Microglia ferroptosis is regulated by SEC24B and contributes to neurodegeneration.

Iron dysregulation has been implicated in multiple neurodegenerative diseases, including Parkinson's disease (PD). Iron-loaded microglia are frequently found in affected brain regions, but how iron accumulation influences microglia physiology and contributes to neurodegeneration is poorly understood. Here we show that human induced pluripotent stem cell-derived microglia grown in a tri-culture system are highly responsive to iron and susceptible to ferroptosis, an iron-dependent form of cell death. Furthermore, iron overload causes a marked shift in the microglial transcriptional state that overlaps with a transcriptomic signature found in PD postmortem brain microglia. Our data also show that this microglial response contributes to neurodegeneration, as removal of microglia from the tri-culture system substantially delayed iron-induced neurotoxicity. To elucidate the mechanisms regulating iron response in microglia, we performed a genome-wide CRISPR screen and identified novel regulators of ferroptosis, including the vesicle trafficking gene SEC24B. These data suggest a critical role for microglia iron overload and ferroptosis in neurodegeneration.

Multipotent Vascular Progenitor Cells of the Mesothelium Lineage Generated from Human Pluripotent Stem Cells.

Vascularization is critical for organ homeostasis and function, but cell-based technologies that promote vascular regeneration are limited. This protocol describes steps to generate human pluripotent stem cell (hPSC)-derived vascular progenitors of the mesothelium lineage. This technology has several advantages for the generation of vascular cells. First and foremost, MesoT cells are multipotent progenitors that can generate smooth muscle cells and endothelial cells. MesoT cells therefore have potential utility in tissue repair, tissue engineering, and in vascularization of laboratory grown organs. For complete details on the use and execution of this protocol, please refer to Colunga et al. (2019).

Human Pluripotent Stem Cell-Derived Multipotent Vascular Progenitors of the Mesothelium Lineage Have Utility in Tissue Engineering and Repair.

In this report we describe a human pluripotent stem cell-derived vascular progenitor (MesoT) cell of the mesothelium lineage. MesoT cells are multipotent and generate smooth muscle cells, endothelial cells, and pericytes and self-assemble into vessel-like networks in vitro. MesoT cells transplanted into mechanically damaged neonatal mouse heart migrate into the injured tissue and contribute to nascent coronary vessels in the repair zone. When seeded onto decellularized vascular scaffolds, MesoT cells differentiate into the major vascular lineages and self-assemble into vasculature capable of supporting peripheral blood flow following transplantation. These findings demonstrate in vivo functionality and the potential utility of MesoT cells in vascular engineering applications.

Comparison of circulating dendritic cell and monocyte subsets at different stages of atherosclerosis: insights from optical coherence tomography.

BACKGROUND: While specific patterns of circulating dendritic cells (DCs) and monocytes are associated with the incidence of coronary artery disease, the characterization of circulating DC and monocyte subsets in patients with different stages of atherosclerosis remains unclear. METHODS: Forty-eight patients with unstable angina pectoris (UAP) diagnosed by angiography were enrolled. Likewise, 31 patients with ST-segment elevation myocardial infarction (STEMI) were enrolled and confirmed with the presence of thrombosis by angiography. Plaque features of 48 UAP patients were evaluated at the culprit lesions by OCT. Circulating myeloid DCs (mDCs), plasmacytoid DCs (pDCs) and monocyte subsets were analyzed using flow cytometry. RESULTS: The proportions and absolute counts of mDC2s, which specifically express CD141 and possess the ability to activate CD8+ T lymphocytes, significantly decreased in patients with UAP and STEMI when compared with controls (0.08 × 104 ± 0.05 × 104/ml and 0.08 × 104 ± 0.06 × 104/ml vs. 0.11 × 104 ± 0.06 × 104/ml, p = 0.027). On the other hand, patients with UAP and STEMI had significantly higher proportions and counts of Mon2 subsets. In the OCT subgroup, patients with thin-cap fibroatheroma (TCFA) had higher proportions and absolute number of Mon2 (11.96% ± 4.27% vs. 9.42% ± 4.05%, p = 0.034; 5.17 × 104/ml ± 1.92 × 104/ml vs. 3.53 × 104/ml ± 2.65 × 104/ml, p = 0.045) than those without TCFA. However, there was no remarkable difference in mDC2s between patients with and without TCFA. CONCLUSIONS: Circulating Mon2 appears to be a promising marker for the severity of atherosclerotic plaque.

XAV939 Inhibits Intima Formation by Decreasing Vascular Smooth Muscle Cell Proliferation and Migration Through Blocking Wnt Signaling.

BACKGROUND: Excessive proliferation, migration, and oxidative stress of vascular smooth muscle cells (VSMCs) are key mechanisms involved in intima formation, which is the basic pathological process of in stent restenosis. This study aims at exploring the role of XAV939 in proliferation, migration, and reactive oxygen species (ROS) generation of VSMCs, and hence evaluating its effects on intima formation. METHODS: Carotid artery ligation models for C57BL/6 mice were established and gave them different intervention: saline, XAV939, Axin2 overexpression adenovirus, and negative control adenovirus. The intima formation was assayed by intima area and intima/media ratio. To investigate the underlying mechanisms, primary rat VSMCs were cultured and treated with XAV939 and platelet-derived growth factor-BB. EdU, direct cell counting, cell wound-healing assay, and flow cytometry were used to measure proliferation, migration, cell cycle, apoptosis, and ROS generation of VSMCs, respectively. By Western blot, we examined proliferating cell nuclear antigen, Cyclin D1, Cyclin E, p21, ß-actin, JNK, phosphorylated JNK, Axin2 and ß-catenin expression. Immunofluorescence staining and confocal microscopy were conducted to detect translocation of ß-catenin. RESULTS: XAV939 inhibited intima formation, which was exhibited by the loss of intima area and I/M ratio and attenuated proliferation, migration, and ROS generation, as well as promoted cell cycle arrest of VSMCs. Specifically, XAV939 inhibited Wnt pathway. CONCLUSIONS: XAV939 attenuates intima formation because of its inhibition of proliferation, migration, and apoptosis of VSMCs through suppression of Wnt signaling pathway.