Three-dimensional cell-culture platform based on hydrogel with tunable microenvironmental properties to improve insulin-secreting function of MIN6 cells

Prussian Blue Nanohybridized Multicellular Spheroids as Composite Engraftment for Antioxidant Bone Regeneration and Photoacoustic Tomography

Regulating the complex microenvironment after tooth extraction to promote alveolar bone regeneration is a pressing challenge for restorative dentistry. In this study, through modulating the mechanical properties of the cellular matrix, we guided various types of cells by self-organizing to form multicellular spheroids (MCSs) and hybridized MCSs with Prussian Blue nanoparticles (PBNPs) in the process. The constructed Prussian Blue nanohybridized multicellular spheroids (PBNPs@MCSs) with empowered antioxidant functions effectively reduced cell apoptosis under peroxidative conditions and exhibited enhanced ability to regulate the microenvironment and promote bone repair both in vitro and in vivo. In addition, the PBNPs@MCSs exhibited enhanced photoacoustic imaging ability to trace low doses of PBNPs. Therefore, the constructed PBNPs@MCSs based on the biomimetic hydrogel can be used as a form of an engraftment building block, with a greater potential for pro-bone repair application in the complex microenvironment of the oral cavity.

Advances in novel biomaterials combined with traditional Chinese medicine rehabilitation technology in treatment of peripheral nerve injury

Peripheral nerve injuries (PNI) represent one of the primary neuropathies leading to lifelong disability. Nerve regeneration and targeted muscle atrophy stand as the two most crucial factors influencing functional rehabilitation post peripheral nerve injury. Over time, traditional Chinese medicine (TCM) rehabilitation approaches such as acupuncture, Tuina, and microneedles serve as pivot means to activate the regeneration of injured nerve Schwann cells. By promoting axon regeneration, these approaches can accomplish nerve repair, reconstruction, and functional rehabilitation. Although TCM rehabilitation approaches have clinically demonstrated effectiveness in promoting the repair and regeneration of PNI, the related molecular mechanisms remain unclear. This significantly hampers the application and promotion of TCM rehabilitation in PNI recovery. Therefore, deeply delving into the cellular and molecular mechanisms of TCM rehabilitation technologies to foster nerve regeneration stands as the most pressing issue. On the other hand, in recent years, novel biomaterials represented by hydrogels, microfluidic platforms, and new chitosan scaffolds have showed their unique roles in treating various degrees of nerve injury. These methods exhibit immense potential in conducting high-throughput cell and organoid culture in vitro and synthesizing diverse tissue engineering scaffolds and drug carriers. We believe that the combination of TCM rehabilitation technology and novel biomaterials can more effectively address precise treatment issues such as identification of treatment target and dosage control. Therefore, this paper not only summarizes the molecular mechanisms of TCM rehabilitation technology and novel biomaterials in treating peripheral nerve injury individually, but also explores the research direction of precise treatment by integrating the two at both macro and micro levels. Such integration may facilitate the exploration of cellular and molecular mechanisms related to neurodegeneration and regeneration, providing a scientific and theoretical foundation for the precise functional rehabilitation of PNI in the future.

Extracellular electrophysiology on clonal human β-cell spheroids

Background

Pancreatic islets are important in nutrient homeostasis and improved cellular models of clonal origin may very useful especially in view of relatively scarce primary material. Close 3D contact and coupling between β-cells are a hallmark of physiological function improving signal/noise ratios. Extracellular electrophysiology using micro-electrode arrays (MEA) is technically far more accessible than single cell patch clamp, enables dynamic monitoring of electrical activity in 3D organoids and recorded multicellular slow potentials (SP) provide unbiased insight in cell-cell coupling.

Objective

We have therefore asked whether 3D spheroids enhance clonal β-cell function such as electrical activity and hormone secretion using human EndoC-βH1, EndoC-βH5 and rodent INS-1 832/13 cells.

Methods

Spheroids were formed either by hanging drop or proprietary devices. Extracellular electrophysiology was conducted using multi-electrode arrays with appropriate signal extraction and hormone secretion measured by ELISA.

Results

EndoC-βH1 spheroids exhibited increased signals in terms of SP frequency and especially amplitude as compared to monolayers and even single cell action potentials (AP) were quantifiable. Enhanced electrical signature in spheroids was accompanied by an increase in the glucose stimulated insulin secretion index. EndoC-βH5 monolayers and spheroids gave electrophysiological profiles similar to EndoC-βH1, except for a higher electrical activity at 3 mM glucose, and exhibited moreover a biphasic profile. Again, physiological concentrations of GLP-1 increased AP frequency. Spheroids also exhibited a higher secretion index. INS-1 cells did not form stable spheroids, but overexpression of connexin 36, required for cell-cell coupling, increased glucose responsiveness, dampened basal activity and consequently augmented the stimulation index.

Conclusion

In conclusion, spheroid formation enhances physiological function of the human clonal β-cell lines and these models may provide surrogates for primary islets in extracellular electrophysiology.

Biomimetic Hydrogels Promote Pseudoislet Formation to Improve Glycemic Control in Diabetic Mice

Islet or β-cell transplantation is currently considered to be the ideal treatment for diabetes, and three-dimensional (3D) bioprinting of a bionic pancreas with physiological stiffness is considered to be promising for the encapsulation and transplantation of β-cells. In this study, a 5%GelMA/2%AlgMA hybrid hydrogel with pancreatic physiological stiffness was constructed and used for β-cell encapsulation, 3D bioprinting, and in vivo transplantation to evaluate glycemic control in diabetic mice. The hybrid hydrogel had good cytocompatibility and could induce insulin-producing cells (IPCs) to form pseudoislet structures and improve insulin secretion. Furthermore, we validated the importance of betacellulin (BTC) in IPCs differentiation and confirmed that IPCs self-regulation was achieved by altering the nuclear and cytoplasmic distributions of BTC expression. In vivo transplantation of diabetic mice quickly restored blood glucose levels. In the future, 3D bioprinting of β-cells using biomimetic hydrogels will provide a promising platform for clinical islet transplantation for the treatment of diabetes.

Transplantable cell-encapsulation device using a semipermeable ethylene-vinyl alcohol copolymer membrane in a mouse diabetic model

Cell-based therapy is an attractive approach, and encapsulation of therapeutic cells is a promising strategy because it prevents immune responses and allows transplanted cells to be retrieved in case of dysfunction. Bioartificial pancreas, in which insulin-secreting cells are encapsulated in a semipermeable membrane bag, is a new class of medical device for treating type-I diabetes. In this study, we developed a macroencapsulation device in which the pancreatic beta cell line MIN6 was encapsulated in a semipermeable bag made of an ethylene-vinyl alcohol copolymer membrane. In vitro evaluation of ATP and insulin levels revealed that MIN6 cells grown in Matrigel within the device secreted insulin in response to glucose levels. Transplantation of the device lowered blood glucose levels for 30 days in diabetic mice. Histological observation revealed that MIN6 cells formed spheroids in Matrigel, and no host cells were detected within the device. Blood levels of inflammatory cytokines in the transplanted mice were similar to those in non-transplanted mice, and antibody levels in the device were lower than those in the intraperitoneal fluid. These results suggest that the semipermeable ethylene-vinyl alcohol copolymer membrane developed in this study is useful for cell encapsulation in cell-based therapies, including beta-cell macroencapsulation for type-1 diabetes.

Mechano-biomimetic hydrogel 3D cell cultivation as a strategy to improve mammalian cell protein expression

Eukaryotic expression systems are frequently employed for the production of recombinant proteins as therapeutics as well as research tools. Among which mammalian cell protein expression approach is the most powerful one, which can express complex proteins or genetic engineered biological drugs, such as PD-1. However, the high expense, which partially derives from its low protein yielding efficiency, limited the further application of such approach in large scale production of target proteins. To address this issue, we proposed a novel technique to promote the protein production efficiency of mammal cells without using conventional genetic engineered approaches. By placing 293T cells in a hydrogel 3D cell culture platform and adjusting the stress relaxation of the matrix hydrogel, cells formed multicellular spheroids by self-organization. In particular, the multicellular spheroids have a significantly enhanced ability to transiently express multiple proteins (SHH-N, PD-1 and PDL-1). We also examined in detail the mechanism underlying this phenomenon, and found that the reorganization of cytoskeleton during spheroids formation enhances the translation process of protein by recruiting ribosomes. Overall, this finding provides a novel approach for subsequent improvement of large-scale mammalian protein expression cell systems.

Dynamic Hydrogels with Viscoelasticity and Tunable Stiffness for the Regulation of Cell Behavior and Fate

The extracellular matrix (ECM) of natural cells typically exhibits dynamic mechanical properties (viscoelasticity and dynamic stiffness). The viscoelasticity and dynamic stiffness of the ECM play a crucial role in biological processes, such as tissue growth, development, physiology, and disease. Hydrogels with viscoelasticity and dynamic stiffness have recently been used to investigate the regulation of cell behavior and fate. This article first emphasizes the importance of tissue viscoelasticity and dynamic stiffness and provides an overview of characterization techniques at both macro- and microscale. Then, the viscoelastic hydrogels (crosslinked via ion bonding, hydrogen bonding, hydrophobic interactions, and supramolecular interactions) and dynamic stiffness hydrogels (softening, stiffening, and reversible stiffness) with different crosslinking strategies are summarized, along with the significant impact of viscoelasticity and dynamic stiffness on cell spreading, proliferation, migration, and differentiation in two-dimensional (2D) and three-dimensional (3D) cell cultures. Finally, the emerging trends in the development of dynamic mechanical hydrogels are discussed.

Functionalized Collagen/Poly(ethylene glycol) Diacrylate Interpenetrating Network Hydrogel Enhances Beta Pancreatic Cell Sustenance

Three-dimensional matrices are a new strategy used to tackle type I diabetes, a chronic metabolic disease characterized by the destruction of beta pancreatic cells. Type I collagen is an abundant extracellular matrix (ECM), a component that has been used to support cell growth. However, pure collagen possesses some difficulties, including a low stiffness and strength and a high susceptibility to cell-mediated contraction. Therefore, we developed a collagen hydrogel with a poly (ethylene glycol) diacrylate (PEGDA) interpenetrating network (IPN), functionalized with vascular endothelial growth factor (VEGF) to mimic the pancreatic environment for the sustenance of beta pancreatic cells. We analyzed the physicochemical characteristics of the hydrogels and found that they were successfully synthesized. The mechanical behavior of the hydrogels improved with the addition of VEGF, and the swelling degree and the degradation were stable over time. In addition, it was found that 5 ng/mL VEGF-functionalized collagen/PEGDA IPN hydrogels sustained and enhanced the viability, proliferation, respiratory capacity, and functionality of beta pancreatic cells. Hence, this is a potential candidate for future preclinical evaluation, which may be favorable for diabetes treatment.

Insulin secretion hot spots in pancreatic β cells as secreting adhesions

Pancreatic β cell secretion of insulin is crucial to the maintenance of glucose homeostasis and prevention of diseases related to glucose regulation, including diabetes. Pancreatic β cells accomplish efficient insulin secretion by clustering secretion events at the cell membrane facing the vasculature. Regions at the cell periphery characterized by clustered secretion are currently termed insulin secretion hot spots. Several proteins, many associated with the microtubule and actin cytoskeletons, are known to localize to and serve specific functions at hot spots. Among these proteins are the scaffolding protein ELKS, the membrane-associated proteins LL5β and liprins, the focal adhesion-associated protein KANK1, and other factors typically associated with the presynaptic active zone in neurons. These hot spot proteins have been shown to contribute to insulin secretion, but many questions remain regarding their organization and dynamics at hot spots. Current studies suggest microtubule- and F-actin are involved in regulation of hot spot proteins and their function in secretion. The hot spot protein association with the cytoskeleton networks also suggests a potential role for mechanical regulation of these proteins and hot spots in general. This perspective summarizes the existing knowledge of known hot spot proteins, their cytoskeletal-mediated regulation, and discuss questions remaining regarding mechanical regulation of pancreatic beta cell hot spots.

Additive Manufacturing and Physicomechanical Characteristics of PEGDA Hydrogels: Recent Advances and Perspective for Tissue Engineering

In this brief review, we discuss the recent advancements in using poly(ethylene glycol) diacrylate (PEGDA) hydrogels for tissue engineering applications. PEGDA hydrogels are highly attractive in biomedical and biotechnology fields due to their soft and hydrated properties that can replicate living tissues. These hydrogels can be manipulated using light, heat, and cross-linkers to achieve desirable functionalities. Unlike previous reviews that focused solely on material design and fabrication of bioactive hydrogels and their cell viability and interactions with the extracellular matrix (ECM), we compare the traditional bulk photo-crosslinking method with the latest three-dimensional (3D) printing of PEGDA hydrogels. We present detailed evidence combining the physical, chemical, bulk, and localized mechanical characteristics, including their composition, fabrication methods, experimental conditions, and reported mechanical properties of bulk and 3D printed PEGDA hydrogels. Furthermore, we highlight the current state of biomedical applications of 3D PEGDA hydrogels in tissue engineering and organ-on-chip devices over the last 20 years. Finally, we delve into the current obstacles and future possibilities in the field of engineering 3D layer-by-layer (LbL) PEGDA hydrogels for tissue engineering and organ-on-chip devices.

Implementation of blood-brain barrier on microfluidic chip: recent advance and future prospects

The complex structure of the blood-brain barrier (BBB) hinders its modeling and the treatment of brain diseases. The microfluidic technology promotes the development of BBB-on-a-chip platforms, which can be used to reproduce the complex brain microenvironment and physiological reactions. Compared with traditional transwell technology, microfluidic BBB-on-a-chip shows great technical advantages in terms of flexible control of fluid shear stress in the chip and fabrication efficiency of the chip system, which can be enhanced by the development of lithography and three-dimensional (3D) printing. It is convenient to accurately monitor the dynamic changes of biochemical parameters of individual cells in the model by integrating an automatic super-resolution imaging sensing platform. In addition, biomaterials, especially hydrogels and conductive polymers, solve the limitations of microfluidic BBB-on-a-chip by compounding onto microfluidic chip to provide a 3D space and special performance on the microfluidic chip. The microfluidic BBB-on-a-chip promotes the development of basic research, including cell migration, mechanism exploration of neurodegenerative diseases, drug barrier permeability, SARS-CoV-2 pathology. This study summarizes the recent advances, challenges and future prospects of microfluidic BBB-on-a-chip, which can help to promote the development of personalized medicine and drug discovery.

Comparative Study of Two Common In Vitro Models for the Pancreatic Islet with MIN6

BACKGROUND

Islet transplantation is currently considered the most promising method for treating insulin-dependent diabetes. The two most-studied artificial islets are alginate-encapsulated β cells or β cell spheroids. As three-dimensional (3D) models, both artificial islets have better insulin secretory functions and transplantation efficiencies than cells in two-dimensional (2D) monolayer culture. However, the effects of these two methods have not been compared yet. Therefore, in this study, cells from the mouse islet β cell line Min6 were constructed as scaffold-free spheroids or alginate-encapsulated dispersed cells.

METHODS

MIN6 cell spheroids were prepared by using Agarose-base microwell arrays. The insulin secretion level was determined by mouse insulin ELISA kit, and the gene and protein expression status of the MIN6 were performed by Quantitative polymerase chain reaction and immunoblot, respectively.

RESULTS

Both 3D cultures effectively promoted the proliferation and glucose-stimulated insulin release (GSIS) of MIN6 cells compared to 2D adherent cells. Furthermore, 1% alginate-encapsulated MIN6 cells demonstrated more significant effects than the spheroids. In general, three pancreatic genes were expressed at higher levels in response to the 3D culture than to the 2D culture, and pancreatic/duodenal homeobox-1 (PDX1) expression was higher in the cells encapsulated in 1% alginate than that in the spheroids. A western blot analysis showed that 1% alginate-encapsulated MIN6 cells activated the phosphoinositide 3-kinase (PI3K)/serine/threonine protein kinase (AKT)/forkhead transcription factor FKHR (FoxO1) pathway more than the spheroids, 0.5% alginate-, or 2% alginate-encapsulated cells did. The 3D MIN6 culture, therefore, showed improved effects compared to the 2D culture, and the 1% alginate-encapsulated MIN6 cells exhibited better effects than the spheroids. The upregulation of PDX1 expression through the activation of the PI3K/AKT/FoxO1 pathway may mediate the improved cell proliferation and GSIS in 1% alginate-encapsulated MIN6 cells.

CONCLUSION

This study may contribute to the construction of in vitro culture systems for pancreatic islets to meet clinical requirements.

Binary Hydrogels: Induction Methods and Recent Application Progress as Food Matrices for Bioactive Compounds Delivery-A Bibliometric Review

Food hydrogels are biopolymeric materials made from food-grade biopolymers with gelling properties (proteins and polysaccharides) and a 3D network capable of incorporating large amounts of water. They have sparked considerable interest because of their potential and broad application range in the biomedical and pharmaceutical sectors. However, hydrogel research in the field of food science is still limited. This knowledge gap provides numerous opportunities for implementing their unique properties, such as high water-holding capacity, moderated texture, compatibility with other substances, cell biocompatibility, biodegradability, and high resemblance to living tissues, for the development of novel, functional food matrices. For that reason, this article includes a bibliometric analysis characterizing research trends in food protein-polysaccharide hydrogels (over the last ten years). Additionally, it characterizes the most recent developments in hydrogel induction methods and the most recent application progress of hydrogels as food matrices as carriers for the targeted delivery of bioactive compounds. Finally, this article provides a future perspective on the need to evaluate the feasibility of using plant-based proteins and polysaccharides to develop food matrices that protect nutrients, including bioactive substances, throughout processing, storage, and digestion until they reach the specific targeted area of the digestive system.

Stress Relaxation-Induced Colon Tumor Multicellular Spheroid Culture Based on Biomimetic Hydrogel for Nanoenzyme Ferroptosis Sensitization Evaluation

Ferroptosis has recently become a research hotspot, and the induction of tumor cell ferroptosis has emerged as a powerful method for tumor therapy. However, the efficiency of tumor cell ferroptosis induction remains unmet for clinical use, which may be attributed to the large discrepancies between in vitro and in vivo models. To address this issue, in this study, a hydrogel platform with stress relaxation is utilized to develop a multicellular spheroid model of the DLD1 colon cancer cell line through cancer cell self-organization. The spheroids are highly similar to real tumor tissue, and ferroptosis resistance at the transcriptional, protein, and cellular levels. Collaboration of the ferroptosis induction reagent erastin and the nanoenzyme MnZnFe₂ O₄ @PEG-COOH to overcome the ferroptosis resistance of the spheroids is also demonstrated. Taken together, this study demonstrates the effectiveness of the model developed using this hydrogel platform for further mechanistic studies, and for the assessment of novel cancer treatment strategies based on ferroptosis.

Extracellular magnetic labeling of biomimetic hydrogel-induced human mesenchymal stem cell spheroids with ferumoxytol for MRI tracking

Labeling of mesenchymal stem cells (MSCs) with superparamagnetic iron oxide nanoparticles (SPIONs) has emerged as a potential method for magnetic resonance imaging (MRI) tracking of transplanted cells in tissue repair studies and clinical trials. Labeling of MSCs using clinically approved SPIONs (ferumoxytol) requires the use of transfection reagents or magnetic field, which largely limits their clinical application. To overcome this obstacle, we established a novel and highly effective method for magnetic labeling of MSC spheroids using ferumoxytol. Unlike conventional methods, ferumoxytol labeling was done in the formation of a mechanically tunable biomimetic hydrogel-induced MSC spheroids. Moreover, the labeled MSC spheroids exhibited strong MRI T2 signals and good biosafety. Strikingly, the encapsulated ferumoxytol was localized in the extracellular matrix (ECM) of the spheroids instead of the cytoplasm, minimizing the cytotoxicity of ferumoxytol and maintaining the viability and stemness properties of biomimetic hydrogel-induced MSC spheroids. This demonstrates the potential of this method for post-transplantation MRI tracking in the clinic.

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An extracellular magnetic labeling method was developed for MSC spheroids using ferumoxytol.

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Ferumoxytol encapsulated into abundant ECM proteins network of MSC spheroids ensured this method is stable and durable.

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Uniformly sized magnetic spheroids induced by mechanically tunable biomimetic hydrogels promoted MSCs stemness properties.

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Magnetically labeled MSC spheroids exhibited superior MRI imaging both in vitro and in vivo.

Ginseng Pectin WGPA Alleviates Exercise-Induced Fatigue by Enhancing Gluconeogenesis

With the development of medicine and sport science, growing attention has been paid to the recovery of exercise-induced fatigue. Ginseng pectin has been shown to be important for a variety of biological functions. Although many studies suggest that ginseng pectin plays an important role in the alleviation of exercise-induced fatigue, the underlying mechanism still remains unclear. In this study, C57BL/6J mice were subjected to a wheel apparatus for exhaustive exercise and fed with ginseng pectin WGPA (acidic fraction of water-soluble ginseng polysaccharides) afterwards. Subsequently, a series of physiological and biochemical indexes, such as blood lactic acid, blood glucose, muscle glycogen, insulin, and glucagon, is evaluated. Meanwhile, enzymatic activity and mRNA level of key enzymes involved in hepatic gluconeogenesis are analyzed. Our results demonstrate that the treatment of ginseng pectin WGPA can result in enhanced gluconeogenesis and decreased insulin and in turn facilitate the recovery of exercise-induced fatigue. In response to WGPA treatment, both phosphoenolpyruvate carboxykinase (PEPCK) and glucose 6 phosphatase (G6Pase) activity were upregulated, indicating that these two enzymes play a critical role in WGPA-induced upregulation in gluconeogenesis. Moreover, mRNA level of G6Pase, but not PEPCK, was increased upon WGPA treatment, suggesting that G6Pase expression is regulated by WGPA. Importantly, the presence of WGPA downregulated insulin both in vivo and in vitro, suggesting the upregulation in gluconeogenesis may be due to alterations in insulin. Together, we provide evidence that ginseng pectin WGPA is able to alleviate exercise-induced fatigue by reducing insulin and enhancing gluconeogenesis.

Recent advances in regenerative biomaterials

Nowadays, biomaterials have evolved from the inert supports or functional substitutes to the bioactive materials able to trigger or promote the regenerative potential of tissues. The interdisciplinary progress has broadened the definition of 'biomaterials', and a typical new insight is the concept of tissue induction biomaterials. The term 'regenerative biomaterials' and thus the contents of this article are relevant to yet beyond tissue induction biomaterials. This review summarizes the recent progress of medical materials including metals, ceramics, hydrogels, other polymers and bio-derived materials. As the application aspects are concerned, this article introduces regenerative biomaterials for bone and cartilage regeneration, cardiovascular repair, 3D bioprinting, wound healing and medical cosmetology. Cell-biomaterial interactions are highlighted. Since the global pandemic of coronavirus disease 2019, the review particularly mentions biomaterials for public health emergency. In the last section, perspectives are suggested: (i) creation of new materials is the source of innovation; (ii) modification of existing materials is an effective strategy for performance improvement; (iii) biomaterial degradation and tissue regeneration are required to be harmonious with each other; (iv) host responses can significantly influence the clinical outcomes; (v) the long-term outcomes should be paid more attention to; (vi) the noninvasive approaches for monitoring in vivo dynamic evolution are required to be developed; (vii) public health emergencies call for more research and development of biomaterials; and (viii) clinical translation needs to be pushed forward in a full-chain way. In the future, more new insights are expected to be shed into the brilliant field-regenerative biomaterials.

Growth of MIN-6 Cells on Salmon Fibrinogen Scaffold Improves Insulin Secretion

The incidence of type I diabetes has been increasing worldwide at an annual rate of approximately 3%. One of the strategies to treat type I diabetes is islet transplantation, in which damaged β-cells are replaced with new islets. To improve β-cells’ expansion and pseudoislet formation, studies are focusing on using extracellular-matrix-resembling substrates. We evaluated the potential of salmon fibrinogen and chitosan electrospun scaffold as cell substrate for cultivating MIN-6 cells. The morphology of cells, insulin secretion and gene expression was evaluated and compared with other substrates (nanofibrous scaffold, microporous scaffold and tissue culture polystyrene). We found that all tested 3D conditions favored the pseudoislet formation of MIN-6 cells. The insulin secretion of MIN-6 cells after stimulation with high-glucose media shows approximately a 9-fold increase compared to the control group when a fibrinogen/chitosan-based electrospun scaffold was used for cultivation. The differences in insulin secretion were corroborated by differences in gene expression. The differences in insulin secretion could probably be attributed to the differences in the mechanical and/or chemical nature of the tested substrates.

Functional thermosensitive hydrogels based on chitin as RIN-m5F cell carrier for the treatment of diabetes

Herein, the thermosensitive hydroxypropyl chitin (HPCT) hydrogel was prepared and the chemical structures, microstructures, rheological properties and degradation in vitro were investigated. The HPCT hydrogel possessed satisfactory biocompatibility in mouse fibroblast cells and Sprague Dawley rats. On the other hand, N-acetylglucosamine (NAG) and carboxymethyl chitosan (CMCS) provided favorable capacity for promoting cell proliferation, delaying cell apoptosis, and facilitating the insulin secretion of rat pancreatic beta cells (RIN-m5F) in three-dimensional culture. Most importantly, the effects of HPCT/NAG and HPCT/CMCS thermosensitive hydrogels as RIN-m5F cells carriers were evaluated via injection into different areas of diabetic rats. Our results demonstrated that HPCT/NAG and HPCT/CMCS hydrogels loaded RIN-m5F cells could keep cells survival, maintain insulin secretion and reduce blood glucose for one week. Overall, the functional thermosensitive hydrogels based on HPCT were effective cell carriers for RIN-m5F cells and might provide novel strategy for the treatment of diabetes via cell engineering.

Self-Organization Formation of Multicellular Spheroids Mediated by Mechanically Tunable Hydrogel Platform: Toward Revealing the Synergy of Chemo- and Noninvasive Photothermal Therapy against Colon Microtumor

Three-dimensional (3D) tumor cell culture offers a more tissue-recapitulating model in cancer treatment evaluation. However, conventional models based on cell-substrate adhesion deprivation are still of insufficient real tumor mimic. In this work, a novel method is proposed for inducing multicellular spheroids (MCSs) formation based on hydrogel with tunable microenvironmental properties. Colon tumor cells DLD1 cultured on hydrogel substrate with proper physical stimulation form MCSs via self-organization. Chemotherapy based on clinical drug and far-infrared photothermal therapy is evaluated with DLD1 MCSs obtained by this method. The synergism of chemotherapy and noninvasive photothermal therapy based on graphene device is further verified in MCSs model and it is believed this method holds potential in in vitro anti-tumor strategies evaluation for precision medicine.

Self-assembled di- and tripeptide gels for the passive entrapment and pH-responsive, sustained release of an antidiabetic drug, glimepiride

Diabetes is a global epidemic that poses a severe challenge to public health. The characteristic features of this disease are hyperglycemia and deterioration of the function of pancreatic β-cells, which...

Highly self-healable and injectable cellulose hydrogels via rapid hydrazone linkage for drug delivery and 3D cell culture

To meet the rising demand of injectable hydrogels with self-healing, robustness and biocompatibility for biomedical engineering, the reversible ketoester-type acylhydrazone linkages was used for the fabrication of novel cellulose-based hydrogel. The ketoester-type acylhydrazone bond exchanged rapidly, endowing the hydrogels with highly efficient self-healing performance without any external stimuli under physiological environment, which was hardly achieved with the widely used arylhydrozone bond. The dynamic hydrogels exhibited tunable mechanical property, pH responsiveness, injectability and biocompatibility, demonstrating immense applications prospect for various biomedicines, such as drug and cell delivery. The pH-responsive controlled release of model drug doxorubicin (DOX) loaded in the hydrogel was demonstrated. In addition, benefitting from the excellent biocompatibility and the reversible ketoester-type acylhydrazone bonds, cells were encapsulated in the hydrogels as 3D carrier. The covalent adaptable network intensified injectability of cell-laden hydrogels and improved the long-lasting viability for cell culture, showing great potential in the biomedical field.

Degradable allyl Antheraea pernyi silk fibroin thermoresponsive hydrogels to support cell adhesion and growth

At present, Antheraea pernyi silk fibroin (ASF) based hydrogels have wide potential applications as biomaterials because of their superior cytocompatibility. Herein, ASF is used as a nucleophilic reagent, reacted with allyl glycidyl ether (AGE) for the preparation of allyl silk fibroin (ASF-AGE). The investigation of ASF-AGE structure by ¹H NMR and FTIR are revealed that reactive allyl groups were obtained on ASF by nucleophilic substitution. A series of ASF based hydrogels are manufactured by N-isopropylacrylamide (NIPAAm) copolymerization bridged with ASF-AGE. By the silk fibroin self-assembly process, stably physical cross-linked hydrogels are formed without any crosslinking agent. These hydrogels exhibit good thermoresponsive and degradability, for which the LCST was about 32 °C, and these hydrogels can be degraded in protease XIV solution. Excellent cell proliferation, viability and morphology is demonstrated for b End.3 cells on the hydrogels by the characteristic MTT assay, CLSM and SEM. The cytocompatibility of b End.3 cells was demonstrated with excellent cell adhesion and growth on these ASF based hydrogels in vitro. These degradable and thermoresponsive ASF based hydrogels may find potential applications for cells delivery devices and tissue engineering.

At present, Antheraea pernyi silk fibroin (ASF) based hydrogels have wide potential applications as biomaterials because of its superior cytocompatibility.

Multicellular Spheroids Formation on Hydrogel Enhances Osteogenic/Odontogenic Differentiation of Dental Pulp Stem Cells Under Magnetic Nanoparticles Induction

Introduction

Promotion odontogenic differentiation of dental pulp stem cells (DPSCs) is essential for dentin regeneration. Physical cellular microenvironment is of critical importance for stem cells differentiation and influences the function of other biological/chemical factors to differentiation.

Methods

Based on adjusting the mechanical/interfacial properties of hydrogels, multicellular spheroids (MCSs) of DPSCs generated through self-organization. The spheroids were characterized by immunofluorescent staining and flow cytometry. Quantitative real-time polymerase chain reaction, alkaline phosphatase (ALP) activity assay, ALP staining and Alizarin Red S staining were performed to evaluate the osteogenic/odontogenic differentiation of DPSCs with or without magnetic iron oxide nanoparticles (IONPs) induction.

Results

MCSs of DPSCs exhibited a significant upregulation of E-cadherin and N-cadherin and enriched CD146 positive subpopulation, along with a stronger osteogenic/odontogenic differentiation ability. Moreover, DPSCs spheroids showed more substantial osteogenic differentiation tendency than the classical two-dimensional cultured DPSCs under the stimulation of magnetic IONPs.

Conclusion

Three-dimensional spheroids culture of DPSCs based on composite viscoelastic materials combined with mechanical/magnetic stimulation may provide a theoretical basis for the subsequent development of dentin or bone regeneration technology.