Trinity of Three-Dimensional (3D) Scaffold, Vibration, and 3D Printing on Cell Culture Application: A Systematic Review and Indicating Future Direction

Unveiling the potential of biomaterials and their synergistic fusion in tissue engineering

Inspired by nature, tissue engineering aims to employ intricate mechanisms for advanced clinical interventions, unlocking inherent biological potential and propelling medical breakthroughs. Therefore, medical, and pharmaceutical fields are growing interest in tissue and organ replacement, repair, and regeneration by this technology. Three primary mechanisms are currently used in tissue engineering: transplantation of cells (I), injection of growth factors (II) and cellular seeding in scaffolds (III). However, to develop scaffolds presenting highest potential, reinforcement with polymeric materials is growing interest. For instance, natural and synthetic polymers can be used. Regardless, chitosan and keratin are two biopolymers presenting great biocompatibility, biodegradability and non-antigenic properties for tissue engineering purposes offering restoration and revitalization. Therefore, combination of chitosan and keratin has been studied and results exhibit highly porous scaffolds providing optimal environment for tissue cultivation. This review aims to give an historical as well as current overview of tissue engineering, presenting mechanisms used and polymers involved in the field.

Bone Regeneration with Mesenchymal Stem Cells in Scaffolds: Systematic Review of Human Clinical Trials

The aim of the study is to determine the effectiveness of stem cells in scaffolds in the treatment of bone deficits, in regard of bone regeneration, safety, rehabilitation and quality of life in humans. The systematic review was conducted in accordance with PRISMA 2020. A systematic search was conducted in three search engines and two registries lastly in 29-9-2022.for studies of the last 15 years. The risk of bias was assessed with RoB-2, ROBINS- I and NIH Quality of Before-After (Pre-Post) Studies with no Control group. The certainty of the results was assessed with the GRADE assessment tool. Due to heterogeneity, the results were reported in tables, graphs and narratively. The study protocol was published in PROSPERO with registration number CRD42022359049. Of the 10,091 studies retrieved, 14 were meeting the inclusion criteria, and were qualitatively analyzed. 138 patients were treated with mesenchymal stem cells in scaffolds, showing bone healing in all cases, and even with better results than the standard care. The adverse events were mild in most cases and in accordance with the surgery received. When assessed, there was a rehabilitation of the deficit and a gain in quality of life was detected. Although the heterogeneity between the studies and the small number of patients, the administration of mesenchymal stem cells in scaffolds seems safe and effective in the regeneration of bone defects. These results pave the way for the conduction of more clinical trials, with greater number of participants, with more standardized procedures.

Three-Dimensional Scaffolds for Intestinal Cell Culture: Fabrication, Utilization, and Prospects

The intestine is a visceral organ that integrates absorption, metabolism, and immunity, which is vulnerable to external stimulus. Researchers in the fields such as food science, immunology, and pharmacology have committed to developing appropriate in vitro intestinal cell models to study the intestinal absorption and metabolism mechanisms of various nutrients and drugs, or pathogenesis of intestinal diseases. In the past three decades, the intestinal cell models have undergone a significant transformation from conventional two-dimensional cultures to three-dimensional (3D) systems, and the achievements of 3D cell culture have been greatly contributed by the fabrication of different scaffolds. In this review, we first introduce the developing trend of existing intestinal models. Then, four types of scaffolds, including Transwell, hydrogel, tubular scaffolds, and intestine-on-a-chip, are discussed for their 3D structure, composition, advantages, and limitations in the establishment of intestinal cell models. Excitingly, some of the in vitro intestinal cell models based on these scaffolds could successfully mimic the 3D structure, microenvironment, mechanical peristalsis, fluid system, signaling gradients, or other important aspects of the original human intestine. Furthermore, we discuss the potential applications of the intestinal cell models in drug screening, disease modeling, and even regenerative repair of intestinal tissues. This review presents an overview of state-of-the-art scaffold-based cell models within the context of intestines, and highlights their major advances and applications contributing to a better knowledge of intestinal diseases. Impact statement The intestine tract is crucial in the absorption and metabolism of nutrients and drugs, as well as immune responses against external pathogens or antigens in a complex microenvironment. The appropriate experimental cell model in vitro is needed for in-depth studies of intestines, due to the limitation of animal models in dynamic control and real-time assessment of key intestinal physiological and pathological processes, as well as the "R" principles in laboratory animal experiments. Three-dimensional (3D) scaffold-based cell cultivation has become a developing tendency because of the superior cell proliferation and differentiation and more physiologically relevant environment supported by the customized 3D scaffolds. In this review, we summarize four types of up-to-date 3D cell culture scaffolds fabricated by various materials and techniques for a better recapitulation of some essential physiological and functional characteristics of original intestines compared to conventional cell models. These emerging 3D intestinal models have shown promising results in not only evaluating the pharmacokinetic characteristics, security, and effectiveness of drugs, but also studying the pathological mechanisms of intestinal diseases at cellular and molecular levels. Importantly, the weakness of the representative 3D models for intestines is also discussed.

Matrix stiffness regulates neovascular homeostasis through autophagy in nude mice

One of the major obstacles to the effective application of vascularized fruit is an insufficient understanding of the relationship between the microenvironment and neovascular homeostasis. The role of extracellular matrix stiffness in regulating the structural and functional stability of neovascularization has not yet been elucidated. This study explored the effects of matrix stiffness on neovascular homeostasis in nude mice. Dextran hydrogels with three different stiffnesses were separately combined with mouse bone marrow-derived endothelial progenitor cells (EPCs) and subcutaneously implanted into the backs of nude mice. After 14 days, neovascular homeostasis indicators in the different groups were measured. Cell autophagy levels were evaluated, and inhibitor assays were performed to explore the underlying mechanism. New blood vessels were generated in the three stiffnesses of the EPC-loaded dextran hydrogels 14 days after implantation. The newly formed vessels tended to have better structural stability in softer hydrogels. Endothelial function markers, such as endothelial nitric oxide synthase and E-selectin, were downregulated as the matrix stiffness increased. Furthermore, we found that cell autophagy levels decreased in stiffer matrices, and autophagy inhibition attenuated neovascular homeostasis. A soft matrix is conducive to maintaining neovascular homeostasis through autophagy in nude mice.

Characterization of Mechanical and Cellular Effects of Rhythmic Vertical Vibrations on Adherent Cell Cultures

This paper presents an innovative experimental setup that employs the principles of audio technology to subject adherent cells to rhythmic vertical vibrations. We employ a novel approach that combines three-axis acceleration measurements and particle tracking velocimetry to evaluate the setup's performance. This allows us to estimate crucial parameters such as root mean square acceleration, fluid flow patterns, and shear stress generated within the cell culture wells when subjected to various vibration types. The experimental conditions consisted of four vibrational modes: No Vibration, Continuous Vibration, Regular Pulse, and Variable Pulse. To evaluate the effects on cells, we utilized fluorescence microscopy and a customized feature extraction algorithm to analyze the F-actin filament structures. Our findings indicate a consistent trend across all vibrated cell cultures, revealing a reduction in size and altered orientation (2D angle) of the filaments. Furthermore, we observed cell accumulations in the G1 cell cycle phase in cells treated with Continuous Vibration and Regular Pulse. Our results demonstrate a negative correlation between the magnitude of mechanical stimuli and the size of F-actin filaments, as well as a positive correlation with the accumulations of cells in the G1 phase of the cell cycle. By unraveling these analyses, this study paves the way for future investigations and provides a compelling framework for comprehending the intricate cellular responses to rhythmic mechanical stimulation.

Fabrication of a Low-Cost Microfluidic Device for High-Throughput Drug Testing on Static and Dynamic Cancer Spheroid Culture Models

Drug development is a complex and expensive process from new drug discovery to product approval. Most drug screening and testing rely on in vitro 2D cell culture models; however, they generally lack in vivo tissue microarchitecture and physiological functionality. Therefore, many researchers have used engineering methods, such as microfluidic devices, to culture 3D cells in dynamic conditions. In this study, a simple and low-cost microfluidic device was fabricated using Poly Methyl Methacrylate (PMMA), a widely available material, and the total cost of the completed device was USD 17.75. Dynamic and static cell culture examinations were applied to monitor the growth of 3D cells. α-MG-loaded GA liposomes were used as the drug to test cell viability in 3D cancer spheroids. Two cell culture conditions (i.e., static and dynamic) were also used in drug testing to simulate the effect of flow on drug cytotoxicity. Results from all assays showed that with the velocity of 0.005 mL/min, cell viability was significantly impaired to nearly 30% after 72 h in a dynamic culture. This device is expected to improve in vitro testing models, reduce and eliminate unsuitable compounds, and select more accurate combinations for in vivo testing.

Preparation of a 3D printable high-performance GelMA hydrogel loading with magnetic cobalt ferrite nanoparticles

Osteosarcoma remains a worldwide concern due to the poor effectiveness of available therapies in the clinic. Therefore, it is necessary to find a safe and effective therapy to realize the complete resection of osteosarcoma and reconstruction of the bone defect. Magnetic hyperthermia based on magnetic nanoparticles can kill tumor cells by raising the temperature without causing the side effects of conventional cancer treatments. This research aims to design a high-performance magnetic hydrogel composed of gelatin methacrylate and highly magnetic cobalt ferrite (CFO) nanoparticles for osteosarcoma treatment. Specifically, CFO is surface functionalized with methacrylate groups (MeCFO). The surface modified CFO has good biocompatibility and stable solution dispersion ability. Afterward, MeCFO nanoparticles are incorporated into GelMA to fabricate a three-dimensional (3D) printable MeCFO/GelMA magnetic hydrogel and then photocross-linked by UV radiation. MeCFO/GelMA hydrogel has high porosity and swelling ability, indicating that the hydrogel possesses more space and good hydrophily for cell survival. The rheological results showed that the hydrogel has shear thinning property, which is suitable as a bioprinting ink to produce desired structures by a 3D printer. Furthermore, 50 μg/mL MeCFO not only decreases the cell activity of osteosarcoma cells but also promotes the osteogenic differentiation of mBMSCs. The results of the CCK-8 assay and live/dead staining showed that MeCFO/GelMA hydrogel had good cytocompatibility. These results indicated that MeCFO/GelMA hydrogel with potential antitumor and bone reconstruction functions is a promising therapeutic strategy after osteosarcoma resection.

Application of Biocompatible Scaffolds in Stem-Cell-Based Dental Tissue Engineering

Tissue engineering as an important field in regenerative medicine is a promising therapeutic approach to replace or regenerate injured tissues. It consists of three vital steps including the selection of suitable cells, formation of 3d scaffolds, and adding growth factors. Mesenchymal stem cells (MSCs) and embryonic stem cells (ESCs) are mentioned as two main sources for this approach that have been used for the treatment of various types of disorders. However, the main focus of literature in the field of dental tissue engineering is on utilizing MSCs. On the other hand, biocompatible scaffolds play a notable role in this regenerative process which is mentioned to be harmless with acceptable osteoinductivity. Their ability in inhibiting inflammatory responses also makes them powerful tools. Indeed, stem cell functions should be supported by biomaterials acting as scaffolds incorporated with biological signals. Naturally derived polymeric scaffolds and synthetically engineered polymeric/ceramic scaffolds are two main types of scaffolds regarding their materials that are defined further in this review. Various strategies of tissue bioengineering can affect the regeneration of dentin-pulp complex, periodontium regeneration, and whole teeth bioengineering. In this regard, in vivo/ex vivo experimental models have been developed recently in order to perform preclinical studies of dental tissue engineering which make it more transferable to be used for clinic uses. This review summarizes dental tissue engineering through its different components. Also, strategies of tissue bioengineering and experimental models are introduced in order to provide a perspective of the potential roles of dental tissue engineering to be used for clinical aims.

The hollow porous sphere cell carrier for the dynamic 3D cell culture

Large-scale mammalian cell culture is essential in stem cell-based therapy, the production of the vaccine, and the manufacturing of therapeutic protein drugs. Due to the adherent growth characteristic of most mammalian cell types, the combination of cell carrier and bioreactor is a common choice in large-scale mammalian cell culture. Cell carriers are usually developed by polymer crosslinking, lithography, and emulsion drops; however, all these methods are difficult to control the uniformed porous structure and porous interior design. Therefore, unable to optimize the dynamic culture condition for cell proliferation, matrix production, and cell differentiation. Here we use fused deposition modelling (FDM) 3D printing technology to fabricate hollow porous spheres (HPS), based on which a novel dynamic 3D culture system has been established. In the meantime, computational fluid dynamics (CFD) simulations were conducted to study liquid flow behaviour in HPS. A dynamic cell seeding was developed and refined using the 3D culture system, which increased 32% (roughly) seeding efficiency compared to the traditional static cell seeding method. The cell proliferation analysis demonstrated that HPSs could speed up cell growth in dynamic cell culture. The HPS with a honeycomb-like structure showed the highest inner pore velocity (CFD analysis) and achieved the fastest cell proliferation and the highest cell viability. Overall, our study, for the first time, developed a 3D printed HPS cell culture device with a uniformed porous structure, which can effectively facilitate cell adhesion and proliferation in the dynamic cultural environment, thereby could be considered an ideal carrier candidate for the manufacturing of cells and cell-based products. Furthermore, this study provides a novel 3D dynamic culture system that can be further applied in cell culture and research in the future.

Design of 3D-Printed Electronic Fiber Optic Sensor to Detect Rhodamine B Reagent: An Initiation to Potential Virus Detection

A fluorescence device based on ultraviolet light is proposed in this paper, which currently stands at the design stage with the eventual aim to potentially detect virus/antibody fluorescence reactions. The designed device is proposed to have the characteristics of high reflectivity, low power consumption, wide spectrum of light source, and proper silver coating. For fabrication and raising product quality, 3D printing technology and a sputtering test will be used. In this connection, this paper firstly introduces the design sources; then, the ideas of inventing fluorescence detection devices based on ultraviolet light, followed by the data analysis as well as discussing the results of computer simulations. The design process, materials, methods, and experiments are demonstrated following the reality work procedure. Instead of directly using a virus or antibodies for the experiment, at the current design stage, we focus on using this device to detect the rhodamine B reagent. Experiment shows that this reagent can be successfully detected. With this achievement, we logically believe that such type of an ultraviolet optical sensor, with further development and testing, may have the possible value to detect a single virus such as COVID-19, as well as other viruses or small molecules. Though there is long way to go to achieve such a goal, future works experimenting with the detection device on real virus or antibodies can take place more efficiently with a good foundation.

Clinical Applications of Cell-Scaffold Constructs for Bone Regeneration Therapy

Bone tissue engineering (BTE) is a process of combining live osteoblast progenitors with a biocompatible scaffold to produce a biological substitute that can integrate into host bone tissue and recover its function. Mesenchymal stem cells (MSCs) are the most researched post-natal stem cells because they have self-renewal properties and a multi-differentiation capacity that can give rise to various cell lineages, including osteoblasts. BTE technology utilizes a combination of MSCs and biodegradable scaffold material, which provides a suitable environment for functional bone recovery and has been developed as a therapeutic approach to bone regeneration. Although prior clinical trials of BTE approaches have shown promising results, the regeneration of large bone defects is still an unmet medical need in patients that have suffered a significant loss of bone function. In this present review, we discuss the osteogenic potential of MSCs in bone tissue engineering and propose the use of immature osteoblasts, which can differentiate into osteoblasts upon transplantation, as an alternative cell source for regeneration in large bone defects.

A Review of Conductive Carbon Materials for 3D Printing: Materials, Technologies, Properties, and Applications

Carbon material is widely used and has good electrical and thermal conductivity. It is often used as a filler to endow insulating polymer with electrical and thermal conductivity. Three-dimensional printing technology is an advance in modeling and manufacturing technology. From the forming principle, it offers a new production principle of layered manufacturing and layer by layer stacking formation, which fundamentally simplifies the production process and makes large-scale personalized production possible. Conductive carbon materials combined with 3D printing technology have a variety of potential applications, such as multi-shape sensors, wearable devices, supercapacitors, and so on. In this review, carbon black, carbon nanotubes, carbon fiber, graphene, and other common conductive carbon materials are briefly introduced. The working principle, advantages and disadvantages of common 3D printing technology are reviewed. The research situation of 3D printable conductive carbon materials in recent years is further summarized, and the performance characteristics and application prospects of these conductive carbon materials are also discussed. Finally, the potential applications of 3D printable conductive carbon materials are concluded, and the future development direction of 3D printable conductive carbon materials has also been prospected.

Novel low shear 3D bioreactor for high purity mesenchymal stem cell production

Bone marrow derived human Mesenchymal Stem Cells (hMSCs) are an attractive candidate for regenerative medicine. However, their harvest can be invasive, painful, and expensive, making it difficult to supply the enormous amount of pure hMSCs needed for future allogeneic therapies. Because of this, a robust method of scaled bioreactor culture must be designed to supply the need for high purity, high density hMSC yields. Here we test a scaled down model of a novel bioreactor consisting of an unsubmerged 3D printed Polylactic Acid (PLA) lattice matrix wetted by culture media. The growth matrix is uniform, replicable, and biocompatible, enabling homogenous cell culture in three dimensions. The goal of this study was to prove that hMSCs would culture well in this novel bioreactor design. The system tested resulted in comparable stem cell yields to other cell culture systems using bone marrow derived hMSCs, while maintaining viability (96.54% ±2.82), high purity (>98% expression of combined positive markers), and differentiation potential.

A State-of-the-Art of Functional Scaffolds for 3D Nervous Tissue Regeneration

Exploring and developing multifunctional intelligent biomaterials is crucial to improve next-generation therapies in tissue engineering and regenerative medicine. Recent findings show how distinct characteristics of in situ microenvironment can be mimicked by using different biomaterials. In vivo tissue architecture is characterized by the interconnection between cells and specific components of the extracellular matrix (ECM). Last evidence shows the importance of the structure and composition of the ECM in the development of cellular and molecular techniques, to achieve the best biodegradable and bioactive biomaterial compatible to human physiology. Such biomaterials provide specialized bioactive signals to regulate the surrounding biological habitat, through the progression of wound healing and biomaterial integration. The connection between stem cells and biomaterials stimulate the occurrence of specific modifications in terms of cell properties and fate, influencing then processes such as self-renewal, cell adhesion and differentiation. Recent studies in the field of tissue engineering and regenerative medicine have shown to deal with a broad area of applications, offering the most efficient and suitable strategies to neural repair and regeneration, drawing attention towards the potential use of biomaterials as 3D tools for in vitro neurodevelopment of tissue models, both in physiological and pathological conditions. In this direction, there are several tools supporting cell regeneration, which associate cytokines and other soluble factors delivery through the scaffold, and different approaches considering the features of the biomaterials, for an increased functionalization of the scaffold and for a better promotion of neural proliferation and cells-ECM interplay. In fact, 3D scaffolds need to ensure a progressive and regular delivery of cytokines, growth factors, or biomolecules, and moreover they should serve as a guide and support for injured tissues. It is also possible to create scaffolds with different layers, each one possessing different physical and biochemical aspects, able to provide at the same time organization, support and maintenance of the specific cell phenotype and diversified ECM morphogenesis. Our review summarizes the most recent advancements in functional materials, which are crucial to achieve the best performance and at the same time, to overcome the current limitations in tissue engineering and nervous tissue regeneration.

Polysaccharide hydrogel based 3D printed tumor models for chemotherapeutic drug screening

A series of stable and ready-to-use bioinks have been developed based on the xeno-free and tunable hydrogel (VitroGel) system. Cell laden scaffold fabrication with optimized polysaccharide-based inks demonstrated that Ink H4 and RGD modified Ink H4-RGD had excellent rheological properties. Both bioinks were printable with 25-40 kPa extrusion pressure, showed 90% cell viability, shear-thinning and rapid shear recovery properties making them feasible for extrusion bioprinting without UV curing or temperature adjustment. Ink H4-RGD showed printability between 20 and 37 °C and the scaffolds remained stable for 15 days at temperature of 37 °C. 3D printed non-small-cell lung cancer (NSCLC) patient derived xenograft cells (PDCs) showed rapid spheroid growth of size around 500 µm in diameter and tumor microenvironment formation within 7 days. IC50 values demonstrated higher resistance of 3D spheroids to docetaxel (DTX), doxorubicin (DOX) and erlotinib compared to 2D monolayers of NSCLC-PDX, wild type triple negative breast cancer (MDA-MB-231 WT) and lung adenocarcinoma (HCC-827) cells. Results of flow property, shape fidelity, scaffold stability and biocompatibility of H4-RGD suggest that this hydrogel could be considered for 3D cell bioprinting and also for in-vitro tumor microenvironment development for high throughput screening of various anti-cancer drugs.

3D Culture Systems for Exploring Cancer Immunology

Simple Summary

To study any disease, researchers need convenient and relevant disease models. In cancer, the most commonly used models are two-dimensional (2D) culture models, which grow cells on hard, rigid, plastic surfaces, and mouse models. Cancer immunology is especially difficult to model because the immune system is exceedingly complex; it contains multiple types of cells, and each cell type has several subtypes and a spectrum of activation states. These many immune cell types interact with cancer cells and other components of the tumor, ultimately influencing disease outcomes. 2D culture methods fail to recapitulate these complex cellular interactions. Mouse models also suffer because the murine and human immune systems vary significantly. Three-dimensional (3D) culture systems therefore provide an alternative method to study cancer immunology and can fill the current gaps in available models. This review will describe common 3D culture models and how those models have been used to advance our understanding of cancer immunology.

Abstract

Cancer immunotherapy has revolutionized cancer treatment, spurring extensive investigation into cancer immunology and how to exploit this biology for therapeutic benefit. Current methods to investigate cancer-immune cell interactions and develop novel drug therapies rely on either two-dimensional (2D) culture systems or murine models. However, three-dimensional (3D) culture systems provide a potentially superior alternative model to both 2D and murine approaches. As opposed to 2D models, 3D models are more physiologically relevant and better replicate tumor complexities. Compared to murine models, 3D models are cheaper, faster, and can study the human immune system. In this review, we discuss the most common 3D culture systems—spheroids, organoids, and microfluidic chips—and detail how these systems have advanced our understanding of cancer immunology.

The Research Advance of Cell Bridges in vitro

The microenvironment in which cells reside in vivo dictates their biological and mechanical functioning is associated with morphogenetic and regenerative processes and may find implications in regenerative medicine and tissue engineering. The development of nano- and micro-fabricated technologies, three-dimensional (3D) printing technique, and biomimetic medical materials have enabled researchers to prepare novel advanced substrates mimicking the in vivo microenvironment. Most of the novel morphologies and behaviors of cells, including contact guidance and cell bridges which are observed in vivo but are not perceived in the traditional two-dimensional (2D) culture system, emerged on those novel substrates. Using cell bridges, cell can span over the surface of substrates to maintain mechanical stability and integrity of tissue, as observed in physiological processes, such as wound healing, regeneration and development. Compared to contact guidance, which has received increased attention and is investigated extensively, studies on cell bridges remain scarce. Therefore, in this mini-review, we have comprehensively summarized and classified different kinds of cell bridges formed on various substrates and highlighted possible biophysical mechanisms underlying cell bridge formation for their possible implication in the fields of tissue engineering and regenerative medicine.

Microfluidics and organ-on-a-chip technologies: A systematic review of the methods used to mimic bone marrow

Bone marrow (BM) is an organ responsible for crucial processes in living organs, e. g., hematopoiesis. In recent years, Organ-on-a-Chip (OoC) devices have been used to satisfy the need for in vitro systems that better mimic the phenomena occurring in the BM microenvironment. Given the growing interest in these systems and the diversity of developed devices, an integrative systematic literature review is required. We have performed this review, following the PRISMA method aiming to identify the main characteristics and assess the effectiveness of the devices that were developed to represent the BM. A search was performed in the Scopus, PubMed, Web of Science and Science Direct databases using the keywords (("bone marrow" OR "hematopoietic stem cells" OR "haematopoietic stem cells") AND ("organ in a" OR "lab on a chip" OR "microfluidic" OR "microfluidic*" OR ("bioreactor" AND "microfluidic*"))). Original research articles published between 2009 and 2020 were included in the review, giving a total of 21 papers. The analysis of these papers showed that their main purpose was to study BM cells biology, mimic BM niches, model pathological BM, and run drug assays. Regarding the fabrication protocols, we have observed that polydimethylsiloxane (PDMS) material and soft lithography method were the most commonly used. To reproduce the microenvironment of BM, most devices used the type I collagen and alginate. Peristaltic and syringe pumps were mostly used for device perfusion. Regarding the advantages compared to conventional methods, there were identified three groups of OoC devices: perfused 3D BM; co-cultured 3D BM; and perfused co-cultured 3D BM. Cellular behavior and mimicking their processes and responses were the mostly commonly studied parameters. The results have demonstrated the effectiveness of OoC devices for research purposes compared to conventional cell cultures. Furthermore, the devices have a wide range of applicability and the potential to be explored.

Nano-CT scans in the optimisation of purposeful experimental procedures: A study on metallic fibre networks

Motive Metallic fibre networks and their mechanical behaviour are only insufficiently understood. In this particular field of research, the use of nano-CT scans offers advanced opportunities for the optimised planning of experimental work and component design. Several novel applications will benefit from this research; in particular, tissue engineering applications where a controlled and reproducible mechanical stimulus on cells is required can make use of these components. MethodFor the present study, the geometry of metallic fibre network samples is measured and digitalised through the use of nano-CT scan protocols and adequate radiological post-processing steps. Fibre medial axes are transferred into finite element assemblies and are exposed to magnetic actuation models. Network displacement of input geometries is quantified by averaging of node displacement fields. Key resultsComplex 3D deformation fields with regions of tension, shear, and compression are obtained. Results from a previous study about matrix material deformation can be confirmed in this study for greater sample geometries. The strain magnitude is not uniform across the samples; several influencing parameters and deformation patterns are identified. A simple analytical model can be presented which quantifies the material deformation. ConclusionsNano-CT scans provide an efficient radiological tool in the planning of relevant experimental procedures. The present study confirms the general usability of fibre networks for the contactless creation of 3D strain fields in tissue engineering. Mechanical effects in tissue growth stimulation known from experimental work are obtained numerically for the investigated assemblies. Further work about the mechanical effects in tissue cultures appears highly worthwhile.

Redox-responsive functionalized hydrogel marble for the generation of cellular spheroids

Liquid marbles (LMs) have recently shown a great promise as microbioreactors to construct self-supported aqueous compartments for chemical and biological reactions. However, the evaporation of the inner aqueous liquid core has limited their application, especially in studying cellular functions. Hydrogels are promising scaffolds that provide a spatial environment suitable for three-dimensional cell culture. Here, we describe the fabrication of redox-responsive hydrogel marbles (HMs) as a three-dimensional cell culture platform. The HMs are prepared by introducing an aqueous mixture of a tetra-thiolated polyethylene glycol (PEG) derivative, thiolated gelatin (Gela-SH), horseradish peroxidase, a small phenolic compound, and human hepatocellular carcinoma cells (HepG2) to the inner aqueous phase of LMs. Eventually, HepG2 cells are encapsulated in the HMs then immersed in culture media, where they proliferate and form cellular spheroids. Experimental results show that the Gela-SH concentration strongly influences the physicochemical and microstructure properties of the HMs. After 6 days in culture, the spheroids were recovered from the HMs by degrading the scaffold, and examination showed that they had reached up to about 180 μm in diameter depending on the Gela-SH concentration, compared with 60 μm in conventional HMs without Gela-SH. After long-term culture (over 12 days), the liver-specific functions (secretion of albumin and urea) and DNA contents of the spheroids cultured in the HMs were elevated compared with those cultured in LMs. These results suggest that the developed HMs can be useful in designing a variety of microbioreactors for tissue engineering applications.

Construction of higher-order cellular microstructures by a self-wrapping co-culture strategy using a redox-responsive hydrogel

In this report, a strategy for constructing three-dimensional (3D) cellular architectures comprising viable cells is presented. The strategy uses a redox-responsive hydrogel that degrades under mild reductive conditions, and a confluent monolayer of cells (i.e., cell sheet) cultured on the hydrogel surface peels off and self-folds to wrap other cells. As a proof-of-concept, the self-folding of fibroblast cell sheet was triggered by immersion in aqueous cysteine, and this folding process was controlled by the cysteine concentration. Such folding enabled the wrapping of human hepatocellular carcinoma (HepG2) spheroids, human umbilical vein endothelial cells and collagen beads, and this process improved cell viability, the secretion of metabolites and the proliferation rate of the HepG2 cells when compared with a two-dimensional culture under the same conditions. A key concept of this study is the ability to interact with other neighbouring cells, providing a new, simple and fast method to generate higher-order cellular aggregates wherein different types of cellular components are added. We designated the method of using a cell sheet to wrap another cellular aggregate the 'cellular Furoshiki'. The simple self-wrapping Furoshiki technique provides an alternative approach to co-culture cells by microplate-based systems, especially for constructing heterogeneous 3D cellular microstructures.

Characterization and printability of Sodium alginate -Gelatin hydrogel for bioprinting NSCLC co-culture

3D bioprinting improves orientation of in vitro tumor models by offering layer by layer positioning of cancer cells and cancer associated fibroblasts (CAFs) which can replicate tumor microenvironment. Aim of this study was to develop a sodium alginate -gelatin (SA-GL) hydrogel by optimizing rheological parameters to print non-small cell lung cancer (NSCLC) patient derived xenograft (PDX) cells and lung CAFs co-cultures. SA-GL hydrogels were prepared, and rheological properties were evaluated. Both the cells were mixed with the hydrogel and printed using INKREDIBLE bioprinter. Hydrogels prepared with 3.25% and 3.5% (w/v) SA and 4% (w/v) GL showed higher printability and cell viability. A significant decline in viscosity with shear rate was observed in these hydrogels suggesting the shear thinning property of hydrogels. Spheroid size distribution after 15 days was in the diameter range of 50-1100 µm. Up-regulation of vimentin, α-SMA and loss of E-cadherin in co-culture spheroids confirmed cellular crosstalk. This study demonstrates that rheological optimization of SA-GL hydrogel enhances printability and viability of NSCLC PDX and CAF co-culture which allows 3D co-culture spheroid formation within the printed scaffold. Therefore, this model can be used for studying high throughput drug screening and other pre-clinical applications.

Modifying the Tumour Microenvironment: Challenges and Future Perspectives for Anticancer Plasma Treatments

Tumours are complex systems formed by cellular (malignant, immune, and endothelial cells, fibroblasts) and acellular components (extracellular matrix (ECM) constituents and secreted factors). A close interplay between these factors, collectively called the tumour microenvironment, is required to respond appropriately to external cues and to determine the treatment outcome. Cold plasma (here referred as ‘plasma’) is an emerging anticancer technology that generates a unique cocktail of reactive oxygen and nitrogen species to eliminate cancerous cells via multiple mechanisms of action. While plasma is currently regarded as a local therapy, it can also modulate the mechanisms of cell-to-cell and cell-to-ECM communication, which could facilitate the propagation of its effect in tissue and distant sites. However, it is still largely unknown how the physical interactions occurring between cells and/or the ECM in the tumour microenvironment affect the plasma therapy outcome. In this review, we discuss the effect of plasma on cell-to-cell and cell-to-ECM communication in the context of the tumour microenvironment and suggest new avenues of research to advance our knowledge in the field. Furthermore, we revise the relevant state-of-the-art in three-dimensional in vitro models that could be used to analyse cell-to-cell and cell-to-ECM communication and further strengthen our understanding of the effect of plasma in solid tumours.

Evaluation of Structural and Mechanical Properties of Porous Artificial Bone Scaffolds Fabricated via Advanced TBA-Based Freeze-Gel Casting Technique

Porous hydroxyapatite (HA) artificial bone scaffolds were prepared via the freeze-gel casting process in order to improve their mechanical strengths. As a porogen, various volumes of poly (methyl methacrylate) (PMMA) powders were added to obtain high porosity, such as in cancellous bone. After fabrication, the porous and mechanical properties of the scaffolds were examined. The HA60 scaffold, with a porosity over 80%, had proper compressive strength and modulus and satisfied the range of properties of cancellous bone. Moreover, it was found that the investigated mechanical properties were affected by the scaffolds’ porosity. However, a section was found where the compressive strength was high despite the increase in the porosity. Specifically, HA30 had a porosity of 62.9% and a compressive strength of 1.73 MPa, whereas the values for HA60 were 81.9% and 3.23 MPa, respectively. The results indicate that there are factors that can preserve the mechanical properties even if the porosity of the scaffold increases. Therefore, in this study, various parameters affecting the porous and mechanical properties of the scaffolds during the manufacturing process were analyzed. It is expected that the improvement in the mechanical properties of the artificial bone scaffold having a high porosity can be applied to tissue engineering.

Drug discovery strategies for acute radiation syndrome

Introduction: There are at the minimum two major, quite different approaches to advance drug discovery. The first being the target-based drug discovery (TBDD) approach that is commonly referred to as the molecular approach. The second approach is the phenotype-based drug discovery (PBDD), also known as physiology-based drug discovery or empirical approach. Area covered: The authors discuss, herein, the need for developing radiation countermeasure agents for various sub-syndromes of acute radiation syndromes (ARS) following TBDD and PBDD approaches. With time and continuous advances in radiation countermeasure drug development research, the expectation is to have multiple radiation countermeasure agents for each sub-syndrome made available to radiation exposed victims. Expert opinion: The majority of the countermeasures currently being developed for ARS employ the PBDD approach, while the TBDD approach is clearly under-utilized. In the future, an improved drug development strategy might be a 'hybrid' strategy that is more reliant on TBDD for the initial drug discovery via large-scale screening of potential candidate agents, while utilizing PBDD for secondary screening of those candidates, followed by tertiary analytics phase in order to pinpoint efficacious candidates that target the specific sub-syndromes of ARS.

PLLA scaffolds with controlled architecture as potential microenvironment for in vitro tumor model

The "microenvironment" where a tumor develops plays a fundamental role in determining its progression, the onset of metastasis and, eventually, its resistance to therapies. Tumor cells can be considered more or less invasive depending both on the nature of the cells and on the site where they are located. Commonly adopted laboratory culture protocols for the investigation of tumor cells take usually place on standard two-dimensional supports. However, such cultures do not allow for reproduction of the biophysical properties of the tumor's microenvironment, thus causing the cells to lose most of their relevant characteristics. In this work MDA-MB 231 breast cancer cells were cultivated within Poly-l-Lactic Acid (PLLA) scaffolds produced via Thermally Induced Phase Separation (TIPS). Starting from a ternary solution (polymer-solvent-nonsolvent) we produced scaffolds with different morphologies, porosities and pore architectures. The influence of porosity and average pore size upon cell adhesion and growth were investigated by using Cell Counting Kit-8 (CCK-8) as cell viability test, a fluorescence assay staining cell with DAPI and Scanning Electron Microscopy (SEM). Our study demonstrates that the average pore size of the polymeric scaffolds influences both the cell adhesion and resulting morphology of the growing breast cancer cells. In particular, the reported data corroborate the evidence that an average pore size ranging from 40 to 50 μm induces tumor cell aggregation and the formation of the irregular tumor masses typically observed in-vivo. In addition, TIPS proved to be a suitable manufacturing technique for finely tuning the scaffolds' architecture, relevant to developing the most effective microenvironment for an in-vitro tumor cells growth closely mimicking in-vivo conditions.

A Systematic Study on Design Initiation of Conceptual 3DPVS

An important product in biomedical and biomimetic engineering is the 3D scaffold, which mimics the real tissue in vitro to achieve the external cultivation of cells. The difference between the 3D scaffold and other biomimetic products lies in the fact that the former mimics the internal features of tissue, while the latter generally approximates the external traits of biological beings. In the field of scaffold engineering, the 3D printed vibratory scaffold, 3DPVS, has been proposed as a present-to-future novel scaffold product, and it currently stays at the stage of conceptual development. To achieve the novel design of the conceptual 3DPVS, a conceptual design process has been established by authors in their previous work, which contain three main stages, namely the design initiation, concept generation, and concept evaluation. In terms of design initiation, it is a ‘must-accomplish’ stage which generates outputs for both the subsequent concept generation and evaluation. Work of design initiation therefore is of significant value and it consists of several tasks; that is, conducting a thorough literature review, summarizing the fundamental issues preparing the general conceptual design, studying the multi-characterization of the 3DPVS, putting forward the potential base model(s), as well as indicating the ideality of the scaffold and establishing potential ideal model(s) for the 3DPVS. In this paper, design initiation will be chiefly focused upon these essential aspects to be discussed, work of which is expected to be useful in establishing a solid ground for future innovation work of the 3DPVS.

Introducing the Language of "Relativity" for New Scaffold Categorization

Research related with scaffold engineering tends to be cross-domain and miscellaneous. Several realms may need to be focused simultaneously, including biomedicine for cell culture and 3D scaffold, physics for dynamics, manufacturing for technologies like 3D printing, chemistry for material composition, as well as architecture for scaffold's geometric control. As a result, researchers with different backgrounds sometimes could have different understanding towards the product described as 'Scaffold'. After reviewing the literature, numerous studies termed their developed scaffold as 'novel', compared with scaffolds previously designed by others using comparing criterion like 'research time', 'manufacturing method', 'geometry', and so on. While it may have been convenient a decade ago to, for example, categorize scaffold with 'Dualistic Thinking' logic into 'simple-complicated' or 'traditional-novel', this method for categorizing 'novelty' and distinguishing scaffold is insufficiently persuasive and precise when it comes to modern or future scaffold. From this departure of philosophical language, namely the language of 'relativity', it is important to distinguish between different scaffolds. Other than attempting to avoid ambiguity in perceiving scaffold, this language also provides clarity regarding the 'evolution stage' where the focused scaffolds currently stand, where they have been developed, and where in future they could possibly evolve.

Inverse opal substrate-loaded mesenchymal stem cells contribute to decreased myocardial remodeling after transplantation into acute myocardial infarction mice

Background

The two-dimensional incubation method is now the most commonly method for mesenchymal stem cell (MSC) production. however, gene expression and secretion of growth factors are relatively low; thus, the transplanted cells cannot be effectively utilized for potential clinical applications after acute myocardial infarction (AMI).

Objectives

We aimed to investigate whether our newly made substrates of inverse opal with specific surface microstructures for MSC culturing can increase the viability of the cells and can contributes to decreased myocardial remodeling after transplanted to AMI mice.

Methods

The inverse opal structure is fabricated by the convenient bottom-up approach of the self-assembly of colloidal nanoparticles. Mouse-derived MSCs were then cultured on the substrates when expanded at different times to investigate the cell growth status including morphology. Then the inverse opal substrates loaded MSCs were transplanted to AMI mice, cardiomyocyte apoptosis and LV remodeling were further compared. To explore the possible mechanisms of curation, the secretions and viability of MSCs on substrates were determined using mice ELISA kits and JC-1 mitochondrial membrane potential assay kits respectively at normal and hypoxic conditions.

Results

6 times expanded inverse opals allowed greatly the orderly growth of MSCs as compared to four (34% ± 10.6%) and two (20%±7.2%) times expanded as well as unexpanded (13%±4.1%) (P<0.001). Nearly 90% of MSCs showed orientation angle intervals of less than 30° when at the 6X expanded (89.6%±25%) compared to the percent of cells with 30°-60° (8.7%±2.6%) or ≥60° (1.7%±1.0%) orientation angle (P<0.001). After inverse opal loaded MSCs transplanted to AMI mice, greatly decreased apoptosis of cardiomyocytes (20.45%±8.64% vs.39.63%±11.71%, P<0.001) and infarction area (5.87±2.18 mm² vs 9.31±3.11 mm², P<0.001) were identified. In the end, the viability of inverse opal loaded MSCs determined by membrane potential (P<0.001) and the secretion of growth factors including VEGF-α, SDF-1 and Ang-1 (P<0.001) were both confirmed significantly higher than that of the conventional culture in petri dish.

Conclusion

The structure of inverse opal can not only adjust the arrangement of MSCs but also contribute to its orientated growth. Inverse opal loaded MSCs transplantation extremely curbed myocardial remodeling, the underlying mechanisms might be the high viability and extremely higher secretions of growth factors of MSCs as devoted by this method.