摘要: Bone defects (BDs), a prevalent clinically refractory orthopaedic disease, presently have no effective treatments. Mesenchymal stem cells (MSCs) can differentiate into osteoblasts and serve as potential seed cells for bone tissue engineering for BD treatment. However, the feasibility of using MSCs as seed cells for bone tissue engineering remains unclear. As a result, the critical issue of large-scale cell-scaffold preparation remains unresolved. In this study, we demonstrated for the first time that human embryonic stem cell-derived MSCs, also known as immunity-and-matrix-regulatory cells (IMRCs), could be inoculated into microcarriers to create osteogenic micro-tissues appropriate for scalable production in 250 mL bioreactor. IMRCs were generally smaller than umbilical cord-derived MSCs (UCMSCs) and could attach, migrate, proliferate and differentiate within the porous microcarriers, whereas UCMSCs could only attach to the surface of microcarriers. Osteogenic micro-tissues generated from IMRCs-seeded microcarriers significantly increased osteocalcin levels after 21 days of differentiation in a bioreactor. Furthermore, the expression levels of osteogenic biomarker genes/proteins such as alkaline phosphatase (ALP), osteocalcin (OCN), runt-related transcription factor 2 (RUNX2), osteopontin (OPN) and osterix (OSX) were significantly higher than osteogenic micro-tissues derived from UCMSCs-seeded microcarriers. Our findings imply that IMRCs could potentially serve as seed cells for the scalable production of osteogenic micro-tissues for BD treatment.

摘要: Small intestinal health and enteritis incidence are tightly coupled to the homeostasis of intestinal stem cells (ISCs), which are sensitive to dietary alterations. However, little is known about the impact of food additives on ISC pool. Here, we demonstrate that chronic exposure to low-dose TiO2 NPs, a commonly used food additive, significantly hampers primary human and mouse ISC-derived organoid formation and growth by specifically attenuating Wnt signal transduction. Mechanistically, TiO2 NPs alter the endocytic trafficking of the Wnt receptor LRP6 and prevent the nuclear entry of beta-catenin. Notably, dietary TiO2 NPs elicit modest chronic stress in healthy intestines and considerably impede the recovery of radiation enteritis by perturbing the homeostasis of ISCs in vivo. Our results identify a health concern of TiO2 NP exposure on ISC homeostasis and radiation enteritis recovery. These findings suggest extra precaution during the treatment of radiation enteritis and provide new insights into food additive-ISC interaction.

摘要: Cell polarity is essential for ameloblast differentiation and enamel formation. Smurf1 can mediate cell polarization through ubiquitination degradation of specific substrates. But it remains unclear whether Smurf1 could regulate ameloblast polarity and the underlying mechanism. Here, immuno-fluorescence staining and RT-qPCR were applied to detect the expression of Smurf1 and F-actin. A mouse lower incisor defect model was constructed. Scanning electron microscope, rat lower incisor culture, western blot, wound healing assay and trans-well migration assay were performed to detect the influence of Smurf1 knockdown on ameloblast. IF double staining, western blot and co-immunoprecipitation were conducted to detect the interaction between Smurf1 and RhoA. The in vivo experiment was also performed. We found that Smurf1 was mainly expressed in the membrane and cell cortex of ameloblast, similar to F-actin. Smurf1 expression increased along ameloblast polarization and differentiation. After knocking down Smurf1, the cytoskeleton and cell morphology changed and the cell polarity was damaged. Smurf1 regulated ameloblast polarity through ubiquitination degradation of activated RhoA in vitro. Local knockdown of Smurf1 in rat lower incisor ameloblast resulted in ameloblast polarity loss, enamel matrix secretion disorder and chalky enamel, but RhoA inhibitor Y-27632 could reverse this effect. Collectively, Smurf1 could regulate the polarization of ameloblast through ubiquitination degradation of activated RhoA, which contributed to the knowledge of tooth development and provided new research ideas for cell polarity.

摘要: Pre-eclampsia (PE) is deemed an ischemia-induced metabolic disorder of the placenta due to defective invasion of trophoblasts during placentation; thus, the driving role of metabolism in PE pathogenesis is largely ignored. Since trophoblasts undergo substantial glycolysis, this study aimed to investigate its function and regulatory mechanism by AMPK in PE development. Metabolomics analysis of PE placentas was performed by gas chromatography-mass spectrometry (GC-MS). Trophoblast-specific AMPK alpha 1-deficient mouse placentas were generated to assess morphology. A mouse PE model was established by Reduced Uterine Perfusion Pressure, and placental AMPK was modulated by nanoparticle-delivered A769662. Trophoblast glucose uptake was measured by 2-NBDG and 2-deoxy-d-[H-3] glucose uptake assays. Cellular metabolism was investigated by the Seahorse assay and GC-MS.PE complicated trophoblasts are associated with AMPK hyperactivation due not to energy deficiency. Thereafter, AMPK activation during placentation exacerbated PE manifestations but alleviated cell death in the placenta. AMPK activation in trophoblasts contributed to GLUT3 translocation and subsequent glucose metabolism, which were redirected into gluconeogenesis, resulting in deposition of glycogen and accumulation of phosphoenolpyruvate; the latter enhanced viability but compromised trophoblast invasion. However, ablation of AMPK in the mouse placenta resulted in decreased glycogen deposition and structural malformation. These data reveal a novel homeostasis between invasiveness and viability in trophoblasts, which is mechanistically relevant for switching between the 'go' and 'grow' cellular programs.

摘要: The mammalian target of rapamycin (mTOR) is a protein kinase that responds to different stimuli such as stresses, starvation and hypoxic conditions. The modulation of this effector can lead to the alteration of cell dynamic growth, proliferation, basal metabolism and other bioactivities. Considering this fact, the mTOR pathway is believed to regulate the diverse functions in several cell lineages. Due to the pleiotropic effects of the mTOR, we here, hypothesize that this effector can also regulate the bioactivity of stem cells in response to external stimuli pathways under physiological and pathological conditions. As a correlation, we aimed to highlight the close relationship between the mTOR signalling axis and the regenerative potential of stem cells in a different milieu. The relevant publications were included in this study using electronic searches of the PubMed database from inception to February 2023. We noted that the mTOR signalling cascade can affect different stem cell bioactivities, especially angiogenesis under physiological and pathological conditions. Modulation of mTOR signalling pathways is thought of as an effective strategy to modulate the angiogenic properties of stem cells.