Architecture of the subendothelial elastic fibers of small blood vessels and variations in vascular type and size

A wearable conductive hydrogel with triple network reinforcement inspired by bio-fibrous scaffolds for real-time quantitatively sensing compression force exerted on fruit surface

INTRODUCTION

Mechanical stresses incurred during post-harvest fruit storage and transportation profoundly impact decay and losses. Currently, the monitoring of mechanical forces is primarily focused on vibrational forces experienced by containers and vehicles and impact forces affecting containers. However, the detection of compressive forces both among interior fruit and between fruit and packaging surfaces remains deficient. Hence, conformable materials capable of sensing compressive stresses are necessary.

OBJECTIVES

In the present study, a triple-network-reinforced PSA/LiCl/CCN@AgNP conductive hydrogel was synthesized for compression force detection on fruit surfaces based on changes in intrinsic impedance under mechanical loading.

METHODS

The conductive hydrogel was characterized in terms of its adhesion, mechanics, frost resistance, water retention, conductivity, mechanical force-sensing properties, and feasibility for monitoring mechanical forces. Then, a portable complex impedance recorder was developed to interface with the conductive hydrogel and its mechanical force sensing ability was evaluated.

RESULTS

Beyond its inherent conductivity, the hydrogel exhibited notable pressure sensitivity within the strain range of 1 % to 80 %. The conductive hydrogel also demonstrated a commendable adhesion property, favorable tensile property (580 % elongation at break), substantial compressive strength and durability, and a long-term water retention capability. After exposure to -20 °C for 96 h, the hydrogel maintained its mechanical strength, affirming its anti-freezing property. In addition, a portable complex impedance recorder with sustained signal measurement stability was developed to quantitatively acquire the hydrogel resistance changes in response to compression forces. Finally, the effectiveness of the conductive hydrogel for sensing compression force on the surface of apple fruits was validated.

CONCLUSION

The conductive hydrogel holds promise for applications in smart packaging, wherein it can detect crucial mechanical stress on fruit, convert it into electrical signals, and further transmit these signals to the cloud, thereby enabling the real-time sensing of mechanical forces experienced by fruits and enhancing post-harvest fruit loss management.

Prostate-Specific Membrane Antigen Expression in Meningioma: A Promising Theranostic Target

Meningioma is the most common intracranial neoplasm, yet there is no effective therapy for recurrent/refractory meningiomas after surgery and radiation. Prostate-specific membrane antigen (PSMA) is an enzyme upregulated on endothelial cells of multiple neoplasms and is being investigated as a theranostic target. Until now, PSMA has not been studied in meningiomas. We aimed to verify PSMA endothelial expression in meningiomas, detect tumor grade variability, and investigate the relationship of PSMA signal with tumor recurrence. We analyzed 96 archival meningiomas including 58 de novo and 38 recurrent specimens. All specimens were stained routinely and immunostained for CD31 and PSMA. Slides were scanned and analyzed producing raw data for images of PSMA, CD31, PSMA/CD31, and PSMA/vasculature. PSMA expression was seen within 98.9% of meningioma samples. In the total cohort, higher-grade tumors had increased expression of raw PSMA and PSMA/CD31, and PSMA/vasculature ratios compared to grade 1 tumors. PSMA expression and PSMA/vasculature ratios (p = 0.0015) were higher in recurrent versus de novo tumors among paired samples. ROC curves demonstrated PSMA/CD31, PSMA/vasculature, and raw CD31 as indicators of tumor recurrence. Thus, PSMA is expressed within endothelial cells of meningiomas, is increased with tumor grade and recurrence, and persists with prior irradiation.

Gradual Not Sudden Change: Multiple Sites of Functional Transition Across the Microvascular Bed

In understanding the role of the neurovascular unit as both a biomarker and target for disease interventions, it is vital to appreciate how the function of different components of this unit change along the vascular tree. The cells of the neurovascular unit together perform an array of vital functions, protecting the brain from circulating toxins and infection, while providing nutrients and clearing away waste products. To do so, the brain's microvasculature dilates to direct energy substrates to active neurons, regulates access to circulating immune cells, and promotes angiogenesis in response to decreased blood supply, as well as pulsating to help clear waste products and maintain the oxygen supply. Different parts of the cerebrovascular tree contribute differently to various aspects of these functions, and previously, it has been assumed that there are discrete types of vessel along the vascular network that mediate different functions. Another option, however, is that the multiple transitions in function that occur across the vascular network do so at many locations, such that vascular function changes gradually, rather than in sharp steps between clearly distinct vessel types. Here, by reference to new data as well as by reviewing historical and recent literature, we argue that this latter scenario is likely the case and that vascular function gradually changes across the network without clear transition points between arteriole, precapillary arteriole and capillary. This is because classically localized functions are in fact performed by wide swathes of the vasculature, and different functional markers start and stop being expressed at different points along the vascular tree. Furthermore, vascular branch points show alterations in their mural cell morphology that suggest functional specializations irrespective of their position within the network. Together this work emphasizes the need for studies to consider where transitions of different functions occur, and the importance of defining these locations, in order to better understand the vascular network and how to target it to treat disease.

The influence of fibrillin-1 and physical activity upon tendon tissue morphology and mechanical properties in mice

Fibrillin‐1 mutations cause pathological changes in connective tissue that constitute the complex phenotype of Marfan syndrome. In this study, we used fibrillin‐1 hypomorphic and haploinsufficient mice (Fbn1^mgr/mgR and Fbn1^+/− mice, respectively) to investigate the impact of fibrillin‐1 deficiency alone or in combination with regular physical activity on tendon tissue morphology and mechanical properties. Morphological and biomechanical analyses revealed that Fbn1^mgr/mgR but not Fbn1^+/− mice displayed smaller tendons with physical properties that were unremarkable when normalized to tendon size. Fbn1^mgR/mgR mice (n = 43) Fbn1^+/−mice (n = 27) and wild‐type mice (WT, n = 25) were randomly assigned to either control cage conditions (n = 54) or to a running on a running wheel for 4 weeks (n = 41). Both fibrillin‐1‐deficient mice ran voluntarily on the running wheel in a manner similar to WT mice (3–4 km/24 h). Regular exercise did not mitigate aneurysm progression in Fbn1^mgR/mgR mice (P < 0.05) as evidenced by unmodified median survival. In spite of the smaller size, tendons of fibrillin‐1‐deficient mice subjected to regular exercise showed no evidence of overt histopathological changes or tissue overload. We therefore concluded that lack of optimal fibrillin‐1 synthesis leads to a down regulation of integrated tendon formation, rather than to a loss of tendon quality, which also implies that fibrillin‐1 deficiency in combination with exercise is not a suitable animal model for studying the development of tendon overuse (tendinopathy).

Human breast cancer decellularized scaffolds promote epithelial-to-mesenchymal transitions and stemness of breast cancer cells in vitro

Breast cancer, with unsatisfactory survival rates, is the leading cause of cancer-related death in women worldwide. Recent advances in the genetic basis of breast cancer have benefitted the development of gene-based medicines and therapies. Tissue engineering technologies, including tissue decellularizations and reconstructions, are potential therapeutic alternatives for cancer research and tissue regeneration. In our study, human breast cancer biopsies were decellularized by a detergent technique, with sodium lauryl ether sulfate (SLES) solution, for the first time. And the decellularization process was optimized to maximally maintain tissue microarchitectures and extracellular matrix (ECM) components with minimal DNA compounds preserved. Histology analysis and DNA quantification results confirmed the decellularization effect with maximal genetic compounds removal. Quantification, immunofluorescence, and histology analyses demonstrated better preservation of ECM components in 0.5% SLES-treated scaffolds. Scaffolds seeded with MCF-7 cells demonstrated the process of cell recellularization in vitro, with increased cell migration, proliferation, and epithelial-to-mesenchymal transition (EMT) process. When treated with 5-fluorouracil, the expressions of stem cell markers, including Oct4, Sox2, and CD49F, were maximally maintained in the recellularized scaffold with decreased apoptosis rates compared with monolayer cells. These results showed that the decellularized breast scaffold model with SLES treatments would help to simulate the pathogenesis of breast cancer in vitro. And we hope that this model could further accelerate the development of effective therapies for breast cancer and benefit drug screenings.

Anatomical Variation of Human Collector Channel Orifices

Purpose

To examine the anatomical variation of normal human collector channel orifices and their relationship with Schlemm's canal.

Methods

Ten human anterior segments fixed by immersion or perfusion were dissected radially and further divided by fine dissection into corresponding inner and outer wall segments. The tissues were dehydrated, critical-point dried, sputter coated, and examined by scanning electron microscopy. Images were obtained at magnifications from ×200 to ×10,000. Selected radial collector channel regions were processed for plastic embedding.

Results

Two classes of collector channel orifices were identified. Simple oval orifices (54.7 ± 4.6–μm diameter) were lined with endothelial cells and most often occurred on a planar region of Schlemm's canal outer wall. Complex orifices (62.7 ± 3.4–μm diameter) were often found associated with septal columns and bridges, and typically covered with flap-like structures (10–40 μm) that extended between the inner and outer wall and over the collector channel orifices. Both simple and complex orifices had complete or partial lip-like rims. In orifices with partial rims, a trough-like groove was often visible on the outer wall surface opposite the lip. Transected septa and inner and outer wall adhesion sites were often found in association with complex collector channel orifices.

Conclusions

Collector channel orifice structure varied from simple ovals to complex tethered flaps and bridges. Collector channel orifices with complex flaps connect the inner and outer walls of Schlemm's canal, and may serve to enhance and regulate aqueous outflow in these regions.

Revascularization of decellularized lung scaffolds: principles and progress

There is a clear unmet clinical need for novel biotechnology-based therapeutic approaches to lung repair and/or replacement, such as tissue engineering of whole bioengineered lungs. Recent studies have demonstrated the feasibility of decellularizing the whole organ by removal of all its cellular components, thus leaving behind the extracellular matrix as a complex three-dimensional (3D) biomimetic scaffold. Implantation of decellularized lung scaffolds (DLS), which were recellularized with patient-specific lung (progenitor) cells, is deemed the ultimate alternative to lung transplantation. Preclinical studies demonstrated that, upon implantation in rodent models, bioengineered lungs that were recellularized with airway and vascular cells were capable of gas exchange for up to 14 days. However, the long-term applicability of this concept is thwarted in part by the failure of current approaches to reconstruct a physiologically functional, quiescent endothelium lining the entire vascular tree of reseeded lung scaffolds, as inferred from the occurrence of hemorrhage into the airway compartment and thrombosis in the vasculature in vivo. In this review, we explore the idea that successful whole lung bioengineering will critically depend on 1) preserving and/or reestablishing the integrity of the subendothelial basement membrane, especially of the ultrathin respiratory membrane separating airways and capillaries, during and following decellularization and 2) restoring vascular physiological functionality including the barrier function and quiescence of the endothelial lining following reseeding of the vascular compartment. We posit that physiological reconstitution of the pulmonary vascular tree in its entirety will significantly promote the clinical translation of the next generation of bioengineered whole lungs.

The effect of magnesium ions on chromosome structure as observed by helium ion microscopy

One of the few conclusions known about chromosome structure is that Mg2+ is required for the organization of chromosomes. Scanning electron microscopy is a powerful tool for studying chromosome morphology, but being nonconductive, chromosomes require metal/carbon coating that may conceal information about the detailed surface structure of the sample. Helium ion microscopy (HIM), which has recently been developed, does not require sample coating due to its charge compensation system. Here we investigated the structure of isolated human chromosomes under different Mg2+ concentrations by HIM. High-contrast and resolution images from uncoated samples obtained by HIM enabled investigation on the effects of Mg2+ on chromosome structure. Chromatin fiber information was obtained more clearly with uncoated than coated chromosomes. Our results suggest that both overall features and detailed structure of chromatin are significantly affected by different Mg2+ concentrations. Chromosomes were more condensed and a globular structure of chromatin with 30 nm diameter was visualized with 5 mM Mg2+ treatment, while 0 mM Mg2+ resulted in a less compact and more fibrous structure 11 nm in diameter. We conclude that HIM is a powerful tool for investigating chromosomes and other biological samples without requiring metal/carbon coating.