Perfusion circuit concepts for hollow-fiber bioreactors used as in vitro cell production systems or ex vivo bioartificial organs

For the development and implementation of primary human cell- and stem cell-based applications in regenerative medicine, large amounts of cells with well-defined characteristics are needed. Such cell quantities can be obtained with the use of hollow fiber-based bioreactors. While the use of such bioreactors generally requires a perfusion circuit, the configuration and complexity of such circuits is still in debate. We evaluated various circuit configurations to investigate potential perfusate volume shifts in the arterial and venous sides of the perfusion circuit, as well as in the feed and waste lines. Volume shifts with changes in flow conditions were measured with graduated bubble traps in the circuit, and perfusion pressures were measured at three points in the circuits. The results of this study demonstrate that the bioreactor perfusion circuit configuration has an effect on system pressures and volume shifts in the circuit. During operation, spikes in post-bioreactor pressures caused detrimental, potentially dangerous volume shifts in the feed and waste lines for configurations that lacked feed pumps and/or waste line check valves. Our results indicate that a more complex tubing circuit adds to safety of operation and avoids technical challenges associated with the use of large-scale hollow fiber bioreactors (e.g., for extracorporeal liver support or erythrocyte production from hematopoietic stem cells), including volume shifts and the need for a large reservoir. Finally, to ensure safe use of bioreactors, measuring pre-, intra-, and post-bioreactor pressures, and pump operation control is also advisable, which suggests the use of specifically developed bioreactor perfusion devices.     

Some physico-chemical and serological properties of isolated protein components of red cell membranes

Exposure of human red cell ghosts to low pH (pH 2–2·2) for 20–24 hr and extraction with a biphasic system (butanol–water) at acid pH yielded a water-phase material which was separated by gel filtration into two major fractions. Fraction A is of glycoprotein nature having a molecular weight of approximately 200,000 and exhibiting A, M and N antigen activity. Fraction B is primarily protein in nature having a molecular weight of about 50,000 to 60,000, and is practically devoid of A and MN antigens.

The materials isolated were found heterogeneous by electrophoresis in urea starch gels. Peak A and peak B differed significantly with respect to number, mobility, and intensity of the separated components.

The physico-chemical and serological properties of the water phase and its sub-fractions are discussed with respect to structural make-up of erythrocyte membrane.

     

老化相关的自发荧光可作为细胞衰老的标志物

目的 观察衰老的脑组织内自发荧光的波长特点,探讨如何合理地利用和消减老化相关的自发荧光。方法 选取3月龄和24月龄自然老化的C57BL/6J雌、雄性小鼠。以衰老相关β-半乳糖苷酶染色（SA-β-Gal）和脂褐素的沉积评估老年鼠脑组织衰老的程度。以激光共焦显微镜分析老化相关自发荧光的波长特点,免疫组织化学和免疫荧光的方法标记星形胶质细胞。结果 老年鼠海马和下丘脑第三脑室室周旁出现强SA-β-Gal染色、脂褐素的聚集及自发荧光。老化相关的自发荧光发射波长介于500～565nm,下丘脑第三脑室室周旁的星形胶质细胞不仅高表达SA-β-Gal,而且出现很强的自发荧光。采用针对脂褐素的自发荧光消除剂处理脑组织后,老化相关的自发荧光几乎完全消失。 结论 老化相关的自发荧光可以作为特定表型细胞衰老的标志物;恰当的处理老化相关的自发荧光,可极大的提高衰老脑组织免疫荧光检测的特异性。     

Immunomodulating properties of substances to be used in combination with liposomes

Liposomes haptenated with tripeptide-enlarged dinitrophenyl (DNP) are known to act as thymus-independent antigens which induce a strong IgM response and only limited amounts of circulating IgG. When haptenated liposomes are used in vaccination studies, it is of practical importance to improve the immunogenicity of these complexes. Therefore, an evaluation was made of the potency of various substances to modulate the immune response in such a way that the total antibody production is increased, including a relative great increase of 2-mercaptoethanol (2-ME)-resistant antibodies and immunological memory is induced. The following substances were used: glycophorin A (GP-A), sialogangliosides (monosialo-, disialo- and trisialoganglioside), 6-0-stearoyl-MDP (MDP-SA) and lipid A (lip A). Lip A incorporated into liposomes was the only substance inducing considerable increases of both total and 2-ME-resistant haemagglutination (HA) titre after immunization. Depending on the dose tested, the sialic-acid-containing protein GP-A had a small and varying influence on the serum antibody response. Sialogangliosides transiently decreased in a dose-dependent manner the total antibody titre in serum. In contrast to lip A, the lipophilic bacterial adjuvant MDP-SA did not influence HA titres significantly. The number of plaque-forming cells (PFC) in the spleen was enhanced considerably after both primary and secondary immunization with liposomes containing lip A. The other substances tested induced only minor differences of the number of PFC. To some extent, lip A induced immunological memory. In conclusion, it can be stated that of the agents tested, only lip A is a potent and consistent stimulator of the humoral immune response to liposomes haptenated with DNP groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Siliconizing glassware to be used for suspension cell culture

Summary Siliconizing glassware to be used for suspension cell culture with the reagent dichlorodimethylsilane after rigorous cleaning of the glass results in a more homogenously treated glass which will survive many detergent washings. The method described was found to be superior to other ways of coating culture glassware.     

中国人肝细胞系1运用于生物人工肝的生物代谢功能

背景：前期研究发现,中国人肝细胞系1细胞分化程度高且生物代谢功能良好, 并且中国人肝细胞系1细胞组织学上来源于正常肝组织,较其他来源于肿瘤源性的肝细胞系更为安全。 目的：探讨中国人肝细胞系中国人肝细胞系1细胞在混合型生物人工肝中的生物代谢功能。 方法：15只食蟹猴随机分成对照组(n=5)和治疗组(n=10),均建立急性肝功能衰竭模型,治疗组接受以全接触灌流型生物反应器接种微载体微重力中国人肝细胞系1细胞建立的人源细胞混合型生物人工肝进行治疗。 结果与结论：急性肝功能衰竭食蟹猴血清谷氨酸转氨酶、总胆红素、总胆汁酸、尿素氮、肌酐、血氨均明显上升,而白蛋白、Fischer指数则显著下降;人源细胞混合型生物人工肝治疗后,急性肝功能衰竭食蟹猴血清谷氨酸转氨酶、总胆红素、总胆汁酸、尿素氮、肌酐、血氨和白蛋白均恢复。提示中国人肝细胞系1细胞在混合型生物人工肝中生物代谢功能良好,表现出良好的肝特异性生物合成及生物代谢功能。     

Mechanical properties of polymeric membranes obtained by radiation cast-polymerization of hydroxyalkyl and hydroxypolyethyleneglycol methacrylate monomers

Polymeric membranes have been prepared by radiation cast-polymerization of hydroxyalkyl and hydroxypolyethyleneglycol methacrylate monomers, and the mechanical properties of the membranes before and after swelling have been studied as a function of the molecular structure of the monomers. The degree of hydration of the polymers from hydroxypolyethyleneglycol methacrylate monomers increased with increasing the number of ethyleneglycol units in the monomers, and that from hydroxyalkyl methacrylate monomers decreased with an increase in the number of methylene units. The mechanical properties such as tensile strength, tear strength, Young's modulus, and elongation at break varied with the length of the methylene and ethyleneglycol units in the monomers. It was found that flexible polymeric membranes having various properties for medical applications could be obtained by radiation cast-polymerization of hydroxyalkyl and hydroxypolyethyleneglycol methacrylate monomers.     

About human tumor antigens to be used in immunotherapy

The choice of antigens to be used in cancer immunotherapy remains a crucial and difficult issue. This review highlights some properties of the different groups of human tumor antigens recognized by T lymphocytes, focusing on parameters that should influence this choice, such as tumor specificity and level of antigen expression.     

Surface properties of and cell adhesion onto allylamine-plasma-coated polyethylenterephtalat membranes

Allylamine was plasma polymerised onto a polyester (PET) membrane to obtain a surface with good cell adhesive properties. Samples were coated using a microwave plasma source operating at different process parameters. The effect of process parameters on the physical, and chemical properties of plasma-polymerised-allylamine (PPAa) was evaluated by studying elemental composition, amine concentration, wettability, and surface morphology. A relatively high amine concentration was measured (up to 50 nmol/cm2). In parallel, nitrogen enrichment was observed after exposure to high-energetic plasma. Irrespective of the treatment conditions, oxygen was incorporated into the polymer structure. PPAa surfaces were found to be more hydrophilic than PET. The wettability of the samples increased with increasing amine concentration. Pictures from scanning electron microscopy indicated that homogeneous pinhole-free PPAa layers were deposited on PET membranes, without a significant change of permeability. In vitro evaluation of biocompatibility was carried out by studying human skin fibroblast interaction with surfaces. Cell attachment and viability on PPAa layers were found to be more intensive than on the control PET, based on the higher metabolic activity of adhering cells, but also on morphological criteria including overall cell morphology.     

Atopy may be related to exercise-induced bronchospasm in asthma

BACKGROUND: Recent studies suggest that atopy may be associated with exercise-induced bronchospasm (EIB) in asthma. However, it is not clear whether atopy is related to EIB, regardless of airway hyper-responsiveness (AHR) to methacholine, because asthmatic subjects often show AHR to exercise and methacholine simultaneously. OBJECTIVE: To investigate whether atopy is related to EIB in asthmatic subjects, independently of AHR to methacholine. METHODS: Fifty-eight male asthmatic subjects were studied. Initial spirometry was performed. Skin prick test was carried out, using 53 common allergens including mites dust antigen. Atopy score was defined as a sum of mean weal diameters to all allergens tested. Methacholine bronchial provocation testing was performed. Twenty-four hours later, free running test was performed. Positive EIB was defined as a 15% reduction or more in FEV1 from baseline after exercise. RESULTS: All subjects had AHR to methacholine. The degree of AHR to methacholine in asthmatics with EIB was similar to that in asthmatics without EIB. However, atopy score and skin reaction to Dermatophagoides pteronyssinus significantly increased in asthmatics with EIB compared with those without EIB (P < 0.05, respectively). Furthermore, the degree of EIB significantly correlated with atopy score in all subjects (r = 0.35, P < 0.01). This relationship was maintained even after the exclusion of EIB-negative asthmatic subjects. CONCLUSION: Atopy defined as skin test reactivity may contribute to the development of EIB in asthma, independently of AHR to methacholine.     

Evaluation of proliferation and functional differentiation of LLC-PK1 cells on porous polymer membranes for the development of a bioartificial renal tubule device

To develop a bioartificial renal tubule system using renal tubular cells and porous polymer membrane hollow fibers, long-term maintenance of a confluent monolayer and the functionally differentiated condition of cells is essential. We examined the proliferation and functional differentiation of LLC-PK1 (Lewis-lung cancer porcine kidney 1) cells on two types of membranes: polysulfone and cellulose acetate. Cell proliferation was significantly higher on the polysulfone membrane than on the cellulose acetate membrane, and was enhanced by coating the membranes with various extracellular matrices. Confluent monolayer formation of cells was observed on matrix-coated polysulfone membrane but not on matrix-coated cellulose acetate membrane within 1 week. Cell proliferation continued for 3 weeks after confluent monolayer formation. Messenger RNA (mRNA) expression of glucose transporters, indicators of the functional differentiation of the LLC-PK1 cells, was observed in the polysulfone and cellulose acetate membrane groups, but was not observed in the nonporous polystyrene plate group under subconfluent conditions. Expression of glucose transporters mRNA was maintained for 3 weeks after confluent monolayer formation. Polysulfone membrane is more suitable than cellulose acetate membrane for a bioartificial renal tubule system with regard to LLC-PK1 cell proliferation. Extracellular matrix coating of the membrane further improves cell proliferation.     

Ex situ bioengineering of bioartificial endocrine glands: A new frontier in regenerative medicine of soft tissue organs

Ex situ bioengineering is one of the most promising perspectives in the field of regenerative medicine allowing for organ reconstruction outside the living body; i.e. on the laboratory bench. A number of hollow viscera of the cardiovascular, respiratory, genitourinary, and digestive systems have been successfully bioengineered ex situ, exploiting biocompatible scaffolds with a 3D morphology that recapitulates that of the native organ (organomorphic scaffold). In contrast, bioengineering of entire soft tissue organs and, in particular endocrine glands still remains a substantial challenge. Primary reasons are that no organomorphic scaffolding for endocrine viscera have as yet been entirely assembled using biocompatible materials, nor is there a bioreactor performance capable of supporting growth within the thickness range of the regenerating cell mass which has proven to be reliable enough to ensure formation of a complete macroscopic gland ex situ. Current technical options for reconstruction of endocrine viscera include either biocompatible 3D reticular scaffolds lacking any organomorphic geometry, or allogenic/xenogenic acellular 3D matrices derived from a gland similar to that to be bioengineered, eventually recellularized by autologous/heterologous cells. In 2007, our group designed, using biocompatible material, an organomorphic scaffold-bioreactor unit for bioengineering ex situ the human thyroid gland, chosen as a model for its simple anatomical organization (repetitive follicular cavities). This unit reproduces both the 3D native geometry of the human thyroid stromal/vascular scaffold, and the natural thyrocyte/vascular interface. It is now under intense investigation as an experimental tool to test cellular 3D auto-assembly of thyroid tissue and its related vascular system up to the ex situ generation of a 3D macroscopic thyroid gland. We believe that these studies will lay the groundwork for a new concept in regenerative medicine of soft tissue and endocrine organs; i.e. that the organomorphism of a biocompatible scaffold-bioreactor complex is essential to both the 3D organization of seeded stem cells/precursor cells and their phenotypic fate as glandular/parenchymal/vascular elements, eventually leading to a physiologically competent and immuno-tolerant bioconstruct, macroscopically suitable for transplantation and clinical applications.