ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
Three-dimensional cell scaffolds play an important role in tissue engineering. They can modulate cell response and guide the regeneration of tissues. Injectable scaffolds can mimic the chemical and physical environments of natural extracellular matrix, and can be easily applied in clinic with the merits of minor or nonsurgical operations. Hence, special care should be given to the use of this kind of scaffolds in tissue engineering hydrogels, and composites with other fillers have been used as a basic component to construct the injectable scaffolds. Most of these injectable scaffolds are applied to repair bone and cartilage. Experimental results have development of the injectable scaffolds in recent years. The advantages and disadvantages are discussed with the development of the injectable scaffolds in recent years. The advantages and disadvantages are discussed with the suggestions for future development.
Subject(s)
Humans , Absorbable Implants , Biocompatible Materials , Bone and Bones , Physiology , Cartilage , Physiology , Guided Tissue Regeneration , Hydrogels , Tissue Engineering , Methods , Tissue ScaffoldsABSTRACT
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.
Subject(s)
Humans , Biocompatible Materials , Chemistry , Collagen , Chemistry , Dermis , Cell Biology , Porosity , Skin, Artificial , Tissue Engineering , MethodsABSTRACT
As regeneration scaffolds or templates in tissue engineering, polymeric materials play key roles in inducing tissue regeneration, and mediating cell growth and differentiation, i.e. functioning as artificial extracellular matrix. The polymeric materials including biological derived biopolymers and synthetic polymers, which are usually employed in tissue engineering, are reviewed in this paper.
Subject(s)
Biocompatible Materials , Cellulose , Collagen , Hyaluronic Acid , Lactic Acid , Polyesters , Polymers , Tissue EngineeringABSTRACT
The schematic structure model, materials selection and microstructure modulation are introduced for the design of artificial dermis equivalent. The artificial skin should also possess a bilayer structure that imitates then natural skin, i.e. the top layer functions as a temporary epidermis which is composed of polymer elastomer that is permeable for moisture but not for water, the bottom layer is the skin regeneration template employing collagen based sponge. In addition to collagen, polysaccharides like glycosaminoglycan is also used in the artificial dermis equivalent in order to simulate the natural extracellular matrix of skin and to modulate the degradation rate. The pore size and morphology of collagen porous membranes can be controlled by variation of the pH value, concentration and freezing temperature. Hence, the microstructure of the dermis equivalent can be optimized. The collagen based artificial dermis equivalent thus fabricated may be an option to skin graft in the clinical treatment of full skin injuries and ulcers.
Subject(s)
Humans , Biocompatible Materials , Collagen , Equipment Design , Models, Structural , Polysaccharides , Skin, Artificial , Tissue EngineeringABSTRACT
AIM: To evaluate the blood compatibility of a new bioartificial reactor membranous material (propylene-acidamide grafted poly propylene membrane, PP-g-AAm) in vitro. METHODS: Contacted PP-g-AAm membrane and PP (polypropylene) memb rane with platelet-rich plasma in a swing bed, 37 ℃, to simulate the conditions in vivo, and another group of PRP without any membranes was set as control group. ELISA was used to study the expression of ?-thromboglobulin, and flow cy tometry was used to study CD62P and CD63 expressio n of the activated blood platelets after contacting the two kinds of membranes w ith PRP. Scanning electrical microscopy was used to study the configuration and numbers of platelet cells adhered on the membranes. RESULTS: After contacting with PRP 30 min, ?-TG expression show ed marked difference between the two kinds of material groups and the control gr oup (P