A microcapsule is a spherical, with a diameter that can be controlled in the range of 200 -1500 μm and biocompatible semipermeable membrane, which allows the bidirectional diffusion of nutrients,oxygen, secreted therapeutic product, and waste but prevents the penetration of high molecular weight substances from the microcapsule, such as antibodies and immunocytes. In comparison to monolayer culture and multicellular tumor spheroid model, orthotopic injection of microencapsulated tumor cells has uncomparable advantages in cell proliferation, mimicking the in vivo situation, making orthotopic tumor model and distant organ metastases model. Microencapsulated tumor assay has the potential of being widely used for in vitro anticancer drug screening and evaluation of the effects. This article mainly reviews the advantages of microencapsulated tumor assay and its application.

Pancreatic cancer is a highly malignant tumor. Animal models of pancreatic cancer included xenograft models, carcinogen induced models, genetically engineered models. Xenograft models are relatively reliable and feasible, but the growth pattern is different between serve immunodeficienct animals and human beings. Carcinogens induced models simulated the environmental factors to reconstruct the development of pancreatic cancer. But carcinogens could have other biological effects. Genetically engineered models could make the occurrence of pancreatic cancer at the molecular level. But it is difficult to control the transgenic product accurately. No model could meet all the needs of different experiments. It is important to choose a suitable animal model in different experiments.

BACKGROUND: Contacting with blood, most of polymer materials lead to different extents of blood coagulation, which limits their clinical application. Therefore, developing polymer materials with excellent anticoagulant property has become a key to clinical study of bioartificial liver materials.OBJECTIVE: To in vitro detect the blood dompatibility of polyacrylamide grafted polypropylene (PP) membrane (PP-g-AAm), a novel artificial liver reactor material.METHODS: Prior to and after modification, hemolytic test, prothrombin time and activated partial thromboplastin time tests of PP membrane were performed; blood platelet CD62P and CD63 expression rates were determined by flow cytometry, and platelet adhesion on PP and PP-g-AAm membranes by scanning electron microscopy.RESULTS AND CONCLUSION: The hemolysis ratio of PP and PP-g-AAm membranes was 1.32% and 1.46%, respectively.Compared with PP-g-AAm membrane, prothrombin time and activated partial thromboplastin time of PP membrane weremarkedly shorter (P < 0.05). CD62P and CD63 expression rates in the PP-g-AAm membrane were significantly lower than PP membrane (P < 0.05). Scanning electron microscopy results revealed that there were obvious changes of platelets adhering to these two membranes, but platelets adhering to PP-g-AAm membrane were fewer than PP membrane. These results indicate that PP-g-AAm membrane exhibits good blood compatibility.

Objective To evaluate reoperations for benign bile duct strictures after a prewousRoux-en-Y hepaticojejunostomy.Methods Clinical date of 28 patients with previous reconstruction of Roux-en-Y hepaticojejunostomy for benign bile duct strictures were retrospectively analyzed.For data staftstical analysis t-test and stepwise logistic regression analysis were used.Results Reoperative surgery was performed for residual biliary stones with bile duct stricture in 10 cases(35.7%),simple anastomotic stricture of hepaticojejunostomy in 11 cases(39.3%),remained biliary stricture after initial rear in 6 cases (21.4%).anastomotic leakage with duodenal leakage in one case(3.6%).Mode of reoperation:18 cases (64.3%)underwent hepatic lobectomy with Roux-en-Y hepaticojejunostomy,liver splitting approach to Roux-en-Y hepaticojejunostomy in 5 cases(17.9%),right hemihepatectomy in one case(3.6%),resection of anastomotic stenosis involved segment and Roux-en-Y hepaticojejunostomy in one case(3.6%),abdominal drainage and duodenum fistulization and jejunum ostomy in one case(3.6%),choledocholithotomy with T-tube drainage in 2 cases(7.1%);Thirteen patients(46.4%)developed postoperative complications.Conclusion Biliary tract stenosis remains the main cause for reoperation in patients undergoing a faeled reconstruction.Wide and patent biliary tract drainage and reconstruction somenmes necessitate a hepatic lobectomy.

BACKGROUND: Presently, there is not an optimal cryopreservation protocol of the microcapsules, which has restrained the application of the microcapsules. OBJECTIVE: To investigate the characteristics of ice crystal and the morphology of alginate-chitosan-alginate (ACA) microcapsules cryopreserved at different solutions and different cooling rates, and to explore the optimal cryopreservationprotocol for ACA microcapsules. DESIGN, TIME AND SETTING: An observational study was performed at the Laboratory of Cryomicroecope in Shanghai University of Science and Technology (China) from February to April in 2008. MATERIALS: The high-voltage pulsing microcapsule shaping device was used to prepare ACA microcapsules.METHODS: The ACA microcapsules were preserved at different cooling rates (1 ℃/minute, 10 ℃/minute, 30 ℃/minute and 100 ℃/minute) by the cryomicroscopy system and then rawarmed at 50 ℃/minute. The protocols were repeated after the supplement of 10% dimethyl sulphoxide. MAIN OUTCOME MEASURES: The growth of ice crystals and the morphology of ACA microcapsules were checked at different cooling rates and in different solutions. The changes of forms and the rates of damage were checked after the microcapsules were rewarmed.RESULTS: The ice crystals grew into big crystals at the freezing process when the cooling rate was low than 10 ℃/minute and cryoprotector was not used. The growth of ice crystals would result in the distortion of microcapsules. It also could reduce the cryodamage of the microcapsules. The size of the ice crystals would grow down when raising the cooling rate and using thecryoprotector. The post-thaw ACA microcapsules were intact when dimethyl sulphoxide was used at a concentration of 10% and the cooling rate was higher than 30 ℃/minute (P ＜ 0.05). CONCLUSION: Mechanical damage occurs mainly during the growing of ice crystals at the time of microcapsules cryopreservation process. The growth of the ice could be restrained effectively by raising the cooling rate and using the cryoprotector.

BACKGROUND: Membrane materials of bioreactor have exchange of substance and good physiochemical characteristics as well as good biocompatibility.OBJECTIVE: To evaluate the biocompatibility of interface of human hepatocyte/microporous polypropylene, i.e. graft modified microporous polypropylene semipermeable ultrafiltration membrane (MPP).DESIGN, TIME AND SETTING: Animal observation was performed at the Organ Transplantation Center, Ruijin Hospital of Shanghai Jiao Tong University Medical School and Polymers Institute of Zhejiang University between September 2005 and October 2007.MATERIALS: The microporous polypropylene ultrafiltration plane thin membranes, 0.2 μm diameter, M<,r> 50 000-100 000 molecular blockage, were used. Photochemical graft polymerization modification technique was adopted to graft hydrophilic acrylamide group through chemical bonds on MPP surface and succeeded in constructing an interface of human hepatocyte/microporous polypropylene, i.e. bioreactor membrane of bioartificial liver, graft modified MPP.METHODS: The biocompatibility of modified MPP was evaluated by hemolysis test, cytotoxicity test, acute systemic toxicity test, pyrogen test, skin sensitization and percutaneous stimulation test according to the requirements and biological evaluation criteria of medical device of ISO10993-1:1992.MAIN OUTCOME MEAURES: The experimental results of hemolysis, cytotoxicity, general acute toxicity, pyrogen, skin sensitization and percutaneous stimulation of modified MPP.RESULTS: The hemolytic rate of modified MPP was 1.90% (<5%), which showed that modified MPP did not lead to hemolysis. The extract solution of modified MPP exhibited no significant inhibition on the proliferative activity of L929 cells. At 24, 48 and 72 hours after MPP injection, no mice death, significant changes in body mass, or acute systemic toxicity were observed, such as ptosis, dyspnea, eyanosis, abdominal stimulation, diarrhea, decreased movement or tremor. In rabbit pyrogen test, the body temperature changed in a range from -0.2 to 0.4, which was consistent with the evaluation criteria of biomedical materials without pyrogen. Only one case was found with very slight erythema in skin sensitization test; its integral was 1 and primary stimulation index was 0.25 (<0.4), and the primary stimulation index of percutaneous stimulation test was 0.2; the average primary stimulation index was 0.068, indicating that modified MPP had no skin irritation.CONCLUSION: Modified MPP has no haemolytieus, cytotoxicity, pyrogenicity or skin sensitization, suggesting good biocompatibility by photochemical graft acrylamide on the surface of MPP.

BACKGROUND: Microcarrier culture technology has become a new and large scale cell culture technology. It has been mainly used in the amplification research of tissue engineering seed cells. Microcarder possesses the advantage of larger surface area and plays an essential role in microcarrier culture technology.OBJECTIVE: To sum up the biomaterials and methods of microcarrier preparation, and provide theoretical foundation for the study of microcarrier culture technology and tissue engineering.METHODS: Articles were retrieved from PubMed, Wanfang, and VIP databases with the key words of "micrecarrier, biomaterials cell culture, tissue englneering" in both English and Chinese between 1967/2009 and 1990/2009, respectively. Inclusion criteria:study addressing microcarrier materials, preparation, and performance; study of microcerrier cell culture; animal experiments and clinical applications. A total of 34 articles were originally retrieved based on their titles and abstracts.RESULTS AND CONCLUSION: Although a lot of studies have reported research and preparation of microcarrier, clinical application remains still difficult. Recently, varying materials will be made into novel compound materials by new technology,which can adjust mechanics and biodegredation of microcarder via surface modification.

With the development of cell separation technique, hepatocyte transplantation becomes a hot topic; however, the application is limited by donor deficiency and immunological rejection. Microencapsulated hepatocytes contribute to the promotion and application for liver cell transplantation, for which provide a large amount of high activity and good function of liver cells, in this paper, liver cell microencapsulation technology and its progress in applications were reviewed, providing prospective way for large-scale and high-active culture in vitro and long-term cryopreservation.

Hepatocyte transplantation may be a viable alternative treatment to liver transplantation for acute/chronic liver failure and metabolic liver disorders. Hepatocyte transplantation is an effective treatment to support liver function around liver transplantation due to its relatively easy manipulation and mild wound. In recent two decades, hepatocyte transplantation have been applied in clinical treatment and showed some effect in acute/chronic liver failure and metabolic liver disorders. Here, we sum up the status of clinical hepatocyte transplantation, discuss its value in clinical application and some challenges need to resolve.

OBJECTIVE: To analyze the research literatures related to bioartificial liver, and to make a conclusion concerning the development of bio-artificial liver.DATA SOURCES: Using bioartificial liver, liver cell, hepatocyte culture and bioreactor as search terms, searching Ovid, Springer Link database, and China National Knowledge Infrastructure, Vip Information database and Wanfang Date (1990.09-2008.09). Literatures search was limited to English and Chinese languages.DATA SELECTION: Researches regarding liver cells of bioartificial liver, reactors and auxiliary equipment was included, and the studies about immune and animal infection studies of bioartificial liver were excluded.MAIN OUTCOME MEASURES: ①The source, quantity and culturing of bio-artificial liver hepatocytes. ②Bioreactor type, nature and type of films. ③Composition of oxygen and temperature control devices of bioartificial liver.RESULTS: Totally 3898 documents seized initially in the searching by computer, according to inclusion and exclusion criteria, 29 were analyzed. Bioartificial liver was a hybrid device in which can culture hepatocytes in vitro, when the patient's blood flows through the device, material exchange with the cultured hepatocytes through semi-permeable membrane or direct contacting can take place, which can perform the same roles of detoxification, synthesis, biological transformation and other functions as real liver cells, so as to achieve the purpose of support and treatment. Bioartificial liver can also be involved in metabolism of the three major nutritive substances, as well as secretion of hepatocyte growth promo ting substances. So it is an effective alternative to the real liver as the function of detoxification and synthesis, and can fills the essential gap between the transplantation and acute liver failure.CONCLUSION: Although the bioartificial liver research has made significant progress, it still faces the problems such as limited liver cells sources, long-term maintenance of liver cell activity and function, and further optimization of the reactor design.