3D Bioprinting of Artificial Skin Substitute with Improved Mechanical Property and Regulated Cell Behavior through Integrating Patterned Nanofibrous Films.

Three-dimensional (3D) bioprinting has advantages for constructing artificial skin tissues in replicating the structures and functions of native skin. Although many studies have presented improved effect of printing skin substitutes in wound healing, using hydrogel inks to fabricate 3D bioprinting architectures with complicated structures, mimicking mechanical properties, and appropriate cellular environments is still challenging. Inspired by collagen nanofibers withstanding stress and regulating cell behavior, a patterned nanofibrous film was introduced to the printed hydrogel scaffold to fabricate a composite artificial skin substitute (CASS). The artificial dermis was printed using gelatin-hyaluronan hybrid hydrogels containing human dermal fibroblasts with gradient porosity and integrated with patterned nanofibrous films simultaneously, while the artificial epidermis was formed by seeding human keratinocytes upon the dermis. The collagen-mimicking nanofibrous film effectively improved the tensile strength and fracture resistance of the CASS, making it sewable for firm implantation into skin defects. Meanwhile, the patterned nanofibrous film also provided the biological cues to guide cell behavior. Consequently, CASS could effectively accelerate the regeneration of large-area skin defects in mouse and pig models by promoting re-epithelialization and collagen deposition. This research developed an effective strategy to prepare composite bioprinting architectures for enhancing mechanical property and regulating cell behavior, and CASS could be a promising skin substitute for treating large-area skin defects.

Natural History and Risk Factors for Glaucoma Progression in Chinese Patients With Normal-Tension Glaucoma.

Purpose: To characterize the natural history of normal-tension glaucoma (NTG) in Chinese patients. Methods: The prospective observational cohort study included patients with untreated NTG with a minimum follow-up of 2 years. Functional progression was defined by visual field (VF) deterioration, while structural progression was characterized by thinning of the retinal nerve fiber layer (RNFL) or ganglion cell inner plexiform layer (GCIPL). Results: Among 84 participants (mean age, 60.5 years; mean deviation, -5.01 decibels [dB]) with newly diagnosed NTG followed for an average of 69.7 months, 63.1% progressed during the observation period. Specifically, 29.8% progressed by VF, and 48.8% progressed by either RNFL or GCIPL. In Cox proportional hazards analysis, disc hemorrhage (hazard ratio [HR], 2.82; 95% confidence interval [CI], 1.48-5.35), female gender (HR, 1.98; 95% CI, 1.08-3.62), and mean IOP during the follow-up period (HR, 1.14 per mm Hg; 95% CI, 1.00-1.31) were significant predictors of glaucomatous progression. Additionally, longer axial length (AL; HR, 0.57 per millimeter; 95% CI, 0.35-0.94) was protective against VF progression faster than -0.50 dB/y, and higher minimum diastolic blood pressure (DBP; HR, 0.96 per mm Hg; 95% CI, 0.92-1.00) was protective against structural progression. Conclusions: Nearly two-thirds of untreated Chinese patients with NTG progressed over an average follow-up of 70 months by VF, RNFL, or GCIPL. Disc hemorrhage, female gender, higher mean IOP, shorter AL, and lower minimum DBP were significant predictors for disease progression.

4D printed hydrogel scaffold with swelling-stiffening properties and programmable deformation for minimally invasive implantation.

The power of three-dimensional printing in designing personalized scaffolds with precise dimensions and properties is well-known. However, minimally invasive implantation of complex scaffolds is still challenging. Here, we develop amphiphilic dynamic thermoset polyurethanes catering for multi-material four-dimensional printing to fabricate supportive scaffolds with body temperature-triggered shape memory and water-triggered programmable deformation. Shape memory effect enables the two-dimensional printed pattern to be fixed into temporary one-dimensional shape, facilitating transcatheter delivery. Upon implantation, the body temperature triggers shape recovery of the one-dimensional shape to its original two-dimensional pattern. After swelling, the hydrated pattern undergoes programmable morphing into the desired three-dimensional structure because of swelling mismatch. The structure exhibits unusual soft-to-stiff transition due to the water-driven microphase separation formed between hydrophilic and hydrophobic chain segments. The integration of shape memory, programmable deformability, and swelling-stiffening properties makes the developed dynamic thermoset polyurethanes promising supportive void-filling scaffold materials for minimally invasive implantation.

Progressive peripapillary capillary vessel density loss and long-term visual field progression in Normal tension glaucoma.

PURPOSE: To explore the association between progressive peripapillary capillary vessel density (pcVD) reduction and the progression of visual field (VF) impairment in individuals with normal tension glaucoma (NTG). DESIGN: Prospective cohort study. METHODS: The study enrolled 110 participants with one eye each, totalling 110 NTG eyes. VF defects were evaluated using standard automated perimetry mean deviation (MD), while pcVD measurements were obtained using optical coherence tomography angiography throughout the follow-up period. Estimates of VF progression were determined by event-based and trend-based analyses. Fast VF progression was defined as an MD slope steeper than -0.5 dB/year, while the slow progression or stable VF was defined as an MD slope better or equal to -0.25 dB/year. Linear mixed-effects models were employed to analyse the rates of change in pcVD reduction and VF MD decline over time. Additionally, univariable and multivariable linear models were used to examine the relationship between pcVD changes and VF loss rates in NTG. RESULTS: Slow VF progression or stable VF was observed in 45% of subjects, while 25% had moderate progression and 30% showed fast progression. Patients with VF progression exhibited faster rate of pcVD reduction in peripapillary global region (-0.73 ± 0.40%/year vs. -0.56 ± 0.35%/year, p = 0.022). Moreover, this rate positively correlated with VF MD decline in NTG (estimate 0.278, 95% CI 0.122-0.433, p = 0.001). CONCLUSION: In individuals with NTG, faster VF progression was linked to a quicker reduction in pcVD, suggesting a positive correlation between pcVD decline and VF deterioration.

Distribution of bone voids in the thoracolumbar spine in Chinese adults with and without osteoporosis: A cross-sectional multi-center study based on 464 vertebrae.

Bone void is a novel intuitive morphological indicator to assess bone quality but its use in vertebrae has not been described. This cross-sectional and multi-center study aimed to investigate the distribution of bone voids in the thoracolumbar spine in Chinese adults based on quantitative computed tomography (QCT). A bone void was defined as a trabecular net region with extremely low bone mineral density (BMD) (<40 mg/cm3), detected by an algorithm based on phantom-less technology. A total of 464 vertebrae from 152 patients (51.8 ± 13.4 years old) were included. The vertebral trabecular bone was divided into eight sections based on the middle sagittal, coronal, and horizontal planes. Bone void of the whole vertebra and each section were compared between healthy, osteopenia, and osteoporosis groups and between spine levels. Receiver operator characteristic (ROC) curves were plotted and optimum cutoff points of void volume between the groups were obtained. The total void volumes of the whole vertebra were 124.3 ± 221.5 mm3, 1256.7 ± 928.7 mm3, and 5624.6 ± 3217.7 mm3 in healthy, osteopenia, and osteoporosis groups, respectively. The detection rate of vertebrae with bone voids was higher and the normalized void volume was larger in the lumbar than in thoracic vertebrae. L3 presented the largest void (2165.0 ± 3396.0 mm3), while T12 had the smallest void (448.9 ± 699.4 mm3). The bone void was mainly located in the superior-posterior-right section (40.8 %). Additionally, bone void correlated positively with age and increased rapidly after 55 years. The most significant void volume increase was found in the inferior-anterior-right section whereas the least increase was found in the inferior-posterior-left section with aging. The cutoff points were 345.1 mm3 between healthy and osteopenia groups (sensitivity = 0.923, specificity = 0.932) and 1693.4 mm3 between osteopenia and osteoporosis groups (sensitivity = 1.000, specificity = 0.897). In conclusion, this study demonstrated the bone void distribution in vertebrae using clinical QCT data. The findings provide a new perspective for the description of bone quality and showed that bone void could guide clinical practice such as osteoporosis screening.

Fibro-Gel: An All-Aqueous Hydrogel Consisting of Microfibers with Tunable Release Profile and its Application in Wound Healing.

Injectable hydrogels are valuable tools in tissue engineering and regenerative medicine due to their unique advantages of injectability with minimal invasiveness and usability for irregularly shaped sites. However, it remains challenging to achieve scalable manufacturing together with matching physicochemical properties and on-demand drug release for a high level of control over biophysical and biomedical cues to direct endogenous cells. Here, the use of an injectable fibro-gel is demonstrated, a water-filled network of entangled hydrogel microfibers, whose physicochemical properties and drug release profiles can be tailored to overcome these shortcomings. This fibro-gel exhibits favorable in vitro biocompatibility and the capability to aid vascularization. The potential use of the fibro-gel for advancing tissue regeneration is explored with a mice excision skin model. Preliminary in vivo tests indicate that the fibro-gel promotes wound healing and new healthy tissue regeneration at a faster rate than a commercial gel. Moreover, it is demonstrated that the release of distinct drugs at different rates can further accelerate wound healing with higher efficiency, by using a two-layer fibro-gel model. The combination of injectability and tailorable properties of this fibro-gel offers a promising approach in biomedical fields such as therapeutic delivery, medical dressings, and 3D tissue scaffolds for tissue engineering.

Infiltration from Suspension Systems Enables Effective Modulation of 3D Scaffold Properties in Suspension Bioprinting.

Bioprinting is a biofabrication technology which allows efficient and large-scale manufacture of 3D cell culture systems. However, the available biomaterials for bioinks used in bioprinting are limited by their printability and biological functionality. Fabricated constructs are often homogeneous and have limited complexity in terms of current 3D cell culture systems comprising multiple cell types. Inspired by the phenomenon that hydrogels can exchange liquids under the infiltration action, infiltration-induced suspension bioprinting (IISBP), a novel printing technique based on a hyaluronic acid (HA) suspension system to modulate the properties of the printed scaffolds by infiltration action, was described in this study. HA served as a suspension system due to its shear-thinning and self-healing rheological properties, simplicity of preparation, reusability, and ease of adjustment to osmotic pressure. Changes in osmotic pressure were able to direct the swelling or shrinkage of 3D printed gelatin methacryloyl (GelMA)-based bioinks, enabling the regulation of physical properties such as fiber diameter, micromorphology, mechanical strength, and water absorption of 3D printed scaffolds. Human umbilical vein endothelial cells (HUVEC) were applied as a cell culture model and printed within cell-laden scaffolds at high resolution and cell viability with the IISBP technique. Herein, the IISBP technique had been realized as a reliable hydrogel-based bioprinting technique, which enabled facile modulation of 3D printed hydrogel scaffolds properties, being expected to meet the scaffolds requirements of a wide range of cell culture conditions to be utilized in bioprinting applications.

The regulatory role of sulfated polysaccharides in facilitating rhBMP-2-induced osteogenesis.

Sulfated polysaccharides have received much attention in recent years due to their special biological activities, especially the regulation of the biological activity of growth factors such as the representative inductive growth factor recombinant human bone morphogenetic protein-2 (rhBMP-2). However, the regulatory mechanisms from the aspect of the molecular chain structure have rarely been reported. In this article, we selected three kinds of sulfonates containing different backbone structures and functional groups, 2-N,6-O-sulfated chitosan (26 SCS), sulfated dextran (DSS) and poly(sodium-p-styrenesulfonate) (PSS), to explore the interaction between them and rhBMP-2. From in vivo and in vitro osteogenesis-related experiments, 26 SCS showed the best promoting effect on rhBMP-2 induced osteogenic differentiation and the sulfated amino group in 26 SCS could specifically bind to rhBMP-2. These findings indicated that the polysaccharide chain structure was a prerequisite for the synergy effect between 26 SCS and rhBMP-2; the effective combination of -SO3- and rhBMP-2 was an important factor in protecting the bioactivity of rhBMP-2. In addition, the presence of the sulfated amino group was the key factor in the specific binding between 26 SCS and rhBMP-2 and provided the possibility of capturing factors in vivo.

Construction of cytokine reservoirs based on sulfated chitosan hydrogels for the capturing of VEGF in situ.

Nutrients and oxygen are delivered mainly by blood vessels to nourish the cells and tissues in the body. Thus, biomaterials are processed by loading cytokines, such as vascular endothelial growth factors (VEGF), to facilitate angiogenesis in order to accelerate tissue regeneration. Nevertheless, the unpredictable biosecurity of exogenous cytokines is still a controversial issue for its clinical application. In this study, we constructed a kind of cytokine reservoir utilizing the binding affinity between heparin-like sulfate polysaccharide and endogenous growth factors. Two types of sulfated chitosan hydrogels, namely 6-O-sulfated chitosan (6-O-SCS) and 2-N,6-O-sulfated chitosan (2-N,6-O-SCS) hydrogels, were formed on the surface of the gelatin sponge matrix. The microstructure of the SCS-coated scaffolds is porous and interconnected, which is beneficial for cellular infiltration. Besides, human umbilical vein endothelial cells (HUVECs) can adhere and proliferate well on the surface of the scaffolds. Notably, sulfated chitosan-coated scaffolds exhibit an ability to capture VEGF in vitro & vivo, especially for the 2-N,6-O-SCS-coated scaffold. It is also verified by mice models that sulfated chitosan-coated scaffolds result in a concentrated VEGF microenvironment in specific domains as cytokine reservoirs and induce mass microvessels after implantation into subcutaneous tissues. As such, the sulfated chitosan-coated scaffolds served as VEGF reservoirs to accelerate angiogenesis and wound healing. This beneficial strategy may be applicable to in situ tissue regeneration by capturing more cytokines and promoting healing.

Coactivation of the PI3K/Akt and ERK signaling pathways in PCB153-induced NF-κB activation and caspase inhibition.

Polychlorinated biphenyls (PCBs) are a group of persistent and widely distributed environmental pollutants that have various deleterious effects, e.g., neurotoxicity, endocrine disruption and reproductive abnormalities. In order to verify the hypothesis that the PI3K/Akt and MAPK pathways play important roles in hepatotoxicity induced by PCBs, Sprague-Dawley (SD) rats were dosed with PCB153 intraperitoneally at 0, 4, 16 and 32mg/kg for five consecutive days; BRL cells (rat liver cell line) were treated with PCB153 (0, 1, 5, and 10µM) for 24h. Results indicated that the PI3K/Akt and ERK pathways were activated in vivo and in vitro after exposure to PCB153, and protein levels of phospho-Akt and phospho-ERK were significantly increased. Nuclear factor-κB (NF-κB) activation and caspase-3, -8 and -9 inhibition caused by PCB153 were also observed. Inhibiting the ERK pathway significantly attenuated PCB153-induced NF-κB activation, whereas inhibiting the PI3K/Akt pathway hardly influenced phospho-NF-κB level. However, inhibiting the PI3K/Akt pathway significantly elevated caspase-3, -8 and -9 activities, while the ERK pathway only synergistically regulated caspase-9. Proliferating cell nuclear antigen (PCNA), a reliable indicator of cell proliferation, was also induced. Moreover, PCB153 led to hepatocellular hypertrophy and elevated liver weight. Taken together, PCB153 leads to aberrant proliferation and apoptosis of hepatocytes through NF-κB activation and caspase inhibition, and coactivated PI3K/Akt and ERK pathways play critical roles in PCB153-induced hepatotoxicity.