Preparation and application of injectable sodium alginate hydrogels / 中国组织工程研究

BACKGROUND:Sodium alginate,a natural polysaccharide,has become one of the ideal materials for preparing injectable hydrogels because it is an abundant and cheap resource,and has good biocompatibility and biodegradability.It has been widely used in the production of injectable hydrogels. OBJECTIVE:To review the properties of sodium alginate,the preparation of injectable sodium alginate hydrogel,and its application progress in tissue engineering. METHODS:Web of Science,PubMed,and CNKI were searched by computer.Chinese search terms were"sodium alginate;hydrogel;injectable",and English search terms were"alginate;hydrogel;inject".The time range of searching literature was mainly from June 2017 to June 2022. RESULTS AND CONCLUSION:Alginic acid comes from a wide range of sources,and there are many modifiable groups in its molecular structure,so many injectable hydrogels with excellent properties can be produced by various chemical crosslinking or physical crosslinking methods.Introducing other bioactive molecules or drugs into sodium alginate gel can adjust its properties and broaden its application fields.In addition,injectable sodium alginate hydrogels have great application prospects in biomedicine because of their good biocompatibility,biodegradability and other physical and chemical properties.Sodium alginate hydrogels are evenly mixed with various drugs,cells,factors or other biological molecules in vitro,and can form gels in the human body,which plays a pivotal role in gene carrier,cell scaffold and wound repair.

Research progress on radioresistance and sensitization of tumor cells in three-dimensional culture system / 中华放射肿瘤学杂志

Three-dimensional cell culture is a novel type of in vitro culture method.This system can mimic the microenvironment of cell growth in vivo,where cells exhibit similar state and function to that in the in vivo environment.Currently,three-dimensional culture system has been widely applied in tissue engineering and tumor cell biology fields,etc.Radiotherapy is an important treatment of cancer.Radioresistance of tumor cells is the main cause of treatment failure,tumor recurrence and metastasis.Tumor cells can exhibit the resistant characteristics in the three-dimensional culture system,similar to those of tumor cells in vivo.Therefore,three-dimensional culture system can be adopted to investigate the radioresistance and underlying mechanism of tumor cells and identify the key factors regulating the radioresistance of tumor cells,which plays a pivotal role in enhancing the radioresistance and improving the effect of radiotherapy.This article will review recent research progress in the radioresistance and sensitization of tumor cells under three-dimensional culture system,aiming to provide reference for relevant investigations.

Effect of microencapsulation on the expression of the oxidative stress genes of HepG2 cells and exogenous regulation / 生物医学工程学杂志

The aim of this research is to investigate the influence of microencapsulation on the expression of the oxidative stress genes and exogenous regulation of HepG2 cells. We compared the expression of hemeoxygenase-1 (HO-1) and glutathione S-transferases-A1 (GST-A1) in HepG2 cells under different culture conditions through real-time PCR. The effects of exogenous antioxidants on cell viability and albumin levels were also evaluated through MTT assay and ELISA assay. The results showed that after culturing for 6 and 16 days, the expression levels of HO-1 in encapsulated cells were approximately 4.9 and 3.1 times higher than that of monolayer cells at the same culture period; As for the expression levels of GST-A1, they were elevated to 11.2 and 33 times of monolayer cells (P < 0.05). Accordingly, we found that NAC at 5-10 mmol/L significantly increased the viability by 40%-70% and the biosynthetic function by 20%-30% in microencapsulated HepG2 cells (P < 0.05). GSH increased the viability of the encapsulated cells by 20%-55% and the biosynthetic function by 15% (P < 0.05). In conclusion, oxidative stress exists in the microcapsules and affects genes expression. Exogenous antioxidants can prevent the inhibition effects of oxidative stress on cellular growth.

Growth and metabolism of osmo-sensentive yeast Y02724 and high-osmotic resistant yeast Hansel in alginate-chitosan-alginate microcapsules / 生物工程学报

To study the effect of the osmotic stress in the microenvironment on the growth and metabolism of the encapsulated cells under aerobic condition, Osmo-sensitive yeast Y02724 and high-osmotic resistant yeast Hansel were used as models to explore the growth and metabolism state of the cells cultivated inalginate-chitosan-alginate (ACA) microcapsules. The changes of the yeast cells' specific growth rate, maximum product quantity and the secretion of ethanol and glycerol were analyzed. For Y02724, the yield of ethanol was increased in the ACA microenvironment compared to suspension cultivation. For Hansel, the maximum growth speed of microencapsulated cultivation had no obvious difference compared to the suspension cultivation. Moreover, after encapsulation, the production of glycerol was decreased for both Y02724 and Hansel compared to suspension cultivation. In conclusion, osmotic stress existed in the ACA microcapsules and affected the growth and metabolism of the cells.

Effect of Transplanting Encapsulated Cells Transfected with Nerve Growth Factor Gene on Peripheral Nerve Regeneration Following Nerve Injury / 中国康复理论与实践

@#ObjectiveTo investigate the effect of microencapsules cells transfected with nerve growth factor (NGF) gene to the sciatic nerve regeneration following sciatic nerve injury in rats.MethodsMicroencapsules containing cells transfected with NGF gene were prepared using drop generative technique and cells were cultured in vitro. Animal model of sciatic nerve cut and sutured was established with Sprague-Dawely rats, and ninety-six animals were randomly divided into group A (in vivo implantation of microencapsules cells transfected with NGF gene), group B (in vivo implantation of microencapsule), group C (in vivo implantation of cells transfected with NGF gene), and group D (negative control group). The nerve conductive velocity (NCV), nerve action potential (NAP), sciatic nerve function index (SFI) were detected in the 4th, 8th and 12th week postimplantation.ResultsThe microencapsules cells transfected with NGF gene in microencapsules retained reliable cell viability and function. The expanded cells formed cell aggregates, with confocal laser scanning microscopy (CLSM), exhibited green fluorescence material in the cell. The NGF concentration in supernatant were arriving at 269 pg/ml when cultured for 10 days. The results of NCV, NAP and SFI tests in group A were higher than those in the other groups (P<0.05).ConclusionAfter implantation, microencapsules cells transfected with NGF gene may secrete NGF continuously in vivo, and has significant improvement effect on nerve regeneration following sciatic nerve injury.

Biological property of microencapsulating material in treatment of Parkinson disease with encapsulated PC12 cell / 中国组织工程研究

BACKGROUND: Parkinson disease(PD) is a series of clinical symptom induced by decreased dopamine (DA) in the striatum due to nigral dopaminergic neuronal degeneration. The intracerebral transplantation of secretory DA can reverse or improve the symptoms to a certain extent, but immunologic rejection is still existed.OBJECTIVE: To probe into cell transplantation with immunoisolation in treatment of in rats without application of immunosuppress and observe its mechanical intensity and the biocompatibility of microcapsule .DESIGN: Randomized controlled experiment was designed.SETTING: Biomedical Material Engineering Group, Dalian Institute of ChemicalPhysics , Chinese Academy of Sciences, and Department of Neurology, Second Hospital of Jilin University.MATERIALS: The experiment was performed in Animal Experimental Center of Second Hospital of Jilin University from August 2003 to February 2004, in which, 40 male Wistar rats were employed. PC12 cell was provided from Shanghai Institute of Cellular Biology of Chinese Academy of Sciences.METHODS: 6-hydroxydopamine solution was infused in the striatum to prepare animal model of Parkinson disease. Twenty-five rats of those had been prepared successfully and were randomized into microencapsulated cell transplantation group (12 rats), in which, 25 μL cell-loading sodium alginate-chitosan-solium alginate(ACA)microencapsul suspension (equal to 2.5×104 cells) was injected stereotaxically on two points of the right (affected side) striatum of animal model; non-microencapsulated cell transplantation group (7 rats), in which, 25 μL PC12 cell suspension (equal to 5×104cells) was injected; and empty microcapsul transplantation group (6 rats),in which, 25 μL empty microcapsules suspension was injected . On the 7th day after transplantation, in every group, apomorphine (APO) prepared with saline solution was injected (0.05 mg/kg) subcutaneously in the neck; afterwards, the revolving behavior was recorded for each rat, once per week,totally for 12 weeks. In the 12th week after operation, the rats were sacrificed with anesthesia. The brain tissue was collected for pathological observation and microcapsule were retrieved to evaluation of biocompatibility and immunoisolation.numbers before and after transplantation of each group.RESULTS:Twenty-five rats entered result analysis and the rest was sule: the retrieved ACA microcapsule was integrative in morphology,munoisolation of microcapsule: microencapsuled PC12 cells were prolifercycles before and after transplantation of each group: the records of lateral revolving of rats in every group before transplantation were not significantly different (P ＞ 0.05). In microencapsuled cell transplantation group, 2weeks later, the average number of revolving was significantly lower than that before the transplantation, or even the revolving stopped; the improved symptoms were maintained till the 12th week after transplantation. In nonmicroencapsulated cell transplantation group, the average revolving number was also significantly lower than that before the transplantation, but that on the 8th and 12th weeks was in tendency of increase, without obvious change compared with that before the transplantation (P ＞ 0.05). The revolving number before and after transplantation in non-microencapsulated transplantation group was similar[(10.5±1.4), (10.5±1.3) cyclos/min, P ＞ 0.05].microcapsule provides immune protection. The grafted encapsulated PC12cells survive for along term in the brain of rats with PD, maintain continuously the normal physiological function and improve the symptoms of PD by synthesizing and releasing DA.