Electrochemical Lactonization Enabled by Unusual Shono-Type Oxidation from Functionalized Benzoic Acids.

A novel method for electrochemical lactonization via C(sp3)-H functionalization was developed. This metal- and oxidant-free strategy enabled the efficient synthesis of various lactones. Gram-scale reaction and derivatization of the lactone product demonstrated the synthetic utility of this methodology. Mechanistic studies using control experiments and CV curves elucidated the proposed intramolecular HAT and the oxidative cyclization pathway. An unusual Shono-type oxidation was realized through this electrochemical approach, proceeding without a traditional nucleophilic addition process.

Mechanisms of gut microbiota-immune-host interaction on glucose regulation in type 2 diabetes.

Intestinal absorption of food is one of the sources of glucose. Insulin resistance and impaired glucose tolerance caused by lifestyle and diet are the precursors of type 2 diabetes. Patients with type 2 diabetes have trouble controlling their blood sugar levels. For long-term health, strict glycemic management is necessary. Although it is thought to be well correlated with metabolic diseases like obesity, insulin resistance, and diabetes, its molecular mechanism is still not completely understood. Disturbed microbiota triggers the gut immune response to reshape the gut homeostasis. This interaction not only maintains the dynamic changes of intestinal flora, but also preserves the integrity of the intestinal barrier. Meanwhile, the microbiota establishes a systemic multiorgan dialog on the gut-brain and gut-liver axes, intestinal absorption of a high-fat diet affects the host's feeding preference and systemic metabolism. Intervention in the gut microbiota can combat the decreased glucose tolerance and insulin sensitivity linked to metabolic diseases both centrally and peripherally. Moreover, the pharmacokinetics of oral hypoglycemic medications are also influenced by gut microbiota. The accumulation of drugs in the gut microbiota not only affects the drug efficacy, but also changes the composition and function of them, thus may help to explain individual therapeutic variances in pharmacological efficacy. Regulating gut microbiota through healthy dietary patterns or supplementing pro/prebiotics can provide guidance for lifestyle interventions in people with poor glycemic control. Traditional Chinese medicine can also be used as complementary medicine to effectively regulate intestinal homeostasis. Intestinal microbiota is becoming a new target against metabolic diseases, so more evidence is needed to elucidate the intricate microbiota-immune-host relationship, and explore the therapeutic potential of targeting intestinal microbiota.

Electroacupuncture Pretreatment Exhibits Lung Protective and Anti-Inflammation Effects in Lipopolysaccharide-Induced Acute Lung Injury via SIRT1-Dependent Pathways.

To investigate the effect of electroacupuncture (EA) on acute lung injury (ALI), a lipopolysaccharide (LPS) induced ALI mouse model was used in this study. Before receiving intratracheal LPS instillation, mice were given EA at ST36 for 7 days as a long-term treatment or one time as a short-term treatment. Lung histopathological examination, lung injury scores, lung wet/dry (W/D) ratio, and inflammatory cytokines included proinflammation factors such as TNF-α, IL-1ß, and IL-6 and anti-inflammation factors such as IL-4 and IL-10 in serum and bronchoalveolar lavage fluid (BALF) were detected at the end of experiment. The results show that EA pretreatment ameliorated the lung damage and inflammatory response by LPS. In addition, we found that SIRT1 and its deacetylation of NF-κB were promoted after EA pretreatment in lung tissues. Meanwhile, the expression of angiotensin-converting enzyme 2 (ACE2) is also enhanced by EA pretreatment. Thus, the present findings suggest that EA could be a potential therapy of ALI.

CDC48B facilitates the intercellular trafficking of SHORT-ROOT during radial patterning in roots.

CELL DIVISION CONTROL PROTEIN48 (CDC48) is essential for membrane fusion, protein degradation, and other cellular processes. Here, we revealed the crucial role of CDC48B in regulating periclinal cell division in roots by analyzing the recessive gen1 mutant. We identified the GEN1 gene through map-based cloning and verified that GEN1 encodes CDC48B. gen1 showed severely inhibited root growth, increased periclinal cell division in the endodermis, defective middle cortex (MC) formation, and altered ground tissue patterning in roots. Consistent with these phenotypes, CYCLIND 6;1(CYCD6;1), a periclinal cell division marker, was upregulated in gen1 compared to Col-0. The ratio of SHRpro :SHR-GFP fluorescence in pre-dividing nuclei versus the adjacent stele decreased by 33% in gen1, indicating that the trafficking of SHORT-ROOT (SHR) decreased in gen1 when endodermal cells started to divide. These findings suggest that the loss of function of CDC48B inhibits the intercellular trafficking of SHR from the stele to the endodermis, thereby decreasing SHR accumulation in the endodermis. These findings shed light on the crucial role of CDC48B in regulating periclinal cell division in roots.

[Effect of electroacupuncture at different acupoint combination on intestinal inflammatory response and intestinal flora in obese rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) at different acupoint combination on intestinal inflammatory response, intestinal flora structure and metabolic function in obese rats. METHODS: Ninety male Wistar rats aged 8 weeks were collected. Ten rats were randomly collected from 15 rats fed with regular forage in a normal group and the rest 75 rats were fed with high-fat forage to induce obesity models. Forty rats were modeled successfully and randomized into a model group, a lower-limb EA group, an abdomen EA group and a biaoben acupoints group, 10 rats in each one. "Zusanli" (ST 36) and "Fenglong" (ST 40) were selected in the lower-limb EA group, "Zhongwan "(CV 12), "Tianshu "(ST 25) and "Guanyuan" (CV 4) were selected in the abdomen EA group. The acupoint prescriptions in the above two groups were combined in the biaoben acupoints group. EA was delivered in all of the intervention groups, with continuous wave, 2 Hz in frequency and 1 mA in current intensity. The intervention was administered three times weekly (on Monday, Wednesday and Friday), for consecutive 8 weeks. Before intervention and on the last day of the 8th week of intervention, the body weight and 24 h food intake were observed. After intervention, using Western blot method, the proteins expressions of interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) were detected in the tissue of the small intestine; 16S rRNA sequencing technology was adopted to detect the distribution structure and metabolic function of intestinal flora. RESULTS: Compared with the normal group, the body weight, the food intake and the proteins expressions of IL-6 and TNF-α in small intestine were all increased in the model group (P<0.01). The above indexes of each EA intervention group were all decreased (P<0.01) when compared with the model group. The proteins expressions of IL-6 and TNF-α in the small intestine tissue of rats in biaoben acupoints group were lower than those in the other two EA intervention groups (P<0.01). Compared with the normal group, the ratio of Firmicutes/Bacteroidetes was elevated (P<0.01), while the abundance of Lactobacillus, Muribaculaceae and Bifidobacteria decreased in the model group (P<0.01). When compared with the model group, the ratio of Firmicutes/Bacteroidetes in each EA intervention group was reduced (P<0.01) and the abundance of Lactobacillus, Bifidobacteria and Bacteroidetes increased (P<0.01). Compared with the other two EA intervention groups, the abundance of Lactobacillus and Muribaculaceae was increased (P<0.01), while the abundance of Collinsella and Ruminococcus Gauvreauii reduced (P<0.01) in the biaoben acupoints group. In the model group, the abundance of clusters of orthologous groups of proteins (COG) function of intestinal flora in the transportation and metabolism of carbohydrate, amino acid and lipid, as well as in the signal transduction mechanisms were reduced when compared with the normal group (P<0.01). In comparison with the model group, the abundance of the above COG function was increased in each EA intervention group (P<0.01, P<0.05). CONCLUSION: Electroacupuncture at biaoben acupoint combination may attenuate intestinal inflammatory response and effectively improve the structure and function of intestinal flora. The effect is superior to the intervention at the acupoints on the lower limbs and those on the abdomen, better regulating the abundance of specific intestinal flora.

[Effect of electroacupuncture stimulation of different acupoint groups on lipid metabolism and liver TLR4/NF-κB signaling in obese rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) of different acupoint combinations on lipid metabolism and liver Toll-like receptor 4 (TLR4)/nuclear factor kappa B (NF-κB) signaling in obese rats, so as to explore the specificity of regulatory effects of different acupoints for obesity. METHODS: Male SD rats were randomly divided into normal control, model, hindlimb acupoint EA ï¼»"Fenglong" (ST40)-"Zusanli" (ST36), hindlimb EAï¼½, abdominal acupoint EA ï¼»("Zhongwan" (CV12)-"Tianshu" (ST25), "Guanyuan" (CV4) - the opposite ST25, abdominal EAï¼½, BiaoBen-acupoint EA ï¼»ST40-ST36, CV12 -CV4, ST25, BiaoBen EAï¼½ groups, with 10 rats in each group. The obesity model was induced by feeding the rats with high fat diet. EA (2 Hz, 1 mA) was applied to the acupoint groups mentioned above for 10 min (per acupoint group), 3 times a week for 8 weeks. After the treatment, the body weight and food intake in each group were recorded. The contents of serum total cholesterol (TC), triglyceride (TG), non-esterified fatty acid (NEFA) were detected by using an automatic biochemical analyzer. The expression levels of TLR4 and NF-κB p65 mRNAs and proteins in the liver tissue were detected by quantitative real-time PCR and Western blot, separately. RESULTS: Compared with the normal group, the body weight and food intake, serum TC, TG and NEFA contents, hepatic TLR4 and NF-κB p65 protein and gene expression were significantly increased in the model group (P<0.05, P<0.01). After the treatment, compared with the model group, the body weight, food intake, TC, TG, NEFA, TLR4 and NF-κB p65 protein and mRNA expression were significantly decreased in the hindlimb EA, abdominal EA and BiaoBen EA groups (P<0.05, P<0.01). Comparison among the 3 treatment groups showed that the serum TC, TG and NEFA contents were significantly lower in the hindlimb EA and BiaoBen EA groups than in the abdominal EA group (P<0.01，P<0.05). The expression levels of TLR4 and NF-κB p65 mRNAs and proteins were significantly lower in the BiaoBen EA group than in the hindlimb EA and abdominal EA groups (P<0.01, P<0.05). CONCLUSION: BiaoBen EA is superior to abdominal EA in improving lipid metabolism in obesity rats, which may be related to its stronger effectiveness in down-regulating hepatic TLR4/NF-κB p65 signaling.

[Mechanism of electroacupuncture for regulation of lipid production and improvement in obesity by mediating Wnt/ ß-catenin pathway through activating SIRT1].

OBJECTIVE: To explore the mechanism of electroacupuncture (EA) for the regulation of lipid production and improvement in obesity by mediating Wnt/ß-catenin pathway through activating silent information regulator 1 (SIRT1). METHODS: Of 75 Wistar male rats, 10 rats were selected randomly as the normal group and fed with standard diet. The rest rats were fed with high-fat diet for 8 weeks to establish the obesity model. Forty rats of successful modeling were randomized into a model group, an EA group, an EA plus inhibitor group (EA+I group) and an agonist group, 10 rats in each one. In the EA group, EA was applied at "Guanyuan" (CV 4), "Zhongwan" (CV 12), "Zusanli" (ST 36) and "Fenglong" (ST 40), with continuous wave, 2 Hz in frequency and around 1 mA in intensity. The needles were retained for 20 min. In the EA+I group, sirtinol solution was injected from caudal vein and EA was exerted simultaneously. In the agonist group, resveratrol solution was given by intragastric administration. The intervention of the above three groups was given once every two days, 3 times a week, consecutively for 8 weeks. Before and after intervention, body mass and Lee's index were recorded in the rats of each group. After intervention, the levels of serum total cholesterol (TC), triglyceride (TG) and free fatty acid (FFA) were detected in the rats of each group. After intervention, the mass of white adipose tissue (WAT) and the area of adipocytes were compared in the rats among the 5 groups. Using Western blot method, the protein expressions of SIRT1, glycogen synthase kinase-3ß (GSK3ß), ß-catenin, cyclin D1 and peroxisome proliferators-activated receptor γ (PPARγ) were detected in WAT in the rats of each group. RESULTS: After intervention, compared with the model group, the body mass and Lee's index were reduced in the rats of the EA group and the agonist group (P<0.01, P<0.05), the body mass was reduced in the rats of the EA+I group (P<0.05). Compared with the normal group, the levels of serum TC, TG and FFA, as well as WAT mass were increased in the rats of the model group (P<0.01), as well as the area of adipocytes (P<0.01). Compared with the model group, the levels of serum TC and TG (except in the EA+I group), the levels of FFA and WAT mass were all decreased (P<0.01, P<0.05) and the area of adipocytes was reduced (P<0.01, P<0.05) in the EA group, the agonist group and the EA+I group. Compared with the EA group, the area of adipocytes was increased in the EA+I group (P<0.05). Compared with the normal group, the protein expressions of SIRT1, ß-catenin and cyclin D1 in WAT were down-regulated (P<0.01) and the protein expressions of GSK3ß and PPARγ in WAT were up-regulated (P<0.01) in the model group. Compared with the model group, the protein expressions of SIRT1, ß-catenin and cyclin D1 in WAT were up-regulated (P<0.05, P<0.01) and the expressions of GSK3ß and PPARγ in WAT were down-regulated (P<0.01, P<0.05) in the EA group and the agonist group, and in the EA+I group, GSK3ß protein expression was down-regulated andß-catenin protein expression was up-regulated (P<0.05). CONCLUSION: Electroacupuncture remarkably improves the body mass, Lee's index and blood lipid metabolism and reduces WAT mass and adipocyte size in obesity model rats, which is probably related to up-regulating the protein expression of SIRT1 in WAT, activating Wnt/ß-catenin pathway and inhibiting the expression of PPARγ of downstream lipogenic gene so as to affect lipid production.

AtSEC22 Regulates Cell Morphogenesis via Affecting Cytoskeleton Organization and Stabilities.

The plant cytoskeleton forms a stereoscopic network that regulates cell morphogenesis. The cytoskeleton also provides tracks for trafficking of vesicles to the target membrane. Fusion of vesicles with the target membrane is promoted by SNARE proteins, etc. The vesicle-SNARE, Sec22, regulates membrane trafficking between the ER and Golgi in yeast and mammals. Arabidopsis AtSEC22 might also regulate early secretion and is essential for gametophyte development. However, the role of AtSEC22 in plant development is unclear. To clarify the role of AtSEC22 in the regulation of plant development, we isolated an AtSEC22 knock-down mutant, atsec22-4, and found that cell morphogenesis and development were seriously disturbed. atsec22-4 exhibited shorter primary roots (PRs), dwarf plants, and partial abortion. More interestingly, the atsec22-4 mutant had less trichomes with altered morphology, irregular stomata, and pavement cells, suggesting that cell morphogenesis was perturbed. Further analyses revealed that in atsec22-4, vesicle trafficking was blocked, resulting in the trapping of proteins in the ER and collapse of structures of the ER and Golgi apparatus. Furthermore, AtSEC22 defects resulted in impaired organization and stability of the cytoskeleton in atsec22-4. Our findings revealed essential roles of AtSEC22 in membrane trafficking and cytoskeleton dynamics during plant development.

[Electroacupuncture improves obesity by lowering gastrointestinal motility, blood lipids and expression of intestinal leptin and cholecystokinin in obese rats].

OBJECTIVE: To investigate the effect of electroacupuncture (EA) on gastrointestinal motility and expression of leptin(LEP) and cholecystokinin(CCK) in the small intestine in obese rats，so as to explore the mechanism of EA underlying improvement of obesity. METHODS: Male Wistar rats were randomized into 5 groups: normal control, obesity model, abdominal acupoints ［"Guanyuan" (CV4), "Zhongwan" (CV12) and bilateral "Tianshu" (ST25)］, lower-leg acupoints ［bilateral "Zusanli" (ST36) and bilateral "Fenglong" (ST40)］, and abdominal+ lower-leg acupoints (n=10 rats in each group). The obesity model was established by feeding the animals with high-fat diet for 8 weeks. EA was applied to the abovementioned acupoints for 20 min every time, 3 times a week for 8 weeks. The food intake and body mass were recorded. The white adipose tissue around the testicles and in the abdominal region was weighed. The serum total cholesterol (TC), triglyceride (TG) and non-esterified fatty acid(NEFA) were detected by using automatic biochemical analyzer. The gastric empty rate and intestinal propulsive rate were calculated. The contents of serum CCK and LEP were detected by using ELISA, and the expression levels of CCK and LEP proteins in the small intestine were detected by using Western blot. RESULTS: Following modeling, the food intake, body mass, weight of white adipose around the testicles and abdomen, the gastric empty rate, and serum TC, TG, NEFA and LEP contents as well as intestinal LEP expression were significantly increased (P<0.05, P<0.01), while the intestinal propulsive rate, serum CCK content and intestinal CCK expression were evidently decreased (P<0.01) in the model group relevant to the normal control group. After EA interventions and compared with the model group, the increased levels of food intake, body mass, white adipose weight, gastric empty rate, TC, TG, and LEP in serum and small intestine, and the decreased levels of intestinal propulsive rate, CCK in the serum and intestine were reversed in the abdominal acupoints, lower-leg acupoints and abdominal+lower-leg acupoints groups (P<0.05, P<0.01). No significant differences were found in the effects of the three EA groups in down-regulating food intake, body mass, white adipose weight, gastric empty rate, serum TC, TG and LEP levels (except NEFA) and in up-regulating intestinal propulsive rate and CCK level (P>0.05). CONCLUSION: EA stimulation of the abdominal and lower-leg acupoints or both can reduce body weight on obesity rats, which is associated with its functions in regulating intestinal motility, food intake, and secretion of LEP and CCK.

Ultrafast and Programmable Shape Memory Hydrogel of Gelatin Soaked in Tannic Acid Solution.

Shape memory hydrogels have been paid plenty of attention as a kind of intelligent soft material. However, complicated preparation and slow and uncontrollable shape change have hindered their applications in smart actuators. In this work, a temperature-responsive strong hydrogel was prepared by a facial soaking method without any chemical reactions, i.e., soaking gelatin hydrogel in aqueous tannic acid solution. The hydrogel was constructed by hydrogen bonding between gelatin and tannic acid beside the triple helix of gelatin chains without any chemical cross-linkers. The hydrogel showed ultrafast shape memory and body-temperature response. The hydrogel can be fixed in temporary shape in only 1 s at 25 °C and recover to the original shape in also 1 s at 37 °C, superior to the reported shape memory hydrogels. Furthermore, the hydrogel shape change can be programmed by fixing the temperature, and the designed shape is achieved stepwise by adjusting the recovery temperature. In addition, the hydrogel is stable in water without further swelling. These excellent features will initiate new prosperity of the shape memory hydrogel in biomedical technology, underwater actuators, and soft robots.

Combinational Hydrogel and Xerogel Actuators Showing NIR Manipulating Complex Actions.

Near-infrared (NIR)-driven shape memory hydrogels are synthesized with a one-pot polymerization of N,N-dimethylacrylamide in the inorganic clay and graphene oxide (GO) suspension. The hydrogel consists of only a physically crosslinked network, which is partially thermoreversible. With the efficient photothermal energy transformation of GO in the hydrogels, the shape recovery from the temporal shape is achieved by NIR irradiation. The optimal shape fixing percentage and recovery rate are found at moderate monomer and crosslinker contents. Meanwhile, the xerogel dried from the hydrogel also shows a fast NIR response shape change. The NIR manipulating combinational hydrogel-xerogel actuators are prepared by combining the wet and soft hydrogel and its dry and rigid xerogel together. The actuators achieve complex actions of turning and lifting under sequential NIR irradiation to carry an object up- and downward and around obstacles, or to transfer an object to a target position. This work provides a new idea for designing combinational actuators to fulfil complex actions.

Cu-Doped α-Fe2O3 Microspheres as Anode Materials for Lithium-Ion Batteries.

α-Fe2O3 and Cu-doped α-Fe2O3 microspheres were similarly synthesized by solvothermal method. These microspheres were characterized by X-ray diffraction (XRD), and scanning electron microscope (SEM) technique. As anode materials for lithium-ion batteries (LIBs), Cu-doped α-Fe2O3 electrodes exhibit better electrochemical performance (higher specific capacities of 600 mAhg-1 and better cycling performance), compared with pure α-Fe2O3 electrode. Additionally, the effects of different Cu2+-doping contents and reaction times on the morphology and the electrochemical properties were also discussed. Cu-doped α-Fe2O3 proves to be a potential anode material for LIB applications.

Facile Synthesis and Lithium Storage Properties of Zn1-xCoxCO3 Microspheres.

Zn1-xCoxCO3 (ZCCO) microspheres were synthesized by a modified solvothermal method (ball milling-solvothermal combination method) using ZnCl2, CoCl2, and NH4HCO3 as raw materials. All samples were characterized by X-ray diffractometer (XRD), Fourier transform infrared spectra (FT-IR), and Scanning electron microscopy (SEM) technique. The results showed the introduction of Co and molar ratio of Zn and Co play crucial roles in the morphology and electrochemical performance of the ZCCO. As anode materials for lithium ion battery (LIB), all ZCCO electrodes possess high specific capacities and good cycle performance. The as-obtained Zn0.5Co0.5CO3 electrode exhibits higher discharge capacity (1526 mAh/g) and better rate properties with the reversible capacity of 976 mAh/g after 100 cycles when the molar ratio of Zn/Co is 1:1. Moreover, the present work provides a new and simple approach to the fabrication of novel anode materials (transition metal carbonates) for LIB applications.

A hydrolytically-tunable photocrosslinked PLA-PEG-PLA/PCL-PEG-PCL dual-component hydrogel that enhances matrix deposition of encapsulated chondrocytes.

In this study, a series of photocrosslinked hydrogels were designed composed of both poly(lactide)-poly(ethylene glycol)-poly(lactide) (PEL) and poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PEC) macromers. The PEL/PEC hydrogels at ratios of 100:0, 75:25, 50;50, 25:75 and 0:100 were studied for their degradation characteristics and their ability to support chondrogenesis of encapsulated chondrocytes. Difference in hydrolytic susceptibility between copolymers led to different degradation patterns where higher PEC content correlated with slower degradation. Increased chondrogenic gene expression was observed in chondrocyte-laden hydrogels within a 4-week culture period. Biochemical and histological evaluations revealed significant accumulation of extracellular matrix proteins such as glycosaminoglycans and collagen in the 50/50 hydrogel owing to appropriate tuning of hydrogel degradation. These results demonstrate that the dual-component photocrosslinked hydrogel system is suitable for use as scaffold to support chondrogenesis and, moreover, the tunability of these systems opens up possibilities for use in different cell culturing applications. Copyright © 2014 John Wiley & Sons, Ltd.

Hydrogel Delivery of Mesenchymal Stem Cell-Expressing Bone Morphogenetic Protein-2 Enhances Bone Defect Repair.

BACKGROUND: The application of bone tissue engineering for repairing bone defects has gradually shown some satisfactory progress. One of the concerns raising scientific attention is the poor supply of growth factors. A number of growth factor delivery approaches have been developed for promoting bone formation. However, there is no systematic comparison of those approaches on efficiency of neobone formation. In this study, the approaches using periosteum, direct supply of growth factors, or gene transfection of growth factors were evaluated to determine the osteogenic capacity on the repair of bone defect. METHODS: In total, 42 male 21-week-old Sprague-Dawley rats weighing 250 to 400 g were used as the bone defect model to evaluate the bone repair efficiency. Various tissue engineered constructs of poly(ethylene glycol)-poly(l-lactic acid) (PEG-PLLA) copolymer hydrogel with periosteum, with external supply of bone morphogenetic protein-2 (BMP2), or with BMP2-transfected bone marrow-derived mesenchymal stem cells (BMMSCs) were filled in a 7-mm bone defect region. Animals were euthanized at 3 months, and the hydrogel constructs were harvested. The evaluation with histological staining and radiography analysis were performed for the volume of new bone formation. RESULTS: The PEG-PLLA scaffold with BMMSCs promotes bone regeneration with the addition of periosteum. The group with BMP2-transfected BMMSCs demonstrated the largest volume of new bone among all the testing groups. CONCLUSIONS: Altogether, the results of this study provide the evidence that the combination of PEG-PLLA hydrogels with BMMSCs and sustained delivery of BMP2 resulted in the maximal bone regeneration.

The effects of different molecular weight chondroitin-4-sulfates in chondrocyte pellet culture.

For this study, we cultured chondrocyte pellets in Dulbecco's modified Eagle's medium plus a 2 % fetal bovine serum medium, and treated them with 2- to 8-mer oligosaccharides of chondroitin sulfate A to examine the effects of these oligosaccharides on the differentiation and protection of chondrocytes. We found low-molecular-weight CSAs to increase the ratio of the gene expression levels of collagen II/collagen I of chondrocytes from the first day up to 14 days after culture compared with those under a CSA-free medium. Moreover, low-molecular-weight CSAs inhibited the expression of matrix metalloproteinases and peptidases, and stimulated an endogenous tissue inhibitor of metalloproteinases. The dp-8 (8-mer) CSA yielded the most effective response among promoting collagen type II protein secretions compared with other groups.

In vitro and in vivo co-culture of chondrocytes and bone marrow stem cells in photocrosslinked PCL-PEG-PCL hydrogels enhances cartilage formation.

Chondrocytes (CH) and bone marrow stem cells (BMSCs) are sources that can be used in cartilage tissue engineering. Co-culture of CHs and BMSCs is a promising strategy for promoting chondrogenic differentiation. In this study, articular CHs and BMSCs were encapsulated in PCL-PEG-PCL photocrosslinked hydrogels for 4 weeks. Various ratios of CH:BMSC co-cultures were investigated to identify the optimal ratio for cartilage formation. The results thus obtained revealed that co-culturing CHs and BMSCs in hydrogels provides an appropriate in vitro microenvironment for chondrogenic differentiation and cartilage matrix production. Co-culture with a 1:4 CH:BMSC ratio significantly increased the synthesis of GAGs and collagen. In vivo cartilage regeneration was evaluated using a co-culture system in rabbit models. The co-culture system exhibited a hyaline chondrocyte phenotype with excellent regeneration, resembling the morphology of native cartilage. This finding suggests that the co-culture of these two cell types promotes cartilage regeneration and that the system, including the hydrogel scaffold, has potential in cartilage tissue engineering. Copyright © 2013 John Wiley & Sons, Ltd.

An ectopic approach for engineering a vascularized tracheal substitute.

Tissue engineering can provide alternatives to current methods for tracheal reconstruction. Here we describe an approach for ectopic engineering of vascularized trachea based on the implantation of co-cultured scaffolds surrounded by a muscle flap. Poly(L-lactic-co-glycolic acid) (PLGA) or poly(ε-caprolactone) (PCL) scaffolds were seeded with chondrocytes, bone marrow stem cells and co-cultured both cells respectively (8 groups), wrapped in a pedicled muscle flap, placed as an ectopic culture on the abdominal wall of rabbits (n = 24), and harvested after two and four weeks. Analysis of the biochemical and mechanical properties demonstrated that the PCL scaffold with co-culture cells seeding displayed the optimal chondrogenesis with adequate rigidity to maintain the cylindrical shape and luminal patency. Histological analysis confirmed that cartilage formed in the co-culture groups contained a more homogeneous and higher extracellular matrix content. The luminal surfaces appeared to support adequate epithelialization due to the formation of vascularized capsular tissue. A prefabricated neo-trachea was transferred to the defect as a tracheal replacement and yielded satisfactory results. These encouraging results indicate that our co-culture approach may enable the development of a clinically applicable neo-trachea.

Evaluation of a mPEG-polyester-based hydrogel as cell carrier for chondrocytes.

Temperature-sensitive hydrogels are attractive alternatives to porous cell-seeded scaffolds and is minimally invasive through simple injection and in situ gelling. In this study, we compared the performance of two types of temperature-sensitive hydrogels on chondrocytes encapsulation for the use of tissue engineering of cartilage. The two hydrogels are composed of methoxy poly(ethylene glycol)- poly(lactic-co-valerolactone) (mPEG-PVLA), and methoxy poly(ethylene glycol)-poly(lactic- co-glycolide) (mPEG-PLGA). Osmolarity and pH were optimized through the manipulation of polymer concentration and dispersion medium. Chondrocytes proliferation in mPEG-PVLA hydrogels was observed as well as accumulation of GAGs and collagen. On the other hand, chondrocytes encapsulated in mPEG-PLGA hydrogels showed low viability and chondrogenesis. Also, mPEG-PVLA hydrogel, which is more hydrophobic, retained physical integrity after 14 days while mPEG-PLGA hydrogel underwent full degradation due to faster hydrolysis rate and more pronounced acidic self-catalyzed degradation. The mPEG-PVLA hydrogel can be furthered tuned by manipulation of molecular weights to obtain hydrogels with different swelling and degradation characteristics, which may be useful as producing a selection of hydrogels compatible with different cell types. Taken together, these results demonstrate that mPEG-PVLA hydrogels are promising to serve as three-dimensional cell carriers for chondrocytes and potentially applicable in cartilage tissue engineering.

A comparative study of the chondrogenic potential between synthetic and natural scaffolds in an in vivo bioreactor.

The clinical demand for cartilage tissue engineering is potentially large for reconstruction defects resulting from congenital deformities or degenerative disease due to limited donor sites for autologous tissue and donor site morbidities. Cartilage tissue engineering has been successfully applied to the medical field: a scaffold pre-cultured with chondrocytes was used prior to implantation in an animal model. We have developed a surgical approach in which tissues are engineered by implantation with a vascular pedicle as an in vivo bioreactor in bone and adipose tissue engineering. Collagen type II, chitosan, poly(lactic-co-glycolic acid) (PLGA) and polycaprolactone (PCL) were four commonly applied scaffolds in cartilage tissue engineering. To expand the application of the same animal model in cartilage tissue engineering, these four scaffolds were selected and compared for their ability to generate cartilage with chondrocytes in the same model with an in vivo bioreactor. Gene expression and immunohistochemistry staining methods were used to evaluate the chondrogenesis and osteogenesis of specimens. The result showed that the PLGA and PCL scaffolds exhibited better chondrogenesis than chitosan and type II collagen in the in vivo bioreactor. Among these four scaffolds, the PCL scaffold presented the most significant result of chondrogenesis embedded around the vascular pedicle in the long-term culture incubation phase.