The factors controlling the microstructure and properties of collagen-based bioactive artificial dermis are reviewed. The second component, the pore diameter and porosity, the thickness of scaffold, the bioactive factors as well as the cross-linking density that are important parameters of artificial dermis should be carefully researched and designed. Experiment methods controlling these parameters are suggested.
Biocompatible Materials ; chemistry ; Collagen ; chemistry ; Dermis ; cytology ; Humans ; Porosity ; Skin, Artificial ; Tissue Engineering ; methods

Objective To investigate the possibility of hair follicle reformation induced by hair follicle bulb cells implanted into collagen/chitosan porous scaffolds in vivo, and to observe the angiogenesis in implanted scaffolds.Methods Hair follicle bulb cells obtained by enzyme digestion from the hack skin of C57BL/6J mice were implanted into collagen/chitosan porous scaffolds followed by 2-week organotypie culture.Then,these collagen/chitosan porous scaffolds were transplanted subcutaneously into the dorsal skin of nude mice.Those nude mice transplanted with empty collagen/chitosan porous scaffolds served as the controls.The growth of hair was observed with naked eyes.Six weeks after the transplantation,skin samples were obtained from the recipient site and subjected to histological examination.Results Five weeks after the transplantation,hair growth was observed in the dorsal skin of nude mice.Six weeks later,histological examination revealed fully differentiated hair follicles and vessel-like structures in the center of collagen/chitosan porous scaffolds.However,the transplantation with empty collagen/chitosan porous scaffolds failed to elicit the same response.No hair or follicles were observed in the control mice alpng with small number of vessel-1ike structures.Con-clusions Hair follicle bulb ceils implanted into collagen/chitosan porous scaffolds in vivo could induce hair follicle reformation and promote the formation of vessel-like structure in the scafffold center.

BACKGROUND: Hepatocyte/polymer interface with good biocompatibility is the key factor in bioreactor design andconstruction, however, bioreactor used in the clinical practice currently is not an ideal one.OBJECTIVE: To establish human hepatocyte compatible polypropylene interface and to lay a foundation for establishingbioartificial liver reactor with polypropylene hollow fiber.DESIGN, TIME AND SETTING: The comparative observation, cell compatibility experiment was performed betweenFebruary and October 2003 at Shanghai Jiao Tong University, Shanghai, China.MATERIALS: Polypropylene Photochemical graft polymerization modification technique was used to graft hydrophilicacrylamide groups on the surface of polypropylene membrane by chemical bonds to form modified polypropylenemembrane.METHODS: L02 human hepatoeytes were seeded on polypropylene membrane, modified polypropylene membrane andpolystyrene membrane, and polystyrene membrane was used as normal control.MAIN OUTCOME MEASURES: Static water contact angle of polypropylene membrane before and after graftmodification; morphology, adherent rate and proliferation activity of L02 human hepatocytes on different material surfaces.RESULTS: Static water contact angle after polypropylene membrane graft modification was smaller than that before graftmodification (P < 0.05). The adherent rate of L02 human hepatocytes on the surface of modified polypropylene membranewas 0, and the proliferation activity of them, which grew as spherical aggregates, was markedly higher than that of cells onpolystyrene membrane and polypropylene membrane without graft modification.CONCLUSION: Grafting polyacrylamide on the surface of polypropylene can establish good interface of L02 humanhepatocytes/polypropylene and form hepatocyte spherical aggregates through simple static culture.

Objective To establish a druggability evaluation method for new targets of anti-tumor drugs by analyzing the mutation genes of common tumors in the digestive system. Methods We collected the mutant gene data of the five common tumors of the digestive system (esophageal cancer, gastric cancer, colorectal cancer, liver cancer and pancreatic cancer) in the Integrative Onco Genomics database, and screened out the genes with higher mutation rates in each tumor. We evaluated the druggability of these genes or their encoded proteins, and discovered the potential targets for the new anti-tumor drugs. Results A total of five tumors, 35 cohorts and 5445 tumor samples were collected in this study. The top 10 mutation genes were selected for further analysis. The canSAR database was used to analyze the druggability of unpublished mutant genes or their encoded proteins, and a total of 17 potential therapeutic drug targets were screened out. Conclusion A method for evaluating druggability of targets based on mutant genes or their encoded protein is established in this study. The application of this method can provide a reference for discovering new anti-tumor therapeutic target, saving the cost and time of target screening in new drug development.

Objective To explore the value of high-resolution MRI in in the preoperative evaluation of children with type Ⅰ focal cortical dysplasia (FCD). Methods The MRI and related clinical data of 52 children with FCD Ⅰ confirmed by pathology were retrospectively analyzed,Compare the detection rates of major MRI signs of type Ⅰ FCD (focal demarcation of gray and white matter,focal cortical structure abnormalities,abnormal white matter signal lesions,and local atrophy / hypoplasia) of high-resolution imaging and conventional MRI sequences,and comparisons in the assessment of lesion extent,borders,and completeness were perfomed. Results The detection rate of high-resolution imaging for blurring of gray-white matter boundaries,focal cortical structural abnormalities,and abnormal white matter abnormalities was higher than that of conventional sequences (P<0.05),there was no significant difference in the detection rate of local atrophy/dysplasia (P>0.05). 3D-T1WI showed the range and boundary of the lesion better than the conventional T1WI sequence,3D-T2FLAIR was more complete than the conventional T2FLAIR sequence. Conclusion The high-resolution MRI could improve the detection rate of various major signs of type Ⅰ FCD,could more fully display the lesion and accurately assess the scope and boundary of the lesion,and was the preferred MRI imaging sequence before surgery.

Specific pathogen-free (SPF) chickens are widely used in the research of avian diseases and vaccines. Vertically transmissible diseases are transmitted to chickens through vertical transmission, seriously affecting their survival rate, increasing production costs, and causing significant economic losses to the poultry industry, while severely impacting the breeding and use of SPF chickens. Therefore, it is crucial for researchers and managers to enhance their understanding of vertically transmissible pathogens in chickens and to develop effective monitoring measures. Quality monitoring is an important part of ensuring the quality of SPF chickens, with pathogen detection being the primary step. Based on this, it is necessary to cultivate qualified SPF chickens through purification methods and biosecurity measures. This paper reviews the major vertically transmissible pathogens in chickens, including viral pathogens, bacterial pathogens and mycoplasmas, as well as their detection methods. This study compares the differences in microbiological testing items and methods for SPF chickens between the U.S. corporate standard and the Chinese national standard. Analysis of the results shows that in both standards, vertically transmissible pathogens such as Escherichia coli, Proteus mirabilis, Salmonella, and avian leukosis are not included in the microbiological testing items for SPF chickens. Instead, these pathogens are characterized by mixed infections, and outbreaks can seriously affect flock health. To produce higher-quality SPF chickens, it is necessary to include these pathogens in the mandatory testing items. The aim of this paper is to help readers understand the relevant standards for microbiological monitoring of SPF chickens, the hazards of vertically transmissible pathogens, and prevention and control strategies, so as to provide a reference for the detection and purification of pathogens in SPF chickens.