Physiological and Pathological Remodeling of Cerebral Microvessels

Investigation of high-dose radiotherapy's effect on brain structure aggravated cognitive impairment and deteriorated patient psychological status in brain tumor treatment

This study aims to investigate the potential impact of high-dose radiotherapy (RT) on brain structure, cognitive impairment, and the psychological status of patients undergoing brain tumor treatment. We recruited and grouped 144 RT-treated patients with brain tumors into the Low dose group (N = 72) and the High dose group (N = 72) according to the RT dose applied. Patient data were collected by using the HADS and QLQ-BN20 system for subsequent analysis and comparison. Our analysis showed no significant correlation between the RT doses and the clinicopathological characteristics. We found that a high dose of RT could aggravate cognitive impairment and deteriorate patient role functioning, indicated by a higher MMSE and worsened role functioning in the High dose group. However, the depression status, social functioning, and global health status were comparable between the High dose group and the Low dose group at Month 0 and Month 1, while being worsened in the High dose group at Month 3, indicating the potential long-term deterioration of depression status in brain tumor patients induced by high-dose RT. By comparing patient data at Month 0, Month 1, Month 3, Month 6, and Month 9 after RT, we found that during RT treatment, RT at a high dose could aggravate cognitive impairment in the short term and lead to worsened patient role functioning, and even deteriorate the overall psychological health status of patients in the long term.

Thymosin beta 10 loaded ZIF-8/sericin hydrogel promoting angiogenesis and osteogenesis for bone regeneration

Angiogenesis is pivotal for osteogenesis during bone regeneration. A hydrogel that promotes both angiogenesis and osteogenesis is essential in bone tissue engineering. However, creating scaffolds with the ideal balance of biodegradability, osteogenic, and angiogenic properties poses a challenge. Thymosin beta 10 (TMSB10), known for its dual role in angiogenesis and osteogenesis differentiation, faces limitations due to protein activity preservation. To tackle this issue, ZIF-8 was engineered as a carrier for TMSB10 (TMSB10@ZIF-8), and subsequently integrated into the self-assembled sericin hydrogel. The efficacy of the composite hydrogel in bone repair was assessed using a rat cranial defect model. Characterization of the nanocomposites confirmed the successful synthesis of TMSB10@ZIF-8, with a TMSB10 encapsulation efficiency of 88.21 %. The sustained release of TMSB10 from TMSB10@ZIF-8 has significantly enhanced tube formation in human umbilical vein endothelial cells (HUVECs) in vitro and promoted angiogenesis in the chicken chorioallantoic membrane (CAM) model in vivo. It has markedly improved the osteogenic differentiation ability of MC 3 T3-E1 cells in vitro. 8 weeks post-implantation, the TMSB10@ZIF-8/ Sericin hydrogel group exhibited significant bone healing (86.77 ± 8.91 %), outperforming controls. Thus, the TMSB10@ZIF-8/Sericin hydrogel, leveraging ZIF-8 for TMSB10 delivery, emerges as a promising bone regeneration scaffold with substantial clinical application potential.

[Mechanobiological Mechanisms Involved in the Regualation of the Blood-Brain Barrier by Fluid Shear Force]

Objective

To explore the mechanobiological mechanism of fluid shear force (FSF) on the protection, injury, and destruction of the structure and function of the blood-brain barrier (BBB) under normal physiological conditions, ischemic hypoperfusion, and postoperative hyperperfusion conditions. BBB is mainly composed of brain microvascular endothelial cells. Rat brain microvascular endothelial cells (rBMECs) were used as model cells to conduct the investigation.

Methods

rBMECs were seeded at a density of 1×105 cells/cm2 and incubated for 48 h. FSF was applied to the rBMECs at 0.5, 2, and 20 dyn/cm2, respectively, simulating the stress BBB incurs under low perfusion, normal physiological conditions, and high FSF after bypass grafting when there is cerebral vascular stenosis. In addition, a rBMECs static culture group was set up as the control (no force was applied). Light microscope, scanning electron microscope (SEM), and laser confocal microscope (LSCM) were used to observe the changes in cell morphology and cytoskeleton. Transmission electron microscope (TEM) was used to observe the tight junctions. Immunofluorescence assay was performed to determine changes in the distribution of tight junction-associated proteins claudin-5, occludin, and ZO-1 and adherens junction-associated proteins VE-cadherin and PECAM-1. Western blot was performed to determine the expression levels of tight junction-associated proteins claudin-5, ZO-1, and JAM4, adherens junction-associated protein VE-cadherin, and key proteins in Rho GTPases signaling (Rac1, Cdc42, and RhoA) under FSF at different intensities.

Results

Microscopic observation showed that the cytoskeleton exhibited disorderly arrangement and irregular orientation under static culture and low shear force (0.5 dyn/cm2). Under normal physiological shear force (2 dyn/cm2), the cytoskeleton was rearranged in the orientation of the FSF and an effective tight junction structure was observed between cells. Under high shear force (20 dyn/cm2), the intercellular space was enlarged and no effective tight junction structure was observed. Immunofluorescence results showed that, under low shear force, the gap between the cells decreased, but there was also decreased distribution of tight junction-associated proteins and adherens junction-associated proteins at the intercellular junctions. Under normal physiological conditions, the cells were tightly connected and most of the tight junction-associated proteins were concentrated at the intercellular junctions. Under high shear force, the gap between the cells increased significantly and the tight junction and adherens junction structures were disrupted. According to the Western blot results, under low shear force, the expression levels of claudin-5, ZO-1, and VE-cadherin were significantly up-regulated compared with those of the control group (P<0.05). Under normal physiological shear force, claudin-5, ZO-1, JAM4, and VE-cadherin were highly expressed compared with those of the control group (P<0.05). Under high shear force, the expressions of claudin-5, ZO-1, JAM4, and VE-cadherin were significantly down-regulated compared with those of the normal physiological shear force group (P<0.05). Under normal physiological shear force, intercellular expressions of Rho GTPases proteins (Rac1, Cdc42, and RhoA) were up-regulated and were higher than those of the other experimental groups (P<0.05). The expressions of Rho GTPases under low and high shear forces were down-regulated compared with that of the normal physiological shear force group (P<0.05).

Conclusion

Under normal physiological conditions, FSF helps maintain the integrity of the BBB structure, while low or high shear force can damage or destroy the BBB structure. The regulation of BBB by FSF is closely related to the expression and distribution of tight junction-associated proteins and adherens junction-associated proteins.

Novel Approaches to the Establishment of Local Microenvironment from Resorbable Biomaterials in the Brain In Vitro Models

The development of brain in vitro models requires the application of novel biocompatible materials and biopolymers as scaffolds for controllable and effective cell growth and functioning. The "ideal" brain in vitro model should demonstrate the principal features of brain plasticity like synaptic transmission and remodeling, neurogenesis and angiogenesis, and changes in the metabolism associated with the establishment of new intercellular connections. Therefore, the extracellular scaffolds that are helpful in the establishment and maintenance of local microenvironments supporting brain plasticity mechanisms are of critical importance. In this review, we will focus on some carbohydrate metabolites-lactate, pyruvate, oxaloacetate, malate-that greatly contribute to the regulation of cell-to-cell communications and metabolic plasticity of brain cells and on some resorbable biopolymers that may reproduce the local microenvironment enriched in particular cell metabolites.

The Role of microRNAs in Epigenetic Regulation of Signaling Pathways in Neurological Pathologies

In recent times, there has been a significant increase in researchers' interest in the functions of microRNAs and the role of these molecules in the pathogenesis of many multifactorial diseases. This is related to the diagnostic and prognostic potential of microRNA expression levels as well as the prospects of using it in personalized targeted therapy. This review of the literature analyzes existing scientific data on the involvement of microRNAs in the molecular and cellular mechanisms underlying the development of pathologies such as Alzheimer's disease, cerebral ischemia and reperfusion injury, and dysfunction of the blood-brain barrier.

Blood Vessels as a Key Mediator for Ethanol Toxicity: Implication for Neuronal Damage

Excessive intake of ethanol is associated with severe brain dysfunction, and the subsequent neurological and behavioral abnormalities are well-established social risks. Many research studies have addressed how ethanol induces neurological toxicity. However, the underlying mechanisms with which ethanol induces neurological toxicity are still obscure, perhaps due to the variety and complexity of these mechanisms. Epithelial cells are in direct contact with blood and can thus mediate ethanol neurotoxicity. Ethanol activates the endothelial cells of blood vessels, as well as lymphatic vessels, in a concentration-dependent manner. Among various signaling mediators, nitric oxide plays important roles in response to ethanol. Endothelial and inducible nitric oxide synthases (eNOS and iNOS) are upregulated and activated by ethanol and enhance neuroinflammation. On the other hand, angiogenesis and blood vessel remodeling are both affected by ethanol intake, altering blood supply and releasing angiocrine factors to regulate neuronal functions. Thus, ethanol directly acts on endothelial cells, yet the molecular target(s) on endothelial cells remain unknown. Previous studies on neurons and glial cells have validated the potential contribution of membrane lipids and some specific proteins as ethanol targets, which may also be the case in endothelial cells. Future studies, based on current knowledge, will allow for a greater understanding of the contribution and underlying mechanisms of endothelial cells in ethanol-induced neurological toxicity, protecting neurological health against ethanol toxicity.