A biocompatible double-crosslinked gelatin/ sodium alginate/dopamine/quaterniazed chitosan hydrogel for wound dressings based on 3D bioprinting technology.

438Severe skin injuries can cause serious problems, which could affect the patient's normal life, if not dealt properly in a timely and effective manner. It is an urgent requirement to develop personalized wound dressings with excellent antibacterial activity and biocompatibility to match the shape of the wound to facilitate clinical application. In this study, a bioink (GAQ) based on gelatin (Gel)/sodium alginate (SA)/ quaternized chitosan (QCS) was prepared, and GAQ hydrogel dressing grafting with dopamine (GADQ) was fabricated by an extrusion three-dimensional (3D) printing technology. QCS was synthesized by modifying quaternary ammonium group on chitosan, and its structure was successfully characterized by nuclear magnetic resonance (1H NMR) and Fourier-transform infrared spectroscopy (FT-IR). Our results showed that the GADQ hydrogel dressing that was double-crosslinked by EDC/ NHS and Ca2+ had good tensile strength, considerable swelling ratio, and effective antioxidation properties. It also showed that GADQ1.5% had 93.17% and 91.06% antibacterial activity against Staphylococcus aureus and Escherichia coli, respectively. Furthermore, the relative survival ratios of fibroblast cells seeded on these hydrogels exceeded 350% after cultured for 7 days, which proved the biocompatibility of these hydrogels. Overall, this advanced 3D-printed GADQ1.5% hydrogels with effective antioxidation, excellent antibacterial activity and good biocompatibility had a considerable application potential for wound healing.

Development of decellularized meniscus extracellular matrix and gelatin/chitosan scaffolds for meniscus tissue engineering.

BACKGROUND: Meniscus tissue engineering has provided a great potential treatment for meniscal injuries. However, few scaffolds in meniscus tissue engineering have matched the mechanical properties of native meniscus. OBJECTIVE: In this study, we developed a composite scaffold using decellularized meniscus extracellular matrix (DMECM) and gelatin/chitosan (G/C) to explore a preferable ratio to enhance the elastic modulus and cytotoxicity properties of scaffolds. METHODS: The microstructure, porosity, cytotoxicity, and strength of the composite scaffolds were evaluated. The micro-architectures of the samples were evaluated using scanning electron microscope (SEM). Fourier Transform Infrared analysis (FTIR) was used to confirm the chemical structure with different type composite scaffolds. The compressive elastic modulus of all the scaffolds were measured by the universal tensile testing machine DNS300. Calcein-AM (fluorescent green) and propidium iodide (fluorescent red) were used to stain live cells and dead cells. Morphology and spatial distribution of cells within scaffolds were observed by confocal laser scanning microscopy FV 1000. RESULTS: SEM showed that the composite scaffolds had suitable porous structure. CCK-8 and live/dead staining demonstrated that the composite scaffolds had no cytotoxicity and could promote bone marrow mesenchymal stem cells (BMSCs) proliferation. The FTIR results demonstrated the successful mixing of these two elements, and the addition of DMECM improved the elastic modulus and cytotoxicity of G/C composite scaffolds. CONCLUSIONS: This study developed a composite scaffold using DMECM and G/C, and demonstrated that it might be suitable for meniscal tissue engineering application.

Dynamic fabrication of tissue-engineered bone substitutes based on derived cancellous bone scaffold in a spinner flask bioreactor system.

The in vitro dynamic fabrications of tissue-engineered bones were performed to assess the advantages of human adipose-derived stem cells (hADSCs) combined with acellular cancellous bone scaffold coming from fresh pig femur in a spinner flask compared with traditional static culture. In this study, the bio-derived cancellous bone was regarded as a biomimetic scaffold, and its surface appearance was observed under scanning electron microscopy (SEM). Moreover, its modulus of elasticity and chemical composition were measured with universal testing machine (UTM) and infrared detector, respectively. hADSCs were inoculated into cancellous bone scaffold at a density of 1 × 10(6) cells/mL and cultured in spinner flask and T-flask with osteogenic medium (OM) for 2 weeks, respectively. Following to this, the osteogenic differentiation was qualitatively and quantitatively detected with alkaline phosphatase (ALP) kits, and the cell growth and viability were assayed using Live/Dead staining; cell adhesion and extracellular matrix secretion were observed under a SEM. The average pore size of cancellous bone scaffold was 284.5 ± 83.62 µm, the elasticity modulus was 41.27 ± 15.63 MPa, and it also showed excellent biocompatibility. The hADSCs with multidifferentiation potentials were well proliferated, could grow to 90 % fusion within 5 days, and were therefore suitable to use as seed cells in the construction of tissue-engineered bones. After 2 weeks of fabrication, cells were well-distributed on scaffolds, and these scaffolds still remained intact. Compared to static environment, the ALP expression, cell distribution, and extracellular matrix secretion on cancellous bones in spinner flask were much better. It confirmed that three-dimensional dynamic culture in spinner flask promoted ADSC osteogenic differentiation, proliferation, and matrix secretion significantly to make for the fabrication of engineered bone substitutes.

Desmoid tumor of posterior cruciate ligament of the knee: a case report.

BACKGROUND: Desmoid tumor is a rare type of cancer that develops in the tissues that form tendons and ligaments. These tumors, also called aggressive fibromatosis, are considered benign with no metastatic potential. They may invade nearby tissues and organs, however, and can be difficult to control. Desmoid tumor in the posterior cruciate ligament (PCL) of the knee has never been described in the literature. CASE PRESENTATION: A 49-year-old man presented with a 2-month history of posteromedial knee dull pain and decreased range of motion of the knee. He was diagnosed desmoid tumor of posterior cruciate ligament of the knee by intraoperative biopsy, and underwent successful PCL resection and reconstruction by Four-strand semitendinosus and gracilis tendon autograft arthroscopically, and fortunately five years after operation, there were no clues as to recurrence of the tumor examined by Magnetic Resonance Imaging (MRI). CONCLUSION: Desmoid tumor is characterized by infiltrative growth and a tendency towards recurrence,as this tumor entity is rare, data giving evidence based recommendations for the optimal treatment algorithm for this disease is lacking. At present there is no definite and effective method of treatment. However, early detection of the tumor play an important role, MRI is now the most important method for the detection of tumor extent, which facilitates the treatment choice as well as the prediction of prognosis. In our case, we followed-up the patient five years postoperatively by MRI and got a good result.

Stimulation of sphingosine-1-phosphate on cardiomyogenic differentiation of mesenchymal stem cells / 生物工程学报

To study the effect of sphingosine-1-phosphate (S1P) on the cardiomyogenic differentiation of human umbilical cord mesenchymal stem cells (UC-MSCs) and human adipose-derived mesenchymal stem cells (AD-MSCs), we seeded the cells in the culture plates and used cardiomyocyte culture medium (CMCM) combining with different concentration of S1P to induce UC-MSCs and AD-MSCs in vitro for 7, 14 and 28 days. Cardiomyogenic differentiations were identified through immunofluorescence staining, and the results were observed with fluorescence microscopy and confocal microscopy. The effects of S1P and CMCM on cell activity were evaluated by the methyl thiazolyl tetrazolium assay. The functional characteristic similar to cardiomyocytes was evaluated through detecting calcium transient. Our results showed that cardiomyogenic differentiation of UC-MSCs or AD-MSCs were enhanced with S1P concentration increasing, but cell activities declined. Results showed that the suitable differentiation time was 14 days, and the optimal concentration of S1P was 0.5 micromol/L. When working together with CMCM, S1P could promote the differentiation of UC-MSCs or AD-MSCs into functional cardiomyocytes, giving rise to specific electrophysiological properties (the calcium transient). Taken together, our results suggested that S1P could promote the differentiation of UC-MSCs or AD-MSCs into functional cardiomyocytes when being cultured in CMCM.

The antitumor effect of mesenchymal stem cells transduced with a lentiviral vector expressing cytosine deaminase in a rat glioma model.

OBJECTIVE: Mesenchymal stem cells (MSCs) have been recognized as promising delivery vehicles for gene therapy of gliomas. The purpose of this study was to evaluate the antitumor effect of cytosine deaminase (CD)-expressing MSCs in a rat C6 glioma model. METHODS: Lentiviral vectors expressing cytosine deaminase (CD) or enhanced green fluorescent protein (eGFP) were constructed and transduced into rat MSCs to generate MSC-CD/eGFP cells. By intracranially injecting C6 glioma cells (1 × 10(6)) alone or in combination with parental MSCs (1 × 10(6) or 2 × 10(6)) or MSC-CD/eGFP cells (1 × 10(6) or 2 × 10(6)) into rats, we examined the effect of engineered MSCs on tumor growth, tumor cell apoptosis, and rat survival in the presence of 5-fluorocytosine (5-FC). RESULTS: MSC-CD/eGFP cells were largely localized at the junction of the tumor with normal tissue. The mean survival time of rats co-injected with C6 glioma cells and MSC-CD/eGFP cells was significantly extended (C6 + MSC-CD/eGFP (1:1), 32.3 days; C6 + MSC-CD/eGFP (1:2), 45.9 days) when compared with rats injected with C6 glioma cells alone (15.3 days) or those co-injected with C6 glioma cells and parental cells (C6 + MSCs (1:1), 16.0 days; C6 + MSCs (1:2), 16.6 days). MSC-CD/eGFP-mediated gene therapy significantly reduced the tumor volume in C6 glioma-bearing rats. On day 14 after cell injection, the reduction in the mean tumor volume in rats co-injected with C6 + MSC-CD/eGFP cells (1:1 and 1:2) was 77.24 and 83.28%, respectively. In addition, MSC-CD/eGFP-mediated gene therapy promoted tumor cell apoptosis in rat C6 gliomas. CONCLUSION: Genetically engineered MSCs have good therapeutic efficacy against experimental gliomas in rats.

Simultaneous expansion and harvest of hematopoietic stem cells and mesenchymal stem cells derived from umbilical cord blood.

The simultaneous expansion and harvest of hematopoietic stem cells and mesenchymal stem cells derived from umbilical cord blood were carried out using bioreactors. The co-culture of umbilical cord blood (UCB)-derived hematopoietic stem cells (HSCs) and mesenchymal stem cells (MSCs) was performed within spinner flasks and a rotating wall vessel (RWV) bioreactor using glass-coated styrene copolymer (GCSC) microcarriers. The medium used was composed of serum-free IMDM containing a cocktail of SCF 15 ng·mL(-1), FL 5 ng·mL(-1), TPO 6 ng·mL(-1), IL-3 15 ng·mL(-1), G-CSF 1 ng·mL(-1) and GM-CSF 5 ng·mL(-1). Accessory stromal cells derived from normal allogeneic adipose tissue were encapsulated in alginate-chitosan (AC) beads and used as feeding cells. The quality of the harvested UCB-HSCs and MSCs was assessed by immunophenotype analysis, methylcellulose colony and multi-lineage differentiation assays. After 12 days of culture, the fold-expansion of total cell numbers, colony-forming units (CFU-C), CD34(+)/CD45(+)/CD105(-) (HSCs) cells and CD34(-)/CD45(-)/CD105(+) (MSCs) cells using the RWV bioreactor were (3.7 ± 0.3)- , (5.1 ± 1.2)- , (5.2 ± 0.4)- , and (13.9 ± 1.2)-fold respectively, significantly better than those obtained using spinner flasks. Moreover, UCB-HSCs and UCB-MSCs could be easily separated by gravity sedimentation after the co-culture period as only UCB-MSCs adhered on to the microcarriers. Simultaneously, we found that the fibroblast-like cells growing on the surface of the GCSC microcarriers could be induced and differentiated towards the osteoblastic, chondrocytic and adipocytic lineages. Phenotypically, these cells were very similarly to the MSCs derived from bone marrow positively expressing the MSCs-related markers CD13, CD44, CD73 and CD105, while negatively expressing the HSCs-related markers CD34, CD45 and HLA-DR. It was thus demonstrated that the simultaneous expansion and harvest of UCB-HSCs and UCB-MSCs is possible to be accomplished using a feasible bioreactor culture system such as the RWV bioreactor with the support of GCSC microcarriers.