Secretome of Mesenchymal Stem Cells from Consecutive Hypoxic Cultures Promotes Resolution of Lung Inflammation by Reprogramming Anti-Inflammatory Macrophages.

The secretome from hypoxia-preconditioned mesenchymal stem cells (MSCs) has been shown to promote resolution of inflammation and alleviate acute lung injury (ALI) through its immunomodulatory function. However, the effects of consecutive hypoxic culture on immunomodulatory function of the MSCs secretome are largely unclarified. Here, we intend to investigate the effects of consecutive hypoxia on therapeutic efficacy of conditioned medium derived from MSCs (MSCs-CM) in alleviating ALI. Human umbilical cord-derived MSCs (UC-MSCs) were consecutively cultured in 21% O2 (Nor-MSCs) or in 1% O2 (Hypo-MSCs) from passage 0. Their conditioned medium (Nor-CM and Hypo-CM respectively) was collected and administered into ALI models. Our findings confirmed that Hypo-MSCs exhibited increased proliferation ability and decreased cell senescence compared with Nor-MSCs. Consecutive hypoxia promoted UC-MSCs to secrete immunomodulatory cytokines, such as insulin-like growth factor 1(IGF1), IL10, TNFα-stimulated gene 6(TSG6), TGFß, and prostaglandin E2 (PGE2). Both Nor-CM and Hypo-CM could effectively limit lung inflammation, promote efferocytosis and modulate anti-inflammatory polarization of lung macrophages in ALI models. Moreover, the effects of Hypo-CM were more potent than Nor-CM. Taken together, our findings indicate that consecutive hypoxic cultures could not only promote both proliferation and quality of UC-MSCs, but also enhance the therapeutic efficacy of their secretome in mitigating lung inflammation by promoting efferocytosis and anti-inflammatory polarization of macrophages.

Antibacterial Soy Protein Isolate Prepared by Quaternization.

Soy protein isolate (SPI) is green, high-yield natural plant protein, which is widely applied in industry (packing material and adhesives) and tissue engineering. It is meaningful to improve the antibacterial property of soy protein isolate to fabricate versatile safe products to meet people's requirements. In this study, quaternized soy protein isolate (QSPI) was synthesized by the reaction between 2,3-epoxypropyltrimethylammonium chloride (EPTMAC) and SPI. The positive charged (17.8 ± 0.23 mV) quaternary ammonium groups endow the QSPI with superior antibacterial properties against multiple bacteria in vitro and in vivo. Notably, QSPI maintains its good biocompatibility and promotes bacterial-infected wound healing in rat models. Furthermore, QSPI possesses superior water solubility in a broad pH range than raw SPI. Altogether, this soy protein isolate derivative with antibacterial property and superior water solubility may extend the application of SPI in industry and tissue engineering.

Construction of nerve guide conduits from cellulose/soy protein composite membranes combined with Schwann cells and pyrroloquinoline quinone for the repair of peripheral nerve defect.

Regeneration and functional reconstruction of peripheral nerve defects remained a significant clinical challenge. Nerve guide conduits, with seed cells or neurotrophic factors (NTFs), had been widely used to improve the repair and regeneration of injured peripheral nerve. Pyrroloquinoline quinone (PQQ) was an antioxidant that can stimulate nerve growth factors (NGFs) synthesis and accelerate the Schwann cells (SCs) proliferation and growth. In present study, three kinds of nerve guide conduits were constructed: one from cellulose/SPI hollow tube (CSC), another from CSC combined with SCs (CSSC), and the third one from CSSC combined with PQQ (CSSPC), respectively. And then they were applied to bridge and repair the sciatic nerve defect in rats, using autograft as control. Effects of different nerve guide conduits on the nerve regeneration were comparatively evaluated by general analysis, sciatic function index (SFI) and histological analysis (HE and TEM). Newly-formed regenerative nerve fibers were observed and running through the transparent nerve guide conduits 12 weeks after surgery. SFI results indicated that the reconstruction of motor function in CSSPC group was better than that in CSSC and CSC groups. HE images from the cross-sections and longitudinal-sections of the harvested regenerative nerve indicated that regenerative nerve fibers had been formed and accompanied with new blood vessels and matrix materials in the conduits. TEM images also showed that lots of fresh myelinated and non-myelinated nerve fibers had been formed. Parts of vacuolar, swollen and abnormal axons occurred in CSC and CSSC groups, while the vacuolization and swell of axons was the least serious in CSSPC group. These results indicated that CSSPC group had the most ability to repair and reconstruct the nerve structure and functions due to the comprehensive contributions from hollow CSC tube, SCs and PQQ. As a result, the CSSPC may have the potential for the applications as nerve guide conduits in the field of nerve tissue engineering.

Fabrication and evaluation of physical properties and cytotoxicity of zein-based polyurethanes.

Polyurethane prepolymer (PUP) was first synthesized from polycaprolactone diol and isophorone diisocyanate; and then a series of zein-based polyurethane (ZEPU) sheets was fabricated from PUP and zein (ZE) using a hot press and moulding process without addition of other additives. Effects of ZE content (WZE) on the structure and properties of the resultant ZEPU sheets were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, dynamic mechanical analysis, tensile testing, and dissolubility testing in alcohol. The results indicated that cross-linking and grafting reactions occurred between ZE and PUP to form new polyurethane showing a higher thermal stability, flexibility, and alcohol-resistance than the neat ZE sheets. For example, the elongation at break of ZEPU with 50 % WZE was 211.2 %, which was 47 times higher than that of neat ZE sheet. ZE molecules acted as both cross-linkers and polymer fillers in ZEPU sheets. The cytotoxicity and cytocompatibility of ZEPU sheets were evaluated by cell culture in vitro. The ZEPU sheets showed non- or low-cytotoxicity, and L929 cells grew and expanded well on the surfaces of the sheets with WZE over 50 %. Undoubtedly, the fabrication of ZE-based polyurethanes without toxic additives such as catalysts, cross-linkers and chain extenders improved the physical properties and cytocompatibility of zein, thus widening the possible range of applications for zein-based biomaterials.

Composite Hydrogel Conduit Incorporated with Platelet-Rich Plasma Improved the Regenerative Microenvironment for Peripheral Nerve Repair.

Peripheral nerve regeneration and functional recovery remain major challenges in clinical practice. Nerve guidance conduits (NGCs) which can regulate the regenerative microenvironment are beneficial for peripheral nerve repair. Platelet-rich plasma (PRP) can secrete multiple growth factors to regulate the regenerative microenvironment. However, current administration methods of PRP are rapidly activated followed by the burst release of growth factors, causing low therapeutic efficiency in vivo. To overcome these disadvantages, a composite nerve conduit was fabricated by incorporating PRP into a gelatin methacrylate (GelMA) and sodium alginate (SA) hydrogel. The GelMA/SA-3/PRP-20 NGCs possess optimal mechanical properties, degradation rate, and superior biological performance. Importantly, GelMA/SA-3/PRP-20 NGCs achieved the sustained release of two major growth factors (VEGF-A, PDGF-BB) from PRP. Moreover, the GelMA/SA-3/PRP-20 NGCs significantly promoted the migration of Schwann cells and the neovascularization of endothelial cells in vitro. While bridging 10 mm rat sciatic nerve defects, the GelMA/SA-3/PRP-20 NGCs promoted axonal regeneration and functional recovery of peripheral nerves. Therefore, the GelMA/SA-3/PRP-20 NGCs could regulate the regenerative microenvironment by sustained release of growth factors from PRP and shed new light on the clinical application of PRP in peripheral nerve repair.

Nerve Defect Treatment with a Capping Hydroxyethyl Cellulose/Soy Protein Isolate Sponge Conduit for Painful Neuroma Prevention.

Painful neuroma, as one of the complications of nerve injury from disease or trauma, results in instinctive neuropathic pain that adversely affects a patient's quality of life. To intercept neuroma development, capping strategies have been performed as effective therapies. Nonetheless, the most appropriate biocompatible material to shield the nerves is an urgent clinical requirement. Herein, a compatible hydroxyethyl cellulose (HEC)/soy protein isolate (SPI) sponge capping conduit (HSSC) is used to prevent neuroma in vivo. Following capping on the sciatic nerve stump in vivo, the behavior of the rats and the structure of tissues are compared through histological assessment and autotomy scoring. The HSSCs gained a dismal autotomy score and enhanced the amelioration, where inflammatory invasions and overdeposition of collagen are defeated. The expression of myelin growth linked genes (Krox20, MPZ, and MAG) in the HSSC group at the eighth week was almost 2 times higher than that of the no capping group. The HSSC conduit served as a physical barrier to repress the infiltration of inflammation as well as provided an optimum microenvironment for facilitating nerve rejuvenation and intercepting neuroma development during nerve amelioration.

Facile fabrication of soy protein isolate-functionalized nanofibers with enhanced biocompatibility and hemostatic effect on full-thickness skin injury.

Extensive full-thickness skin defect lacks self-healing ability. Tissue engineering wound dressing is considered as the most promising approach to promote wound healing. In this study, a series of biocompatible and hemostatic nanofiber dressings were fabricated. Soy protein isolate (SPI) and poly(L-lactic acid) (PLLA) solutions were mixed in certain proportions for high-voltage electrospinning. The obtained products were coded as SPNF-n (n = 100, 80, 60 and 40, corresponding to the weight percentage of PLLA solution). We found that SPNF-n (n = 100, 80, 60 and 40) could facilitate the adhesion and spread of L929 cells. In particular, SPNF-80 was capable of promoting fibroblast proliferation and diminishing inflammation. Compared with the neat PLLA film (SPNF-100), the biosafety and hemostatic effect of SPNF-80 got significantly improved. The hemostatic effect of SPNF-80 was comparable with that of a commercial gelatin sponge. In vivo wound healing assay demonstrated that SPNF-80 could accelerate the wound healing process by enhancing vascularization, re-epithelization and collagen formation. In conclusion, our results reveal that SPNF-n has good biocompatibility and hemostatic effect, and exhibits great application potential in wound healing.

Natural Flammulina velutipes-Based Nerve Guidance Conduit as a Potential Biomaterial for Peripheral Nerve Regeneration: In Vitro and In Vivo Studies.

The treatment and repair of serious peripheral nerve injuries remain challenging in the clinical practice, while the application of multifunctional nerve guidance conduits (NGCs) based on naturally derived polymers has attracted much attention in recent years because of their excellent physicochemical properties and biological characteristics. Flammulina velutipes (Curt. ex FV) is a popular edible mushroom characterized by hollow tubular structures, antibacterial activities, and high nutritional properties. In this study, FV is utilized to construct NGCs (labeled FVC) via a freeze-drying technique without chemical modifications. The morphology, physical properties, cellular biocompatibility, antibacterial properties, and nerve regeneration capacity of FVC were assessed both in vitro and in vivo. FVC is composed of hollow tubes and evenly irregular interconnected micropores with 73.8 ± 5.5% porosity and 476.1 ± 12.9 µm hollow tube diameter. The inner surface of the FVC presents multiple microgrooves elongated parallel to the long axis. Moreover, FVC possessed strong antibacterial activity and could inhibit Gram-positive Staphylococcus aureus growth by up to 96.0% and Gram-negative Escherichia coli growth by up to 94.8% in vitro. FVC exhibited excellent biocompatibility and effectively promoted PC-12 cell proliferation and elongation in vitro. When applied to repair critical-sized sciatic nerve defects, FVC could effectively stimulate nerve functional recovery and axonal outgrowth in a rat model. Interestingly, Western blot analysis indicated that growth-associated protein 43 (GAP-43) had increased expression levels in the FVC group compared with the autograft group. This result suggested that by activating the Janus activated kinase2 (JAK2)/Phosphorylation ofsignal transducer and activator of transcription-3 (STAT3) signaling pathway, FVC upregulated Phosphorylation of signal transducer and activator of transcription-3 (P-STAT3) in vivo, resulting in the secretion of GAP-43. Collectively, a natural NGC FVC was fabricated based on FV without chemical modifications. The morphology, physical properties, cellular biocompatibility, antibacterial properties, and nerve regeneration capacity of FVC provide new insights for its further optimization and application in the field of nerve tissue engineering.

Comprehensive strategy of conduit guidance combined with VEGF producing Schwann cells accelerates peripheral nerve repair.

Peripheral nerve regeneration requires stepwise and well-organized establishment of microenvironment. Since local delivery of VEGF-A in peripheral nerve repair is expected to promote angiogenesis in the microenvironment and Schwann cells (SCs) play critical role in nerve repair, combination of VEGF and Schwann cells may lead to efficient peripheral nerve regeneration. VEGF-A overexpressing Schwann cells were established and loaded into the inner wall of hydroxyethyl cellulose/soy protein isolate/polyaniline sponge (HSPS) conduits. When HSPS is mechanically distorted, it still has high durability of strain strength, thus, can accommodate unexpected strain of nerve tissues in motion. A 10 mm nerve defect rat model was used to test the repair performance of the HSPS-SC (VEGF) conduits, meanwhile the HSPS, HSPS-SC, HSPS-VEGF conduits and autografts were worked as controls. The immunofluorescent co-staining of GFP/VEGF-A, Ki67 and MBP showed that the VEGF-A overexpressing Schwann cells could promote the proliferation, migration and differentiation of Schwann cells as the VEGF-A was secreted from the VEGF-A overexpressing Schwann cells. The nerve repair performance of the multifunctional and flexible conduits was examined though rat behavioristics, electrophysiology, nerve innervation to gastrocnemius muscle (GM), toluidine blue (TB) staining, transmission electron microscopy (TEM) and NF200/S100 double staining in the regenerated nerve. The results displayed that the effects on the repair of peripheral nerves in HSPS-SC (VEGF) group was the best among the conduits groups and closed to autografts. HSPS-SC (VEGF) group exhibited notably increased CD31+ endothelial cells and activation of VEGFR2/ERK signaling pathway in the regenerated nerve tissues, which probably contributed to the improved nerve regeneration. Altogether, the comprehensive strategy including VEGF overexpressing Schwann cells-mediated and HSPS conduit-guided peripheral nerve repair provides a new avenue for nerve tissue engineering.

Mesenchymal stromal cells for sepsis and septic shock: Lessons for treatment of COVID-19.

Sepsis is defined as life-threatening organ dysfunction caused by a deregulated immune host response to infection. The emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has highlighted this multifactorial and complex syndrome. The absence of specific treatment neither against SARS-CoV-2 nor against acute respiratory distress syndrome (ARDS), the most serious stage of this infection, has emphasized the need to find alternative treatments. Several therapeutics are currently being tested, including mesenchymal stromal cells. These cells, already used in preclinical models of ARDS, sepsis, and septic shock and also in a few clinical trials, appear well-tolerated and promising, but many questions remain unanswered.

Brain Derived Neurotrophic Factor and Glial Cell Line-Derived Neurotrophic Factor-Transfected Bone Mesenchymal Stem Cells for the Repair of Periphery Nerve Injury.

Peripheral nerve injury is a common clinical neurological disease. In our previous study, highly oriented poly (L-lactic acid) (PLLA)/soy protein isolate (SPI) nanofiber nerve conduits were constructed and exhibited a certain repair capacity for peripheral nerve injury. In order to further improve their nerve repairing efficiency, the bone mesenchymal stem cells (BMSCs) overexpressing brain derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) were introduced into the conduits as seed cells and then were used to repair the 10-mm sciatic nerve defects in rats. The nerve repair efficiency of the functional nerve conduits was evaluated by gait experiment, electrophysiological test, and a series of assays such as hemotoxylin-eosin (HE) staining, immunofluorescence staining, toluidine blue (TB) staining, transmission electron microscopy (TEM) observation of regenerated nerve and Masson's trichrome staining of gastrocnemius muscle. The results showed that the conduits containing BMSCs overexpressing BDNF and GDNF double-factors group had better nerve repairing efficiency than blank BMSCs and single BDNF or GDNF factor groups, and superior to autografts group in some aspects. These data demonstrated that BDNF and GDNF produced by BMSCs could synergistically promote peripheral nerve repair. This study shed a new light on the conduits and stem cells-based peripheral nerve repair.

Are the Immune Properties of Mesenchymal Stem Cells from Wharton's Jelly Maintained during Chondrogenic Differentiation?

BACKGROUND: Umbilical mesenchymal stem/stromal cells (MSCs), and especially those derived from Wharton's jelly (WJ), are a promising engineering tool for tissue repair in an allogeneic context. This is due to their differentiation capacity and immunological properties, like their immunomodulatory potential and paracrine activity. Hence, these cells may be considered an Advanced Therapy Medicinal Product (ATMP). The purpose of this work was to differentiate MSCs from WJ (WJ-MSCs) into chondrocytes using a scaffold and to evaluate, in vitro, the immunomodulatory capacities of WJ-MSCs in an allogeneic and inflammatory context, mimicked by IFN-γ and TNF-α priming during the chondrogenic differentiation. METHODS: Scaffolds were made from hydrogel composed by alginate enriched in hyaluronic acid (Alg/HA). Chondrogenic differentiation, immunological function, phenotype expression, but also secreted soluble factors were the different parameters followed during 28 days of culture. RESULTS: During chondrocyte differentiation, even in an allogeneic context, WJ-MSCs remained unable to establish the immunological synapse or to induce T cell alloproliferation. Moreover, interestingly, paracrine activity and functional immunomodulation were maintained during cell differentiation. CONCLUSION: These results show that WJ-MSCs remained hypoimmunogenic and retained immunomodulatory properties even when they had undergone chondrocyte differentiation.

An Ergonomic Assessment Of Four Different Donor Nephrectomy Approaches For The Surgeons And Their Assistants.

INTRODUCTION: Open surgery is increasingly being replaced by laparoscopic approaches that are more demanding for the surgical team. The physical and mental workload of these approaches have not been quantified. MATERIALS AND METHODS: A multicenter prospective study was performed evaluating the physical and mental stresses of 4 surgical approaches (open surgery [OS], standard laparoscopy [SL], hand-assisted laparoscopy [HAL], and robot-assisted laparoscopy [RAL]) for donor nephrectomy for the surgeon and their assistant. The Borg Scale was used to evaluate exertion in different body parts every 30 mins during surgery and the NASA-TLX score was used to evaluate overall workload. RESULTS: 264 nephrectomies were performed over a 33-month period and 258 questionnaires evaluating these surgeries were obtained. Surgeons experienced less left shoulder and arm exertion and left forearm and hand exertion, but greater lower back exertion, as measured by the Borg scale, with RAL. Leg exertion was significantly greater with OS. Assistant surgeons experienced increased exertion in the back, right shoulder and arm, and right forearm and hand with RAL. NASA Task load index (TLX) surgeon scores showed mental demand was similar for all 4 surgical approaches. Physical demand was lower and overall performance was higher with RAL. DISCUSSION: Four different nephrectomy surgical approaches were evaluated in a multicenter setting. Surgeon and assistant scores of physical exertions were generally in the "easy" range but confirmed that robotic surgery is an ergonomic progress compared to other techniques, except for the axial skeleton. Further, it degrades the working conditions for the assistant.

Phenotypic analysis of cell surface markers and gene expression of human mesenchymal stem cells and chondrocytes during monolayer expansion.

Both chondrocytes and mensenchymal stem cells (MSCs) are the most used cell sources for cartilage tissue engineering. However, monolayer expansion to obtain sufficient cells leads to a rapid chondrocyte dedifferentiation and a subsequent ancillary reduced ability of MSCs to differentiate into chondrocytes, thus limiting their application in cartilage repair. The aim of this study was to investigate the influence of the monolayer expansion on the immunophenotype and the gene expression profile of both cell types, and to find the appropriate compromise between monolayer expansion and the remaining chondrogenic characteristics. To this end, human chondrocytes, isolated enzymatically from femoral head slice, and human MSCs, derived from bone marrow, were maintained in monolayer culture up to passage 5. The respective expressions of cell surface markers (CD34, CD45, CD73, CD90, CD105, CD166) and several chondrogenic-related genes for each passage (P0-P5) of those cells were then analyzed using flow cytometry and quantitative real-time PCR, respectively. Flow cytometry analyses showed that, during the monolayer expansion, some qualitative and quantitative regulations occur for the expression of cell surface markers. A rapid increase in mRNA expression of type 1 collagen occurs whereas a significant decrease of type 2 collagen and Sox 9 was observed in chondrocytes through the successive passages. On the other hand, the expansion did not induced obvious change in MSCs gene expression. In conclusion, our results suggest that passage 1 might be the up-limit for chondrocytes in order to achieve their subsequent redifferentiation in 3D scaffold. Nevertheless, MSCs could be expanded in monolayer until passage 5 without loosing their undifferentiated phenotypes.

Effect of alginate culture and mechanical stimulation on cartilaginous matrix synthesis of rat dedifferentiated chondrocytes.

To investigate whether the application of alginate culture and mechanical stimulation will improve the synthesis of cartilaginous matrix in dedifferentiated chondrocytes, rat chondrocytes underwent dedifferentiation upon serial monolayer culture up to passage 6, and then were encapsulated in 2% alginate gel and subject to static culture. After 28 days culture in static, the beads were exposed to 48 h of mechanical stimulation with continuous agitation. The sGAG content in alginate bead was measured by alcian blue staining. The expression of collagen protein was detected using immunofluorescence. After 28 days culture in alginate bead, the dedifferentiated chondrocytes remained round in shape and re-synthesized the chondrocyte-specific matrix. Compared with static culture, mechanical stimulation induced statistically increases in the production of glycosaminoglycan (p< or =0.01), as well as in the synthesis of collagen type II protein (p< or =0.05). On the contrary, no positive expression of collagen type I protein was observed at the end of culture. Our results demonstrated that both of alginate culture and mechanical stimulation help to restore chondrocyte phenotype and promotes the synthesis of cartilaginous matrix.

Mechanical stimulations on human bone marrow mesenchymal stem cells enhance cells differentiation in a three-dimensional layered scaffold.

Scaffolds laden with stem cells are a promising approach for articular cartilage repair. Investigations have shown that implantation of artificial matrices, growth factors or chondrocytes can stimulate cartilage formation, but no existing strategies apply mechanical stimulation on stratified scaffolds to mimic the cartilage environment. The purpose of this study was to adapt a spraying method for stratified cartilage engineering and to stimulate the biosubstitute. Human mesenchymal stem cells from bone marrow were seeded in an alginate (Alg)/hyaluronic acid (HA) or Alg/hydroxyapatite (Hap) gel to direct cartilage and hypertrophic cartilage/subchondral bone differentiation, respectively, in different layers within a single scaffold. Homogeneous or composite stratified scaffolds were cultured for 28 days and cell viability and differentiation were assessed. The heterogeneous scaffold was stimulated daily. The mechanical behaviour of the stratified scaffolds were investigated by plane-strain compression tests. Results showed that the spraying process did not affect cell viability. Moreover, cell differentiation driven by the microenvironment was increased with loading: in the layer with Alg/HA, a specific extracellular matrix of cartilage, composed of glycosaminoglycans and type II collagen was observed, and in the Alg/Hap layer more collagen X was detected. Hap seemed to drive cells to a hypertrophic chondrocytic phenotype and increased mechanical resistance of the scaffold. In conclusion, mechanical stimulations will allow for the production of a stratified biosubstitute, laden with human mesenchymal stem cells from bone marrow, which is capable in vivo to mimic all depths of chondral defects, thanks to an efficient combination of stem cells, biomaterial compositions and mechanical loading.

Accelerated skin wound healing by soy protein isolate-modified hydroxypropyl chitosan composite films.

In this study, a series of hydroxypropyl chitosan (HPCS)/soy protein isolate (SPI) composite films (HCSFs) with different SPI contents were developed via crosslinking, solution casting, and evaporation process. Effects of the SPI content on the structure and physical properties of the HCSFs were characterized by Fourier transform infrared spectroscopy, X-ray diffraction patterns, scanning electron microscopy, swelling kinetics analysis, and mechanical testing. The HCSFs exhibited a lower swelling ratio with an increase in the SPI content. The tensile strength was in a tunable range from 7.88 ±â€¯3.08 to 40.44 ±â€¯2.31 MPa by adjusting the SPI content. Cytocompatibility and hemocompatibility of the HCSFs were evaluated by a series of in vitro assays, including MTT assay, live/dead assay, cell morphology observation, hemolysis ratio testing, and plasma recalcification time measurement. Results showed that the HCSFs support L929 cells attachment and proliferation without obvious hemolysis, indicating good cytocompatibility and hemocompatibility. The potential of resultant HCSFs as the wound dressings was investigated using a full-thickness skin wound model in rats. Results exhibited that the HCSFs with 50% SPI content had the fastest healing speed and the best skin regeneration efficiency and may be a potential candidate as the wound dressing.

Electrodeposition to construct mechanically robust chitosan-based multi-channel conduits.

A series of electrodeposited chitosan-based multi-channel conduits (ECMC) with potential for peripheral nerve tissue engineering were constructed using a novel electrodeposition method combined with homemade molds. The structural and mechanical properties of the ECMC were characterized by scanning electron microscopy, Fourier-transformed infrared spectroscopy, X-ray diffraction patterns and mechanical testing. The results showed that the electrodeposition process did not change the chemical structure of the chitosan molecules, but endowed the ECMC with high levels of flexibility and elasticity. Hemocompatibility and cytocompatibility of the ECMC were evaluated by hemolysis assay, MTT assay and live/dead assay. The results indicated that the ECMC had a low hemolysis rate, and can promote cell proliferation and support cell adhesion. This work provides a safe and feasible electrodeposition method to construct chitosan-based conduits with potential applications for peripheral nerve tissue engineering.

Comparison of MSC properties in two different hydrogels. Impact of mechanical properties.

Once articular cartilage is damaged, it has poor ability to heal. At present, alginate-based hydrogels have 3D-dimensional physical structures with great potential for applications in carilage tissue engineering. For osteochondral defect, it will be necessary to use stratified scaffold to mimic zonal organization of cartilage. This study aims to compare the characteristics of alginate (Alg)/hyaluronic acid (HA) hydrogels which will mimic cartilage with alginate (Alg)/hydroxyapatite (Hap) hydrogels which will mimic subchondral bone. In this work, we fabricated the 3D-Alg/HA and Alg/Hap hydrogel scaffolds by the original spraying method. From the physical-mechanical properties, we compared mechanical behaviour of Alg/HA and Alg/Hap hydrogel scaffolds, which were examined using indentation testing and viscosity behaviour. This results showed that the Alg/Hap hydrogels exhibited a relative high mechanical strength, as well as the viscosity of Alg/Hap hydrogels is slight slower than Alg/HA hydrogels. However, autoclaving has more deleterious effect on the mechanical and viscosity properties of Alg/HA and Alg/Hap hydrogels. Cytotoxicity was evaluated through the culture of hydrogel beads-laden Wharton's jelly mesenchymal stem cells (WJ-MSC). In addition, the chondrogenic differentiation of WJ-MSC encapsulated into Alg/HA and Alg/Hap hydrogels were performed by histological analyzing during 30 days of culture. From these results, the percentage of living cells for Alg/Hap is significantly higher than Alg/HA, which also is associated with the results of shear viscosity. Both of hydrogels exhibited differentiate into chondrocyte matrix as collagen and proteoglycans. In conclusion, Alg/Hap hydrogels presented better mechanical property, cytocompatibility and differentiation characteristics than Alg/HA hydrogels.