Evaluation of residual bone mass of the mandibular third molar and the risk of mandibular fracture

BACKGROUND

A quantification of the residual bone mass of the mandible (B/A) was utilized in this study to examine the correlation between mandibular fracture and residual bone mass. To improve the clinical utilization rate and reduce the incidence of iatrogenic mandibular fractures, the B/A ratio calculation should be simplified.

MATERIAL AND METHODS

Data were collected from the Yanbian University Hospital on 175 cases of mandibular fracture with third molar (M3), 67 normal cases without fractures and 20 cases of impacted teeth extraction. Twenty cases of iatrogenic mandibular fracture were collected, and the case records and panoramic radiographs of the patients were recorded.

RESULTS

The average B/A ratio of mandibular angle fracture group was 0.61±0.10.The value of B/A was found to be statistically significant in terms of whether M3 emerged from alveolar bone (P = 0.001), location (horizontal P < 0.001, vertical P < 0.001), the degree of impaction (P < 0.001), the number of roots (P < 0.001), the difference in impaction (P < 0.001), and the fracture type (P = 0.002). The average B/A ratio of normal group was 0.62±0.10. In the statistical results of the B/A value of normal patients, M3 involving alveolar bone (P < 0.001), position classification (P < 0.05), degree of impaction (P < 0.001) and presence or absence of a root (P < 0.05) were statistically significant. The average B/A ratio of iatrogenic mandibular angle fracture group was 0.28±0.08. The average B/A ratio of the extraction group for impacted teeth was 0.62 ± 0.09.

CONCLUSIONS

There is a high risk of mandibular angle fracture when the (B/A) value of the residual bone height (B) in the mandibular M3 area compared to the mandibular bone height (A) in the M3 area is less than 0.4.

Transcription of a centromere-enriched retroelement and local retention of its RNA are significant features of the CENP-A chromatin landscape

Centromeres depend on chromatin containing the conserved histone H3 variant CENP-A for function and inheritance, while the role of centromeric DNA repeats remains unclear. Retroelements are prevalent at centromeres across taxa and represent a potential mechanism for promoting transcription to aid in CENP-A incorporation or for generating RNA transcripts to maintain centromere integrity. Here, we probe into the transcription and RNA localization of the centromere-enriched retroelement G2/Jockey-3 (hereafter referred to as Jockey-3 ) in Drosophila melanogaster , currently the only in vivo model with assembled centromeres. We find that Jockey-3 is a major component of the centromeric transcriptome and produces RNAs that localize to centromeres in metaphase. Leveraging the polymorphism of Jockey-3 and a de novo centromere system, we show that these RNAs remain associated with their cognate DNA sequences in cis , suggesting they are unlikely to perform a sequence-specific function at all centromeres. We show that Jockey-3 transcription is positively correlated with the presence of CENP-A, and that recent Jockey-3 transposition events have occurred preferentially at CENP-A-containing chromatin. We propose that Jockey-3 contributes to the epigenetic maintenance of centromeres by promoting chromatin transcription, while inserting preferentially within these regions, selfishly ensuring its continued expression and transmission. Given the conservation of retroelements as centromere components through evolution, our findings have broad implications in understanding this association in other species.

Chemical and Structural Engineering of Gelatin-Based Delivery Systems for Therapeutic Applications: A Review

As a biodegradable and biocompatible protein derived from collagen, gelatin has been extensively exploited as a fundamental component of biological scaffolds and drug delivery systems for precise medicine. The easily engineered gelatin holds great promise in formulating various delivery systems to protect and enhance the efficacy of drugs for improving the safety and effectiveness of numerous pharmaceuticals. The remarkable biocompatibility and adjustable mechanical properties of gelatin permit the construction of active 3D scaffolds to accelerate the regeneration of injured tissues and organs. In this Review, we delve into diverse strategies for fabricating and functionalizing gelatin-based structures, which are applicable to gene and drug delivery as well as tissue engineering. We emphasized the advantages of various gelatin derivatives, including methacryloyl gelatin, polyethylene glycol-modified gelatin, thiolated gelatin, and alendronate-modified gelatin. These derivatives exhibit excellent physicochemical and biological properties, allowing the fabrication of tailor-made structures for biomedical applications. Additionally, we explored the latest developments in the modulation of their physicochemical properties by combining additive materials and manufacturing platforms, outlining the design of multifunctional gelatin-based micro-, nano-, and macrostructures. While discussing the current limitations, we also addressed the challenges that need to be overcome for clinical translation, including high manufacturing costs, limited application scenarios, and potential immunogenicity. This Review provides insight into how the structural and chemical engineering of gelatin can be leveraged to pave the way for significant advancements in biomedical applications and the improvement of patient outcomes.

Harnessing 3D in vitro systems to model immune responses to solid tumours: a step towards improving and creating personalized immunotherapies

In vitro 3D models are advanced biological tools that have been established to overcome the shortcomings of oversimplified 2D cultures and mouse models. Various in vitro 3D immuno-oncology models have been developed to mimic and recapitulate the cancer-immunity cycle, evaluate immunotherapy regimens, and explore options for optimizing current immunotherapies, including for individual patient tumours. Here, we review recent developments in this field. We focus, first, on the limitations of existing immunotherapies for solid tumours, secondly, on how in vitro 3D immuno-oncology models are established using various technologies - including scaffolds, organoids, microfluidics and 3D bioprinting - and thirdly, on the applications of these 3D models for comprehending the cancer-immunity cycle as well as for assessing and improving immunotherapies for solid tumours.

[Utilization of sexual and reproductive health services and its correlates among community- based older adults in Chongqing]

Objective: To investigate the utilization of sexual health services among community-based older adults in Chongqing and explore its potential correlates. Methods: A cross-sectional survey using multistage sampling among community-based older adults aged ≥50 years was conducted in Chongqing between June 2020 and December 2022. A questionnaire including information on demographic characteristics, general health, sexual health status, and sexual health services utilization was collected. Sexual health and reproductive services utilization was defined as having ever been tested for human immunodeficiency virus (HIV), or having had a male/gynecological reproductive health examination in the past year. Logistic regression was used to examine the correlates of the utilization of sexual health services. Results: A total of 794 community-based older adults participated in the study (482 were male, and 312 were female). The mean age was (62.8±8.2) years. The proportion of HIV testing was 18.0%, and the proportion of reproductive health examination was 10.1% among community-based older adults. The results of multivariate logistic regression analysis showed that the age group of 60-69 years (aOR=0.37, 95%CI: 0.18-0.76), female (aOR=11.34, 95%CI: 5.71-22.52), monthly income ≥5 000 yuan (aOR=3.05, 95%CI: 1.01-9.27), being sexual activity (aOR=4.99, 95%CI: 2.23-11.15) was significantly associated with had a reproductive health examination in the past year. Conclusions: The proportion of sexual health services utilization among older adults was low. Older sexual health education should be further strengthened, the close relationship between older adults should be correctly guided and dealt with, and the sexual health services suitable for the older population should be formulated.

[Condom use and its correlates among community-based older adults in Chongqing]

Objective: To understand the current status of condom use and its correlates among community-based older adults in Chongqing, China. Methods: Cross-sectional study based on a multistage sampling method was conducted in Chongqing from June 2020 to December 2022. The estimated sample size was 735. Through face-to-face interviews, the investigators collected the sociodemographic characteristics, sexual behavior characteristics, awareness of AIDS prevention knowledge, etc. A multivariable logistic regression model was used to explore the correlates of condom use during the last sexual behavior among the participants. Results: A total of 761 participants were included in this study, with 476 males and 285 females, whose average age was (63.8±8.2) years old, mainly in the age group of 60-69 years (44.5%). Among the participants, the rate of condom use during the last sexual behavior was 9.7%. The multivariable logistic regression analysis indicated that correlates of condom use during the last sexual behavior included urban household registration (aOR=2.34, 95%CI: 1.12-4.89), monthly income of 1 000-4 999 Yuan, and 5 000 Yuan and above (aOR=4.49, 95%CI: 1.31-15.41; aOR=16.33, 95%CI: 4.30-62.00), self-assessed sexual behavior risk as very risky/relatively risky (aOR=3.97, 95%CI: 1.40-11.31), awareness of AIDS prevention knowledge (aOR=0.36, 95%CI: 0.21-0.62). Conclusions: The rate of condom use among community-based older adults in Chongqing is low. Comprehensive intervention measures should be taken in combination with the characteristics and needs of community-based older adults to improve awareness of AIDS prevention knowledge and perception of AIDS risk and promote condom use among this population.

Creating a semi-opened micro-cavity ovary through sacrificial microspheres as an in vitro model for discovering the potential effect of ovarian toxic agents

The bio-engineered ovary is an essential technology for treating female infertility. Especially the development of relevant in vitro models could be a critical step in a drug study. Herein, we develop a semi-opened culturing system (SOCS) strategy that maintains a 3D structure of follicles during the culture. Based on the SOCS, we further developed micro-cavity ovary (MCO) with mouse follicles by the microsphere-templated technique, where sacrificial gelatin microspheres were mixed with photo-crosslinkable gelatin methacryloyl (GelMA) to engineer a micro-cavity niche for follicle growth. The semi-opened MCO could support the follicle growing to the antral stage, secreting hormones, and ovulating cumulus-oocyte complex out of the MCO without extra manipulation. The MCO-ovulated oocyte exhibits a highly similar transcriptome to the in vivo counterpart (correlation of 0.97) and can be fertilized. Moreover, we found that a high ROS level could affect the cumulus expansion, which may result in anovulation disorder. The damage could be rescued by melatonin, but the end of cumulus expansion was 3h earlier than anticipation, validating that MCO has the potential for investigating ovarian toxic agents in vitro. We provide a novel approach for building an in vitro ovarian model to recapitulate ovarian functions and test chemical toxicity, suggesting it has the potential for clinical research in the future.

Polysaccharide-Polyplex Nanofilm Coatings Enhance Nanoneedle-Based Gene Delivery and Transfection Efficiency

Non-viral vectors represent versatile and immunologically safer alternatives for nucleic acid delivery. Nanoneedles and high-aspect ratio nanostructures are unconventional but interesting delivery systems, in which delivery is mediated by surface interactions. Herein, nanoneedles are synergistically combined with polysaccharide-polyplex nanofilms and enhanced transfection efficiency is observed, compared to polyplexes in suspension. Different polyplex-polyelectrolyte nanofilm combinations are assessed and it is found that transfection efficiency is enhanced when using polysaccharide-based polyanions, rather than being only specific for hyaluronic acid, as suggested in earlier studies. Moreover, results show that enhanced transfection is not mediated by interactions with the CD44 receptor, previously hypothesized as a major mechanism mediating enhancement via hyaluronate. In cardiac tissue, nanoneedles are shown to increase the transfection efficiency of nanofilms compared to flat substrates; while in vitro, high transfection efficiencies are observed in nanostructures where cells present large interfacing areas with the substrate. The results of this study demonstrate that surface-mediated transfection using this system is efficient and safe, requiring amounts of nucleic acid with an order of magnitude lower than standard culture transfection. These findings expand the spectrum of possible polyelectrolyte combinations that can be used for the development of suitable non-viral vectors for exploration in further clinical trials.

Recombinant Human Collagen-Based Bioinks for the 3D Bioprinting of Full-thickness Human Skin Equivalent

As a major extracellular matrix component within the skin, collagen has been widely used to engineer human skin tissues. However, most collagen is extracted from animals. Here, we introduced recombinant human type III collagen (rhCol3) as a bioactive component to formulate bioinks for the bioprinting of a full-thickness human skin equivalent. Human dermal fibroblasts were encapsulated in the gelatin methacryloyl-rhCol3 composite bioinks and printed on a transwell to form the dermis layer, on which human epidermal keratinocytes were seeded to perform an air-liquid interface culture for 6 weeks. After optimizing the bioink formulation and bioprinting process, we investigated the effect of rhCol3 on skin tissue formation. The results suggest that a higher concentration of rhCol3 would enhance the growth of both cells, resulting in a more confluent (~100%) spreading of the epidermal keratinocytes at an early stage (3 days), compared to the rhCol3-free counterpart. Moreover, in an in vivo experiment, adding rhCol3 in the hydrogel formulation would contribute to the skin wound healing process. Taken together, we conclude that rhCol3 could act as a functional bioink component to promote basic skin cellular processes for skin tissue engineering.

Advances in Digital Light Processing of Hydrogels

Hydrogels, three-dimensional (3D) networks of hydrophilic polymers formed in water, are a significant type of soft matter used in fundamental and applied sciences. Hydrogels are of particular interest for biomedical applications, owing to their soft elasticity and good biocompatibility. However, the high water content and soft nature of hydrogels often make it difficult to process them into desirable solid forms. The development of 3D printing (3DP) technologies has provided opportunities for the manufacturing of hydrogels, by adopting a freeform fabrication method. Owing to its high printing speed and resolution, vat photopolymerization 3DP has recently attracted considerable interest for hydrogel fabrication, with digital light processing (DLP) becoming a widespread representative technique. Whilst acknowledging that other types of vat photopolymerization 3DP have also been applied for this purpose, we here only focus on DLP and its derivatives. In this review, we first comprehensively outline the most recent advances in both materials and fabrication, including the adaptation of novel hydrogel systems and advances in processing (e.g., volumetric printing and multimaterial integration). Secondly, we summarize the applications of hydrogel DLP, including regenerative medicine, functional microdevices, and soft robotics. To the best of our knowledge, this is the first time that either of these specific review focuses has been adopted in the literature. More importantly, we discuss the major challenges associated with hydrogel DLP and provide our perspectives on future trends. To summarize, this review aims to aid and inspire other researchers investigatng DLP, photocurable hydrogels, and the research fields related to them.

Tunable Microgel-Templated Porogel (MTP) Bioink for 3D Bioprinting Applications

Micropores are essential for tissue engineering to ensure adequate mass transportation for embedded cells. Despite the considerable progress made by advanced 3D bioprinting technologies, it remains challenging to engineer micropores of 100 µm or smaller in cell-laden constructs. Here, a microgel-templated porogel (MTP) bioink platform is reported to introduce controlled microporosity in 3D bioprinted hydrogels in the presence of living cells. Templated gelatin microgels are fabricated with varied sizes (≈10, ≈45, and ≈100 µm) and mixed with photo-crosslinkable formulations to make composite MTP bioinks. The addition of microgels significantly enhances the shear-thinning and self-healing viscoelastic properties and thus the printability of bioinks with cell densities up to 1 × 108 mL-1 in matrix. Consistent printability is achieved for a series of MTP bioinks based on different component ratios and matrix materials. After photo-crosslinking the matrix phase, the templated microgels dissociated and diffused under physiological conditions, resulting in corresponding micropores in situ. When embedding osteoblast-like cells in the matrix phase, the MTP bioinks support higher metabolic activity and more uniform mineral formation than bulk gel controls. The approach provides a facile strategy to engineer precise micropores in 3D printed structures to compensate for the limited resolution of current bioprinting approaches.

3D-printed Bioresorbable Stent Coated with Dipyridamole-Loaded Nanofiber for Restenosis Prevention and Endothelialization

Intimal hyperplasia and restenosis caused by excessive proliferation of smooth muscle cells (SMC) are the main factors for the failure of stent implantation. Drug-eluting stents carried with antiproliferative drugs have emerged as a successful approach to alleviate early neointimal development. However, these agents have been reported to have an undesirable effect on re-endothelialization. In this study, we proposed an integrated bioresorbable stent coated with dipyridamole (DP)-loaded poly(D,L-lactide) (PDLLA) nanofibers. Three-dimensional (3D) bioresorbable stents were fabricated by printing on a rotation mandrel using polycaprolactone (PCL), and the stents were further coated with PDLLA/DP nanofibers. The in vitro degradation and drug release evaluation illustrated the potential for long-term release of DP. Stents coated with PDLLA/DP nanofibers showed excellent hemocompatibility. The cell viability, proliferation, and morphology analysis results revealed that stents coated with PDLLA/DP nanofibers could prevent the proliferation of SMC and have no adverse effects on endothelial cells. The in vivo implantation of stents coated with PDLLA/DP nanofibers showed initial patency and continuous endothelialization and alleviated neointimal formation. The attractive in vitro and in vivo performance indicated its potential for restenosis prevention and endothelialization.

3D Bioprinting of Multifunctional Dynamic Nanocomposite Bioinks Incorporating Cu-Doped Mesoporous Bioactive Glass Nanoparticles for Bone Tissue Engineering

Bioprinting has seen significant progress in recent years for the fabrication of bionic tissues with high complexity. However, it remains challenging to develop cell-laden bioinks exhibiting superior physiochemical properties and bio-functionality. In this study, a multifunctional nanocomposite bioink is developed based on amine-functionalized copper (Cu)-doped mesoporous bioactive glass nanoparticles (ACuMBGNs) and a hydrogel formulation relying on dynamic covalent chemistry composed of alginate dialdehyde (oxidized alginate) and gelatin, with favorable rheological properties, improved shape fidelity, and structural stability for extrusion-based bioprinting. The reversible dynamic microenvironment in combination with the impact of cell-adhesive ligands introduced by aminated particles enables the rapid spreading (within 3 days) and high survival (>90%) of embedded human osteosarcoma cells and immortalized mouse bone marrow-derived stroma cells. Osteogenic differentiation of primary mouse bone marrow stromal stem cells (BMSCs) and angiogenesis are promoted in the bioprinted alginate dialdehyde-gelatin (ADA-GEL or AG)-ACuMBGN scaffolds without additional growth factors in vitro, which is likely due to ion stimulation from the incorporated nanoparticles and possibly due to cell mechanosensing in the dynamic matrix. In conclusion, it is envisioned that these nanocomposite bioinks can serve as promising platforms for bioprinting complex 3D matrix environments providing superior physiochemical and biological performance for bone tissue engineering.

Review of emerging nanotechnology in bone regeneration: progress, challenges, and perspectives

The application of nanotechnology to regenerative medicine has increased over recent decades. The development of materials that can influence biology at the nanoscale has gained interest as our understanding of the interactions between cells and biomaterials at the nanoscale has grown. Materials that are either nanostructured or influence the nanostructure of the cellular microenvironment have been developed and shown to have advantages over their microscale counterparts. There are several reviews which have been published that discuss how nanomaterials have been used in regenerative medicine, particularly in bone regeneration. Most of these studies have explored this concept in specific areas, such as the application of glass-based nanocomposites, nanotechnology for targeted drug delivery to stimulate bone repair, and the progress in nanotechnology for the treatment of osteoporosis. In this review paper, the impact of nanotechnology in biomaterials development for bone regeneration will be discussed highlighting specifically, nanostructured materials that influence mechanical properties, biocompatibility, and osteoinductivity.

Optimizing Bifurcated Channels within an Anisotropic Scaffold for Engineering Vascularized Oriented Tissues

Despite progress in engineering both vascularized tissues and oriented tissues, the fabrication of 3D vascularized oriented tissues remains a challenge due to an inability to successfully integrate vascular and anisotropic structures that can support mass transfer and guide cell alignment, respectively. More importantly, there is a lack of an effective approach to guiding the scaffold design bearing both structural features. Here, an approach is presented to optimize the bifurcated channels within an anisotropic scaffold based on oxygen transport simulation and biological experiments. The oxygen transport simulation is performed using the experimentally measured effective oxygen diffusion coefficient and hydraulic permeability of the anisotropic scaffolds, which are also seeded with muscle precursor cells and cultured in a custom-made perfusion bioreactor. Symmetric bifurcation model is used as fractal unit to design the channel network based on biomimetic principles. The bifurcation level of channel network is further optimized based on the oxygen transport simulation, which is then validated by DNA quantification assay and pimonidazole immunostaining. This study provides a practical guide to optimizing bifurcated channels in anisotropic scaffolds for oriented tissue engineering.

Expanding and optimizing 3D bioprinting capabilities using complementary network bioinks

A major challenge in three-dimensional (3D) bioprinting is the limited number of bioinks that fulfill the physicochemical requirements of printing while also providing a desirable environment for encapsulated cells. Here, we address this limitation by temporarily stabilizing bioinks with a complementary thermo-reversible gelatin network. This strategy enables the effective printing of biomaterials that would typically not meet printing requirements, with instrument parameters and structural output largely independent of the base biomaterial. This approach is demonstrated across a library of photocrosslinkable bioinks derived from natural and synthetic polymers, including gelatin, hyaluronic acid, chondroitin sulfate, dextran, alginate, chitosan, heparin, and poly(ethylene glycol). A range of complex and heterogeneous structures are printed, including soft hydrogel constructs supporting the 3D culture of astrocytes. This highly generalizable methodology expands the palette of available bioinks, allowing the biofabrication of constructs optimized to meet the biological requirements of cell culture and tissue engineering.

Advances in the Fabrication of Biomaterials for Gradient Tissue Engineering

Natural tissues and organs exhibit an array of spatial gradients, from the polarized neural tube during embryonic development to the osteochondral interface present at articulating joints. The strong structure-function relationships in these heterogeneous tissues have sparked intensive research into the development of methods that can replicate physiological gradients in engineered tissues. In this Review, we consider different gradients present in natural tissues and discuss their critical importance in functional tissue engineering. Using this basis, we consolidate the existing fabrication methods into four categories: additive manufacturing, component redistribution, controlled phase changes, and postmodification. We have illustrated this with recent examples, highlighted prominent trends in the field, and outlined a set of criteria and perspectives for gradient fabrication.

Suppressor of cytokine signaling 1 inhibits the maturation of dendritic cells involving the nuclear factor kappa B signaling pathway in the glioma microenvironment

Recurrence and diffuse infiltration challenge traditional therapeutic strategies for malignant glioma. Immunotherapy appears to be a promising approach to obtain long-term survival. Dendritic cells (DCs), the most specialized and potent antigen-presenting cells (APCs), play an important part in initiating and amplifying both the innate and adaptive immune responses against cancer cells. However, cancer cells can escape from immune surveillance by inhibiting maturation of DCs. Until the present, molecular mechanisms of maturation inhibition of DCs in the tumor microenvironment (TME) have not been fully revealed. Our study showed that pretreatment with tumor-conditioned medium (TCM) collected from supernatant of primary glioma cells significantly suppressed the maturation of DCs. TCM pretreatment significantly changed the morphology of DCs, TCM decreased the expression levels of CD80, CD83, CD86 and interleukin (IL)-12p70, while it increased the expression levels of IL-10, transforming growth factor (TGF)-β and IL-6. RNA-Seq showed that TCM pretreatment significantly increased the gene expression level of suppressor of cytokine signaling 1 (SOCS1) in DCs. suppressor of cytokine signaling 1 (SOCS1) knock-down significantly antagonized the maturation inhibition of DCs by TCM, which was demonstrated by the restoration of maturation markers. TCM pretreatment also significantly suppressed T cell viability and T helper type 1 (Th1) response, and SOCS1 knock-down significantly antagonized this suppressive effect. Further, TCM pretreatment significantly suppressed p65 nuclear translocation and transcriptional activity in DCs, and SOCS1 knock-down significantly attenuated this suppressive effect. In conclusion, our research demonstrates that TCM up-regulate SOCS1 to suppress the maturation of DCs via the nuclear factor-kappa signaling pathway.

Void-free 3D Bioprinting for In-situ Endothelialization and Microfluidic Perfusion

Two major challenges of 3D bioprinting are the retention of structural fidelity and efficient endothelialization for tissue vascularization. We address both of these issues by introducing a versatile 3D bioprinting strategy, in which a templating bioink is deposited layer-by-layer alongside a matrix bioink to establish void-free multimaterial structures. After crosslinking the matrix phase, the templating phase is sacrificed to create a well-defined 3D network of interconnected tubular channels. This void-free 3D printing (VF-3DP) approach circumvents the traditional concerns of structural collapse, deformation and oxygen inhibition, moreover, it can be readily used to print materials that are widely considered "unprintable". By pre-loading endothelial cells into the templating bioink, the inner surface of the channels can be efficiently cellularized with a confluent endothelial layer. This in-situ endothelialization method can be used to produce endothelium with a far greater uniformity than can be achieved using the conventional post-seeding approach. This VF-3DP approach can also be extended beyond tissue fabrication and towards customized hydrogel-based microfluidics and self-supported perfusable hydrogel constructs.

Void-free 3D Bioprinting for In-situ Endothelialization and Microfluidic Perfusion

Two major challenges of 3D bioprinting are the retention of structural fidelity and efficient endothelialization for tissue vascularization. We address both of these issues by introducing a versatile 3D bioprinting strategy, in which a templating bioink is deposited layer-by-layer alongside a matrix bioink to establish void-free multimaterial structures. After crosslinking the matrix phase, the templating phase is sacrificed to create a well-defined 3D network of interconnected tubular channels. This void-free 3D printing (VF-3DP) approach circumvents the traditional concerns of structural collapse, deformation and oxygen inhibition, moreover, it can be readily used to print materials that are widely considered "unprintable". By pre-loading endothelial cells into the templating bioink, the inner surface of the channels can be efficiently cellularized with a confluent endothelial layer. This in-situ endothelialization method can be used to produce endothelium with a far greater uniformity than can be achieved using the conventional post-seeding approach. This VF-3DP approach can also be extended beyond tissue fabrication and towards customized hydrogel-based microfluidics and self-supported perfusable hydrogel constructs.

Preparation and Properties of Polyaminosiloxane Modified Polyester Waterborne Polyurethane

In this study, a organosilicon modified waterborne polyurethane (WPU) is synthesized with polyethylene glycol 1,4-butanediol adipate ester diol (PBA) to form the soft segment, dimethylolpropionic acid (DMPA) as the hydrophilic chain extender, and isophorone diisocyanate as the hard segment to synthesize the WPU prepolymer, and aminoethyl aminopropyl dimethicone (AEAPS) as the graft chain extender. The properties of the formed WPU films are then characterized by using Fourier transform infrared spectrometry, thermogravimetric analysis, X-ray diffraction, and dynamic mechanical analysis. It is found that when the amount of AEAPS in the WPU is increased from 0 to 30 wt%, the particle size of the AEAPS modified WPU emulsion is increased from 84.8 nm to 271.9 nm and maintained high centrifugal stability. Moreover, the water absorption of the WPU film is reduced from 43.4% to 24.1%, and the hardness is enhanced from 3H to 5H, while the glass-transition temperature (Tg) of the soft segment of the modified WPU shifts from -37.4 °C to -44.3 °C, and the Tg of the hard segment shifts from 73.6 °C to 118.1 °C. Therefore, the overall performance of AEAPS modified WPU is improved.

Void-free 3D Bioprinting for In-situ Endothelialization and Microfluidic Perfusion

Two major challenges of 3D bioprinting are the retention of structural fidelity and efficient endothelialization for tissue vascularization. We address both of these issues by introducing a versatile 3D bioprinting strategy, in which a templating bioink is deposited layer-by-layer alongside a matrix bioink to establish void-free multimaterial structures. After crosslinking the matrix phase, the templating phase is sacrificed to create a well-defined 3D network of interconnected tubular channels. This void-free 3D printing (VF-3DP) approach circumvents the traditional concerns of structural collapse, deformation and oxygen inhibition, moreover, it can be readily used to print materials that are widely considered "unprintable". By pre-loading endothelial cells into the templating bioink, the inner surface of the channels can be efficiently cellularized with a confluent endothelial layer. This in-situ endothelialization method can be used to produce endothelium with a far greater uniformity than can be achieved using the conventional post-seeding approach. This VF-3DP approach can also be extended beyond tissue fabrication and towards customized hydrogel-based microfluidics and self-supported perfusable hydrogel constructs.

Buoyancy-Driven Gradients for Biomaterial Fabrication and Tissue Engineering

The controlled fabrication of gradient materials is becoming increasingly important as the next generation of tissue engineering seeks to produce inhomogeneous constructs with physiological complexity. Current strategies for fabricating gradient materials can require highly specialized materials or equipment and cannot be generally applied to the wide range of systems used for tissue engineering. Here, the fundamental physical principle of buoyancy is exploited as a generalized approach for generating materials bearing well-defined compositional, mechanical, or biochemical gradients. Gradient formation is demonstrated across a range of different materials (e.g., polymers and hydrogels) and cargos (e.g., liposomes, nanoparticles, extracellular vesicles, macromolecules, and small molecules). As well as providing versatility, this buoyancy-driven gradient approach also offers speed (<1 min) and simplicity (a single injection) using standard laboratory apparatus. Moreover, this technique is readily applied to a major target in complex tissue engineering: the osteochondral interface. A bone morphogenetic protein 2 gradient, presented across a gelatin methacryloyl hydrogel laden with human mesenchymal stem cells, is used to locally stimulate osteogenesis and mineralization in order to produce integrated osteochondral tissue constructs. The versatility and accessibility of this fabrication platform should ensure widespread applicability and provide opportunities to generate other gradient materials or interfacial tissues.

[A clinical analysis of 10 cases with cardiac lymphoma]

目的

分析心脏淋巴瘤的发病情况、临床特征、治疗效果及预后。

方法

收集2000年1月至2016年6月期间确诊并有心脏累及的10例淋巴瘤患者的资料，对患者的一般资料、临床表现、病理诊断、实验室检查、心脏累及方式、心脏并发症、治疗方式、疗效及预后进行分析。

结果

3 918例淋巴瘤患者中，心脏累及者10例，其中原发性心脏淋巴瘤（PCL）1例（主要累及左右心房，以心肌内多发结节包块为主），继发性心脏淋巴瘤（SCL）9例（主要为心包包块，其中出现心包积液5例，心肌肿块2例）。男性6例，女性4例，中位年龄55（19~88）岁，主要临床表现为呼吸困难7例，胸痛5例，乏力、水肿各2例。病理类型包括弥漫大B细胞淋巴瘤（DLBCL）7例，T淋巴母细胞淋巴瘤、霍奇金淋巴瘤、Burkitt淋巴瘤各1例。心脏并发症包括充血性心力衰竭7例，心律失常4例（主要为窦性心动过速、心房颤动和房室传导阻滞）。除1例高龄、一般状况差未接受治疗外，其余9例患者均接受治疗（单纯化疗4例，化疗联合放疗5例）。中位随访时间为9（1~28）个月。1例PCL患者化疗后获部分缓解（PR），无进展生存（PFS）期为6个月，总生存（OS）期为21个月。SCL患者中6例起病累及心脏者，治疗后1例获完全缓解，5例获PR，中位PFS期为5个月，中位OS期为19个月；3例病情进展累及心脏者，2例治疗后获PR，1例未治疗者死亡，中位PFS期为4个月，OS因数据截尾，未能获得。

结论

心脏淋巴瘤为少见类型，DLBCL为最常见类型，呼吸困难、胸痛为最常见临床表现，并易出现充血性心力衰竭和心律失常，治疗以系统化疗为主，总体预后差。

Facile Biofabrication of Heterogeneous Multilayer Tubular Hydrogels by Fast Diffusion-Induced Gelation

Multilayer (ML) hydrogels are useful to achieve stepwise and heterogeneous control over the organization of biomedical materials and cells. There are numerous challenges in the development of fabrication approaches toward this, including the need for mild processing conditions that maintain the integrity of embedded compounds and the versatility in processing to introduce desired complexity. Here, we report a method to fabricate heterogeneous multilayered hydrogels based on diffusion-induced gelation. This technique uses the quick diffusion of ions and small molecules (i.e., photoinitiators) through gel-sol or gel-gel interfaces to produce hydrogel layers. Specifically, ionically (e.g., alginate-based) and covalently [e.g., gelatin methacryloyl (GelMA-based)] photocross-linked hydrogels are generated in converse directions from the same interface. The ML (e.g., seven layers) ionic hydrogels can be formed within seconds to minutes with thicknesses ranging from tens to hundreds of micrometers. The thicknesses of the covalent hydrogels are determined by the reaction time (or the molecule diffusion time). Multiwalled tubular structures (e.g., mimicking branched multiwalled vessels) are mainly investigated in this study based on a removable gel core, but this method can be generalized to other material patterns. The process is also demonstrated to support the encapsulation of viable cells and is compatible with a range of thermally reversible core materials (e.g., gelatin and Pluronic F127) and covalently cross-linked formulations (e.g., GelMA and methacrylated hyaluronic acid). This biofabrication process enhances our ability to fabricate a range of structures that are useful for biomedical applications.

[Risk factors related to HIV new infections among men who have sex with men in a cohort study]

Objectives: To analyze and understand the risk factors related to HIV new infections among men who have sex with men (MSM). Methods: A longitudinal observational study among MSM was conducted to collect information on HIV related behaviors and sero-conversion. Univariate and multivariate generalized estimating equations (GEE) were used to discuss the risk factors for HIV new infection. Results: A total number of 4 305 MSM were followed during 2013-2015. Among those self-reported MSM who are seeking partners on the Interner tended to have higher proportion on receptive anal intercourse and consistent condom use during anal intercourse than the subgroups seeking their partners in gay bars or bathrooms. HIV incidence among followed MSM during the study period appeared as 4.3/100 person years, with adjusted RR (aRR) of HIV infection for receptive anal intercourse as group 2.20 (95% CI: 1.49-3.24) times than that of insertion anal intercourse group. Those who used rush-poppers (aRR=1.55, 95% CI: 1.10-2.17), unprotected anal intercourse (aRR=2.24, 95%CI: 1.62-3.08), and those with syphilis infection (aRR=2.95, 95%CI: 2.00-4.35) were also risk factors for HIV new infections. After controlling other factors, the relationship between the ways of seeking partners and HIV new infection was not statistical significant. Conclusion: Risk factors for HIV new infection among MSM appeared complex and interactive, suggesting that further studies are needed to generate tailored strategies for the prevention of HIV epidemic among MSM population.

[Influence of sociocultural factors on HIV transmission among men who have sex with men: a qualitative study]

Objective: To understand how social and cultural factors influence sexual perceptions, sexual practices, and HIV transmission among men who have sex with men at selected sites in China. Methods: Qualitative methodology was used and face to face, semi-structured, in-depth interviews conducted from April 2013 to October 2015 in Sichuan, Jiangxi, Henan, Heilongjiang provinces and Chongqing municipality of China. Results: A total of 184 men who have sex with men participated in the interviews. Forty-eight originated from Henan Province, and 12, 50, 47, and 27 from Jiangxi, Heilongjiang, Sichuan provinces and Chongqing municipality, respectively. A total of 122 participants(66.3%)were under 30 years of age, 111 were college graduates(61.3%), 140 were unmarried(76.5%), and 74 were HIV positive(40.2%). Among interviewees, 6%(11 MSM)were employed at nongovernmental organizations. The main findings revealed that: Owing to sociocultural influences and social norms, most homosexual men concealed their sexual orientation and married females so as to fulfill their family obligation; this may encourage HIV transmission from a high-risk population to the general population; the main features of male homosexual behaviors, as well as those of the associated community and subculture, included hedonism, less concern about health, drug abuse, encouraging of high risk behaviors among men who have sex with men, and negative attitudes regarding HIV prevention; subgroups among MSM were found to have differential HIV transmission risk behaviors, with young men more vulnerable to infection with HIV. Conclusion: Sociocultural factors, including external socioenvironmental circumstances and internal MSM community subcultures, have adverse impacts on HIV transmission among men who have sex with men. Because there were varied behavior modes and HIV transmission risks among MSM subgroups, further study focusing on MSM subgroups is imperative, to provide a basis for more targeted and effective prevention strategies.

A Generalizable Strategy for the 3D Bioprinting of Hydrogels from Nonviscous Photo-crosslinkable Inks

An in situ crosslinking strategy is used for 3D bioprinting of nonviscous photo-crosslinkable hydrogels. This method can be generalized to various photo-crosslinkable formulations, maintaining high embedded cell viability and tunable cell behavior. Heterogeneous and hollow filaments can be printed using this strategy, allowing fabrication of complex engineered cell-laden constructs.

Norbornene-modified poly(glycerol sebacate) as a photocurable and biodegradable elastomer

Photocurable norbornene-functionalized poly(glycerol sebacate) (Nor-PGS) has been developed to fabricate cytocompatible, biodegradable and elastomeric scaffolds for tissue engineering applications.

3D printing of photocurable poly(glycerol sebacate) elastomers

Three-dimensional (3D) printed scaffolds have great potential in biomedicine; however, it is important that we are able to design such scaffolds with a range of diverse properties towards specific applications. Here, we report the extrusion-based 3D printing of biodegradable and photocurable acrylated polyglycerol sebacate (Acr-PGS) to fabricate scaffolds with elastic properties. Two Acr-PGS macromers were synthesized with varied molecular weights and viscosity, which were then blended to obtain photocurable macromer inks with a range of viscosities. The quality of extruded and photocured scaffolds was dependent on the initial ink viscosity, with flow of printed material resulting in a loss of structural resolution or sample breaking observed with too low or too high viscosity inks, respectively. However, scaffolds with high print resolution and up to ten layers were fabricated with an optimal ink viscosity. The mechanical properties of printed scaffolds were dependent on printing density, where the scaffolds with lower printing density possessed lower moduli and failure properties than higher density scaffolds. The 3D printed scaffolds supported the culture of 3T3 fibroblasts and both spreading and proliferation were observed, indicating that 3D printed Acr-PGS scaffolds are cytocompatible. These results demonstrate that Acr-PGS is a promising material for the fabrication of elastomeric scaffolds for biomedical applications.

Effect of bioink properties on printability and cell viability for 3D bioplotting of embryonic stem cells

3D cell printing is an emerging technology for fabricating complex cell-laden constructs with precise and pre-designed geometry, structure and composition to overcome the limitations of 2D cell culture and conventional tissue engineering scaffold technology. This technology enables spatial manipulation of cells and biomaterials, also referred to as 'bioink', and thus allows study of cellular interactions in a 3D microenvironment and/or in the formation of functional tissues and organs. Recently, many efforts have been made to develop new bioinks and to apply more cell sources for better biocompatibility and biofunctionality. However, the influences of printing parameters on the shape fidelity of 3D constructs as well as on cell viability after the cell printing process have been poorly characterized. Furthermore, parameter optimization based on a specific cell type might not be suitable for other types of cells, especially cells with high sensibility. In this study, we systematically studied the influence of bioink properties and printing parameters on bioink printability and embryonic stem cell (ESC) viability in the process of extrusion-based cell printing, also known as bioplotting. A novel method was established to determine suitable conditions for bioplotting ESCs to achieve both good printability and high cell viability. The rheological properties of gelatin/alginate bioinks were evaluated to determine the gelation properties under different bioink compositions, printing temperatures and holding times. The bioink printability was characterized by a newly developed semi-quantitative method. The results demonstrated that bioinks with longer gelation times would result in poorer printability. The live/dead assay showed that ESC viability increased with higher printing temperatures and lower gelatin concentrations. Furthermore, an exponential relationship was obtained between ESC viability and induced shear stress. By defining the proper printability and acceptable viability ranges, a combined parameters region was obtained. This study provides guidance for parameter optimization and the fine-tuning of 3D cell printing processes regarding both bioink printability and cell viability after bioplotting, especially for easily damaged cells, like ESCs.

Plant natural products: from traditional compounds to new emerging drugs in cancer therapy

Natural products are chemical compounds or substances produced naturally by living organisms. With the development of modern technology, more and more plant extracts have been found to be useful to medical practice. Both micromolecules and macromolecules have been reported to have the ability to inhibit tumour progression, a novel weapon to fight cancer by targeting its 10 characteristic hallmarks. In this review, we focus on summarizing plant natural compounds and their derivatives with anti-tumour properties, into categories, according to their potential therapeutic strategies against different types of human cancer. Taken together, we present a well-grounded review of these properties, hoping to shed new light on discovery of novel anti-tumour therapeutic drugs from known plant natural sources.

3D printing of HEK 293FT cell-laden hydrogel into macroporous constructs with high cell viability and normal biological functions

3D printing has evolved into a versatile technology for fabricating tissue-engineered constructs with spatially controlled cells and biomaterial distribution to allow biomimicking of in vivo tissues. In this paper, we reported a novel study of 3D printing of cell lines derived from human embryonic kidney tissue into a macroporous tissue-like construct. Nozzle temperature, chamber temperature and the composition of the matrix material were studied to achieve high cell viability (>90%) after 3D printing and construct formation. Long-term construct stability with a clear grid structure up to 30 days was observed. Cells continued to grow as cellular spheroids with strong cell-cell interactions. Two transfected cell lines of HEK 293FT were also 3D printed and showed normal biological functions, i.e. protein synthesis and gene activation in responding to small molecule stimulus. With further refinement, this 3D cell printing technology may lead to a practical fabrication of functional embryonic tissues in vitro.

In silico analysis and experimental validation of active compounds from fructus Schisandrae chinensis in protection from hepatic injury

OBJECTIVES

The aim of this study was to explore mechanisms by which fructus Schisandrae chinensis (Wuweizi) is able to reveal its protective capacity against hepatocyte injury.

MATERIALS AND METHODS

Identification of candidate small molecular compounds was performed by text-mining, extraction and isolation, reverse-docking, network construction, molecular docking and molecular dynamics (MD) simulation. In vitro cytological examination and western blotting were used to validate efficacy of selected compounds.

RESULTS

We analyzed chemical composition of fructus Schisandrae chinensis and constructed protein-protein networks of key targets. Networks of miRNA-protein were constructed. Molecular docking and MD simulation results supported good interaction between selected compound 11/12 and GBA3/SHBG. Further in vitro examination divulged molecular mechanisms involved.

CONCLUSIONS

In silico analysis and experimental validation together demonstrated that compound 11/12 of fructus Schisandrae chinensis targetted GBA3/SHBG in hepatocytes. Hopefully this will shed light on exploration of its complex molecular mechanisms.