Wnt signal-dependent antero-posterior specification of early-stage CNS primordia modeled in EpiSC-derived neural stem cells

Yangyin Yiqi Huoxue Decoction improves the mechanism of microglia activation against CIS-induced neuroinflammatory injury by regulating the Wnt signaling pathway

BACKGROUND

Ischemic stroke is a predominant cause of neurological disability, characterized by neuroinflammation and neuronal apoptosis. The Wnt signaling pathway plays a critical role in brain repair. Yangyin Yiqi Huoxue Decoction, a traditional Chinese herbal formula, has shown potential in alleviating neuroinflammatory injury, yet, the precise mechanism underlying its effects remains unclear.

PURPOSE

This study aims to explore the therapeutic efficacy of Yangyin Yiqi Huoxue Decoction on ischemic stroke and its potential mechanism of action, particularly focusing on its modulation of the Wnt signaling pathway and impact on neuroinflammation and neural stem cells activity.

STUDY DESIGN AND METHODS

The middle cerebral artery occlusion (MCAO) rat model and an Oxygen glucose deprivation/re-oxygenation (OGD/R) cell model were employed. In vivo experiments were conducted to investigate the therapeutic effects of the Yangyin Yiqi Huoxue Decoction at high, medium, and low dosages (3.3, 1.65, and 0.83 g/kg). The effects of Yangyin Yiqi Huoxue Decoction on neuroinflammatory cytokine levels, microglial activation, and neural stem cells proliferation and differentiation were assessed in vivo experiments. Wnt signaling components were evaluated through Quantitative Real-Time PCR and Western blot in both vivo and vitro. Additionaly, the Wnt inhibitor Dickkopf-related protein 1(DKK1) was used to confirm the pathway's involvement.

RESULTS

The high-dose group(3.3 g/kg) of the Yangyin Yiqi Huoxue Decoction exhibited the most pronounced therapeutic effects. Yangyin Yiqi Huoxue Decoction significantly reduced pro-inflammatory cytokine levels, inhibited microglial overactivation, and enhanced neural stem cells proliferation and differentiation. It also modulated the Wnt pathway by upregulating Wnt Family Member 3A(Wnt3a) and β-catenin, while downregulating Wnt Family Member 5A(Wnt5a) and glycogen synthase kinase-3β(GSK-3β). The inhibition of Wnt signaling by Dickkopf-related protein 1(DKK1) reversed these beneficial effects, confirming Yangyin Yiqi Huoxue Decoction 's mechanism.

CONCLUSIONS

Yangyin Yiqi Huoxue Decoction exerts neuroprotective effects by suppressing neuroinflammation and promoting neural-stem-cell-mediated brain repair through the Wnt signaling pathway, positioning it as a potential candidate for ischemic stroke treatment.

Chicken embryo cultures in the dorsal-upward orientation for the manipulation of epiblasts

Chicken embryos have many advantages in the study of amniote embryonic development. In particular, culture techniques developed for early-stage embryos have promoted the advancement of modern developmental studies using chicken embryos. However, the standard technique involves placing chicken embryos in the ventral-upward (ventral-up) orientation, limiting manipulation of the epiblast at the dorsal surface, which is the primary source of ectodermal and mesodermal tissues. To circumvent this limitation, we developed chicken embryo cultures in the dorsal-up orientation and exploited this technique to address diverse issues. In this article, we first review the history of chicken embryo culture techniques to evaluate the advantages and limitations of the current standard technique. Then, the dorsal-up technique is discussed. These technological discussions are followed by three different examples of experimental analyses using dorsal-up cultures to illustrate their advantages: (1) EdU labeling of epiblast cells to assess potential variation in the cell proliferation rate; (2) migration behaviors of N1 enhancer-active epiblast cells revealed by tracking cells with focal fluorescent dye labeling in dorsal-up embryo culture; and (3) neural crest development of mouse neural stem cells in chicken embryos.

The Origin and Regulation of Neuromesodermal Progenitors (NMPs) in Embryos

Neuromesodermal progenitors (NMPs), serving as the common origin of neural and paraxial mesodermal development in a large part of the trunk, have recently gained significant attention because of their critical importance in the understanding of embryonic organogenesis and the design of in vitro models of organogenesis. However, the nature of NMPs at many essential points remains only vaguely understood or even incorrectly assumed. Here, we discuss the nature of NMPs, focusing on their dynamic migratory behavior during embryogenesis and the mechanisms underlying their neural vs. mesodermal fate choice. The discussion points include the following: (1) How the sinus rhomboidals is organized; the tissue where the neural or mesodermal fate choice of NMPs occurs. (2) NMPs originating from the broad posterior epiblast are associated with Sox2 N1 enhancer activity. (3) Tbx6-dependent Sox2 repression occurs during NMP-derived paraxial mesoderm development. (4) The nephric mesenchyme, a component of the intermediate mesoderm, was newly identified as an NMP derivative. (5) The transition of embryonic tissue development from tissue-specific progenitors in the anterior part to that from NMPs occurs at the forelimb bud axial level. (6) The coexpression of Sox2 and Bra in NMPs is conditional and is not a hallmark of NMPs. (7) The ability of the NMP pool to sustain axial embryo growth depends on Wnt3a signaling in the NMP population. Current in vitro models of NMPs are also critically reviewed.