Applications of nanotechnology in remodeling the tumour microenvironment for glioblastoma treatment.

With the increasing research and deepening understanding of the glioblastoma (GBM) tumour microenvironment (TME), novel and more effective therapeutic strategies have been proposed. The GBM TME involves intricate interactions between tumour and non-tumour cells, promoting tumour progression. Key therapeutic goals for GBM treatment include improving the immunosuppressive microenvironment, enhancing the cytotoxicity of immune cells against tumours, and inhibiting tumour growth and proliferation. Consequently, remodeling the GBM TME using nanotechnology has emerged as a promising approach. Nanoparticle-based drug delivery enables targeted delivery, thereby improving treatment specificity, facilitating combination therapies, and optimizing drug metabolism. This review provides an overview of the GBM TME and discusses the methods of remodeling the GBM TME using nanotechnology. Specifically, it explores the application of nanotechnology in ameliorating immune cell immunosuppression, inducing immunogenic cell death, stimulating, and recruiting immune cells, regulating tumour metabolism, and modulating the crosstalk between tumours and other cells.

An engineered lymph node comprising porous collagen scaffold with hybridized biological signals embedded in B cell membrane coatings.

Complications can arise from damaging or removing lymph nodes after surgeries for malignant tumours. Our team has developed an innovative solution to recreate lymph nodes via an engineering approach. Using a Type II collagen scaffold coated with B cell membranes for the sake of attracting T cells in different regions, we could mimic the thymus-dependent and thymus-independent areas in vitro. This engineering strategy based on biophysical mimicry has a great potential for clinical applications. By further conjugating biological signals, anti-CD3/28, onto the scaffold coated with the B cell membrane, we achieved an 11.6-fold expansion of T cells within 14 days of in vitro culture while ensuring their activity, phenotype homeostasis, and differentiation capacity kept intact. Artificial lymph nodes had excellent biocompatibility and caused no pathological or physiological adverse effects after implantation into C57BL6 mice. In vivo assays also demonstrated that this artificial lymph node system positively adhered to omental tissues, creating an environment that fostered T cell growth and prevented cellular failure and death. Additionally, it induced vascular and lymphatic vessel invasion, which was beneficial to the migration and circulation of T cells between this system and peripheral blood. Due to the porous collagen fibre structure, it also facilitated the infiltration of host immune cells. This work opens new avenues to immune organ regeneration via a tissue engineering approach.

Catechin-Functionalized Cationic Lipopolymer Based Multicomponent Nanomicelles for Lung-Targeting Delivery.

Catechins from green tea are one of the most effective natural compounds for cancer chemoprevention and have attracted extensive research. Cancer cell-selective apoptosis-inducing properties of catechins depend on efficient intracellular delivery. However, the low bioavailability limits the application of catechins. Herein, a nano-scaled micellar composite composed of catechin-functionalized cationic lipopolymer and serum albumin is constructed. Cationic liposomes tend to accumulate in the pulmonary microvasculature due to electrostatic effects and are able to deliver the micellar system intracellularly, thus improving the bioavailability of catechins. Albumin in the system acts as a biocompatible anti-plasma absorbent, forming complexes with positively charged lipopolymer under electrostatic interactions, contributing to prolonged in vivo retention. The physicochemical properties of the nano-micellar complexes are characterized, and the antitumor properties of catechin-functionalized materials are confirmed by reactive oxygen species (ROS), caspase-3, and cell apoptosis measurements. The role of each functional module, cationic polymeric liposome, and albumin is revealed by cell penetration, in vivo animal assays, etc. This multicomponent micellar nanocomposite has the potential to become an effective vehicle for the treatment of lung diseases such as pneumonia, lung tumors, sepsis-induced lung injury, etc. This study also demonstrates that it is a great strategy to create a delivery system that is both tissue-targeted and biologically active by combining cationic liposomes with the native bioactive compound catechins.

Editorial: Focus issue on biomaterials approaches to the repair and regeneration of cartilage tissue.

Traditional joint replacement surgery faces the risk of enormous trauma and secondary revision while using medication to relieve symptoms can cause bone thinning, weight gain and interference with the patient's pain signalling. Medical research has therefore focused on minimally invasive solutions for implanting tissue-engineered scaffolds to induce cartilage regeneration and repair. In cartilage tissue engineering, there are still technical barriers to seed cells, scaffold construction techniques, mechanical properties, and the regulation of the internal environment on the transplanted material. This issue focuses on the development of cartilage repair, cutting-edge discoveries, manufacturing technologies, and the current technological queries still faced in cartilage regenerative medicine research. The articles in this collection cover the coordination of physical and biochemical signals, genes, and regulations by the extracellular environment.

In vitro expansion of hematopoietic stem cells in a porous hydrogel-based 3D culture system.

Hematopoietic stem cell (HSC) transplantation remains the most effective therapy for hematologic and lymphoid disorders. However, as the primary therapeutic cells, the source of HSCs has been limited due to the scarcity of matched donors and difficulties in ex vivo expansion. Here, we described a facile method to attempt the expansion of HSCs in vitro through a porous alginate hydrogel-based 3D culture system. We used gelatin powders as the porogen to create submillimeter-scaled pores in alginate gel bulk while pre-embedding naïve HSCs in the gel phase. The results indicated that this porous hydrogel system performed significantly better than those cultured via conventional suspension or encapsulation in non-porous alginate hydrogels in maintaining the phenotype and renewability of HSCs. Only the porous hydrogel system achieved a two-fold growth of CD34+ cells within seven days of culture, while the number of CD34+ cells in the suspension system and nonporous hydrogel showed different degrees of attenuation. The expansion efficiency of the porous hydrogel for CD34+CD38- cells was more than 2.2 times that of the other two systems. Mechanistic study via biophysical analysis revealed that the porous alginate system was competent to reduce the electron capture caused by biomaterials, decrease cellular oxygen stress, avoid oxidative protection, thus maintaining the cellular phenotype of the CD34+ cells. The transcriptomic analysis further suggested that the porous alginate system also upregulated the TNF signaling pathway and activated the NF-κB signaling pathway to promote the CD34+ cells' survival and maintain cellular homeostasis so that renewability was substantially favoured. STATEMENT OF SIGNIFICANCE: • The reported porous hydrogel system performs significantly better in terms of maintaining the phenotype and renewability of HSCs than those cultured via conventional suspension or encapsulation in non-porous alginate hydrogel. • The reported porous alginate system is competent to reduce the electron capture caused by biomaterials, decrease cellular oxygen stress, avoid oxidative protection, and therefore maintain the cellular phenotype of the CD34+ cells. • The reported porous alginate system can also upregulate the TNF signaling pathway and activate the NF-κB signaling pathway to promote the CD34+ cells' survival and maintain cellular homeostasis so that the renewability is substantially favored..

An Instant Underwater Tissue Adhesive Composed of Catechin-Chondroitin Sulfate and Cholesterol-Polyethyleneimine.

Due to the safety issue and poor underwater adhesion of current commercially available bioadhesives, they are hard to apply to in vivo physiological environments and more diverse medical use conditions. In this study, a novel and facile bioadhesive for underwater medical applications are designed based on the coacervation of electrostatic interactions and hydrophobic interactions, with the introduction of catechin as a provider of catechol moieties for adhesion to surrounding tissues. The orange-colored bio-adhesive, named PcC, is generated within seconds by mixing catechin-modified chondroitin sulfate and cholesterol chloroformate-modified polyethyleneimine with agitation. In vitro mechanical measurements prove that this novel PcC bio-adhesive is superior in underwater adhesion performance when applied to cartilage. Animal experiments in a rat mastectomy model and rat cartilage graft implantation model demonstrate its potential for diverse medical purposes, such as closing surgical incisions, reducing the formation of seroma, and tissue adhesive applied in orthopedic or cartilage surgery.

A catechol bioadhesive for rapid hemostasis and healing of traumatic internal organs and major arteries.

Uncontrolled hemorrhage caused by trauma to internal organs or major arteries poses critical threats to lives. However, rapid hemostasis followed by tissue repair remains an intractable challenge in surgery owing to the lack of ideal internal-use adhesives that can achieve fast and robust wet adhesion and accelerate wound healing. Herein, we develop a robust hemostatic bioadhesive (CAGA) from novel highly-branched aminoethyl gelatin with end-grafted abundant catechol (Gel-AE-Ca). The unique chemical structure of Gel-AE-Ca makes CAGA capable of gelling on wet tissues via synergetic cross-linking of catechol-Fe3+ chelation and horseradish peroxidase (HRP)/H2O2-triggered covalent bonds using a dual-channel needle, meeting the key demands of internal medical applications (e.g., instant and strong wet adhesion, injectability, biocompatibility, self-healing, stretching flexibility, infection resistance, and proper biodegradability). It exhibits rapid gelation within 10 s and robust wet tissue adhesion up to 115.0 ± 13.1 kPa of shear strength and 245.0 ± 33.8 mm Hg of sealing strength. In vivo trials demonstrate that CAGA can not only effectively seal anastomosis of the carotid artery, but achieve rapid hemostasis on the sites of liver incisions and penetrating cardiac wounds within 10 s. The wound closure by CAGA and its timely biodegradation promote wound healing of the vital organs.

Engineering strategies to achieve efficient in vitro expansion of haematopoietic stem cells: development and improvement.

Haematopoietic stem cells are the basis for building and maintaining lifelong haematopoietic mechanisms and an important resource for the treatment of blood disorders. Haematopoietic niches are a microenvironment in the body where stem cells tend to accumulate, with some nurse cells protecting and regulating stem cells. On the basis of biology, materials science, and engineering, researchers have constructed stem cell niches to address the current clinical shortage of stem cells and to explore stem cell behaviour for biomedical research. Herein, three main resource categories involved in haematopoietic stem cell niche engineering are reviewed: first, the basic approach to construct bionic cell culture environments is to use cytokines, nurse cells or extracellular matrix; second, microscale technologies are applied to mimic the properties of natural stem cell niches; and finally, biomaterials are used to construct the three-dimensional extracellular matrix-like culture environment.

Progress of gelatin-based microspheres (GMSs) as delivery vehicles of drug and cell.

Gelatin has various attractive features as biomedical materials, for instance, biocompatibility, low immunogenicity, biodegradability, and ease of manipulation. In recent years, various gelatin-based microspheres (GMSs) have been fabricated with innovative technologies to serve as sustained delivery vehicles of drugs and genetic materials as well as beneficial bacteria. Moreover, GMSs have exhibited promising potentials to act as both cell carriers and 3D scaffold components in tissue engineering and regenerative medicine, which not only exhibit excellent injectability but also could be integrated into a macroscale construct with the laden cells. Herein, we aim to thoroughly summarize the recent progress in the preparations and biomedical applications of GMSs and then to point out the research direction in future. First, various methods for the fabrication of GMSs will be described. Second, the recent use of GMSs in tumor embolization and in the delivery of cells, drugs, and genetic material as well as bacteria will be presented. Finally, several key factors that may enhance the improvement of GMSs were suggested as delivery vehicles.

Autologous cell membrane coatings on tissue engineering xenografts for suppression and alleviation of acute host immune responses.

Xenogeneic extracellular matrix (ECM) based tissue engineering graft is one of the most promising products for transplantation therapies, which could alleviate the pain of patients and reduce surgery cost. However, in order to put ECM based xenografts into clinical use, the induced inflammatory and immune responses have yet to be resolved. Cell membrane is embedded with membrane proteins for regulation of cell interactions including self-recognition and potent in reducing foreign body rejections. In this study, a novel and facile method for evasion from immune system was developed by coating autologous red blood cell membrane as a disguise on xenogeneic ECM based tissue engineering graft surface. Porcine source Living Hyaline Cartilage Graft (LhCG) and decellularized LhCG (dLhCG) established by our group for cartilage tissue engineering were chosen as model grafts. The cell membrane coating was quite stable on xenografts with no obvious decrease in amount for 4 weeks. The autologous cell membrane coated xenograft has been proved to be recognized as "self" by immune system on cell, protein and gene levels according to the 14-day lasting in vivo study on rats with less inflammatory cells infiltrated and low inflammation-related cytokines gene expression, showing alleviated acute immune and inflammatory responses.

Surface modifications to polydimethylsiloxane substrate for stabilizing prolonged bone marrow stromal cell culture.

Polydimethylsiloxane (PDMS) has been extensively used as a supporting material for studies of cell mechanobiology, cell micropatterning and microscale-cell analysis in microfluidic chips due to its numerous advantages, such as low cytotoxicity, ease of modification, inexpensive costs and biocompatibility. However, the innate hydrophobicity of PDMS often poses a problem for stable cell adhesion, seriously limiting its applicability for prolonged cell culture. UV exposure and protein coating are suboptimal solutions, while chemical surface functionalization is often associated with laborious procedures and producing environmental toxics. Plasma treatment can render a hydrophilic substrate by altering the surface chemistry, but such effect is often short-lived due to its tendency to hydrophobic recovery. Variation of physical properties of the substratum are known to influence cell behaviour. Nevertheless, the combination of varying PDMS substratum properties via base:curing agent ratio and plasma treatment to stabilize the long-term culture of bone marrow derived stromal cells (BMSCs) still remain poorly understood. In this study, we developed a protocol to maintain the hydrophilicity of the plasma-treated PDMS over a range of substratum properties. This study demonstrated that varying the substratum properties of PDMS can enhance the stability of BMSC culture for at least three weeks, while plasma treatment with or without additional collagen coating further enhanced such effect. The changes in the physical properties of PDMS have rendered difference in BMSCs adhesion, proliferation and in-vitro plasticity, thereby offering a simple and effective strategy for PDMS surface modification to enable long term cell analysis in PDMS-based culture platform.

Scaffold-Free tissue engineering with aligned bone marrow stromal cell sheets to recapitulate the microstructural and biochemical composition of annulus fibrosus.

Current tissue engineering strategies through scaffold-based approaches fail to recapitulate the complex three-dimensional microarchitecture and biochemical composition of the native Annulus Fibrosus tissue. Considering limited access to healthy annulus fibrosus cells from patients, this study explored the potential of bone marrow stromal cells (BMSC) to fabricate a scaffold-free multilamellar annulus fibrosus-like tissue by integrating micropatterning technologies into multi-layered BMSC engineering. BMSC sheet with cells and collagen fibres aligned at ~30° with respect to their longitudinal dimension were developed on a microgroove-patterned PDMS substrate. Two sheets were then stacked together in alternating directions to form an angle-ply bilayer tissue, which was rolled up, sliced to form a multi-lamellar angle-ply tissue and cultured in a customized medium. The development of the annulus fibrosus-like tissue was further characterized by histological, gene expression and microscopic and mechanical analysis. We demonstrated that the engineered annulus fibrosus-like tissue with aligned BMSC sheet showed parallel collagen fibrils, biochemical composition and microstructures that resemble the native disk. Furthermore, aligned cell sheet showed enhanced expression of annulus fibrosus associated extracellular matrix markers and higher mechanical strength than that of the non-aligned cell sheet. The present study provides a new strategy in annulus fibrosus tissue engineering methodology to develop a scaffold-free annulus fibrosus-like tissue that resembles the microarchitecture and biochemical attributes of a native tissue. This can potentially lead to a promising avenue for advancing BMSC-mediated annulus fibrosus regeneration towards future clinical applications.

Engineering a multiphasic, integrated graft with a biologically developed cartilage-bone interface for osteochondral defect repair.

Tissue engineering is a promising approach to repair osteochondral defects, yet successful reconstruction of different layers in an integrated graft, especially the interface remains challenging. The multiphasic, functionally integrated tissue engineering graft described herein mimics the entire osteochondral tissue in terms of structure and composition at the cartilage, bone and cartilage-bone interface layer to repair osteochondral defects. In this manuscript, we report the fabrication of a multiphasic graft via bonding of a cartilaginous hydrogel and a sintered poly(lactic-co-glycolic acid) microsphere scaffold by an endogenous fibrotic cartilaginous extracellular matrix. We demonstrated that culturing chondrocytes within the alginate hydrogel conjugated to the poly(lactic-co-glycolic acid) scaffold allows for (i) gradient transition and integration from the cartilage layer to the subchondral bone layer as assessed by scanning electron microscopy, histology and biochemistry, and (ii) superior tissue repair efficacy in a rabbit knee defect model. Industrialization of the graft remains an unsolved challenge as after decellularization the tissue repair efficacy of the graft decreased. Taken together, the multiphasic osteochondral graft repaired the osteochondral defects successfully and has the potential to be applied clinically as an implant in orthopaedic surgery.

A novel cell encapsulatable cryogel (CECG) with macro-porous structures and high permeability: a three-dimensional cell culture scaffold for enhanced cell adhesion and proliferation.

Hydrogel scaffold is a popular cell delivery vehicle in tissue engineering and regenerative medicine due to its capability to encapsulate cells as well as its modifiable properties. However, the inherent submicron- or nano-sized polymer networks of conventional hydrogel will produce spatial constraints on cellular activities of encapsulated cells. In this study, we endeavor to develop an innovative cell encapsulatable cryogel (CECG) platform with interconnected macro-pores, by combining cell cryopreservation technique with cryogel preparation process. The hyaluronan (HA) CECG constructs are fabricated under the freezing conditions via UV photo-crosslinking of the HA methacrylate (HA-MA) that are dissolved in the 'freezing solvent', namely the phosphate buffered saline supplemented with dimethyl sulphoxide and fetal bovine serum. Two model cell types, chondrocytes and human mesenchymal stem cells (hMSCs), can be uniformly three-dimensionally encapsulated into HA CECG constructs with high cell viability, respectively. The macro-porous structures, generated from phase separation under freezing, endow HA CECG constructs with higher permeability and more living space for cell growth. The chondrocytes encapsulated in HA CECG possess enhanced proliferation and extracellular matrix secretion than those in conventional HA hydrogels. In addition, the HA-Gel CECG constructs, fabricated with HA-MA and gelatin methacrylate precursors, provide cell-adhesive interfaces to facilitate hMSCs attachment and proliferation. The results of this work may lay the foundation for us to explore the applications of the CECG-based scaffolds in the field of tissue engineering and regenerative medicine.

Co-culture of human umbilical vein endothelial cells and human bone marrow stromal cells into a micro-cavitary gelatin-methacrylate hydrogel system to enhance angiogenesis.

Vascular tissue engineering seeks to develop functional blood vessels that comprise of both endothelial cells and pericytes for translational medicine and is often faced with numerous challenges such as nutrients and wastes diffusion problem in the centre of the scaffolds. Various strategies have been adopted to solve the diffusion problem in thick engineered scaffolds. Typically, microchannels or dissolvable microspheres are introduced into three-dimensional (3D) scaffolds as an alternative way to improve the infiltration of scaffolds and endothelial cells are usually incorporated into the biomaterials. While some research groups now focus on finding supporting cells to build further vascularized structures in the scaffolds. In this study, a bioinspired 3D gelatin-methacrylate (Gel-MA) hydrogel with dissolvable microspheres was created to encapsulate human bone marrow stromal cells (HMSCs) and human umbilical vein endothelial cells (HUVECs) which was used to investigate whether HMSCs could play a pericytes-like role and enhance vascularization within the engineered scaffolds. The results showed co-culture of HMSCs and HUVECs demonstrated significantly improved vascularization when compared to either HUVECs or HMSCs monoculture. Angiogenic genes were expressed significantly higher in co-culture group. Moreover, when implanting the pre-vascularized scaffolds in vivo, co-culture system integrated more successfully with host tissue and showed higher host tissue invasion than any other groups. More importantly, both the qPCR and immunofluorescence results indicated MSCs differentiated towards pericytes to enhance vascularization in this study. This paper highlights the enhanced capability of 3D micro-cavitary Gel-MA hydrogel for co-culturing HUVECs and HMSCs to promote vascularization which presents a potential strategy for future tissue repair and regeneration.

Albumin conjugates and assemblies as versatile bio-functional additives and carriers for biomedical applications.

As the most abundant plasma protein, serum albumin has been extensively studied and employed for therapeutic applications. Despite its direct clinical use for the maintenance of blood homeostasis in various medical conditions, this review exclusively summarizes and discusses albumin-based bio-conjugates and assemblies as versatile bio-functional additives and carriers in biomedical applications. As one of the smallest-sized proteins in the human body, albumin is physiochemically stable and biochemically inert. Moreover, albumin is also endowed with abundant specific binding sites for numerous therapeutic compounds, which also endow it with superior bioactivities. Firstly, due to its small size and binding specificity, albumin alone or its derived assemblies can be utilized as competent drug carriers, which can deliver drugs through the enhanced permeability and retention (EPR) effect or actively target lesion sites through binding with gp60 and secreted protein acidic and rich in cysteine (SPARC) in tumor sites. Furthermore, its biochemical stability and inertness make it a safe and biocompatible coating material for use in biomedical applications. Albumin-based surface modifying additives can be used to functionalize both macro substrates (e.g. surfaces of medical devices or implants) and nanoparticle surfaces (e.g. drug carriers and imaging contrast agents). In this review, we elaborate on the synthesis and applications of albumin-based bio-functional coatings and drug carriers, respectively.

Decellularized orthopaedic tissue-engineered grafts: biomaterial scaffolds synthesised by therapeutic cells.

In orthopaedic surgery, the reconstruction of musculoskeletal defects is a constant challenge. Biomaterials in tissue engineering are utilized as scaffolds which serve as templates for cell proliferation and secretion as well as guides for new tissue formation. The extracellular matrix (ECM) is a desirable biological scaffold due to its complex composition and three-dimensional ultrastructure, which drive the homeostasis and regeneration of tissues. Successfully used in a variety of regenerative medicine applications, ECM scaffolds can be achieved by decellularization of engineered tissue. In addition to using decellularized grafts directly as scaffolds, decellularized grafts can also be coated on or incorporated into synthetic biomaterials to substantially enhance their biological performance regarding integration into the surrounding tissue and bioactivity for neo-tissue generation. However, at present, the most widely adopted decellularized scaffolds are decellularized native scaffolds, which have the limitations of inherent heterogeneity, fixed shapes and insufficient sources. Decellularized tissue-engineered scaffolds are promising to avoid these restrictions and are receiving attention in the regenerative medicine field. This review describes the rationale of using decellularized tissue-engineered grafts for different regenerative purposes and details their application in the repair of orthopaedic defects.

Establishment of an in vitro three-dimensional model for cartilage damage in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic inflammatory disease that leads to progressive joint destruction. To further understand the process of rheumatoid cartilage damage, an in vitro model consisting of an interactive tri-culture of synovial fibroblasts (SFs), LPS-stimulated macrophages and a primary chondrocyte-based tissue-engineered construct was established. The tissue-engineered construct has a composition similar to that of human cartilage, which is rich in collagen type II and proteoglycans. Data generated from this model revealed that healthy chondrocytes were activated in the presence of SFs and macrophages. The activated chondrocytes subsequently displayed aberrant behaviours as seen in a disease state such as increased apoptosis, decreased gene expression for matrix components such as type II collagen and aggrecan, increased gene expression for tissue-degrading enzymes (MMP-1, -3, -13 and ADAMTS-4, -5), and upregulation of inflammatory mediator gene expression (TNF-α, IL-1ß, IL-6 and IKBKB). Additionally, the inclusion of SFs and macrophages in the model enabled both cell types to more closely replicate an in vivo role in mediating cartilage destruction. This is evidenced by extensive matrix loss, detected in the model through immunostaining and biochemical analysis. Subsequent drug treatment with celecoxib has shown that the model was able to respond to the therapeutic effects of this drug by reversing cartilage damage. This study showed that the model was able to recapitulate certain pathological features of an RA cartilage. If properly validated, this model potentially can be used for screening new therapeutic drugs and strategies, thereby contributing to the improvement of anti-rheumatic treatment. Copyright © 2017 John Wiley & Sons, Ltd.

Sustained releasing sponge-like 3D scaffolds for bone tissue engineering applications.

Tissue engineering (TE) is envisaged to play a vital role in improving quality of life by restoring, maintaining or enhancing tissue and organ functions. TE scaffolds that are two-dimensional in structure suffer from undesirable issues, such as pore blockage, and do not closely mimic the native extra-cellular matrix in tissues. Significant efforts have therefore been channeled to fabricate three-dimensional (3D) scaffolds using various techniques, especially electrospinning. In this study, we propose a modified one-step electrospinning process to arrive at a 3D scaffold with highly interconnected pores. Using a blend of poly (L-lactide)/polycaprolactone/poly (ethylene oxide), this mechanically viable, sponge-like 3D scaffold exhibited sufficiently large pores and enabled cell penetration beyond 500 µm. Dexamethasone (Dex) was loaded into the fibers and a sustained drug release was achieved. Further, the potential of this Dex-loaded 3D scaffold was evaluated for upregulation of osteogenic genes with mesenchymal stem cells. The as-produced Dex-loaded 3D scaffold possesses a unique intertwined sub-micron fibrous morphology that can be tailored for use in bone tissue engineering and beyond.

A novel glucosamine derivative with low cytotoxicity enhances chondrogenic differentiation of ATDC5.

Glucosamine (GlcN) is a component of native cartilage extracellular matrix and useful in cartilage repair, but it was limited by toxicity in high concentrations. With the aim of altering bioactive properties of GlcN to reduce the toxicity and to facilitate chondrogenesis for hyaline cartilage formation, we introduced an amino-group modification with double bond into GlcN to produce N-acryloyl-glucosamine (AGA). The cell ATDC5 was chosen to evaluate its cytotoxicity and chondrogenesis capability. Cell proliferation and cytotoxicity assay showed that AGA had significantly reduced the cytotoxicity compared to GlcN, and promoted ATDC5 proliferation. Alcian blue staining and biochemical analysis indicated that AGA enhanced extracellular matrix deposition. Both the mRNA and protein levels of articular cartilage markers, like Collagen II and Aggrecan were up-regulated, as shown by quantitative real-time PCR and immunofluorescence staining. Moreover, the level of fibrocartilage marker Collagen I and hypertrophic marker Collagen Χ weren't significantly changed. Overall, these results demonstrated that the AGA achieved the functional double-bond, reduction in toxicity and enhancement in chondrogenesis could be more potential in cartilage repair.