Variable responsiveness of rat tracheal epithelial cells to bovine serum albumin in serum-free culture

Development of early porcine embryos in vitro and in vivo

In vitro development of early porcine embryos under different culture conditions was evaluated and compared to in vivo development. First, one- and two-cell embryos were collected and cultured individually in 20- microl drops under 5% CO2 in air for 4 days. Embryos from one oviduct were cultured in NCSU-23, and those from the contralateral oviduct were cultured in KSOM/AA. The embryos developed in NCSU-23 had a higher mean number of inner cell mass (ICM) nuclei compared to those developed in KSOM/AA (p = 0.025). They also had higher trophectoderm (TE) and total nuclear number (p = 0.001), while there was no difference in the average ratio of ICM to TE nuclei (p = 0.731). When the effect of different gas atmospheres was tested, the numbers of TE and total nuclei were higher (p < 0.01 and p < 0.025, respectively) in embryos cultured in an atmosphere with 5% CO2 in air than in those developed under 5% CO2:5% O2:90% N2. Next the development of embryos cultured in NCSU-23 was compared to that of embryos incubated in vivo. By the end of the 4-day incubation, the cultured embryos had higher nuclear numbers and a higher ratio of ICM to TE nuclei than those developed in vivo (p < 0.001). Finally, the embryos that developed in NCSU-23 or in vivo were transferred into recipients. By Day 40 of pregnancy, 37.1 +/- 15.3% of the in vitro- and 53.8 +/- 15.3% of the in vivo-incubated embryos formed conceptuses. These results indicate that despite the lower nuclear numbers caused by in vitro conditions, the cultured embryos were developmentally competent.

Proinflammatory activity on rat carotid endothelium of albumins obtained by different procedures

To investigate whether the proinflammatory activity of intravenously administered albumins is related to their preparation method, we compared bovine albumins obtained by alcohol precipitation and by heat shock. This last procedure produced a notable increase in monocyte adhesion/mm2 in rat carotid endothelium (48 +/- 31, n = 32 rats, vs 7 +/- 6, n = 24 rats, mean +/- S.D., P < 0.001). We found no changes in fluorescence emission in these two groups, and no correlation was observed between leukocyte adhesion and the contents of free fatty acids, free -SH groups, fructosamine, dimers and polymers. The inhibition profile of the proinflammatory activity by polyanionic molecules (fucoidan and dextran sulfate 500 kD) was compatible with the recognition of heat-shocked albumins by scavenger receptors. Thiol disulfide exchange in albumins was produced by ageing with cysteine and by incubation with protein disulfide isomerase. Albumins thus modified increased the adhesion of leukocytes to the endothelium, which indicates that some isomeric forms of albumin generated by thiol disulfide exchange may acquire proinflammatory behavior.

Influence of fatty acids and bovine serum albumin on the growth of human hepatoma and immortalized human kidney epithelial cells

The protective influence of bovine serum albumin against growth inhibition caused by fatty acids was studied in human hepatoma (HepG2) and immortalized human kidney epithelial (IHKE) cells. In general, growth inhibition by unsaturated fatty acids (0.15 mmol/liter) increased with increasing number of double bonds. For HepG2 cells crude albumin (1 g/100 ml) did not greatly modify growth inhibition by arachidonic, eicosapentaenoic, and docosahexaenoic acid. With oleic, linoleic, and linolenic acids, crude and defatted albumin stimulated cell growth. In contrast, for IHKE cells both albumins counteracted growth inhibition by unsaturated fatty acids to approximately the same extent. When HepG2 cells were cultured in the presence of saturated fatty acids (0.3 mmol/liter), C2, C6, and C8 had no or little inhibitory effect. C10 and C12 inhibited cell growth appreciably, whereas C14, and especially C16, had poor inhibitory effects. Crude albumin counteracted growth inhibition by all these fatty acids. In contrast, defatted albumin had little or no effect (except against C10 and C12), and even increased the growth inhibition by C14 and C16. With unsaturated fatty acids there seemed to be an inverse relationship between cell growth and the concentration of thiobarbituric acid reactive substances (TBARS) in media. Vitamin E abolished growth inhibition (and the increase in TBARS concentration) by unsaturated fatty acids. The complex interaction between fatty acids and albumins calls for great caution when interpreting data on growth effects.

Effect of albumin on adenylate cyclase receptor-related signal transduction of human peripheral blood mononuclear cells

In the present study we investigated in vitro the effect of human serum albumin (HSA) on receptor-stimulated cAMP production in isolated human peripheral blood mononuclear cells (PBMC). The cAMP production is strongly correlated with the pH of the medium during long incubations with albumin. Adenylate cyclase is stimulated by receptor agonists like histamine, forskolin, prostaglandin E2 and the beta-adrenergic agonist isoprenaline, in the presence or absence of HSA. This protein, at concentrations above 0.1%, dose-dependently inhibits both basal and agonist-stimulated cAMP levels in PBMC. In the presence of 0.5% HSA a significant reduction of 30-60% (cell batch dependent) is induced, a reduction which is not incubation time dependent. Washing the cells after a period of incubation with 2% HSA does not reverse the HSA-induced cAMP inhibition. Oleic acid-evoked conformational changes in HSA were not capable of influencing the inhibition processes of HSA on the isoprenaline-stimulated cAMP production. Structure-controlled interactions between HSA and membrane or adenylate cyclase are therefore unlikely. Bovine serum albumin and chicken albumin had different effects upon the agonist-stimulated cAMP production as compared with HSA. At this moment no explanation for this behavior can be provided. The findings indicate that albumin may inhibit non-specifically cAMP production in PBMC and possibly influences membrane-controlled processes.

Critical variables controlling cell proliferation in primary cultures of rat tracheal epithelial cells

The purpose of our experiments was to examine variables affecting early events in the establishment of rat tracheal epithelial (RTE) cultures as well as factors regulating long-term RTE cell growth. The experiments showed that when RTE cells were seeded into complete serum-free medium between 13 and 30% of the seeded cells attached. Of the seeded cells, only approximately 2% entered into DNA synthesis and underwent repeated cell divisions to form colonies containing greater than 20 cells. Coating the dishes with extracellular matrix components had little effect on cell attachment or colony forming efficiency (CFE). However, coating the dishes with fetal bovine serum markedly increased CFE. The media components bovine serum albumin and bovine pituitary extract were shown to be important in promoting cell attachment as well as CFE. Cholera toxin on the other hand had no effect on cell attachment but significantly increased CFE. These and other studies showed that cell attachment and cell proliferation are independently regulated. Studies on long-term culture growth indicated that the number of progeny produced per colony forming unit (CFU) is inversely proportional to the number of CFUs seeded. Inasmuch as the cultures did not become confluent under any of the culture conditions tested and media obtained from high density cultures were shown to be growth inhibitory, these findings suggest that a diffusible growth restraining factor is being produced by the cultures limiting clonal expansion. Experiments showing growth inhibitory effects of media conditioned by high cell density cultures support this interpretation. The putative factor reaches critical concentrations earlier in cultures seeded with high numbers of CFU than in cultures seeded with low numbers of CFU. Because the cultures are known to produce transforming growth factor-beta, this growth regulator probably plays a role in controlling RTE cell proliferation. However, it is likely than other events, such as depletion of growth factors from the media, also are significant in regulating the growth of the cultures.