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Highlights d Human germline cell specification begins from a transitional pluripotent state d Human primordial germ cells are specified from lineageprimed progenitors d Lineage-primed TFAP2A progenitors have gastrulating and amnion cell identity d TFAP2C regulates SOX17 at the point of human primordial germ cell specification

Classic embryological studies have successfully applied genetics and cell biology principles to understand embryonic development. However, it remains unresolved how mechanics, as an integral driver of development, is involved in controlling tissue-scale cell fate patterning. Here we report a micropatterned human pluripotent stem (hPS)-cell-based neuroectoderm developmental model, in which pre-patterned geometrical confinement induces emergent patterning of neuroepithelial and neural plate border cells, mimicking neuroectoderm regionalization during early neurulation in vivo. In this hPS-cell-based neuroectoderm patterning model, two tissue-scale morphogenetic signals-cell shape and cytoskeletal contractile force-instruct neuroepithelial/neural plate border patterning via BMP-SMAD signalling. We further show that ectopic mechanical activation and exogenous BMP signalling modulation are sufficient to perturb neuroepithelial/neural plate border patterning. This study provides a useful microengineered, hPS-cell-based model with which to understand the biomechanical principles that guide neuroectoderm patterning and hence to study neural development and disease.

Despite its importance in central nervous system development, development of the human neural tube (NT) remains poorly understood, given the challenges of studying human embryos, and the developmental divergence between humans and animal models. We report a human NT development model, in which NT-like tissues, neuroepithelial (NE) cysts, are generated in a bioengineered neurogenic environment through self-organization of human pluripotent stem cells (hPSCs). NE cysts correspond to the neural plate in the dorsal ectoderm and have a default dorsal identity. Dorsal-ventral (DV) patterning of NE cysts is achieved using retinoic acid and/or sonic hedgehog and features sequential emergence of the ventral floor plate, P3, and pMN domains in discrete, adjacent regions and a dorsal territory progressively restricted to the opposite dorsal pole. This hPSC-based, DV patterned NE cyst system will be useful for understanding the self-organizing principles that guide NT patterning and for investigations of neural development and neural disease.

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The critical role of angiogenesis for solid tumor growth and metastatic spread has been well established. In contrast, even though increased vascularity has been commonly observed in bone marrows of patients with hematological malignancies (liquid tumors), the pathophysiology of leukemia induced angiogenesis in the bone marrow remains elusive. In this paper, we demonstrated the usage of a microengineered 3D biomimetic model to study leukemic cell induced bone marrow angiogenesis. Rational design of the 3D angiogenesis chip incorporating endothelial cells (ECs), leukemic cells, and bone marrow stromal fibroblasts provided an efficient biomimetic means to promote and visualize early angiogenic processes. Morphological features of angiogenesis induced by three different leukemic cell lines (U937, HL60, and K562) were investigated and compared. Quantitative measurements of angiogenic factors secreted from monocultures and cocultures of leukemic cells with bone marrow stromal fibroblasts suggested a synergistic relationship between ECs, leukemic cells, and bone marrow stromal fibroblasts for angiogenic induction, and also confirmed the necessity of conducting functional angiogenic assays in proper 3D biomimetic cell culture systems like the one developed in this work.

The aim of the present study was to investigate the neuroprotective mechanism of the miR-9-mediated activation of the nuclear factor (NF)-κB signaling pathway by electroacupuncture (EA) stimulation of the Quchi (LI11) and Zusanli (ST36) acupoints in a rat model of middle cerebral artery occlusion (MCAO). The present study demonstrated that EA alleviated the symptoms of neurological deficits and reduced the infarct volume in the rat brains. The expression of miR-9 in the peri-infarct cortex was increased in the EA group compared with the MCAO group, and the expression of NF-κB signaling pathway-associated factors, NF-κB p65, tumor necrosis factor (TNF)-α and interleukin (IL)-1β were reduced. Notably, miR-9 inhibitors were revealed to have the ability to suppress EA-alleviated cerebral inflammation and the expression of NF-κB downstream-related factors, NF-κB p65, TNF-α and IL-1β, and caused no alteration on the level of NF-κB upstream-related protein inhibitor of κBα, suggesting that the cerebral protective efficacy of EA targets miR-9-mediated NF-κB downstream pathway following ischemic stroke.

Embryonic development is largely conserved among mammals. However, certain genes show divergent functions. By generating a transcriptional atlas containing >30,000 cells from post-implantation non-human primate embryos, we uncover that ISL1, a gene with a well-established role in cardiogenesis, controls a gene regulatory network in primate amnion. CRISPR/Cas9-targeting of ISL1 results in non-human primate embryos which do not yield viable offspring, demonstrating that ISL1 is critically required in primate embryogenesis. On a cellular level, mutant ISL1 embryos display a failure in mesoderm formation due to reduced BMP4 signaling from the amnion. Via loss of function and rescue studies in human embryonic stem cells we confirm a similar role of ISL1 in human in vitro derived amnion. This study highlights the importance of the amnion as a signaling center during primate mesoderm formation and demonstrates the potential of in vitro primate model systems to dissect the genetics of early human embryonic development.