Substrate nesting guides cyst morphogenesis of human pluripotent stem cells without 3D extracellular matrix overlay.

Understanding the principles underlying the self-organization of stem cells into tissues is fundamental for deciphering human embryo development. Here, we report that, without three-dimensional (3D) extracellular matrix (ECM) overlay, human pluripotent stem cells (hPSCs) cultured on two-dimensional soft elastic substrates can self-organize into 3D cysts resembling the human epiblast sac in a stiffness-dependent manner. Our theoretical modeling predicts that this cyst organization is facilitated and guided by the spontaneous nesting of the soft substrate, which results from the adhesion-dependent mechanical interaction between cells and substrate. Such substrate nesting is sufficient for the 3D assembly and polarization of hPSCs required for cyst organization, even without 3D ECM overlay. Furthermore, we identify that the reversible substrate nesting and cyst morphogenesis also require appropriate activation of ROCK-Myosin II pathway. This indicates a unique set of tissue morphomechanical signaling mechanisms that clearly differ from the canonical cystogenic mechanism previously reported in 3D ECM. Our findings highlight an unanticipated synergy between mechanical microenvironment and mechanotransduction in controlling tissue morphogenesis and suggest a mechanics-based strategy for generation of hPSCs-derived models for early human embryogenesis. STATEMENT OF SIGNIFICANCE: Soft substrates can induce the self-organization of human pluripotent stem cells (hPSCs) into cysts without three-dimensional (3D) extracellular matrix (ECM) overlay. However, the underlying mechanisms by which soft substrate guides cystogenesis are largely unknown. This study shows that substrate nesting, resulting from cell-substrate interaction, plays an important role in cyst organization, including 3D assembly and apical-basal polarization. Additionally, actomyosin contractility mediated by the ROCK-Myosin II pathway also contributes to the substrate deformation and cyst morphology. These findings demonstrate the interplay between the mechanical microenvironment and cells in tissue morphogenesis, suggesting a mechanics-based strategy in building hPSC-derived models for early human embryo development.

Mechanically enhanced biogenesis of gut spheroids with instability-driven morphomechanics.

Region-specific gut spheroids are precursors for gastrointestinal and pulmonary organoids that hold great promise for fundamental studies and translations. However, efficient production of gut spheroids remains challenging due to a lack of control and mechanistic understanding of gut spheroid morphogenesis. Here, we report an efficient biomaterial system, termed micropatterned gut spheroid generator (µGSG), to generate gut spheroids from human pluripotent stem cells through mechanically enhanced tissue morphogenesis. We show that µGSG enhances the biogenesis of gut spheroids independent of micropattern shape and size; instead, mechanically enforced cell multilayering and crowding is demonstrated as a general, geometry-insensitive mechanism that is necessary and sufficient for promoting spheroid formation. Combining experimental findings and an active-phase-field morphomechanics theory, our study further reveals an instability-driven mechanism and a mechanosensitive phase diagram governing spheroid pearling and fission in µGSG. This work unveils mechanobiological paradigms based on tissue architecture and surface tension for controlling tissue morphogenesis and advancing organoid technology.

GxcM-Fbp17/RacC-WASP signaling regulates polarized cortex assembly in migrating cells via Arp2/3.

The actin-rich cortex plays a fundamental role in many cellular processes. Its architecture and molecular composition vary across cell types and physiological states. The full complement of actin assembly factors driving cortex formation and how their activities are spatiotemporally regulated remain to be fully elucidated. Using Dictyostelium as a model for polarized and rapidly migrating cells, we show that GxcM, a RhoGEF localized specifically in the rear of migrating cells, functions together with F-BAR protein Fbp17, a small GTPase RacC, and the actin nucleation-promoting factor WASP to coordinately promote Arp2/3 complex-mediated cortical actin assembly. Overactivation of this signaling cascade leads to excessive actin polymerization in the rear cortex, whereas its disruption causes defects in cortical integrity and function. Therefore, apart from its well-defined role in the formation of the protrusions at the cell front, the Arp2/3 complex-based actin carries out a previously unappreciated function in building the rear cortical subcompartment in rapidly migrating cells.

Nano/Micromotors in Active Matter.

Nano/micromotors (NMMs) are tiny objects capable of converting energy into mechanical motion. Recently, a wealth of active matter including synthetic colloids, cytoskeletons, bacteria, and cells have been used to construct NMMs. The self-sustained motion of active matter drives NMMs out of equilibrium, giving rise to rich dynamics and patterns. Alongside the spontaneous dynamics, external stimuli such as geometric confinements, light, magnetic field, and chemical potential are also harnessed to control the movements of NMMs, yielding new application paradigms of active matter. Here, we review the recent advances, both experimental and theoretical, in exploring biological NMMs. The unique dynamical features of collective NMMs are focused on, along with some possible applications of these intriguing systems.

Long non-coding RNA H19 protects against intracerebral hemorrhage injuries via regulating microRNA-106b-5p/acyl-CoA synthetase long chain family member 4 axis.

Intracerebral hemorrhage (ICH) is one of the most common refractory diseases. Long non-coding RNAs (lncRNAs) play crucial roles in ICH. This study was designed to investigate the role of lncRNA H19 in ICH and the underlying molecular mechanisms involved. Real-time quantitative polymerase chain reaction (RT-qPCR) was performed to determine mRNA expression. Cell viability was analyzed using Cell Counting Kit 8 (CCK8). PI staining Flow cytometry and TdT-mediated biotinylated nick end-labeling (TUNEL) assays were performed to determine ferroptosis in brain microvascular endothelial cells (BMVECs). Targeting relationships were predicted using Starbase and TargetScan and verified by RNA pull-down and luciferase reporter gene assays. Western blotting was performed to assess protein expression. LncRNA H19 is highly expressed in ICH model cells. Over-expression of H19 suppressed cell viability and promoted ferroptosis of BMVECs. miR-106b-5p is predicted to be a target of H19. The expression of miR-106b-5p was lower in oxygen and glucose deprivation hemin-treated (OGD/H-treated) cells. Over-expression of miR-106b-5p reversed the effects of H19 on cell viability and ferroptosis in BMVECs. Furthermore, acyl-CoA synthetase long-chain family member 4 (ACSL4) was verified to be a target gene of miR-106b-5p and was highly expressed in OGD/H-treated cells. Upregulation of ACSL4 inhibited the effects of miR-106b-5p and induced BMVEC dysfunction. In conclusion, lncRNA H19 was overexpressed in ICH. Knockdown of H19 promoted cell proliferation and suppressed BMVECs ferroptosis by regulating the miR-106b-5p/ACSL4 axis. Therefore, H19 knockdown may be a promising therapeutic strategy for ICH.

Improved photothermal therapy of brain cancer cells and photogeneration of reactive oxygen species by biotin conjugated gold photoactive nanoparticles.

Herein, we report on the design and development of functionalized acrylic polymeric nanoparticles with Spiropyrans (SPs) and imidazole moieties via superficial polymerizations. Then, Au3+ ions were immobilized and reduced on their surface to obtain photoresponsive gold-decorated polymer nanoparticles(Au-NPs). The synthesized Au-NPs were surface adapted with biotin as specific targeting tumor penetration cells and enhance the intercellular uptake through the endocytosis. FT-IR (Fourier-transform Infrared Spectroscopy), UV-Vis (Ultra Violet-Visible Spectrophotometer), EDS (Energy Dispersive X-Ray Spectroscopy), SEM (Scanning Electron Microscope) and HR-TEM (High-resolution transmission electron microscopy) descriptions were engaged to illustrate their spectral analysis and morphological examinations of Bt@Au-NPs. Fluorescence microscopy images of cellular uptake descriptions and ICP-MS (Inductively coupled plasma mass spectrometry) investigation established the cell lines labeling ability and enhanced targetting efficacy of biotin-conjugated Au-NPs (Bt@Au-NPs) toward C6 glioma cells (brain cancer cells) with 72.5% cellular uptake relative to 30.2% for non-conjugated lone. These were further established through intracellular ROS examinations and in vitro cytotoxicity investigation on the C6 glioma cell line. The solid surface plasmon absorptions of the Au-NPs and Bt@Au-NPs providing raised photothermal therapy under UV irradiation. The synthesized multifunctional Bt@Au-NPs with an inclusive combination of potential resources presented encouraging nanoprobe with targeting capability, improved photodynamic and photothermal cancer therapy.

Prognostic value of free DNA quantification in serum and cerebrospinal fluid in glioma patients.

Unlike uniformly truncated DNA released from apoptotic nondiseased cells, free DNA released from dead tumor cells varies in size. Free DNA has been considered as a candidate biomarker for malignant tumors. We obtained serum samples from 70 patients with glioma and 22 healthy volunteers as control and cerebrospinal fluid (CSF) samples from 20 patients with glioma and eight nonneoplastic controls with hydrocephalus or arachnoid cyst and performed preoperative analysis of free DNA concentration and integrity by a quantitative polymerase chain reaction. With two primers sets amplifying short and long free DNA fragments (ALU115 and ALU247), free DNA integrity was determined by ratio of the concentration of ALU247 over ALU115 (ALU247/115). Our results indicate that free DNA integrity and the ratio of long fragments to short fragments may be a useful diagnostic assay for glioma. In summary, the CSF-free DNA concentration and integrity may serve as a new marker for the diagnosis of glioma.