Search

Three-dimensional (3D) bioprinting is an advanced technology to fabricate artificial 3D tissue constructs containing cells and hydrogels for tissue engineering and regenerative medicine. Nanocomposite reinforcement endows hydrogels with superior properties and tailored functionalities. A broad range of nanomaterials, including silicon-based, ceramic-based, cellulose-based, metal-based, and carbon-based nanomaterials, have been incorporated into hydrogel networks with encapsulated cells for improved performances. This review emphasizes the recent developments of cell-laden nanocomposite bioinks for 3D bioprinting, focusing on their reinforcement effects and mechanisms, including viscosity, shear-thinning property, printability, mechanical properties, structural integrity, and biocompatibility. The cell-material interactions are discussed to elaborate on the underlying mechanisms between the cells and the nanomaterials. The biomedical applications of cell-laden nanocomposite bioinks are summarized with a focus on bone and cartilage tissue engineering. Finally, the limitations and challenges of current cell-laden nanocomposite bioinks are identified. The prospects are concluded in designing multi-component bioinks with multi-functionality for various biomedical applications. STATEMENT OF SIGNIFICANCE: 3D bioprinting, an emerging technology of additive manufacturing, has been one of the most innovative tools for tissue engineering and regenerative medicine. Recent developments of cell-laden nanocomposite bioinks for 3D bioprinting, and cell-materials interactions are the subject of this review paper. The reinforcement effects and mechanisms of nanocomposites on viscosity, printability and biocompatibility of bioinks and 3D printed scaffolds are addressed mainly for bone and cartilage tissue engineering. It provides detailed information for further designing and optimizing multi-component bioinks with multi-functionality for specialized biomedical applications.

Laparoscopic liver resection (LLR) for hepatocellular carcinoma (HCC) remains controversial, especially for tumors larger than 5 cm. We compared the short- and long-term outcomes of laparoscopic and open liver resection (OLR) for large HCC.Patients with large HCC after curative hepatectomy were enrolled. To compare the short-term outcomes, propensity score matching (PSM) and inverse probability treatment weighting (IPTW) were performed to reduce the effect of confounding factors, respectively. Subsequently, Cox-regression analyses were conducted to identify the independent risk factors associated with decreased recurrence-free survival (RFS) and poor overall survival (OS).There were 265 patients enrolled in the final analysis: 146 who underwent OLR and 119 who underwent LLR. There was no significant difference between the OLR and LLR groups according to PSM and IPTW analysis (all P 0.05). Multivariable analysis revealed that LLR was not independently associated with poorer OS (HR 1.15, 95% CI 0.80-1.67, P = 0.448) or RFS (HR 1.22, 95% CI 0.88-1.70, P = 0.238).There were no significant differences in perioperative complications or long-term prognosis between LLR and OLR for large HCC, which provides evidence for standard laparoscopic surgical practice with adequate surgeon experience and careful patient selection.

The role of angiogenesis in health and disease have gained considerable momentum in recent years. Visualizing angiogenic patterns and associated events of surrounding vascular beds in response to therapeutic and laboratory-grade biomolecules have become a commonplace in regenerative medicine and the biosciences. To aid imaging investigations in angiogenesis, the two-photon excitation fluorescence microscopy (2PEF), or multiphoton fluorescence microscopy is increasingly utilized in scientific investigations. The 2PEF microscope confers several distinct imaging advantages over other fluorescence excitation microscopy techniques - for the observation of in-depth, three-dimensional vascularity in a variety of tissue formats, including fixed tissue specimens and in vivo vasculature in live specimens. Understanding morphological and subcellular changes that occur in cells and tissues during angiogenesis will provide insights to behavioral responses in diseased states, advance the engineering of physiologically-relevant tissue models and provide biochemical clues for the design of therapeutic strategies. We review the applicability and limitations of the 2PEF microscope on the biophysical and molecular-level signatures of angiogenesis in various tissue models. Imaging techniques and strategies for best practices in 2PEF microscopy will be reviewed.

Purpose This paper aims to detect the printing failures (such as warpage and collapse) in material extrusion (MEX) process effectively and timely to reduce the waste of printing time, energy and material. Design/methodology/approach The approach is designed based on the frequently observed fact that printing failures are accompanied by abnormal material phenomena occurring close to the nozzle. To effectively and timely capture the phenomena near the nozzle, a camera is delicately installed on a typical MEX printer. Then, aided by the captured phenomena (images), a smart printing failure predictor is built based on the artificial neural network (ANN). Finally, based on the predictor, the printing failures, as well as their types, can be effectively detected from the images captured by the camera in real-time. Findings Experiments show that printing failures can be detected timely with an accuracy of more than 98% on average. Comparisons in methodology demonstrate that this approach has advantages in real-time printing failure detection in MEX. Originality/value A novel real-time approach for failure detection is proposed based on ANN. The following characteristics make the approach have a great potential to be implemented easily and widely: (1) the scheme designed to capture the phenomena near the nozzle is simple, low-cost, and effective; and (2) the predictor can be conveniently extended to detect more types of failures by using more abnormal material phenomena that are occurring close to the nozzle.

The impact of diabetes mellitus (DM) on the survival of patients with hepatocellular carcinoma (HCC) is still unclear. The present study aims to draw a firm conclusion in terms of evaluating the impact of DM on the prognosis of HCC after hepatectomy.The pattern of recurrence for HCC was often stratified into early-stage (2 years) and late-stage (≥2 years) recurrence. Because the early-stage recurrence was mainly attributed to aggressive tumor pathological characteristics, patients who recurrence or die within 2 years were excluded. Cumulative overall survival (OS) and recurrence-free survival (RFS) were determined by the method of Kaplan-Meier, and the independent risk factors of OS/RFS were determined by Cox regression analysis.A total of 426 patients were eventually included. The 3- and 5-year OS in patients with and without DM was 83.7%, 55.1%; and 90.9%, 77.4%, respectively. Multivariate analysis showed that DM was an independent risk factor for OS (HR 1.166, 95% CI 1.056-2.036,DM is an independent risk factor for long-term prognosis in patients with HCC. Patients with DM after hepatectomy for HCC, thus, need to actively control DM and closer follow-up.

Wound healing is a dynamic process that involves a series of molecular and cellular events aimed at replacing devitalized and missing cellular components and/or tissue layers. Recently, extracellular vesicles (EVs), naturally cell-secreted lipid membrane-bound vesicles laden with biological cargos including proteins, lipids, and nucleic acids, have drawn wide attention due to their ability to promote wound healing and tissue regeneration. However, current exploitation of EVs as therapeutic agents is limited by their low isolation yields and tedious isolation processes. To circumvent these challenges, bioinspired cell-derived nanovesicles (CDNs) that mimic EVs were obtained by shearing mesenchymal stem cells (MSCs) through membranes with different pore sizes. Physical characterisations and high-throughput proteomics confirmed that MSC-CDNs mimicked MSC-EVs. Moreover, these MSC-CDNs were efficiently uptaken by human dermal fibroblasts and demonstrated a dose-dependent activation of MAPK signalling pathway, resulting in enhancement of cell proliferation, cell migration, secretion of growth factors and extracellular matrix proteins, which all promoted tissue regeneration. Of note, MSC-CDNs enhanced angiogenesis in human dermal microvascular endothelial cells in a 3D PEG-fibrin scaffold and animal model, accelerating wound healing in vitro and in vivo. These findings suggest that MSC-CDNs could replace both whole cells and EVs in promoting wound healing and tissue regeneration. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) Nanyang Technological University Published version This work was supported by the National University of Singapore (NanoNash Program A-0004336-00-00 & A-0008504- 00-00, Singapore), and Nanyang Technological University, Singapore (grant number 001487-00001). Giorgia Pastorin. would also like to thank the Industry Alignment FunddPre-Positioning (IAF-PP) grant (A20G1a0046 and R-148-000-307-305/A0004345-00-00). This work was also supported by the Singapore Ministry of Education, under its Singapore Ministry of Education Academic Research Fund Tier 1 (10051 - MOE AcRF Tier 1: Thematic Call 2020) from Bertrand Czarny. Jiong-Wei Wang would like to thank the National University of Singapore NanoNASH Program (NUHSRO/2020/002/NanoNash/LOA) and the National University of Singapore Yong Loo Lin School of Medicine Nanomedicine Translational Research Program (NUHSRO/ 2021/034/TRP/09/Nanomedicine). Authors would also like to thank for the financial supports from Agency for Science, Technology, and Research (A*STAR, Singapore) Advanced Manufacturing and Engineering Individual Research Grant (AME IRG) (Project ID: A1883c0013, Singapore).

Although anatomical hepatectomy (AH) is widely used in the treatment of hepatocellular carcinoma (HCC), the prognosis is still unsatisfactory. The present study aimed to evaluate the survival benefit of adjuvant transcatheter arterial chemoembolization (TACE) for patients with HCC after AH. A total of 832 patients were stratified into with adjuvant TACE (443, 53.2%) and without adjuvant TACE group (389, 46.8%) AH. Propensity score matching (PSM) was performed to control for confounding factors, and multivariable Cox regression was performed to determine the independent risk factors. After PSM, the results showed that the adjuvant TACE group had better overall survival (OS) and recurrence-free survival (RFS). Among the patients with tumor recurrence, adjuvant TACE was associated with a high rate of early-stage tumor at recurrence, a lower recurrence rate around the frontal margin and extrahepatic metastases, and a higher rate of receiving curative treatment. Multivariable Cox regression analysis showed that adjuvant TACE was an independent prognostic factor for OS (HR 0.673, P = 0.001) and RFS (HR 0.650, P = 0.001). Patients with HCC after AH can benefit from postoperative adjuvant TACE. Therefore, adjuvant TACE should be considered for patients with a high risk of recurrence.

This chapter presents the basic concepts of aesthetic needs and product specifications in conceptual design. The user aesthetics needs are considered one of the significant determinants in increasing user satisfaction. In this regard, the importance of establishing product appearance specifications to identify user aesthetic needs is discussed. A method is introduced to demonstrate the significance of considering aesthetic and emotional needs when establishing product appearance specifications in product conceptual design. To improve appearance specifications based on aesthetic experiences collected from users and designers, an approach using fuzzy logic is proposed and illustrated by a case study of digital camera design.

Multiple common databases were integrated to analyze the expression status and prognostic meaning ofThe transcription of

Among different treatments of critical-sized bone defects, bone tissue engineering (BTE) is a fast-developing strategy centering around the fabrication of scaffolds that can stimulate tissue regeneration and provide mechanical support at the same time. This area has seen an extensive application of bioceramics, such as calcium phosphate, for their bioactivity and resemblance to the composition of natural bones. Moreover, recent advances in additive manufacturing (AM) have unleashed enormous potential in the fabrication of BTE scaffolds with tailored porous structure as well as desired biological and mechanical properties. Robocasting is an AM technique that has been widely applied to fabricate calcium phosphate scaffolds, but most of these scaffolds do not meet the mechanical requirements for load-bearing BTE scaffolds. In light of this challenge, various approaches have been utilized to mechanically strengthen the scaffolds. In this review, the current state of knowledge and existing research on robocasting of calcium phosphate scaffolds are presented. Applying the Gibson-Ashby model, this review provides a meta-analysis from the published literature of the compressive strength of robocast calcium phosphate scaffolds. Furthermore, this review evaluates different approaches to the mechanical strengthening of robocast calcium phosphate scaffolds. The aim of this review is to provide insightful data and analysis for future research on mechanical strengthening of robocast calcium phosphate scaffolds and ultimately for their clinical applications.

Apparent anisotropies have been found in the microstructure and mechanical properties of selective laser melted (SLM) Ti–6Al–4V alloy, which will significantly influence the comprehensive performance of the SLM parts. In this study, the effect of scanning strategies on material anisotropy, including surface morphology, microstructure, microhardness, quasi-static and dynamic mechanical properties, were comprehensively investigated with 0°, 67.5°, and 90° scanning strategies. The SLM Ti6Al4V alloy prepared by the 0° scanning strategy exhibited the most pronounced anisotropy. The size of the primary columnar crystals on the front surface (158–173 μm) is approximately 1.8–3.2 times larger than that of the top surface (54–88 μm), and the microhardness at the top surface is ∼30% higher than that of the front surface. In addition, the modified Johnson-Cook constitutive model for the SLM Ti6Al4V alloy was developed based on the results of quasi-static compression and dynamic compression with the average absolute relative error controlled within 10%. This provides a reliable solution and an effective material constitutive model for modeling and simulation of the machining SLM parts with higher accuracy and enhanced physical meaning.

Part integration is to integrate parts to be a fabrication and assembly unit. It can effectively reduce the fabrication and assembly unit quantity of a product and has been deemed as an effective way to promote the productivity of manufacturing. Although additive manufacturing (AM) has great potential to further promote the part integration for any product (assembly) model, part integration works using AM at present are often ad hoc, human-dependent and time-consuming. One main cause for this problem is that determining which parts in an assembly model can be integrated to be a fabrication and assembly unit automatically is still very difficult, especially when the model has kinematics (inner relative motions embodied by kinematic joints). In this paper, a novel part clustering approach is proposed, based on which, an input assembly model can smartly cluster all its parts to fewer sub-assembly models (each of them fits being integrated to be a fabrication and assembly unit in AM) according to its kinematics. To ensure that the input model after part integration can effectively realize its kinematics using AM, the criteria for part clustering are first defined. Accompanying with the criteria, the methods to determine the kinematics-related fabrication orientation for each part are proposed based on heuristic rules. Then, to make an accurate and efficient part clustering, an attributed part kinematic graph is put forward according to the above criteria. After that, by breaking through the detection automation challenges in sealing support structure and assembly feasibility, an efficient optimization objective function is defined based on the above criteria and graph. Finally, integrating a new adaptive perturbation strategy into the particle swarm optimization algorithm to avoid premature convergence, a novel graph-based part clustering optimization method is designed to cluster all the parts of the input model to be a high-quality (optimized) set of the above-mentioned sub-assembly models. Experiments and analyses are presented to verify the advantages of the proposed approach. Besides, complying with the general guidelines in AM, the proposed approach provides great potential to maximize part integration using AM in a wider application.