Formulation and production of a blood-free and chemically defined virus production media for VERO cells.

Vaccines provide effective protection against many infectious diseases as well as therapeutics for select pathologies, such as cancer. Many viral vaccines require amplification of virus in cell cultures during manufacture. Traditionally, cell cultures, such as VERO, have been used for virus production in bovine serum-containing culture media. However, due to concerns of potential adventitious agents present in fetal bovine serum (FBS), regulatory agencies suggest avoiding the use of bovine serum in vaccine production. Current serum-free media suitable for VERO-based virus production contains high concentrations of undefined plant hydrolysates. Although these media have been extensively used, the lack of chemical definition has the potential to adversely affect cell growth kinetics and subsequent virus production. As plant hydrolysates are made from plant raw materials, performance variations could be significant among different lots of production. We developed a chemically defined, serum-free medium, OptiVERO, which was optimized specifically for VERO cells. VERO cell growth kinetics were demonstrated to be equivalent to EMEM-10% FBS in this chemically defined medium while the plant hydrolysate-containing medium demonstrated a slower doubling time in both two-dimensional (2D) and 3D cultures. Virus production comparisons demonstrated that the chemically defined OptiVERO medium performed at least as good as the EMEM-10%FBS and better than the plant hydrolysate-containing media. We report the success in using recombinant proteins to replace undefined plant hydrolysates to formulate a chemically defined medium that can efficiently support VERO cell expansion and virus production.

A Comparative In Vitro Analysis of the Osteogenic Potential of Human Dental Pulp Stem Cells Using Various Differentiation Conditions.

Dental pulp stem cells (DPSCs) have excellent proliferative properties, mineralization potential and can be easily obtained from third molar teeth. Recently, many studies have focused on isolation and differentiation of DPSCs. In our study, we focused on biological properties of non-differentiated DPSCs in comparison with osteogenic differentiated cells from DPSCs. We analyzed morphology as well as mineralization potential using three varied osteogenic differentiation media. After fifteen days of differentiation, calcium deposit production was observed in all three osteogenic differentiation media. However, only one osteogenic medium, without animal serum supplement, showed rapid and strong calcification-OsteoMAX-XF™ Differentiation Medium. Therefore, we examined specific surface markers, and gene and protein expression of cells differentiated in this osteogenic medium, and compared them to non-differentiated DPSCs. We proved a decrease in expression of CD9 and CD90 mesenchymal stem cell surface markers, as well as downregulation in the expression of pluripotency genes (NANOG and OCT-4) and increased levels of expression in osteogenic genes (ALP, BSP, OCN and RUNX2). Moreover, osteogenic proteins, such as BSP and OCN, were only produced in differentiated cells. Our findings confirm that carefully selected differentiation conditions for stem cells are essential for their translation into future clinical applications.

Characterization and Therapeutic Application of Mesenchymal Stem Cells with Neuromesodermal Origin from Human Pluripotent Stem Cells.

Rationale: Mesenchymal stem cells (MSC) hold great promise in the treatment of various diseases including autoimmune diseases, inflammatory diseases, etc., due to their pleiotropic properties. However, largely incongruent data were obtained from different MSC-based clinical trials, which may be partially due to functional heterogeneity among MSC. Here, we attempt to derive homogeneous mesenchymal stem cells with neuromesodermal origin from human pluripotent stem cells (hPSC) and evaluate their functional properties. Methods: Growth factors and/or small molecules were used for the differentiation of human pluripotent stem cells (hPSC) into neuromesodermal progenitors (NMP), which were then cultured in animal component-free and serum-free induction medium for the derivation and long-term expansion of MSC. The resulted NMP-MSC were detailed characterized by analyzing their surface marker expression, proliferation, migration, multipotency, immunomodulatory activity and global gene expression profile. Moreover, the in vivo therapeutic potential of NMP-MSC was detected in a mouse model of contact hypersensitivity (CHS). Results: We demonstrate that NMP-MSC express posterior HOX genes and exhibit characteristics similar to those of bone marrow MSC (BMSC), and NMP-MSC derived from different hPSC lines show high level of similarity in global gene expression profiles. More importantly, NMP-MSC display much stronger immunomodulatory activity than BMSC in vitro and in vivo, as revealed by decreased inflammatory cell infiltration and diminished production of pro-inflammatory cytokines in inflamed tissue of CHS models. Conclusion: Our results identify NMP as a new source of MSC and suggest that functional and homogeneous NMP-MSC could serve as a candidate for MSC-based therapies.

A novel cell-free method to culture Schistosoma mansoni from cercariae to juvenile worm stages for in vitro drug testing.

BACKGROUND: The arsenal in anthelminthic treatment against schistosomiasis is limited and relies almost exclusively on a single drug, praziquantel (PZQ). Thus, resistance to PZQ could constitute a major threat. Even though PZQ is potent in killing adult worms, its activity against earlier stages is limited. Current in vitro drug screening strategies depend on newly transformed schistosomula (NTS) for initial hit identification, thereby limiting sensitivity to new compounds predominantly active in later developmental stages. Therefore, the aim of this study was to establish a highly standardized, straightforward and reliable culture method to generate and maintain advanced larval stages in vitro. We present here how this method can be a valuable tool to test drug efficacy at each intermediate larval stage, reducing the reliance on animal use (3Rs). METHODOLOGY/PRINCIPAL FINDINGS: Cercariae were mechanically transformed into skin-stage (SkS) schistosomula and successfully cultured for up to four weeks with no loss in viability in a commercially available medium. Under these serum- and cell-free conditions, development halted at the lung-stage (LuS). However, the addition of human serum (HSe) propelled further development into liver stage (LiS) worms within eight weeks. Skin and lung stages, as well as LiS, were submitted to 96-well drug screening assays using known anti-schistosomal compounds such as PZQ, oxamniquine (OXM), mefloquine (MFQ) and artemether (ART). Our findings showed stage-dependent differences in larval susceptibility to these compounds. CONCLUSION: With this robust and highly standardized in vitro assay, important developmental stages of S. mansoni up to LiS worms can be generated and maintained over prolonged periods of time. The phenotype of LiS worms, when exposed to reference drugs, was comparable to most previously published works for ex vivo harvested adult worms. Therefore, this in vitro assay can help reduce reliance on animal experiments in search for new anti-schistosomal drugs.

Isolation, Culture and Identification of Choriocarcinoma Stem-Like Cells from the Human Choriocarcinoma Cell-Line JEG-3.

BACKGROUND/AIMS: Cancer stem cells (CSCs) exhibit enhanced proliferative capacity and resistance to chemotherapy; however, choriocarcinoma CSCs have not yet been reported. In this study the human choriocarcinoma cell line JEG-3 was cultured in serum free media, and the characteristics of suspension and parental adherent JEG-3 cells were compared. METHODS: Cell proliferation, colony-formation, soft agar clonogenicity, and transwell invasion assays were performed in vitro, and tumor xenografts in BALB/c nude mice were used to evaluate stem cell properties. RESULTS: In serum-supplemented medium (SSM), JEG-3 cells were 4.51 ± 1.71% CD44+, 7.67 ± 2.67% CD133+, and 13.85 ± 2.95% ABCG2+. In serum-free medium (SFM), the expression of these markers increased to 53.08 ± 3.15%, 47.40 ± 2.67%, and 78.70 ± 7.16%, respectively. Moreover, suspension JEG-3 cells exhibited enhanced colony-formation capability as well as invasive and proliferative ability in vitro, alongside enhanced tumorigenic properties in vivo. Suspension JEG-3 cells also exhibited resistance to the chemotherapeutic drugs methotrexate, fluorouracil and etoposide. When seeded in serum supplemented medium, suspension JEG-3 cells readopted an adherent phenotype and continued to differentiate with no significant difference in the morphology between suspension and parent cells. CONCLUSION: In this study, choriocarcinoma stem-like cells (CSLCs) were isolated from the human choriocarcinoma JEG-3 cell line by SFM culture and characterized.

Nutrient deprivation increases vulnerability of endothelial cells to proinflammatory insults.

Nutrient deprivation is a stimulus for oxidative stress and is an established method for induction of cell autophagy and apoptosis. The aims of this study were to identify conditions that evoke superoxide production in cultured human umbilical vein endothelial cells (HUVECs), determine the mechanism of action for this response, and examine whether the stimulus might facilitate the adhesion of human isolated neutrophils to the HUVECs. HUVECs were incubated in M199 medium under conditions of serum starvation (serum-free M199 medium), low serum (medium containing 2% fetal calf serum), and high serum (medium containing 20% fetal calf serum). HUVECs were also incubated under proinflammatory conditions, in medium supplemented with 50ng/ml tumor necrosis factor-α (TNF-α) or neutrophils preactivated with 10nM phorbol 12-myristate 13-acetate (PMA). Superoxide production was increased fourfold in serum-starved HUVECs compared to cells incubated in 20% medium, and this was reduced by inhibitors of the mitochondrial electron transport chain and mitochondrial Ca(2+) uniporter. Superoxide production was 23.6% higher in HUVECs incubated with TNF-α in 2% medium compared to 2% medium alone, but unchanged with TNF-α in 20% medium. PMA-activated neutrophils adhered to morphologically aberrant HUVECs, which were mainly evident under the low-serum condition. The findings show a role of mitochondrial enzymes in superoxide production in response to nutrient deprivation and suggest that proinflammatory responses in HUVECs become manifest when HUVECs are in an already-compromised state.

Norepinephrine stimulates progesterone production in highly estrogenic bovine granulosa cells cultured under serum-free, chemically defined conditions.

BACKGROUND: Since noradrenergic innervation was described in the ovarian follicle, the actions of the intraovarian catecholaminergic system have been the focus of a variety of studies. We aimed to determine the gonadotropin-independent effects of the catecholamine norepinephrine (NE) in the steroid hormone profile of a serum-free granulosa cell (GC) culture system in the context of follicular development and dominance. METHODS: Primary bovine GCs were cultivated in a serum-free, chemically defined culture system supplemented with 0.1% polyvinyl alcohol. The culture features were assessed by hormone measurements and ultrastructural characteristics of GCs. RESULTS: GCs produced increasing amounts of estradiol and pregnenolone for 144h and maintained ultrastructural features of healthy steroidogenic cells. Progesterone production was also detected, although it significantly increased only after 96h of culture. There was a highly significant positive correlation between estradiol and pregnenolone production in high E2-producing cultures. The effects of NE were further evaluated in a dose-response study. The highest tested concentration of NE (10 (-7) M) resulted in a significant increase in progesterone production, but not in estradiol or pregnenolone production. The specificity of NE effects on progesterone production was further investigated by incubating GCs with propranolol (10 (-8) M), a non-selective beta-adrenergic antagonist. CONCLUSIONS: The present culture system represents a robust model to study the impact of intrafollicular factors, such as catecholamines, in ovarian steroidogenesis and follicular development. The results of noradrenergic effects in the steroidogenesis of GC have implications on physiological follicular fate and on certain pathological ovarian conditions such as cyst formation and anovulation.

Use of a Plackett-Burman statistical design to determine the effect of selected amino acids on monoclonal antibody production in CHO cells.

Culture media design is central to the optimization of monoclonal antibody (mAb) production. Although general strategies do not currently exist for optimization of culture media, the combined use of statistical design and analysis of experiments and strategies based on simple material balances can facilitate culture media design. In this study, we evaluate the effect of selected amino acids on the growth rate and monoclonal antibody production of a Chinese hamster ovary DG-44 (CHO-DG44) cell line. These amino acids were selected based on their relative mass fraction in the specific mAb produced in this study, their consumption rate during bioreactor experiments, and also through a literature review. A Plackett-Burman statistical design was conducted to minimize the number of experiments needed to obtain statistically relevant information. The effect of this set of amino acids was evaluated during exponential cell culture (considering viable cell concentration and the specific growth rate as main output variables) and during the high cell-density stage (considering mAb final concentration and specific productivity as relevant output variables). For this particular cell line, leucine (Leu) and arginine (Arg) had the highest negative and positive effects on cell viability, respectively; Leu and threonine (Thr) had the highest negative effect on growth rate, and valine (Val) and Arg demonstrated the highest positive impact on mAb final concentration. Results suggest the pertinence of a two-stage strategy for amino acid supplementation, with a mixture optimized for cell growth and a different amino acid mixture for mAb production at high density.

Establishment of an advanced chemically defined medium for early embryos derived from in vitro matured and fertilized bovine oocytes.

A chemically defined medium would be useful for analyzing promoters or inhibitors in in vitro culture (IVC) of bovine embryos. However, an IVC system for bovine embryos in a chemically defined medium has not been fully established. The present study was carried out to establish an advanced chemically defined medium for bovine embryos that supports a high rate of embryo development to the blastocyst stage. In the first experiment, we examined the effects of addition of Medium RD (RPMI1640 and Dulbecco's MEM, 1:1 v/v) to mKSOM/aa on developmental competence. The addition of 10% RD to mKSOM/aa with BSA improved the rate of development to the blastocyst stage; however, 10% RD-mKSOM/aa with PVP, which is a chemically defined medium, caused a reduction in the percentage of hatching blastocysts. In the second experiment, embryos were cultured in the chemically defined medium of 10% RD-mKSOM/aa containing 11.7, 23.4, 46.8, 70.2 or 96.8 µM inositol. Inositol at the concentration of 70.2 µM improved the rate of development to the hatching blastocyst stage. In the third experiment, the optimal RD concentration in the IVC medium was evaluated. Embryos were cultured in the chemically defined medium supplemented with 10, 20 or 30% (v/v) RD. The rate of development to the blastocyst stage was highest with 20% RD. In the fourth experiment, the effects of N-acetylglucosamine (GlcNAc) as an IVC medium supplement on developmental competence were examined. The rate of development to the blastocyst stage with 1.0 mM GlcNAc was significantly higher than that without GlcNAc, but the rate of development with 1.2 mM GlcNAc was not different from that without GlcNAc. We also evaluated the ability of blastocysts produced in RD-mKSOM/aa to develop to normal calves after being transferred into recipients. Ten of the 16 recipients became pregnant, with 9 delivering normal calves. These results indicate that 20% RD-mKSOM/aa containing 70.2 µM myo-inositol and 1 mM GlcNAc is useful as a chemically defined medium for IVC of bovine embryos.

Supplementation of serum free media with HT is not sufficient to restore growth properties of DHFR-/- cells in fed-batch processes - Implications for designing novel CHO-based expression platforms.

DHFR-deficient CHO cells are the most commonly used host cells in the biopharmaceutical industry and over the years, individual substrains have evolved, some have been engineered with improved properties and platform technologies have been designed around them. Unexpectedly, we have observed that different DHFR-deficient CHO cells show only poor growth in fed-batch cultures even in HT supplemented medium, whereas antibody producer cells derived from these hosts achieved least 2-3 fold higher peak cell densities. Using a set of different expression vectors, we were able to show that this impaired growth performance was not due to the selection procedure possibly favouring fast growing clones, but a direct consequence of DHFR deficiency. Re-introduction of the DHFR gene reproducibly restored the growth phenotype to the level of wild-type CHO cells or even beyond which seemed to be dose-dependent. The requirement for a functional DHFR gene to achieve optimal growth under production conditions has direct implications for cell line generation since it suggests that changing to a selection system other than DHFR would require another CHO host which - especially for transgenic CHO strains and tailor-suited process platforms - this could mean significant investments and potential changes in product quality. In these cases, DHFR engineering of the current CHO-DG44 or DuxB11-based host could be an attractive alternative.

Development of a serum-free medium for in vitro expansion of human cytotoxic T lymphocytes using a statistical design.

BACKGROUND: Serum-containing medium (SCM), which has a number of poorly defined components with varying concentrations, hampers standardization of lymphocyte cultures. In order to develop a serum-free medium (SFM) for the expansion of human lymphocytes from peripheral blood mononuclear cells (PBMCs), a statistical optimization approach based on a fractional factorial method and a response surface method was adopted. A basal medium was prepared by supplementing RPMI1640 medium with insulin, albumin, ferric citrate, ethanolamine, fatty acids, glutamine, sodium pyruvate, 2-mercaptoethanol, 1-thioglycerol, nonessential amino acids, and vitamins. We identified additional positive determinants and their optimal concentrations for cell growth through a statistical analysis. RESULTS: From a statistical analysis using the fractional factorial method, cholesterol and polyamine supplement were identified as positive determinants for cell growth. Their optimal concentrations were determined by the response surface method. The maximum viable cell concentration in the developed SFM was enhanced by more than 1.5-fold when compared to that in RPMI1640 supplemented with 10% fetal bovine serum (FBS). Furthermore, a cytotoxicity assay and an enzyme-linked immunospot assay revealed that the effector function of cytotoxic T lymphocytes generated from PBMCs grown in SFM, by stimulation of peptide-presenting dendritic cells, was retained or even better than that in SCM. CONCLUSIONS: The use of a developed SFM with cholesterol and polyamine supplement for human lymphocyte culture resulted in better growth without loss of cellular function when compared to SCM.

Development of a serum-free supplement for primary neuron culture reveals the interplay of selenium and vitamin E in neuronal survival.

Serum-free media require a number of supplements in order to support long-term neuronal survival. Commercially available B27, in combination with Neurobasal medium, supports neuronal survival and suppresses glial proliferation. However, B27 contains many biological antioxidants as well as catalase and superoxide dismutase, eventually demanding the application of unphysiologically high peroxide concentrations in survival assays. Moreover, optimal amounts of selenium (Se) are included in "B27 supplement minus antioxidants", a commercially available supplement used for the study of the role of antioxidants. Hence, Se-dependent enzymes like glutathione peroxidase are maximally expressed when this supplement is used and Se-depletion studies are not possible without changing the medium composition. We have therefore developed a modified serum-free media supplement which allows for free variation of all constituents. Our supplement was comparable to B27 with regard to cell survival and expression of neurochemical markers. Reduction of Se content in the supplement reduced selenoprotein expression and made cortical neurons more sensitive towards challenges with peroxides. Withdrawal from the medium supplement of vitamin E alone did not alter the survival of neurons in response to peroxides, while simultaneous reduction of Se and vitamin E rendered neurons hypersensitive towards peroxide challenge. This finding implied that adequate Se supply of neurons is required to minimize lipid peroxidation. Our medium supplement is easily prepared, inexpensive, and should be applicable to the analysis of survival mechanisms beyond peroxide challenge.

Investigations into the metabolism of two-dimensional colony and suspended microcarrier cultures of human embryonic stem cells in serum-free media.

Metabolic studies of human embryonic stem cells (hESCs) can provide important information for stem cell bioprocessing. To this end, we have examined growth and metabolism of hESCs in both traditional 2-dimensional (2D) colony cultures and 3-dimensional microcarrier cultures using a conditioned medium and 3 serum-free media. The 2D colony cultures plateaued at cell densities of 1.1-1.5 × 106 cells/mL at day 6 due to surface limitation. Microcarrier cultures achieved 1.5-2 × 106 cells/mL on days 8-10 before reaching a plateau; this growth arrest was not due to surface limitation, but probably due to metabolic limitations. Metabolic analysis of the cultures showed that amino acids (including glutamine) and glucose are in excess and are not limiting cell growth; on the other hand, the high levels of waste products (25 mM lactate and 0.8 mM ammonium) and low pH (6.6) obtained at the last stages of cell propagation could be the causes for growth arrest. hESCs cultured in media supplemented with lactate (up to 28 mM) showed reduced cell growth, whereas ammonium (up to 5 mM) had no effect. Lactate and, to a lesser extent, ammonia affected pluripotency as reflected by the decreasing population of cells expressing pluripotent marker TRA-1-60. Feeding hESC cultures with low concentrations of glucose resulted in lower lactate levels (∼10%) and a higher pH level of 6.7, which leads to a 40% increase in cell density. We conclude that the high lactate levels and the low pH during the last stages of high-density hESC culture may limit cell growth and affect pluripotency. To overcome this limitation, a controlled feed of low levels of glucose and online control of pH can be used.

Simultaneous enhancement of photothermal stability and gene delivery efficacy of gold nanorods using polyelectrolytes.

The propensity of nanoparticles to aggregate in aqueous media hinders their effective use in biomedical applications. Gold nanorods (GNRs) have been investigated as therapeutics, imaging agents, and diagnostics. We report that chemically generated gold nanorods rapidly aggregate in biologically relevant media. Depositing polyelectrolyte multilayers on gold nanorods enhanced the stability of these nanoparticles for at least up to 4 weeks. Dispersions of polyelectrolyte (PE)-gold nanorod assemblies (PE-GNRs) demonstrate a stable Arrhenius-like photothermal response, which was exploited for the hyperthermic ablation of prostate cancer cells in vitro. Subtoxic concentrations of PE-GNR assemblies were also employed for delivering exogenous plasmid DNA to prostate cancer cells. PE-GNRs based on a cationic polyelectrolyte recently synthesized in our laboratory demonstrated higher transfection efficacy and lower cytotoxicity compared to those based on polyethyleneimine, a current standard for polymer-mediated gene delivery. Our results indicate that judicious engineering of biocompatible polyelectrolytes leads to multifunctional gold nanorod-based assemblies that combine high stability and low cytotoxicity with photothermal ablation, gene delivery, and optical imaging capabilities on a single platform.

Development of standardized cell culture conditions for tumor cells with potential clinical application.

BACKGROUND: Tumor cell lines have enormous value for the study of different aspects of cancer biology and have also recently gained great importance in autologous cell-based anti-tumor therapies. However, the use of these cells is still limited because in vitro growth is hampered by suboptimal culture conditions and current media contain fetal bovine serum (FBS), which poses serious safety concerns regarding clinical application. METHODS: To address this drawback, we aimed to develop a strategy for optimization of the culture medium for human medullary thyroid carcinoma (MTC) cell lines as a model system. We combined the general cell screening system (GCSS), which continuously measured the growth behavior of cells in a 96-well plate format, with statistically based experimental designs. RESULTS: The results obtained clearly demonstrated that, just by changing the composition of the basal medium, a significantly enhanced growth rate could be observed, and by subsequent addition of several substances a serum-free cell culture medium could be developed. This medium allowed the propagation of two MTC cell lines comparable with conventionally used serum-supplemented medium. DISCUSSION: We present a fast and easy way to screen for substances that are essential for tumor cell growth in vitro. Furthermore, these tumor cells can be adapted to culture conditions that allow the use of the cells in safe cell-based therapies. This is of utmost importance because of increasing regulatory requirements.

Human primary brain tumor cell growth inhibition in serum-free medium optimized for neuron survival.

Glioblastoma is the most common primary brain tumor in adults from which about 15,000 patients die each year in the United States. Despite aggressive surgery, radiotherapy and chemotherapy, median survival remains only 1 year. Here we evaluate growth of primary human brain tumor cells in a defined nutrient culture medium (Neuregen) that was optimized for neuron regeneration. We hypothesized that Neuregen would inhibit tumor cell growth because of its ability to inhibit gliosis in rat brain. Tumor tissue was collected from 18 patients including 10 males and 8 females (mean age 60+/-12 years) who underwent craniotomy for newly diagnosed, histologically confirmed brain tumors. The tissue was shipped overnight in Hibernate transport medium. Tumor cells were isolated and plated in Neurobasal/serum or Neuregen on culture plastic. After 1 week, growth in Neuregen was significantly less in 9/10 glioblastoma multiforme cases, 5/5 meningioma cases and 3/3 cases of brain metastasis. Analysis of deficient formulations of Neuregen and formulations to which selected components were added back implicate no single active component. However, individual cases were sensitive to corticosterone, selenium, ethanolamine, fatty acids and/or antioxidants. Therefore, a defined culture medium that promotes neuron regeneration inhibits the growth of human primary glioblastoma, meningioma and metastatic tumor cells in culture. The possible in vivo efficacy of Neuregen for treatment of brain tumor resections remains to be determined.

Generation and differentiation of human embryonic stem cell-derived keratinocyte precursors.

Human embryonic stem cells (hESC) hold tremendous potential in the future of tissue engineering, offering promise as a source of virtually unlimited quantities of desired cell and tissue types. We have identified soluble chemical and extracellular matrix factors that permit isolation of keratinocyte precursors from hESCs. Culturing embryoid bodies (EB) formed from hESCs in a defined serum-free keratinocyte growth medium on a gelatin matrix generated keratin 14 (K14) expressing cells with an epithelial morphology. These K14 expressing cells could be subcultured in medium supplemented with hydrocortisone and induced to stratify and terminally differentiate by addition of calcium. Optimum times for obtaining K14 expressing cells were found for EB formation and for differentiation and growth of cultures after EB plating. EB formation was not necessary to generate keratinocyte precursors; direct transfer of hESC colonies to keratinocyte growth medium permitted differentiation into the keratinocyte lineage. With further studies to optimize generation and purification of hESC-derived keratinocyte precursors, these cells could provide a source of epidermal cells for skin tissue engineering applications in vitro or in vivo.

One-step induction of neurons from mouse embryonic stem cells in serum-free media containing vitamin B12 and heparin.

We present a simple method for neural cell fate specification directly from mouse embryonic stem cells (ES cells) in serum-free conditions in the absence of embryoid body formation. Dissociated ES cells were cultured in serum-free media supplemented with vitamin B12 and heparin, but without any expensive cytokines. After 14 days in culture, beta-tubulin type III (TuJ1) and tyrosine hydroxylase (TH)-positive colonies were detected by immunocytochemical examinations. In addition, specific gene analyses by RT-PCR demonstrated expression of an early central nerve system, mature neuron, and midbrain dopaminergic neuron-specific molecules (i.e., nestin, middle molecular mass neurofilament protein, Nurr1, and TH, respectively). Dopamine was also detected in the culture media by reverse-phase HPLC analysis. These facts indicate that addition of vitamin B12/heparin to serum-free culture media induced neurons from ES cells, which included cells that released dopamine. Other supplements, such as putrescine, biotin, and Fe2+, could not induce neurons from ES cells by themselves, but produced synergistic effects with vitamin B12/heparin. The rate of TuJ1+/TH+ colony formation was increased threefold and the amounts of dopamine released increased 1.5-fold by the addition of a mixture of putrescine, biotin, and Fe2+ to vitamin B12/heparin culture media. Our method is a simple tool to differentiate ES cells to dopaminergic neurons for the preparation of dopamine-releasing cells for the cell transplantation therapy of Parkinson's disease. In addition, this method can facilitate the discovery of soluble factors and genes that can aid in the induction of the ES cell to its neural fate.

Comparison of an animal product free medium and normal growth supplement on the growth and barrier integrity of a human corneal epithelial cell line.

With the development of defined media for general and specific use with cell cultures, and concern over the use of human cells and over potential prion infections associated with growth factor extracts such as bovine pituitary extract, an animal product-free medium has become available. The basic keratinocyte defined medium can be used with a choice of animal product-containing or animal product-free supplements. Human corneal epithelia cell lines were cultured in the media with these two types of supplement, and compared in terms of their growth rates, their capacity to form tight barriers, and calcium regulation of the location of a junction-associated protein, zonula occludins-1 (ZO-1). The growth rates were not different in the two media, as long as the recommended coating was applied to the culture flask for the animal product-free medium. The barrier function was equally effective for confluent cultures seeded at the same densities. A calcium concentration of 100 microM or above resulted in ZO-1 localisation at the cell membrane in either medium. Hence, cultures in the media are comparable, when the coating is employed. Further experiments are being conducted to establish the comparability of responses to chronic treatment with surfactants.

Entamoeba invadens: in vitro axenic encystation with a serum substitute.

The current media for axenic cultivation of Entamoeba histolytica and Entamoeba invadens are supplemented with bovine or equine serum, which provides several essential nutrients to amoebas. Serum has also been considered an essential component in encystation media for E. invadens. A substitute of serum, PACSR has been described as an alternative for growth of E. histolytica and also maintains growth of E. invadens. When PACSR was used instead of serum for encystation of E. invadens the efficiency was the same as for serum. Our present data show that PACSR can support the growth and induction of encystation of E. invadens strain IP-1.