NGF), which in turn sensitizes skin sensory nerves (Koui et al., PMID: 40160426). We are currently investigating whether managing vascular permeability can help reduce pain in DIO mice. These findings present a compelling opportunity: by targeting skin capillary leakage, we can control the diffusion of key soluble factors from the microcirculation and potentially manage neuropathic pain, an obesity-related complication. 4) Neuron-like pericytes as a negative regulator in a lung fibrosis mouse model. We identify neuronal β-III tubulin (Tuj1) as a distinctive marker for fibrosis-associated pericytes in the lung, which is conserved across bleomycin-induced pulmonary fibrosis mouse model and human pulmonary fibrosis patients. While Tuj1 expression is normally restricted to neuronal cells under normal conditions, most pericytes in fibrotic regions are Tuj1-positive and display a highly branched morphology with their projections to multiple endothelial cells. Furthermore, these Tuj1+ pericytes localize near pro-fibrotic fibroblasts and macrophages. Tuj1 gene (Tubb3) knockout in mice exacerbates lung fibrosis, accompanied by an expansion of the neighboring pro-fibrotic cell populations, suggesting an anti-fibrotic role for Tuj1+ pericytes (Sato et al. Revision Submitted; bioRxiv. PMID: 40568101). Our results provide insights into potential novel therapeutic strategies targeting these protective cell populations for pulmonary fibrosis patients.