The serum-free growth of cultured cells in bovine colostrum and in milk obtained later in the lactation period

Seven established cell lines, including both epithelial cells and fibroblasts (MDCK, Vero, CV-1, NRK, 3T3, F2408, and NIL8) and four early passage cell strains (bovine articular chondrocytes, bovine smooth muscle cells, human foreskin fibroblasts, and rat embryo cells) were cultured in serum-free medium supplemented with milk obtained 1 day after birth (colostrum) or 80 days after birth (older milk). MDCK, Vero, CV-1, NRK, and 3T3 grew readily in colostrum and attained saturation densities ranging from 22% to 63% of that in serum. There was no growth of F2408, NIL8, or the early passage strains in bovine colostrum. None of the 11 cell cultures grew in older milk. The temporal dependence of growth in milk was examined in detail using MDCK cells. Growth equivalent to that in serum occurred in 3% colostrum and in 15% milk obtained 2 days after birth. Milk obtained 3 days and 10 days after birth was not effective as a growth supplement for MDCK cells at any concentration. Those cells, unable to grow in colostrum or in older milk, could be induced to grow if culture dishes were precoated with fibronectin. In addition to fibronectin, it was necessary in some cultures to supplement colostrum or older milk with insulin and/or transferrin in order to achieve growth. In the presence of fibronectin and appropriate factors, the final saturation density attained in colostrum or older milk ranged from 25% to 100% of that in serum. The fibronectin contents of bovine colostrum and milk were determined. The fibronectin level of colostrum was found to be approximately 5% of bovine serum. There was no detectable fibronectin in the 80-day-old milk.     

Selective maintenance of cultured epithelial cells from DMBA-induced mammary tumours by bovine colostrum supplement

Growth kinetics in cultures of DMBA-induced mammary tumours supplemented with bovine colostrum were compared with the kinetics of cultures maintained with the conventional supplement of foetal calf serum. Although the latter permitted a greater degree of cell proliferation, a substantial amount of the cell growth was due to the fibroblastic proliferation. In the presence of bovine colostrum, epithelial islands surrounded by a few solitary cells became established. Unlike the foetal calf serum supplemented cultures, these cultures frequently did not become completely confluent within 7 days. The absence of fibroblasts in colostrum supplemented cultures was confirmed by electron microscopy. Results from this study suggest that colostrum may be useful in selective maintenance of primary cultures of epithelial origin.     

Studies on the growth-stimulatory activity of pigeon milk-comparison and synergistic effects with serum

Pigeon milk, a nutritive secretion from the crop of breeding pigeons, was tested (on v/v basis) for growth factor activity either separately or in combination with other growth supplements. Synthesis of DNA in confluent monolayers of quiescent Chinese hamster ovary cells was enhanced by the homogenates of pigeon milk in the presence of both fetal bovine serum and bovine serum albumin, although the response with fetal bovine serum was greater than that with bovine serum albumin. The in vitro growth stimulation by pigeon milk was also reflected in the increase in cell number. Specific activity of pigeon milk growth factor, measured against both Chinese hamster ovary cells and mouse embryo fibroblasts, was found to be higher than that of fetal calf serum, fetal bovine serum, and goat, horse, pig and human serum. The growth-stimulatory property of pigeon milk did not change in the first 5 days of its secretion.Abbreviations BSA bovine serum albumin - CHO Chinese hamster ovary cells - DMEM Dulbecco's modified minimum essential medium - DNA deoxyribonucleic acid - EDTA ethylenediaminetetraacetic acid - EGF epidermal growth factor - FBS fetal bovine serum - FCS fetal calf serum - GF growth factor - GS goat serum - NIH/3T3 mouse embryo fibroblasts - PBS phosphate-buffered saline - PDGF platelet-derived growth factor - PM pigeon milk     

Bovine colostrum or milk as a serum substitute for the cultivation of a mouse hybridoma

A mouse-mouse hybridoma was grown in serum-free medium supplemented with bovine milk or colostrum. Bovine colostrum supported growth of the hybridoma whereas bovine milk alone did not support cellular proliferation. For growth in medium supplemented with colostrum, the maximum cell concentration achieved was 1.4 x 10(6) cells/mL in 2.2% colostrum, which is 44% of that obtained in 9% serum. When cells were grown in media containing milk and low amounts of serum (<1%) the maximum cell concentration in 2.2% milk with 0.4% serum was 2 x 10(6) cells/ml, whereas it was only 0.2 x 10(6) cells/ml and 1.3 x 10(6) cells/ml in 2.2% milk alone and 0.4% serum alone, respectively. Similar behavior was observed for growth in media containing colostrum and low amounts of serum. The monoclonal antibody production in media containing combinations of serum and milk or colostrum was comparable to that obtained in media with higher serum concentrations. Experiments performed with conditioned media suggest that the rapid decrease in viability, after the maximum cell concentration has been reached, is partially due to the presence of some inhibitory components generated during the cell culture rather than due to depletion of some serum components.     

Milk-derived growth factors as serum supplements for the growth of fibroblast and epithelial cells

Summary We have investigated the response of several epithelial and fibroblastic cells to a mitogenic extract of bovine milk. Cation exchange chromatography was used to produce a mitogen-rich fraction from an industrial whey source that, although comprising only 0.5% of total whey protein, contained the bulk of the growth factor activity. This fraction was a source of potent growth promoting activity for all mesodermal-derived cells tested, including human skin and embryonic lung fibroblasts, Balb/c 3T3 fibroblasts, and rat L6 myoblasts. Maximal growth of all these cell types exceeded that observed in 10% fetal bovine serum. Feline kidney and baby hamster fibroblasts and Chinese hamster ovary cells were less responsive, achieving a maximal growth response of 50–75% that observed in 10% fetal bovine serum. Maximal growth achieved in whey-extract-supplemented cultures of Balb/c 3T3 and human skin fibroblasts, and L6 myoblast cultures exceeded that seen in response to recombinant acidic or basic fibroblast growth factor, platelet-derived growth factor, insulin-like growth factor, or epidermal growth factor. Importantly, addition of low concentrations of fetal bovine serum to the whey-derived mitogenic fraction produced an additive response. However, concentrated milk-derived factors were found to be inhibitory to the growth of all epithelial lines tested, including rat intestinal epithelial cells, canine kidney epithelial cells, and mink lung cells. It is concluded that industrial whey extracted in this form constitutes an important source of potent growth-promoting agents for the supplementation of mesodermal-derived cell cultures.     

Bovine-Associated Mucoprotein

Bovine-associated mucoprotein (BAMP), solubilized with water from the delipidated membranes of bovine milk fat globules, is not restricted to fat globules or to the alveolar epithelial cells from which they are formed. BAMP also has a widespread distribution on other bovine glandular epithelial cells and on undifferentiated cells in lymphoid germinal centers and in several fetal tissues. Free BAMP is present in bovine colostrum, milk, other secretory fluids, and in fetal serum but is absent from adult and colostrum-deprived calf sera. In bronchoalveolar fluids, BAMP is preferentially found in the mucusrich fraction. BAMP is antigenically distinct from all adult serum proteins, free secretory component, β₂-microglobulin, lactoferrin, α-lactalbumin, β-lactoglobulin, and five different caseins. BAMP as a free protein constitutes one-sixth of the total amount of BAMP present in milk. The BAMP-related component of fetal serum lacks antigenic determinants present on the BAMP of milk as demonstrated by immunoprecipitation and partial blocking of immunofluorescence. The fetal component is not fetuin or α₁-fetoprotein. These data suggest that BAMP may be useful in studies of the membranes of proliferating or differentiating epithelial cells.     

Bovine-associated mucoprotein: I. Distribution among adult and fetal bovine tissues and body fluids

Bovine-associated mucoprotein (BAMP), solubilized with water from the delipidated membranes of bovine milk fat globules, is not restricted to fat globules or to the alveolar epithelial cells from which they are formed. BAMP also has a widespread distribution on other bovine glandular epithelial cells and on undifferentiated cells in lymphoid germinal centers and in several fetal tissues. Free BAMP is present in bovine colostrum, milk, other secretory fluids, and in fetal serum but is absent from adult and colostrum-deprived calf sera. In bronchoalveolar fluids, BAMP is preferentially found in the mucus-rich fraction. BAMP is antigenically distinct from all adult serum proteins, free secretory component, beta 2-microglobulin, lactoferrin, alpha-lactalbumin, beta-lactoglobulin, and five different caseins. BAMP as a free protein constitutes one-sixth of the total amount of BAMP present in milk. The BAMP-related component of fetal serum lacks antigenic determinants present on the BAMP of milk as demonstrated by immunoprecipitation and partial blocking of immunofluorescence. The fetal component is not fetuin or alpha 1-fetoprotein. These data suggest that BAMP may be useful in studies of the membranes of proliferating or differentiating epithelial cells.     

Changes in serum influence the fatty acid composition of established cell lines

Summary The fatty acid composition of different kinds of commercially available serum used to supplement cell culture media differs widely. As compared with fetal bovine serum, horse and bovine calf serum have a very high content of linoleic acid (18:2) and are low in arachidonic acid (20:4). (Fatty acids are abbreviated as number of carbon atoms: number of double bonds). Swine serum contains substantial amounts of both 18:2 and 20:4. Only fetal bovine serum contains more than 1% docosahexaenoic acid (22:6). Considerable differences in fatty acid composition occur when cells are grown in media containing any of these different serum supplements. The 18:2 and 20:4 content of 3T3 mouse fibroblast phospholipids is highest when the medium contains horse serum, intermediate with bovine calf serum, and lowest with swine or fetal bovine serum. Likewise, the highest phospholipid 18:2 content in Madin-Darby canine kidney cells (MDCK) occurs when the medium contains horse serum. With MDCK cells, however, growth in swine serum produces the highest 20:4 content. The 3T3 cell phospholipids accumulate more than 1% 22:6 only when the medium contains fetal bovine serum, whereas in no case do the MDCK cell phospholipids accumulate appreciable amounts of 22:6. The fact that the cellular fattyacid composition is likely to change should be taken into account when changes are contemplated in the serum used to grow established cell lines. These studies were supported by Arteriosclerosis Specialized Center of Research Grant HL 14,230 from the National Heart, Lung, and Blood Institute, National Institutes of Health.     

Adaptation of BHK-21 Cells to Growth in Shaker Culture and Subsequent Challenge by Japanese Encephalitis Virus

Baby hamster kidney (BHK-21) cells were adapted to grow in shaker culture using Waymouth medium 752/1 containing 20 mM N-2-hydroxyethyl-piperazine-N'-2'-ethanesulfonic acid buffer and supplemented with 2.5% (vol/vol) calf serum, 0.002% (wt/vol) sodium oleate, and 0.2% fatty acid-free bovine serum albumin (WO2.5). Infectivity of Japanese encephalitis virus grown in the cells adapted to WO2.5 approached 2 x 10(8) plaque-forming units per ml. The culture volume of infected cells was reduced fivefold 12 h after infection. This step resulted in a 10-fold increase in infectivity over that obtained from infected cultures not subjected to volume reduction.     

Mitogenic effect of fibroblast growth factor on early passage cultures of human and murine fibroblasts

Fibroblast growth factor (FGF), a polypeptide that has been shown to stimulate division in 3T3 cells, was tested for mitogenic effects on diploid, early-passage cells from human and murine sources. The quantitative assay of [3H]thymidine incorporation into acid-insoluble material showed that FGF at low concentrations (10 minus 9 M) was more effective than additional serum for provoking the initiation of DNA synthesis in human foreskin fibroblasts or mouse fibroblasts maintained in 5 or 10% serum, respectively. The growth of the human fibroblasts was twice as fast in the presence of FGF plus 10% calf serum as it was in the presence of 10% calf serum or 20% fetal calf serum alone. The addition of FGF to primary cultures of mouse fibroblasts in 0.4% serum resulted in a twofold increase in cell number compared to controls. In contrast to results obtained with 3T3 cells, neither insulin nor a glucocorticoid potentiated the effects of FGF on either human or mouse cells.     

Growth of functional primary cultures of kidney epithelial cells in defined medium

Primary cultures of baby mouse kidney epithelial cells can grow without fibroblast overgrowth in a hormone-supplemented serum-free medium (Medium K-1) designed for an established kidney epithelial cell line, MDCK. The five supplements in Medium K-1 are insulin, transferrin, PGE1, T3, and hydrocortisone. Medium K-1 also supports the growth of kidney epithelial cell cultures from a number of animals, including man, without fibroblast overgrowth. Outgrowth of kidney epithelial cells from kidney explants was also observed with Medium K-1. Thus, the medium appears to be selective for epithelial cell growth. The physiological properties of primary cultures of baby mouse kidney epithelial cells were studied in detail. Baby mouse kidney epithelial cells grew at equal rates (0.5 doublings/day) in Medium K-1 and serum-supplemented medium. Medium K-1 also supported the formation of baby mouse kidney epithelial colonies at low cell densities. The dependence of baby mouse kidney epithelial colony formation upon the five factors in Medium K-1 was examined. These studies indicated that the formation of baby mouse kidney epithelial colonies in defined medium depended upon all the five supplements in Medium K-1, in a manner similar, although not identical, to MDCK colonies. Primary cultures of baby mouse kidney epithelial cells grown in Medium K-1 retained kidney cell-associated properties, including the ability to form multicellular domes, a phenomenon associated with transepithelial salt transport. Amiloride-sensitive Na+ uptake and the mucosal surface enzyme leucine aminopeptidase were also observed in baby mouse kidney cultures. Similar functions were observed in MDCK monolayers.     

Use of synthetic serum-free medium for culture of human dermal fibroblasts to establish an experimental system similar to living dermis

In this study, we sought to establish a defined experimental system for fibroblast growth similar to that of the living dermis. To this end, we evaluated the growth and biochemical characteristics of fibroblasts cultured with serum-free HFDM-1, a finely tuned synthetic medium for human fibroblast culture. Three culture conditions were used to grow fibroblasts obtained from primary culture: (1) culture with Dulbecco’s modified Eagle medium (DMEM) plus 10 % fetal bovine serum (serum-supplemented DMEM), (2) culture with DMEM (serum-free DMEM), and (3) culture with HFDM-1 (HFDM-1), and fibroblast morphology, growth, collagen type I production, and lipid composition were analyzed. Fibroblasts grown in HFDM-1 maintained cell numbers at nearly 100 % from days 14 to 21 and produced more collagen type I than cells grown in serum-supplemented and serum-free DMEM. Arachidonic acid (20:4) and total polyunsaturated fatty acids were lower in cells grown in serum-free DMEM and HFDM-1 than in serum-supplemented DMEM. These results suggested that HFDM-1 recapitulated growth conditions in the dermis better than traditional, serum-supplemented DMEM. In addition, the controlled chemical composition of HFDM-1 eliminated a potential source of variability in cell culture conditions.     

Optimization of bovine satellite cell-derived myotube formation in vitro

Post-natal myogenic satellite cells, isolated from the sternomandibularis muscles of bovine at slaughter were used for primary culture studies. Isolated satellite cells tended to differentiate into multinucleated myotubes more efficiently if initially plated on to a fibronectin substratum. Bovine-derived satellite cells displayed greater fused cell numbers when exposed to Dulbecco's Modified Eagle's Medium (DMEM) supplemented with horse serum than similar supplementation with fetal calf serum (P less than 0.05) or sheep serum (P less than 0.05). In addition, differentiation appeared nearly complete after 4 days exposure to DMEM-1% horse serum as verified by beta-D-arabinofuranosyl-cytosine addition to cultures. Collectively, these data provide the first evidence that satellite cells can be isolated from a bovine skeletal muscle. Furthermore, these data indicate that bovine-derived satellite cells can be induced to undergo substantial morphological differentiation in vitro.     

Human IgA inhibits adherence of Acanthamoeba polyphaga to epithelial cells and contact lenses

Specific anti-Acanthamoeba IgA antibodies have been detected in the serum and tears of patients and healthy individuals. However, the role of human secretory IgA antibodies in inhibiting the adherence of Acanthamoeba had not been previously investigated. Therefore, the purpose of this study was to purify secretory IgA from human colostrum and analyze its effect on the adherence of Acanthamoeba trophozoites to contact lenses and Madin-Darby canine kidney (MDCK) cells. IgA antibodies to Acanthamoeba polyphaga in colostrum of healthy women as well as in saliva and serum of healthy subjects were analyzed by ELISA and Western blot analysis. In serum, saliva, and colostrum, we detected IgA antibodies that recognized several antigens of A. polyphaga. In addition, colostrum and IgA antibodies purified from it inhibited adherence of A. polyphaga trophozoites to contact lenses and MDCK cells. These results suggest that IgA antibodies may participate in the resistance to the amoebic infection, probably by inhibiting the adherence of the trophozoites to contact lenses and corneal epithelial cells.     

Confrontation of an invasive (MO4) and a noninvasive (MDCK) cell line with embryonic chick heart fragments in serum-free culture media

Summary Confronting cultures of precultured embryonic chick heart fragments (PHF) with aggregates of malignant cells in vitro have been shown to be relevant for a number of aspects of tumor invasion in vivo. Preculture of the heart fragments, formation of cell aggregates and subsequent culture of confronting pairs have so far been done only in serum-containing culture media. We describe here confronting cultures of PHF with invasive MO₄ mouse cell aggregates or noninvasive MDCK dog kidney cell aggregates in serum-free media. Heart fragments precultured in the absence of serum seemed to be necrotic after confronting culture in serum-free media. However, preculturing in media supplemented with 10% fetal bovine serum allowed us to do subsequent confronting cultures in absence of serum. Cell aggregates were also prepared in serum-containing medium. MO₄ cells occupied and replaced the heart tissue within 4 d, whereas MDCK cells remained at the periphery, of the PHF. This indicates that serum-free confronting cultures can discriminate between invasive and noninvasive cells. The viability of individual PHF and cell aggregates cultured in the same way as in confrontations was ascertained by histology and by explantation and postculturing on a solid tissue culture substrate. Growth of the cultures was smaller in serum-free media than in media supplemented with 10% fetal bovine serum. The main advantage of serum-free culture conditions in vitro is the elimination of the influence of serum components on invasion, and the ability to examine the effect on invasion of drugs that are, susceptible to inactivation by serum. This work was supported by the Fonds van de Sport Vereniging tegen de Kanker, Brussels, Belgium, and the Fonds voor Geneeskundig Wetenschappelijk Onderzoek Brussels, Belgium     

Long-term cultures of chicken bone marrow cells

We report an adaptation to cultures of chicken bone marrow cells of the Dexter culture technique for obtaining long-term hemopoiesis in vitro. Cells were seeded in DMEM supplemented with fetal calf serum (20%) and hydrocortisone (10(-6) M) with or without chicken serum (1%). Cultures were incubated at 37 degrees C and fed every 2 weeks. An adherent cell layer composed of macrophages, fibroblasts, and adipocytes became established, over which hemopoietic cells formed foci and were released into the supernatant. Granulocytes and monocytes-macrophages differentiated in a constant proportion until Week 6, whereafter differentiation became progressively restricted to the monocytic lineage. As demonstrated by the generation of colony-forming cells, hemopoiesis was maintained for either 12 or 28 weeks.     

Demonstration of competence and progression activities for human fibroblasts

Human embryonic lung fibroblasts (HEL) completed 4.5 population doublings in 6 days when maintained in DMEM supplemented with 10% human whole blood serum (WBS), plasma-derived serum (PDS) or defibrinogenated plasma containing 10 mM CaCl₂. Plasma in the absence of additional calcium promoted less growth. Sera and plasma chromatographed through carboxymethyl Sephadex (CMS) supported only one population doubling. Increased growth resulting in three doublings was observed in CMS-treated WBS or PDS supplemented with commercially prepared platelet-derived growth factor (PDGF). The magnitude of this PDGF response was dependent on serum concentration. A significant increase in the proportion of cells incorporating [³H]thymidine was observed in confluent cultures exposed to PDGF prior to incubation in WBS-CMS or PDS-CMS indicating competence and progression activities for human fibroblasts. In contrast, cells maintained in the presence of plasma-CMS failed to grow in response to PDGF. Factors bound to CMS columns restored growth-promoting activity to PDGF-supplemented WBS-CMS, PDS-CMS and plasma-CMS. However, growth-promoting CMS-bound components from plasma were lost during dialysis through membranes excluding materials above 12000 MW.     

Expression and action of hepatocyte growth factor in bovine endometrial stromal and epithelial cells in vitro.

Hepatocyte growth factor (HGF) is a pleiotropic growth factor that acts on various epithelial cells. The objectives of this study were to determine whether HGF altered the proliferation and prostaglandin (PG) secretion of bovine endometrial stromal and epithelial cells in vitro. We also observed HGF and HGF receptor (c-met) mRNA expression in cultured bovine endometrial stromal and epithelial cells by RT-PCR. Stromal and epithelial cells obtained from cows in early stage of the estrous cycle (days 2-5) were cultured in DMEM/Ham's F-12 supplemented with 10% calf serum. The cells were exposed to HGF (0-10 ng/ml) for 2, 4, or 6 days. HGF significantly increased the total DNA in epithelial (P < 0.05), but not stromal cells. In another experiment, when the cells reached confluence, the culture medium was replaced with fresh medium with 0.1% BSA containing HGF 0-100 ng/ml and the cells were cultured for 24 hr. The HGF stimulated PGF2alpha secretion in epithelial, but not stromal cells. RT-PCR revealed that mRNA of HGF is expressed only in stromal cells, and that c-met mRNA is expressed in both stromal and epithelial cells. These results suggest that HGF plays roles in the proliferation and the regulation of secretory function of bovine endometrial epithelial cells in a paracrine fashion.     

Alterations in growth requirements of kidney epithelial cells in defined medium associated with malignant transformation

The possibility has been investigated that (1) the supplements required for the growth of the Madin Darby Canine Kidney (MDCK) cell line in serum-free Medium K-l are indeed requirements for the growth of normal kidney cells in vitro, and (2) that alterations in these growth requirements are associated with malignant transformation. Consistent with the hypothesis that MDCK cells resemble normal kidney cells in culture, primary cultures of baby mouse kidney epithelial cells grow in Medium K-l and respond to the 5 components in the-medium. The growth properties of Moloney sarcoma virus (MSV)-transformed MDCK cells in defined media have been examined. Unlike MDCK cells, MSV-transformed MDCK cells form tumors in adult nude mice. Although they still respond to the 5 factors in Medium K-l, the optimal dosage for insulin is lower for the MSV transformants than for MDCK cells. The MSV transformants also have an additional requirement for growth in Medium K-l – fibronectin. Variants of MDCK cells have been isolated that have lost the PGE₁ requirement for growth in defined medium. These variant cells have acquired (1) the ability to form tumors in adult nude mice and (2) an alteration affecting cAMP metabolism, in addition to PGE₁ independence.