Apoptosis of breast cancer cell MCF-7 induced by morcantharidin(NCTD)

To study the cytotoxic effects and antitumour mechanism of norcantharidin(NCTD) on human breast cancer cell, MCF-7 cells were exposed to culture medium with NCTD in different doses and hours. The cell growth inhibition curves of NCTD on MCF-7 cells were acquired by detecting the growth ratio of MCF-7 cells with MTT methods. The results indicated that NCTD had inhibition effects on growth of MCF-7 cells depending on the doses and times of treatment. When the concentrations of NCTD used was lower than 5 μg/ml, the cells grew as same as the control cells. With increasing doses and times of treatment, the inhibition effects of NCTD on the cells' growth increased, for example, when exposed to 10 μg/ml NCTD     

Quantitative aspects of the selective killing of transformed cells by methotrexate in the presence of leucovorin

Summary A quantitative study was made of the cytotoxicity of methotrexate (MTX) for nontransformed and transformed NIH 3T3 cells in the presence and absence of leucovorin. The study was preceded by an analysis of the growth rates of the cells at low and high population density combined with low and high concentrations of calf serum (CS). The reduced maximal growth rates of the transformed cells at low population densities relative to the nontransformed cells reinforced earlier evidence that heritable damage involving chromosome aberrations drives the process of transformation. When small numbers of transformed cells are cocultured with a large excess of nontransformed cells in the assay for transformed foci, the transformed cells were more readily killed by MTX than the nontransformed cells. The selectivity was increased when leucovorin (folinic acid) was present in the medium. The selective killing of the transformed cells actively multiplying in foci was most pronounced when the background of nontransformed cells had become confluent and their growth was inhibited. However, selectivity has also been demonstrated when transformed and nontransformed cells are growing at their maximum rates at low density despite the lower growth rate of the transformed cells under these conditions. The sensitivity of transformed cells in pure culture to MTX was lower during the first 3 d of subculture than in the following 6 d but decreased to zero a few d after net growth had ceased. The nontransformed cells were more susceptible to killing by MTX in Dulbecco’s modified Eagle’s medium (DMEM) than in MCDB 402, but the transformed cells were sensitive to MTX in both media. The high selectivity of MTX for transformed over nontransformed cells in MCDB 402 results from the presence of 1.0 μM leucovorin (5-formyltetrahydrofolate), a reduced form of the folic acid present in most other culture media. When leucovorin was added to DMEM with its high concentration of folic acid, the resistance to MTX of both nontransformed and transformed cells was greatly increased, but the selectivity of MTX for transformed cells was almost entirely lost. The results indicate that leucovorin protects nontransformed cells against concentrations of MTX that kill transformed cells, but the protection is dependent on the relative amounts of leucovorin to folic acid in the medium. The relative sensitivities of transformed and nontransformed cells in our system to MTX when both cell types are exhibiting their characteristic differential in growth behavior is similar to that described for tumor and normal cells in vivo. Since the unregulated growth behavior of the transformed, tumor-producing cells is efficiently and quantitatively measured in this system, it can be used to develop general principles of treatment and resolve questions of cytotoxic mechanism.     

The effects of cell density, attachment substratum and dexamethasone on spontaneous apoptosis of rat hepatocytes in primary culture

Summary The rates of spontaneous cell detachment, cell viability, and apoptosis in primary cultures of rat hepatocytes plated at high and low density were compared. Apoptosis was frequent in detached cells, and the rates of cell detachment and apoptosis were greater in high-density than in low-density cultures. Among attached cells, more cells had condensed or fragmented nuclei in high-density than in low-density cultures. Further, ladder-like DNA fragmentation was not seen in low-cell-density cultures but was clearly evident in high-density cultures. Bax was more highly expressed in cells cultured at high density, and on collagen vs. matrigel, whereas changes of Bcl-2 and Fas expression observed in culture appeared unrelated to the rate of apoptosis. The rate of hepatocyte apoptosis appeared to be identical in low-density cultures on collagen 1 and matrigel, but when cells were cultured at high density, matrigel suppressed apoptosis by more than 50% at 36 h. In hepatocytes cultured on collagen 1, dexamethasone (0.1 μM) suppressed apoptosis in both low- and high-density cultures; higher doses had no further effects. In high density cultures, aurintricarboxylic acid (10 μM) suppressed apoptosis and this improved cell attachment at 48 h. It is concluded that cell viability in primary cultures of rat hepatocytes grown on collagen I is dependent on optimal culture density and that the cell population is regulated, at least in part, by apoptosis. Corticosteroids suppress spontaneous apoptosis of cultured hepatocytes in a non-dose-dependent manner, whereas matrigel abolishes apoptosis induced by increasing cell density. Bax may be an important protein in the cell density and cell matrix-dependent regulation of apoptosis in cultured hepatocytes.     

Inhibitory effect of parvovirus H—1 on the formation of colonies of human hepatoma cell line in vitro and its tumors in nude mice

The inhibitory effect of parvovirus H-1 on the colonyforming ability.in vitro of QGY-7703,a cultured human hepatoma cell line,and on the formation and growth of its tumors in nude mice was studied.With higher multiplicity of infection(MOI) of H-1 given,survival of the QGY-7703 cells was found to be decreased.H-1 DNA amplification level at 30h postinfection(p.i.) was detected to be 7.4 times higher than that at 2h by dispersed cells assay,while the cells were delayed to enter into S phase.Plaques were formed in the indicator cells(new-born human kidney cell line,NBK) by progeny H-1 virus particles released from the infected QGY-7703 cells by infectious cell center assay.The formation of tumors in nude mice by QGY-7703 cells which were injected s c at 2h postinfection was observed to by prevented in 2 proups with given MOI 25 and 50.The tumor growth of MOI 10 group occurred at a lower exponential rate than that of control,after a 20d latent period.It was evident that parvovirus H-1 exhibited a direct inhibitory effect on the formation and growth of human hepatoma cells in vivo as well as in vitro.     

Comparative studies on histological and ultra-structure of the pituitary of different ploidy level fishes

The histological and ultra-structure of the pituitary in diploid red crucian carp(Carassius auratus red var.),triploid crucian carp and allotetraploid hybrids within and after the breeding season were comparatively studied.The result showed that there were six endocrine cell types in the pituitary of these three kinds of fishes,and there was an obvious difference in cell size among different ploidy level fishes.As for the same type of pituitary cells,the cell size was increased gradually with the in- creasing ploidy level.In the breeding season,the allotetraploid hybrids had higher proportion of go- nadotropin cells(GTH)than triploids,and the triploids had higher proportion of GTH than diploids.The results were related to the earlier sexual maturity of allotetraploid hybrids and sterility of triploid cru- cian carp.On the other hand,among the three kinds of fishes,the proportion of somatotropin(STH) cells in triploids crucian carp was the highest,whereas that in allotetraploid hybrids was the lowest. The results might be connected with the faster growth rate of triploids and slower growth rate of al- lotetraploid hybrids.In addition,in GTH cells of meso-adenohypophysis after the breeding season, there were many endocrine particles in triploids,while those endocrine particles were released from the cells in allotetraploids and diploids.This result showed that the sterility of triploid crucian carp might be related to the hormone which was not released from the GTH cells.In a word,the present study indicated that the differences in the structure of pituitary among different ploidy level fishes contributed to their difference in the growth rate and gonadal development.     

Correlation of hyaluronic acid accumulation and the growth of preneoplastic mammary cells in collagen: A lonitudinal study

Summary Hyaluronic acid accumulation is characteristic of mammary tumor cells, and the amount that accumulates seems to correlate with the degree of malignancy of the producing cells. We have tested directly the relationship between hyaluronic acid accumulation and the replication rate of preneoplastic mammary cells in culture. We used nontumorigenic but immortal CL-S1 mouse mammary cells that were derived from a hyperplastic alveolar nodule. Using a collagen gel culture system, we found clear differences in the growth properties of cells before and after Passages 68 to 70. Late passage cells replicated earlier and faster than early passage cells in collagen and on plastic. The rate of cycling resembled that of tumorigenic mouse mammary cells during the first week of culture. Cells seeded at low densities cycled faster than those seeded at high densities during the second week in culture. Exogenous hyaluronic acid, at 10 to 1000μg/ml, neither enhanced nor inhibited CL-S1 cell growth significantly in collagen, regardless of passage. However, by the third day in collagen, late passage cells produced 7 times more total glycosaminoglycans and 12 times more hyaluronic acid per cell than did early passage cells. Late passage cells also deposited 12 times more labeled hyaluronic acid in the matrix than did early passage cells, on a per-cell basis. After a decline in the deposition of hyaluronic acid in the extracellular matrix, growth ceased. The late passage cells did not grow in soft agar, indicating that they had not become neoplastic spontaneously during passage. However, their accelerated growth rate, coupled with the synthesis and secretion of large amounts of hyaluronic acid into the extracellular matrix, may characterize a distinct step in tumor progression in preneoplastic CL-S1 cells.     

Expression of the human fast-twitch skeletal muscle troponin I cDNA in a human ovarian carcinoma sup-presses tumor growth

To explore the efficiency and mechanism of ovarian carcinoma gene therapy with the human fast-twitch skeletal muscle troponin I gene (TnI-fast), TnI-fast cDNA was transferred into human ovarian adeno-carcinoma cell-line SK-OV-3. In vitro, the cell growth and cell cycle of TnI-fast-, vector-, and mock-transfected cells were determined by MTT and flow cytometry assay, respectively. The condi-tioned media of TnI-fast-, vector-, and mock-transfected SK-OV-3 cells were collected, and the cell pro-liferation inhibiting rates of human umbilical cord venous endothelial cells (HUVECs) by the three conditioned media were assayed. All the three cell lines were implanted into node mice, and the tumor growth, cell apoptosis, angiogenesis, and expression of TnI-fast were observed or analyzed, respec-tively. In vitro, expression of TnI-fast protein had no inhibiting effect on the growth of the dominant and stable transfectant cells, but endothelium, when compared with vector-transfected cells and nontrans-fected parental SK-OV-3 cells. Implantation of stable clone expressing TnI-fast in the female BALB/c nude mice inhibits primary tumor growth by an average of 73%. The nude mice grafts expressing TnI-fast exhibit a significant decrease of microvascular density, a higher rate of tumor cells apoptosis and a comparable proliferation rate as control. Our study, to our knowledge, shows the slowed down growth of the primary ovarian carcinoma, suggested that grafts were self-inhibitory by halting angio-genesis. Our data might also provide a novel useful strategy for cancer therapy by antiangiogenic gene therapy with a specific angiogenesis inhibitor TnI-fast.     

The fluorescence brightener Rylux BSU induces dimorphism inBasidiobolus ranarum

The fluorescence brightener Rylux BSU (RBSU) showed an affinity for polysaccharide components of cell walls and accumulated in the extension zones of hyphal apices inBasidiobolus ranarum. It inhibited the polarized growth of mycelial hyphae and induced isotropic growth resulting in spherical thick-walled cells up to 456 μm in diameter. On the inner cell wall surface, massive protuberances were formed. The cell wall and protuberances were positive in PAS and the Grocott method and stained with fluorochromes Blankophor BA, Calcofluor, Uvitex 2B, Rylux BSU and FITC-labeled WGA- and ConA-lectins. The WGA-FITC fluorescence intensity of the wall’s outermost layer, if not connected with neighbouring cells, and the fluorescence intensity of the innermost layer and of some protuberances mainly in their apical parts were on the average twice higher than the fluorescence intensity of the remaining wall material. RBSU binding to the cell wall material was stable. The process of converting from polarized to isotropic growth was reversible, depending upon contact with RBSU-containing medium. Repeated transfers of cells from RBSU-containing medium to an RBSU-free medium resulted in the development of apical swollen dumbbell-shaped cells.     

Geometric control of switching between growth, apoptosis, and differentiation during angiogenesis using micropatterned substrates

Summary Past studies using micropatterned substrates coated with adhesive islands of extracellular matrix revealed that capillary endothelial cells can be geometrically switched between growth and apoptosis. Endothelial cells cultured on single islands larger than 1500 μm² spread and progressed through the cell cycle, whereas cells restricted to areas less than 500 μm² failed to extend and underwent apoptosis. The present study addressed whether island geometries that constrained cell spreading to intermediate degrees, neither supporting cell growth nor inducing apoptosis, cause cells to differentiate. Endothelial cells cultured on substrates micropatterned with 10-μm-wide lines of fibronectin formed extensive cell-cell contacts and spread to approximately 1000 μm². Within 72 h, cells shut off both growth and apoptosis programs and underwent differentiation, resulting in the formation of capillary tube-like structures containing a central lumen. Accumulation of extracellular matrix tendrils containing fibronectin and laminin beneath cells and reorganization of platelet endothelial cell adhesion molecule-positive cell-cell junctions along the lengths of the tubes preceded the formation of these structures. Cells cultured on wider (30-μm) lines also formed cell-cell contacts and aligned their actin cytoskeleton, but these cells spread to larger areas (2200 μm²), proliferated, and did not form tubes. Use of micropatterned substrates revealed that altering the geometry of cell spreading can switch endothelial cells among the three major genetic programs that govern angiogenesis—growth, apoptosis and differentiation. The system presented here provides a well-defined adhesive environment in which to further investigate the steps involved in angiogenesis.     

Hepatogenic differentiation of mesenchymal stem cells induced by insulin like growth factor-I

AIM:To improve hepatic differentiation of human mesenchymal stem cell(MSC)using insulin growth factor 1(IGF-Ⅰ),which has important role in liver development,hepatocyte differentiation and function.METHODS:Bone marrow of healthy donors was aspirated from the iliac crest.The adherent cells expanded rapidly and were maintained with periodic passages until a relatively homogeneous population was established.The identification of these cells was carried out by immunophenotype analysis and differentiation potential into osteocytes and adipocytes.To effectively induce hepatic differentiation,we designed a protocol based on a combination of IGF-Ⅰ and liver specificfactors(hepatocyte growth factor,oncostatin M and dexamethasone).Morphological features,hepatic functions and cytological staining were assessed to evaluate transdifferentiation of human marrow-derived MSCs.RESULTS:Flow cytometric analysis and the differentiation potential into osteoblasts and adipocytes showed that more than 90% of human MSCs which were isolated and expanded were positive by specif ic markers and functional tests.Morphological assessment and evaluation of glycogen storage,albumin and α-feto protein expression,as well as albumin and urea secretion revealed a statistically signif icant difference between the experimental groups and control.CONCLUSION:In vitro differentiated MSCs using IGF-Ⅰwere able to display advanced liver metabolic functions,supporting the possibility of developing them as potential alternatives to primary hepatocytes.     

Influence of biodegradable and non-biodegradable material surfaces on the differentiation of human monocyte-derived macrophages

Monocyte-derived macrophages (MDM) and multinucleated foreign body giant cells (FBGC) are the primary cell types that remain at the cell-material interface of polyurethane (PU)-based medical devices as a result of chronic inflammatory responses. In vitro studies have demonstrated that MDM possess degradative potential toward PU, which can result in device failure. Because most studies have followed the degradation potential, morphology, and function of these cells only once fully differentiated, the current study investigated the influence of a non-degradable control tissue culture-grade polystyrene (TCPS) surface relative to two degradable model polycarbonate-urethanes (PCNU), of different chemistry, on various parameters of MDM morphology and function during a 14-day differentiation time course. The differentiation of human monocytes isolated from whole blood on PCNU materials resulted in increased cell attachment, decreased multinucleation, and significant decreases in cell spreading when compared with cells differentiated on TCPS. Actin-stained podosome-like cell adhesion structures were increased in PCNU-adherent cells, accompanied by an alteration in beta-actin and vinculin protein expression. The expression of the CD68 macrophage marker was reduced when cells were adherent to the PCNU materials and compared with TCPS, suggesting altered cell activation by the degradable relative to non-degradable materials. The degradative potential of these cells was altered by the material surface they were exposed to as measured by esterase activity and protein expression of monocyte-specific esterase. This was also supported by physical material breakdown evident in scanning electron microscopy images that illustrated holes in the PCNU films generated by the presence of differentiating MDM. It was concluded from these studies that PCNU materials significantly alter the function and morphology of differentiating MDM. This must be taken into consideration when studying cell-material interactions because these cells will receive cues from their immediate environment (including the biomaterial) upon differentiation, thereby affecting their resulting phenotype.     

In vitro biocompatibility of electrospun poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) fiber mats

In the present contribution, the potential for use of the ultrafine electrospun fiber mats of poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) as scaffolding materials for skin and nerve regeneration was evaluated in vitro using mouse fibroblasts (L929) and Schwann cells (RT4-D6P2T) as reference cell lines. Comparison was made with PHB and PHBV films that were prepared by solution-casting technique. Indirect cytotoxicity assessment of the as-spun PHB and PHBV fiber mats with mouse fibroblasts (L929) and Schwann cells (RT4-D6P2T) indicated that the materials were acceptable to both types of cells. The attachment of L929 on all of the fibrous scaffolds was significantly better than that on both the film scaffolds and tissue-culture polystyrene plate (TCPS), while RT4-D6P2T appeared to attach on the flat surfaces of TCPS and the film scaffolds much better than on the rough surfaces of the fibrous scaffolds. For L929, all of the fibrous scaffolds were superior in supporting the cell proliferation to the film counterparts, but inferior to TCPS at days 3 and 5, while, for RT4-D6P2T, the rough surfaces of the fibrous scaffolds appeared to be very poor in supporting the cell proliferation when comparing with the smooth surfaces of TCPS and the film scaffolds. Scanning electron microscopy was also used to observe the behavior of both types of cells that were cultured on both the fibrous and the film scaffolds and glass substrate for 24 h.     

Enhanced adhesion/spreading and proliferation of mammalian cells on electropolymerized porphyrin film for biosensing applications

A polymer film of porphyrin was formed through electropolymerization of p-amino-substituted tetraphenylporphyrin on indium tin oxide (ITO) surfaces. The adhesion and proliferation of MCF-7 cells (human breast cancer cell line) on the film were investigated. It was found that cells cultured on this film could attach and spread more rapidly than on glass, ITO and tissue culture polystyrene (TCPS), and thus the film was demonstrated to be a good adhering substrate. MTT experimental results show that the viability of cells cultured on this film is higher than on TCPS, and fluorescence microscopic observation indicates that cells cultured on the film are not under apoptosis. Based on its excellent cytocompatibility, the polyporphyrin film was used to modify the gold electrode surface of a piezoelectric quartz crystal, and quartz crystal microbalance (QCM) technique was applied for real-time monitoring of MCF-7 cell growth and assessment of chemical cytotoxicity. The proliferation and condition of cells on the surface of the film-modified quartz crystal gold electrode were investigated through fluorescence microscopic observation. The results obtained from QCM experiments are consistent with that from microscopic observation. Additionally, the polymerized film on gold surface can be removed completely and easily, which greatly improves the reproducibility of the quartz crystal gold electrode.     

Culture of neural cells on polymers coated surfaces for biosensor applications

We focused our study on the olfactory cells growth on biocompatible polymer films electrodeposited on a silicon microsystem. Several substrates such as polyethyleneimine (PEI), polypropyleneimine (PPI), and polypyrrole (PPy), acting as potentially good candidates for cell culture, were tested in order to allow cells to adhere and proliferate. During their growth, the evolution of their morphology was monitored using both confocal microscope and immunohistochemistry, leading to the conclusion of a normal development. An estimation of the adhesion and proliferation rates of rat neuronal cell cultures indicated that PEI and PPI were the best substrates for cultivating olfactory cells.     

A chemical surface modification of chitosan by glycoconjugates to enhance the cell-biomaterial interaction

The use of wheat germ agglutinin (WGA), a lectin molecule, to modify chitosan and enhance the cell-biomaterial interaction was examined. The percentage of living fibroblast cells on the surfaces of tissue culture polystyrene (TCPS) control, WGA-modified chitosan, and unmodified chitosan films increased to 99%, 99%, and 85%, respectively, after seeding for 48 h. DNA staining revealed that a portion of fibroblasts cultivated on chitosan films( )were undergoing apoptosis. In contrast, fibroblasts growing on WGA-modified chitosan film surfaces did not show any indication of apoptosis. The number of fibroblast cells was the highest on the WGA-modified chitosan surfaces, followed by the TCPS and unmodified chitosan surfaces. This WGA-mediated enhancement on the fibroblast cell-biomaterial interaction was cell type dependent. Other types of cells may need different lectin molecules for enhanced interaction with biomaterials. Further, the evaluation of the heat shock protein (HSP) mRNA expression indicated that HSP 90 expression was increased in the fibroblast cells cultivated on chitosan films and decreased to basal levels on the WGA-modified chitosan films. Taken together, our data suggest that the use of WGA and other lectin molecules to enhance the cell-biomaterial interaction via oligosaccharide-mediated cell adhesion is a promising way to improve cell adhesion and proliferation, the two key issues in tissue engineering.     

Effect of cell-seeding density on the proliferation and gene expression profile of human umbilical vein endothelial cells within ex vivo culture

Background aimsCharacterization of endothelial cell–biomaterial interaction is crucial for the development of blood-contacting biomedical devices and implants. However, a crucial parameter that has largely been overlooked is the cell-seeding density.MethodsThis study investigated how varying cell-seeding density influences human umbilical vein endothelial cell (HUVEC) proliferation on three different substrata: gelatin, tissue culture polystyrene (TCPS) and poly-l-lactic acid (PLLA).ResultsThe fastest proliferation was seen on gelatin, followed by TCPS and PLLA, regardless of seeding density. On both TCPS and gelatin, maximal proliferation was attained at an initial seeding density of 1000 cells/cm². At seeding densities above and below 1000 cells/cm², the proliferation rate decreased sharply. On PLLA, there was a decrease in cell numbers over 7 days of culture, below a certain threshold seeding density (c. 2500–3000 cells/cm²), which meant that some of the cells were dying off rather than proliferating. Above this threshold seeding density, HUVEC displayed slow proliferation. Subsequently, quantitative real-time polymerase chain reaction (RT-qPCR) analysis of eight gene markers associated with adhesion and endothelial functionality (VEGF-A, integrin-α5, VWF, ICAM1, ICAM2, VE-cadherin, endoglin and PECAM1) was carried out on HUVEC seeded at varying densities on the three substrata. A significant downregulation of gene expression was observed at an ultralow cell-seeding density of 100 cells/cm². This was accompanied by an extremely slow proliferation rate, probably because of an acute lack of intercellular contacts and paracrine signaling.ConclusionHence, this study demonstrates that seeding density has a profound effect on the proliferation and gene expression profile of endothelial cells seeded on different biomaterial surfaces.     

Control of neural stem cell survival by electroactive polymer substrates

Stem cell function is regulated by intrinsic as well as microenvironmental factors, including chemical and mechanical signals. Conducting polymer-based cell culture substrates provide a powerful tool to control both chemical and physical stimuli sensed by stem cells. Here we show that polypyrrole (PPy), a commonly used conducting polymer, can be tailored to modulate survival and maintenance of rat fetal neural stem cells (NSCs). NSCs cultured on PPy substrates containing different counter ions, dodecylbenzenesulfonate (DBS), tosylate (TsO), perchlorate (ClO(4)) and chloride (Cl), showed a distinct correlation between PPy counter ion and cell viability. Specifically, NSC viability was high on PPy(DBS) but low on PPy containing TsO, ClO(4) and Cl. On PPy(DBS), NSC proliferation and differentiation was comparable to standard NSC culture on tissue culture polystyrene. Electrical reduction of PPy(DBS) created a switch for neural stem cell viability, with widespread cell death upon polymer reduction. Coating the PPy(DBS) films with a gel layer composed of a basement membrane matrix efficiently prevented loss of cell viability upon polymer reduction. Here we have defined conditions for the biocompatibility of PPy substrates with NSC culture, critical for the development of devices based on conducting polymers interfacing with NSCs.     

Human bone derived cell culture on PLGA flat sheet membranes of different lactide:glycolide ratio

Providing a scaffold that can supply nutrients on a large scale (several cubic centimeters) is the key to successfully regenerating vascularized tissue: biodegradable membranes are a promising new scaffold suited to this purpose. Poly(lactic-co-glycolic-acid) (PLGA) flat sheet membranes of different lactide:glycolide ratios, prepared by phase inversion using 1-methyl-2-pyrrolidinone (NMP) as the solvent and water as the nonsolvent, were compared by assessing attachment, proliferation and osteogenic function of human bone derived cells (HBDC). Three different lactide:glycolide ratios, 50:50, 75:25, and 100:0, were compared to tissue culture polystyrene (TCPS). For attachment, 50:50 and 75:25 had similar numbers to TCPS but 100:0 had significantly fewer cells than TCPS. 50:50 and 75:25 had significantly lower HBDC numbers after 7 days but 100:0 had similar numbers compared to TCPS. For proliferation the cell number on the membranes were similar to each other. After 3 weeks, osteoblastic function of the HBDC, shown by mineralization and alkaline phosphatase activity, was present but was significantly lower compared to the TCPS control but similar when the membranes were compared. PLGA membranes fabricated from a range of ratios support HBDC culture so the optimum scaffold composition can be selected based on other factors, such as degradation rate.     

Heparin/polypyrrole (PPy) composite on gold-coated matrix for the neurite outgrowth of PC12 cells by electrical stimulation

A heparin/polypyrrole (PPy) composite, an electrical conducting polymer, was designed to enhance the interactions between a gold-coated matrix and nerve cells, with the cell (PC12 cells) interactions investigated under different conditions, both with and without electrical stimulation. The heparin concentration in the composites increased with increasing current density under the preparation condition, indicating that the heparin concentration in the composite could be controlled by managing the current density. Optical imaging showed that PC12 cells well attached to the PPy surfaces covered with heparin, but were poorly interacted to PPy surfaces without the heparin and gold coated matrix. The neurite length of the PC12 cells on the surfaces with an electrical stimulation (100 mV for 1h) significantly increased, with a median length of 77.5 μm; whereas, that without electrical stimulation was 10∼20 μm. Therefore, the heparin/polypyrrole (PPy) composite may provide insight for the development of an ideal nerve guidance channel.     

The influence of the chemical composition of cell culture material on the growth and antibody production of hybridoma cells

The multiplication and antibody production of murine hybridoma cells cultured on five different polymer membranes were tested and compared with conventional tissue culture polystyrene (TCPS). Membranes were prepared from polyacrylonitrile (PAN) and acrylonitrile copolymerized with N-vinylpyrrolidone (NVP20, NVP30), Na-methallylsulfonate (NaMAS) and N-(3-amino-propyl-methacrylamide-hydrochloride) (APMA). Cell number and antibody concentration were quantified as criteria for viability and productivity. Adhesion of hybridoma cells was characterized by vital and scanning electron microscopy. The results suggest that a strong adhesion of cells, observed on APMA and TCPS, increased cell growth but reduced monoclonal antibody production. In contrast membranes with lowered adhesivity such as NVP20 provided favourable conditions for monoclonal antibody production. In addition it was shown that this membrane also possessed a minor fouling as indicated by the low decrease of water flux across the membrane after protein adsorption. It was concluded that NVP20 could be a suitable material for the development of hollow fibre membranes for bioreactors.