Quality control studies on fetal bovine serum used in tissue culture

Progress on Electro-Enhancement of Cell Manufacturing

With the long persistence of complex, chronic diseases in society, there is increasing motivation to develop cells as living medicine to treat diseases ranging from cancer to wounds. While cell therapies can significantly impact healthcare, the shortage of starter cells meant that considerable raw materials must be channeled solely for cell expansion, leading to expensive products with long manufacturing time which can prevent accessibility by patients who either cannot afford the treatment or have highly aggressive diseases and cannot wait that long. Over the last three decades, there has been increasing knowledge on the effects of electrical modulation on proliferation, but to the best of the knowledge, none of these studies went beyond how electro-control of cell proliferation may be extended to enhance industrial scale cell manufacturing. Here, this review is started by discussing the importance of maximizing cell yield during manufacturing before comparing strategies spanning biomolecular/chemical/physical to modulate cell proliferation. Next, the authors describe how factors governing invasive and non-invasive electrical stimulation (ES) including capacitive coupling electric field may be modified to boost cell manufacturing. This review concludes by describing what needs to be urgently performed to bridge the gap between academic investigation of ES to industrial applications.

Preparing and Evaluating the Stability of Therapeutically Relevant Oligonucleotide Duplexes

The field of oligonucleotide therapeutics is rapidly advancing, particularly for combating orphan diseases and cancer. However, the intrinsic instability of oligonucleotides, especially RNA, poses a substantial challenge in the face of the harsh conditions encountered intracellularly and in circulation. Therefore, evaluating the stability of oligos in serum is of great significance when developing oligonucleotide therapeutics. This protocol outlines a dependable and reproducible method for preparing oligonucleotide duplexes, coupled with confirmation by gel electrophoresis. Subsequently, the protocol defines a mechanism to assess the stability of the oligo duplexes in serum. This protocol seeks to establish a standardized reference for researchers, enabling them to compare the impact of various modifications on oligo stability and assess the degradation kinetics effectively. Key features • Adaptable for use with small interfering RNA (siRNA), microRNA (miRNA), antisense oligonucleotides (ASOs), and other unmodified and modified oligonucleotides. • Does not necessitate any Biological Safety Level clearance and offers a rapid, cost-effective, and entirely in vitro procedure. • Allows researchers to evaluate multiple modification patterns that, when coupled with targeting activity, allow for selecting the best modification pattern prior to in vivo analysis.

Evaluation of a Serum-Free Medium for Human Epithelial and Stromal Cell Culture

Over the past decade, growing demand from many domains (research, cosmetics, pharmaceutical industries, etc.) has given rise to significant expansion of the number of in vitro cell cultures. Despite the widespread use of fetal bovine serum, many issues remain. Among them, the whole constitution of most serums remains unknown and is subject to significant variations. Furthermore, the presence of potential contamination and xenogeny elements is challenging for clinical applications, while limited production is an obstacle to the growing demand. To circumvent these issues, a Serum-Free Medium (SFM) has been developed to culture dermal and vesical fibroblasts and their corresponding epithelial cells, namely, keratinocytes and urothelial cells. To assess the impact of SFM on these cells, proliferation, clonogenic and metabolic assays have been compared over three passages to conditions associated with the use of a classic Fetal Bovine Serum-Containing Medium (FBSCM). The results showed that the SFM enabled fibroblast and epithelial cell proliferation while maintaining a morphology, cell size and metabolism similar to those of FBSCM. SFM has repeatedly been found to be better suited for epithelial cell proliferation and clonogenicity. Fibroblasts and epithelial cells also showed more significant mitochondrial metabolism in the SFM compared to the FBSCM condition. However, the SFM may need further optimization to improve fibroblast proliferation.

A Review of Fetal Bovine Serum in the Culture of Mesenchymal Stromal Cells and Potential Alternatives for Veterinary Medicine

Fetal bovine serum (FBS) remains widely used as a supplement in cell culture media used in the isolation and expansion of mesenchymal stromal cells (MSC) despite longstanding practical, clinical, and ethical concerns over its use. As a result, research on alternative culture media supplement solutions that conserve crucial MSC characteristics has become increasingly relevant. Species-specific supplements and serum-free media such as platelet lysate or chemically defined media have been assessed for their effect in MSC cultures regarding proliferation, differentiation, and immunomodulatory capacity. While none of the alternatives offer a complete solution in replacing traditional FBS supplemented media for culturing MSCs for all species, short-term or transitional use of FBS-free media can perform equally well and could address some of the concerns over the use of FBS.

Human Platelet Lysate Can Replace Fetal Calf Serum as a Protein Source to Promote Expansion and Osteogenic Differentiation of Human Bone-Marrow-Derived Mesenchymal Stromal Cells

Fetal calf serum (FCS) is frequently used as a growth factor and protein source in bone-marrow-derived mesenchymal stromal cell (BMSC) culture media, although it is a xenogenic product presenting multiple disadvantages including but not limited to ethical concerns. A promising alternative for FCS is human platelet lysate (hPL), which is produced out of human platelet concentrates and happens to be a stable and reliable protein source. In this study, we investigated the influence of hPL in an expansion medium (ESM) and an osteogenic differentiation medium (ODM) on the proliferation and osteogenic differentiation capacity of human BMSC. Therefore, we assessed population doublings during cell expansion, performed alizarin red staining to evaluate the calcium content in the extracellular matrix and determined the activity of alkaline phosphatase (ALP) as osteogenic differentiation correlates. The proliferation rate of BMSC cultured in ESM supplemented with hPL exceeded the proliferation rate of BMSC cultured in the presence of FCS. Furthermore, the calcium content and ALP activity was significantly higher in samples incubated in hPL-supplemented ODM, especially in the early phases of differentiation. Our results show that hPL can replace FCS as a protein supplier in cell culture media and does not negatively affect the osteogenic differentiation capacity of BMSC.

Interaction of graphene oxide with cell culture medium: Evaluating the fetal bovine serum protein corona formation towards in vitro nanotoxicity assessment and nanobiointeractions

The interaction of single-layer graphene oxide (SLGO) and multi-layered graphene oxide (MLGO) with a cell culture medium (i.e. DMEM) was studied by evaluating fetal bovine serum (FBS) protein corona formation towards in vitro nanotoxicity assessment and nanobiointeractions. SLGO and MLGO exhibited different colloidal behavior in the culture medium, which was visualized by cryogenic transmission electron microscopy in situ analysis. Exploring proteomics and bioinformatics tools, 394 and 290 proteins were identified on the SLGO and MLGO hard corona compositions, respectively. From this amount, 115 proteins were exclusively detected on the SLGO and merely 11 on MLGO. SLGO enriched FBS proteins involved in metabolic processes and signal transduction, while MLGO enriched proteins involved in cellular development/structure, and lipid transport/metabolic processes. Such a distinct corona profile is due to differences on surface chemistry, aggregation behavior and the surface area of GO materials. Hydrophilic interactions were found to play a greater role in protein adsorption by MLGO than SLGO. Our results point out implications for in vitro studies of graphene oxide materials concerning the effective dose delivered to cells and corona bioactivity. Finally, we demonstrated the importance of integrating conventional and modern techniques thoroughly to understand the GO-FBS complexes towards more precise, reliable and advanced in vitro nanotoxicity assessment.

A consensus introduction to serum replacements and serum-free media for cellular therapies

The cell therapy industry is a fast-growing industry targeted toward a myriad of clinical indications. As the cell therapy industry matures and clinical trials hit their pivotal Phase 3 studies, there will be a significant need for scale-up, process validation, and critical raw material quality assurance. Part of the well discussed challenges of upscaling manufacturing processes there is a less discussed issue relating to the availability of raw materials in the needed quality and quantities. The FDA recently noted that over 80% of the 66 investigational new drug (IND) applications for mesenchymal stem cell (MSC) products analyzed described the use of FBS during manufacturing. Accumulated data from the past years show an acceleration in serum consumption by at least 10%-15% annually, which suggests that the global demand for serum may soon exceed the supply. Ongoing concerns of safety issues due to risks of various pathogen contaminations, as well as issues related to the aforementioned serum variability that can affect final product reproducibility, are strong motivators to search for serum substitutes or serum-free media. it is important to note that there are no accepted definitions for most of these terms which leads to misleading's and misunderstandings, where the same term might be defined differently by different vendors, manufacturer, and users. It is the drug developer's responsibility to clarify what the supplied labels mean and to identify the correct questions and audits to ensure quality. The paper reviews the available serum replacements, main components, basic strategies for replacement of serum and suggests definitions.

Effect of fatty acids on human bone marrow mesenchymal stem cell energy metabolism and survival

Successful stem cell therapy requires the optimal proliferation, engraftment, and differentiation of stem cells into the desired cell lineage of tissues. However, stem cell therapy clinical trials to date have had limited success, suggesting that a better understanding of stem cell biology is needed. This includes a better understanding of stem cell energy metabolism because of the importance of energy metabolism in stem cell proliferation and differentiation. We report here the first direct evidence that human bone marrow mesenchymal stem cell (BMMSC) energy metabolism is highly glycolytic with low rates of mitochondrial oxidative metabolism. The contribution of glycolysis to ATP production is greater than 97% in undifferentiated BMMSCs, while glucose and fatty acid oxidation combined only contribute 3% of ATP production. We also assessed the effect of physiological levels of fatty acids on human BMMSC survival and energy metabolism. We found that the saturated fatty acid palmitate induces BMMSC apoptosis and decreases proliferation, an effect prevented by the unsaturated fatty acid oleate. Interestingly, chronic exposure of human BMMSCs to physiological levels of palmitate (for 24 hr) reduces palmitate oxidation rates. This decrease in palmitate oxidation is prevented by chronic exposure of the BMMSCs to oleate. These results suggest that reducing saturated fatty acid oxidation can decrease human BMMSC proliferation and cause cell death. These results also suggest that saturated fatty acids may be involved in the long-term impairment of BMMSC survival in vivo.

Insulin-like growth factor I enhances collagen synthesis in engineered human tendon tissue

OBJECTIVE

Isolated human tendon cells form 3D tendon constructs that demonstrate collagen fibrillogenesis and feature structural similarities to tendon when cultured under tensile load. The exact role of circulating growth factors for collagen formation in tendon is sparsely examined. We investigated the influence of insulin-like growth factor I (IGF-I) on tendon construct formation in 3D cell culture.

DESIGN

Tendon constructs were grown in 0.5 or 10% FBS with or without IGF-I (250 mg/ml) supplementation. Collagen content (fluorometric), mRNA levels (PCR) and fibril diameter (transmission electron microscopy) were determined at 7, 10, 14, 21 and 28 days.

RESULTS

IGF-I revealed a stimulating effect on fibril diameter (up to day 21), mRNA for collagen (to day 28), tenomodulin (to day 28) and scleraxis (at days 10 and 14), and on overall collagen content. 10% FBS diminished the development of fibril diameter (day 14), collagen content (at days 21 and 28) and mRNA expression for collagen, tenomodulin and scleraxis.

CONCLUSION

IGF-I supplementation promotes early onset of tensile load induced collagen formation and tendon structural arrangement, whereas the FBS concentration routinely used in cultures diminishes collagen expression, collagen content and fibril formation.

Molecular gradients of bioinertness reveal a mechanistic difference between mammalian cell adhesion and bacterial biofilm formation

Chemical gradients play an important role in guiding the activities of both eukaryotic and prokaryotic cells. Here, we used molecularly well-defined chemical gradients formed by self-assembled monolayers (SAMs) on gold films to reveal that mammalian cell adhesion and bacterial biofilm formation respond differently to a gradient of surface chemistry that resists cell attachment. Gradient self-assembled monolayers (SAMs) consisting of two mixed alkanethiols were fabricated by differential exposure of the gold film to one alkanethiol, followed by soaking in another alkanethiol solution. A gradient in bioinertness that resisted cell attachment was created on SAMs from a gradient in the surface density of HS(CH2)11(OCH2CH2)3OH, backfilled with either HS(CH2)11OH or HS(CH2)11CH3. Measurements of the amounts of mammalian cells and bacterial biofilms on these gradient surfaces reveal that, for mammalian cells, a critical density of adhesion ligands from absorbed proteins on surfaces exists for supporting maximum adhesion and proliferation, whereas for the bacterium Escherichia coli , the amount of biofilm formed on surfaces increased linearly with the surface density of adhesive groups (methyl or hydroxyl groups) in different media. These results are consistent with mammalian cell adhesion requiring an anchorage via specific molecular recognitions and suggest that biofilms can form by immobilization of bacteria via nonspecific interaction between bacteria and surfaces.

Proteomic Analysis for the Assessment of Different Lots of Fetal Bovine Serum as a Raw Material for Cell Culture. Part IV. Application of Proteomics to the Manufacture of Biological Drugs

Fetal bovine serum (FBS) is the most widely used growth supplement for cell cultures, primarily because of its high levels of growth stimulatory factors and low levels of growth inhibitory factors. Maintaining successful and consistent cell fermentations can be difficult, as FBS is a complex natural product and may vary from lot to lot even from a single manufacturer. The quality and concentration of both bulk and specific proteins can affect cell growth. Quality control tools for FBS are relatively primitive and expensive given the complexity of the sample and the large amounts of FBS used. We undertook this study to examine whether proteomics could be used as a tool to analyze the variability of different fermentation processes. We hypothesized that inconsistent cell growth in fermentations could be due to the quality of FBS and that different lots of FBS had varying concentrations of proteins such as growth stimulatory factors, growth inhibitory factors, and/or other proteins that may correlate with cellular growth rate. To investigate whether this was the case, we grew three batches of adult retinal pigment epithelial cells (ARPE-19) using three different lots of fetal bovine serum (FBS-Ia, FBS-Ib, and FBS-II). We found that the growth rate of the culture was significantly and consistently higher in the FBS-II lot. To determine why the other lots promoted different growth properties, we used proteomic techniques to analyze the protein composition of the three lots. We then performed a time course study to monitor specific changes in individual proteins in the fermentation medium. The amount of several extracellular matrix and structural proteins, which are indicators of cell growth, increased over time. Alternatively, components supplied by the FBS addition, such as nutritional-related and cell-spreading-related proteins, decreased over time.

Genomics and proteomics in process development: opportunities and challenges

Global gene expression profiling by genomic and proteomic analyses has changed the face of drug discovery and biological research in the past few years. The benefit of these technologies in the area of process development for recombinant protein production has been increasingly realized. This review discusses the application of genome-wide expression profiling tools in the design and optimization of bioprocesses, with the emphasis on the effect on process development of mammalian cell culture. Despite the lack of genome sequence information for most of the relevant mammalian cell lines used, these technologies can be applied during various process development steps. Although there are only a few examples in the literature that present a major improvement in productivity based on genomics and proteomics, further advances in analytical tools and genome sequencing technologies will greatly increase our knowledge at the molecular level and will drive the design of future bioprocesses.

Babesia divergens (Phylum Apicomplexa) in vitro growth in the presence of calf serum

Resistance to severe babesiosis in young calves has frequently been ascribed to an unknown serum factor(s) which inhibits growth of Babesia bovis in vitro. Our experiments show that young calf sera are as suitable as adult bovine sera for the in vitro culture of Babesia divergens, indicating that in this species at least inverse age resistance is due to alternative mechanisms. The suitability of commercial foetal calf sera for B. divergens cultures seems highly variable.

Media for hybridoma growth and monoclonal antibody production

For the economical production of monoclonal antibodies (MAbs), the cell-culture medium must be optimized for three different phases: growth of the hybridomas, MAb productivity of the hybridomas, and MAb purification or downstream processing. Medium improvements are necessary to meet these requirements for large-scale MAb production. Information bearing on this issue is being addressed in two research areas, cell biology and biochemical engineering, and is reviewed in this article.

Comparison of whole serum-deprived media for ex vivo expansion of hematopoietic progenitor cells from cord blood and mobilized peripheral blood mononuclear cells

A whole serum-deprived (WSD) medium was developed and optimized for expansion of colony-forming cells (CFC) in cord blood (CB) mononuclear cell (MNC) cultures. This medium was compared with four commercially available WSD media (commercial media), three WSD media whose compositions have been publicly disclosed (public media), two serum-containing media, and two basal media, for cell and CFC expansion in 10-day CB and mobilized peripheral blood (PB) MNC cultures supplemented with interleukin-3 (IL-3), IL-6, and stem cell factor (SCF). Selected WSD media and both serum-containing media gave significant CFC expansion in CBMNC and PBMNC cultures. The serum-containing human long-term medium gave the greatest cell (3.0-fold) and CFC (25-fold) expansions in CBMNC cultures, whereas our medium maintained the most cells (93% of input) and gave the greatest CFC expansion (6.1-fold) for PBMNC cultures. Of the commercial media, Progenitor-34 gave the greatest cell expansion (1.2-fold) and X VIVO-10 gave the greatest CFC expansion (11-fold) for CBMNC cultures, and Progenitor-34 maintained the most cells (83% of input) and gave the greatest CFC expansion (3.1-fold) for PBMNC cultures. Of the public media (including ours), our medium gave the greatest cell (1.4-fold) and CFC (6.1-fold) expansion for CBMNC cultures. Although there were slight correlations between cell and CFC expansion in 10-day CBMNC and PBMNC cultures (r2 of 0.848 and 0.594, respectively), the correlations did not give reliable predictions for medium selection. In addition, the different media favored expansion of different CFC types and performed differently for cultures using different cell sources (CB versus PB). Taken together, these results suggest that media must be carefully screened for the cell source to be cultured and the cell type(s) to be produced (e.g. total cells, CFC).

Adventitious pestivirus RNA in live virus vaccines against bovine and swine diseases

Live virus vaccines against bovine and porcine diseases were examined for the presence of adventitious pestivirus RNA or pestiviruses by reverse transcription-polymerase chain reaction (PCR). Pestivirus RNA was detected in the live virus vaccines against Akabane disease, Ibaraki disease, infectious bovine rhinotracheitis, porcine parvovirus infection, transmissible gastroenteritis and Japanese encephalitis. Pestivirus RNA or pestivirus in the fetal bovine serum used to grow the host cells used to prepare the bovine and swine viral vaccines is a likely source of the contamination. Nucleotide sequence analysis of the PCR products suggests that modified live virus vaccines being used for immunization of cattle against bovine viral diarrhoea was not responsible for the contamination of the vaccines examined.

Effects of gonadotropin-releasing hormone (GnRH) on the cytodifferentiation of gonadotropes in rat adenohypophysial primordia in organ culture

The effects of gonadotropin-releasing hormone (GnRH) on the development of gonadotropes were investigated by the use of organ culture and by means of immunocytochemistry and radioimmunoassay. Pituitary primordia from rat fetuses were cultured in a medium with or without 10(-9) M GnRH during the first 24 h of culture. The ratio of the number of immunoreactive LH cells to the total number of cells in the explants derived from 13.5-day fetuses was increased by the GnRH treatment after 6 or 8 days of culture, while the total number of cells was not altered. LH released into the medium and LH content of explants were not affected by the GnRH treatment. Subsequent treatment with 10(-9) M GnRH for 4 h after 7 days of culture resulted in a marked release of LH, accompanying a significant decline in LH content, in both explants exposed or unexposed to the first GnRH treatment. However, the former explants contained a lower amount of LH than the latter explants. The present results indicate that pituitary primordia at 13.5 days of gestation are capable to respond to GnRH, and that GnRH is effective in stimulating the responsiveness of gonadotropes to GnRH during early pituitary cytodifferentiation.

Comparison of fortified calf serum, serum substitutes and fetal calf serum with or without extenders for propagation of cell cultures for virus plaque assays

Two studies comparing sewage-isolated and laboratory stock viruses were conducted to determine if alternative forms of serum or serum extenders could be used in place of fetal bovine serum without a significant loss of viral titer. In the first study, BGM cells were grown in standard MEM-L15 medium which was supplemented with Nuserum, Sigma serum replacement (CPSR-1), HyClone defined iron supplemented calf bovine serum, fetal bovine serum (FBS) or FBS supplemented with either SerXtend or Mito serum extenders. Comparison of virus titers showed that CPSR-1 gave the best overall results and was comparable to FBS. Of the serum extenders, only SerXtend improved virus recovery from sewage samples. In the second study, all sera were tested with and without SerXtend. In these experiments, SerXtend enhanced virus sensitivity of the BGM cell line grown in the HyClone serum but reduced the sensitivity of those cultured in Sigma serum. In both series, the growth of BGM cells was monitored for 12 weeks and all test products were shown to support long-term cell growth.

Factors affecting and significance of G2 chromatin radiosensitivity in predisposition to cancer

The frequencies of chromatid breaks and gaps in metaphase cells fixed 2 h after G2 phase X-irradiation (1 Gy) were in almost all cases at least two- to three-fold higher in skin fibroblasts from individuals with genetic conditions predisposing to cancer than in comparable cells from clinically normal controls. Previously, we reported this response in all cancer-prone genetic disorders tested including ataxia telangiectasia, Bloom's syndrome, Fanconi's anemia, xeroderma pigmentosum (XP), familial polyposis, Gardner's syndrome, hereditary malignant melanoma, dysplastic nevus syndrome and cancer family members. One exception was XP-A. In this report we add information on skin fibroblasts from retinoblastoma, Wilms' tumor and XP-C patients, 13 clinically normal controls and six cell lines from fetal or infant cells. Factors affecting the response are identified and include pH, temperature, cell density, culture medium or serum, microbial contamination and visible light exposure (effective wavelength 405 nm). Because of experimental variability, known normal controls should be used in each group of assays. With adequate control of the above factors this response could provide the basis of a test for detecting individuals carrying genes that predispose to a high risk of cancer.

A survey of mycoplasma detection in veterinary vaccines

Nine live virus veterinary vaccines from six sources were found to be contaminated with mycoplasma. The vaccines were for use in canine, feline and avian species, and 53 batches of the products were at fault. The isolates were identified as Mycoplasma hominis, M. arginini, M. orale, M. hyorhinis and M. gallinarum. Investigation of the contamination rate of other batches or other products from the same source in some cases helped to determine the source of infection. Mycoplasma contaminants can be considered important not only because of their role as pathogens but also because they may indicate that insufficient care has been taken during vaccine manufacture or quality control.

A technique to obviate the risk of inadvertent infection of cell cultures with bovine viral diarrhoea virus

When bovine embryonic kidneys collected at the Gorgie Abattoir, Edinburgh were examined for evidence of infection with bovine viral diarrhoea virus (BVDV), 11 out of 26 kidneys were found to be positive. A technique that detected the presence of inadvertent BVDV in cell cultures consisted of processing and digesting the kidneys to produce cell suspensions, adding dimethyl sulphoxide and dispersing the suspensions in small aliquots that were stored frozen at - 114 degrees C. One aliquot was cultured and screened for BVDV by indirect immuno-fluorescence and interference tests. Bovine embryonic kidney cells so processed retained their viability and virus susceptibility for 15 to 18 months. Selected stocks of "clean" cells only are then used for vaccine production or diagnostic purposes. The cytopathic NADL strain of BVDV multiplied in naturally infected cell cultures but the titres attained were significantly lower than in "clean" cell cultures.

A simple endpoint dilution method for evaluating serum used for cell culture

A simple endpoint dilution method for evaluating foetal calf serum quality is described. The test uses a series of doubling dilutions of cells on microtitre trays with the test sera added to replicate dilution series. After five to six days of incubation the cells are stained with crystal violet and the end points read macroscopically. The cell growth-promoting property of serum may be expressed as a reciprocal of the cell dilution resulting in an approximately 50% coverage of cells.

Rotavirus-specific antibodies in fetal bovine serum and commercial preparations of serum albumin

Rotavirus-specific antibodies were detected in fetal bovine serum, bovine serum albumin, and human serum albumin by radioimmunoprecipitation with the NCDV strain of bovine rotavirus as the detecting antigen. Fetal bovine sera neutralized bovine rotavirus in a plaque reduction neutralization test to titers of 1:20 or greater. Immunoglobulins purified from fetal bovine serum by protein A-agarose affinity chromatography precipitated rotavirus antigens but did not neutralize bovine rotavirus. Rotavirus antibodies in fetal bovine serum and in purified serum albumin preparations may interfere with diagnostic assays for the detection of rotavirus antigens or antibodies.

Use of protein A to remove immunoglobulins from serum in hybridoma culture media

The levels of protein A-reactive immunoglobulin (PA-Ig) in foetal bovine serum were measured in commercial batches. For tissue culture media incorporating 10% foetal bovine serum, the levels of bovine PA-Ig were of a similar order to those of mouse monoclonal antibodies produced by hybridomas grown in such media. The equilibrium constants were calculated for the binding to protein A-Sepharose of a number of mouse monoclonal antibodies, and of PA-Ig in foetal bovine serum and normal mouse serum. The average affinity of the mouse PA-Ig was 10 times higher than that of the bovine PA-Ig, suggesting that the two could be separated by affinity chromatography on protein A-Sepharose. The mouse monoclonal antibodies, however, displayed a range of affinity 1.5-100 times that of the bovine PA-Ig, indicating that such separation could not be generally applied. The optimal technique involved removing PA-Ig from bovine serum before its inclusion in the culture medium and then purifying the monoclonal antibody on a second protein A-Sepharose column.

Role of serum in survival of Treponema pallidum in tissue culture

During attempts to cultivate Treponema pallidum, it was determined that length of time for survival of virulent treponemes was highly dependent on the quality of the fetal bovine serum (FBS) used as a protein supplement in the culture medium. Eighteen lots of commercial FBS were tested for their ability to maintain survival of T. pallidum in cultures of cottontail rabbit epithelial (SflEp) cells. All were capable of supporting growth of these cells. However, in tests on five of the lots, attachment of treponemes to the SflEp cells was either extremely poor or the 50% survival time (ST50) was less than 5 days. With two of these lots, no treponemes survived for 5 days. By contrast, in tests with 11 of the FBS lots, the ST50 of the treponemes was 12 days or greater; however, there was a great variation in the number of treponemes that attached. Selection of lots of FBS for ultimate experimental use was based on their influence both to extend length of time for survival of treponemes and to increase the number of treponemes that attached to the SflEp cells during that period.

The effect of serum on monolayer cell culture of mammalian articular chondrocytes

Large variations were found in the ability of six species of sera to support growth of rabbit, human and dog articular chondrocytes in monolayer culture. In most instances the DNA content of the cell pellets increased directly as the serum concentration rose from 10 to 30%. Indications of inhibitory as well as growth-promoting actions were found in some sera. Stimulation of rabbit chondrocyte proliferation by increasing concentrations of serum was accompanied by a reduction of radiosulfate incorporation and cell protein content. There was no consistent relation between the response of chondrocytes from a given species and its homologous serum. However, the growth of human chondrocytes was greatly potentiated by human serum provided that interference with initial attachment of the cells to the culture flask by homologous serum was overcome by priming with fetal calf serum.

A method for testing the growth activity of tissue culture media using suspension lymphoblastoid cells

A new rapid method for testing the growth activity of tissue culture media using the 'Raji' and 'Simpson' strains of lymphoblastoid cells grown in suspension is described. This method has advantages for rapidly assessing the quality of a culture medium.

Effect of fetal bovine serum on 3-methylcholanthrene-induced transformation of hamster cells in vitro

Eighteen lots of fetal bovine serum were tested for their ability to support clonal growth and 3-methylcholanthrene-induced morphological transformation of hamster embryo cells in vitro. Most of them supported cloning efficiencies of over 11%. However, cloning efficiency alone was an inadequate criterion for selecting serum for transformation studies, since no transformation was observed with some lots, even though their cloning efficiencies were over 16%. This shows the importance of pretesting serum for its ability to support morphological transformation before it is used in mammalian cell carcinogenesis tests.

Serum-induced chromosome damage and neoplastic transformation of mouse cells in vitro

In previous studies, mouse cells grown in medium supplemented with horse serum (HS) developed more chromosomal aberrations and underwent malignant transformation earlier than cells from the same pool grown with fetal bovine serum (FBS) supplement. In the present study cells derived from C3Hf/HeN mouse embryos were grown in medium NCTC-135 supplemented with various combinations of large- and small-molecule fractions of HS and FBS in an effort to determine the effective components. The results indicate that the large-molecule fraction of HS (mare or stallion) produces alterations in chromosome number and structure. HS is also shown to cause chromatid breaks and exchanges at or near the centromere in contrast to fluorescent-light-induced breaks and exchange at or near the centromere in contrast to fluorescent-light-induced breaks which occur randomly along the chromatid. However, efforts to control completely chromosome stability and malignant transformation through the use of large- and small-molecule fractions of HS and FBS or combinations thereof were unsuccessful. In connection with this study, diagnosis of malignant transformation in vitro was made by a direct sampling method based on cytologic criteria previously described and documented. With one exception, the diagnoses of 11 different cell lines were consistent with results of in vivo assays.

Effects of serum concentrations on the clonal growth of Syrian golden hamster fetal lung cells

In order to gain an insight into the mechanisms of clonal growth of early-passage Syrian golden hamster fetal lung (SGHFL) cells, a study was undertaken, in which the effects of various serum concentrations on the cloning efficiency and on the colony size of these cells were examined. The results suggest that both cloning efficiency and colony size are influenced by at least two factors present in the serum.

Persistent infection with bovine herpesvirus-1 (infectious bovine rhinotracheitis virus) in cultured hamster cells

Bovine herpesvirus-1 infection in hamster embryo cells was found to be dependent upon input multiplicity; productive infection was achieved at input multiplicities greater than one, while persistent infection was established when input multiplicities were about 0.5. This persistence was characterized by a noncyclic, minimal degree of cytopathic effect with a low level of released virus. Maintenance of the persistently infected cultures did not require external supportive measures. Subcultivation of the persistently infected cultures led to virus replication followed by CPE and then cell regrowth. With 3 to 4 weeks after subcultivation a persistent infection was re-established. The possible mechanism for the bovine herpesvirus persistence in hamster cells is discussed.

Autoclavable low cost serum-free cell culture media: the growth of established cell lines and production of viruses

Five cell lines (BSC-1, CHO, Balb/c 3T3, HeLa, and KB) have been grown in serum-free media for several months with regular schedules of media changing and subculturing. The medium found to be successful in all cases was MEM-alpha (without the ribosides and deoxyribosides) supplemented with 1% bacteropeptone, although simple MEM (minimum essental medium (Eagle) with bacteropeptone (BP) gave fairly good growth in the case of BSC-1 and 3T3 cells. The addition of insulin was necessary for CHO, 3T3, HeLa, and KB cells. Only the BSC-1 cells grew exclusively as a stationary suspensions and the 3T3 cells growing as a combination of monalayer and suspension depending on the age of the culture and the nature of the growth surface. SV40 was produced in BSC-1 cells grown and infected in the MEM-alpha, bactopeptone medium and adenovirus-2 was produced in spinners of HeLa and KB cells grown in MEM-alpha, bactopeptone, PVP-360, and insulin. The yield of virus and infectivity of the viruses produced were about the same as those produced in conventional serum-containing systems.

Detection of bovine viruses in fetal bovine serum used in cell culture

This investigation employed a viral screening method detect endogenous bovine virus contaminants in commercially supplied fetal bovine serum. Fifty-one lots of fetal bovine serum from 14 suppliers were examined. Over 30% of the lots tested were found to contain bovine viruses; they included bovine virus diarrhea virus, parainfluenza type3-like virus, bovine herpesvirus-1, bovine enterovirus type 4, and an unidentified cytopathogenic agent. Of the 51 lots, 20 had been pretested by the suppliers and were considered to be free of known viral contaminants. Our viral screening methods revealed that five of these pretested lots, or 25%, contained endogenous bovine viruses.

Effect of exogenous lipid on lipid synthesis by bone and bone cell cultures

Newborn rat calvaria and isolated calvaria cells are capable of de novo lipid synthesis when grown in the presence or absence of exogenous lipid sources. Synthesis decreases when exogenous lipids are supplied. Several cholesterol precursors were found in these tissues and the presence of dihydrocholesterol was established for the first time.

Growth control of differentiated fetal rat hepatocytes in primary monolayer culture. V. Occurrence in dialyzed fetal bovine serum of macromolecules having both positive and negative growth regulatory functions

Dialyzed fetal bovine serum contains two distinct growth-controlling macromolecular fractions: one stimulates and the other inhibits proliferation of primary cultured differentiated fetal rat hepatocytes. Both fractions are precipitated by ammonium sulfate (50% saturation, pH 7.4, 4 degrees C). Serum fraction I (SFI, mol wt >/= 120,000 daltons estimated by gel filtration with Bio-gel P200) appears to contain at least two factors which function, respectively, to initiate DNA synthesis (activity pH 4-10 stable) and to increase the rate at which initiated cells traverse the cell cycle (activity pH 4 and pH 10 labile). Intraperitoneal injections of SFI into adult rats have produced detectable stimulation of hepatic but not renal DNA synthesis. Serum fraction II (SFII, mol wt 40,000-80,000 daltons) suppresses in vitro incorporation of CH(3)-[(3)H]thymidine into DNA under conditions which diminish neither cell viability nor cell attachment. Mixing experiments indicate that SFI and SFII mutually antagonize each other with respect to DNA synthesis and cell multiplication. Thus, both the relative and absolute serum levels of multiple factors control in vitro fetal hepatocyte proliferation.

Antibody to viruses affecting cattle in commercial tissue culture grade fetal calf serum

Commercial fetal calf serum (FCS) for tissue culture use was tested for neutralizing activity against several viruses which affect cattle. Certain lots of FCS contained no neutralizing activity, whereas other lots contained neutralizing activity to several viruses. It was concluded that the neutralizing activity found in certain lots of sera was due to specific antibody and that its presence could be most easily explained by the contamination of the FCS with serum from postcolostral bovine serum. A nonantibody inhibitor to vesicular stomatitis virus was also found at low levels in most lots of serum. Because those sera which had antibody had antibody to several viruses, it was suggested that the use of the micro-serum neutralization test with a few bovine viruses which are widespread in the bovine population should be satisfactory to detect FCS which was contaminated with postcolostral bovine serum.

Plating efficiency for primary hamster embryo cells as an index of efficacy of fetal bovne serum for cell culture

Attachment and growth of mammalian cells plated at low cell density require optimum conditions for the cells to form colonies. Reliability, reproducibility, and validity of the plating efficiency test for evaluating cell culture sera were determined by measuring the plating efficiency of 37 lots of fetal bovine serum obtained from 8 suppliers (5 lots from each of 7, 2 lots from 1 supplier), by using hamster embryo fibroblasts plated at low cell density. The test revealed considerable variation between lots of serum and between suppliers. The five lots from some suppliers had consistently high plating efficiencies, whereas one or more lots from other suppliers had quite low efficiencies. The results were reproducible in repeated tests, and control experiments indicated that the test measured the efficiency of the test serum independently of the efficiency of the serum used for the primary outgrowth of the hamster embryo cells.