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Efficient coordination between Mg2+ and vitamin D maintains adequate Ca2+ levels during lactation. This study explored the possible interaction between Mg2+ (0.3, 0.8, and 3 mM) and 1,25-dihydroxyvitamin D3 (1,25D; 0.05 and 5 nM) during osteogenesis using bovine mesenchymal stem cells. After 21 days, differentiated osteocytes were subjected to OsteoImage analysis, alkaline phosphatase (ALP) activity measurements, and immunocytochemistry of NT5E, ENG (endoglin), SP7 (osterix), SPP1 (osteopontin), and the BGLAP gene product osteocalcin. The mRNA expression of NT5E, THY1, ENG, SP7, BGLAP, CYP24A1, VDR, SLC41A1, SLC41A2, SLC41A3, TRPM6, TRPM7, and NIPA1 was also assessed. Reducing the Mg2+ concentration in the medium increased the accumulation of mineral hydroxyapatite and ALP activity. There was no change in the immunocytochemical localization of stem cell markers. Expression of CYP24A1 was higher in all groups receiving 5 nM 1,25D. There were tendencies for higher mRNA abundance of THY1, BGLAP, and NIPA1 in cells receiving 0.3 mM Mg2+ and 5 nM 1,25D. In conclusion, low levels of Mg2+ greatly enhanced the deposition of bone hydroxyapatite matrix. The effect of Mg2+ was not modulated by 1,25D, although the expression of certain genes (including BGLAP) tended to be increased by the combination of low Mg2+ and high 1,25D concentrations.

To establish the influence of fetal bovine serum (FBS) and bovine serum lipids (BSL) on cell differentiation marker expression, bovine adipose-derived stem cells from subcutaneous tissue were incubated for 14 days in 4 types of differentiation media containing 10% FBS and 10 µL/mL BSL (TRT-1), no FBS and 10 µL/mL of BSL (TRT-2), 10% FBS and no BSL (TRT-3), or no supplements (TRT-4). Cells were subjected to Nile red staining, immunocytochemistry (CD73, CD90, CD105, DLK1, FabP4), and quantitative real-time PCR (CD73, CD90, CD105, FabP4). The number of cells presenting FabP4 and the percentage of mature adipocytes with large lipid droplets were increased in TRT-2, accompanied by a robust increase in FabP4 mRNA abundance and a decrease in DLK1-positive cells. In preadipocytes, CD73 was present around the nucleus and translocated towards cell membranes during differentiation. Although the percentage of CD73-positive cells was not different among treatments, its mRNA abundance, immunocytochemical staining intensity, and translocation towards cell membranes were decreased when the medium contained no FBS (TRT-2 and TRT-4). All cells showed a diffuse distribution of CD90 and CD105 and remained positive for these markers irrespective of the treatment. However, the CD90 and CD105 mRNA abundance was decreased in TRT-2 and TRT-4; i.e., in media containing no FBS. The presence of FBS increased the absolute number of cell nuclei as assessed by DAPI fluorescence. Our results suggest that bovine subcutaneous preadipocytes display typical stem cell markers. The differentiation into mature adipocytes is promoted by BSL, whereas FBS endorses cell proliferation.

A protease-deficient strain of Aspergillus niger has been used as a host for the production of human tissue plasminogen activator (t-PA). In defined medium, up to 0.07 mg t-PA (g biomass)(-1) was produced in batch and fed-batch cultures and production was increased two- to threefold in two-phase batch cultures in which additional glucose was provided as a single pulse at the end of the first batch growth phase. Production was increased [up to 1.9 mg t-PA (g biomass)(-1)] by the addition of soy peptone to the defined medium. The rate of t-PA production in batch cultures supplemented with soy peptone (0.2 to 0.6 mg t-PA L(-1) h(-1)) was comparable to rates observed previously in high-producing mammalian or insect cell cultures. In glucose-limited chemostat culture supplemented with soy peptone, t-PA was produced at a rate of 0.7 mg t-PA L(-1) h(-1). Expression of t-PA in A. niger resulted in increased expression of genes (bipA, pdiA, and cypB) involved in the unfolded protein response (UPR). However, when cypB was overexpressed in a t-PA-producing strain, t-PA production was not increased. The t-PA produced in A. niger was cleaved into two chains of similar molecular weight to two-chain human melanoma t-PA. The two chains appeared to be stable for at least 16 h in culture supernatant of the host strain. However, in general

The polycyclic aromatic hydrocarbon (PAH) benzo[a]pyrene (BP) is metabolized into a complex pattern of BP derivatives, among which the ultimate carcinogen (+)-anti-BP-7,8-diol-9,10-epoxide (BPDE) is formed to certain extents. Skin is frequently in contact with PAHs and data on the metabolic capacity of skin tissue toward these compounds are inconclusive. We compared BP metabolism in excised human skin, commercially available in vitro 3D skin models and primary 2D skin cell cultures, and analyzed the metabolically catalyzed occurrence of seven different BP follow-up products by means of liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). All models investigated were competent to metabolize BP, and the metabolic profiles generated by ex vivo human skin and skin models were remarkably similar. Furthermore, the genotoxicity of BP and its derivatives was monitored in these models via comet assays. In a full-thickness skin, equivalent BP-mediated genotoxic stress was generated via keratinocytes. Cultured primary keratinocytes revealed a level of genotoxicity comparable with that of direct exposure to 50-100 nM of BPDE. Our data demonstrate that the metabolic capacity of human skin ex vivo, as well as organotypic human 3D skin models toward BP, is sufficient to cause significant genotoxic stress and thus cutaneous bioactivation may potentially contribute to mutations that ultimately lead to skin cancer.

Eschericha coli was genetically engineered to produce recombinant human bone morphogenetic protein-2 (rhBMP-2) in a non-active aggregated form using a temperature-inducible expression system. High concentrations of both biomass (75 g cell dry weight per liter of culture broth) and inactive rhBMP-2 (8.6 g l−1) were obtained by applying a high-cell-density cultivation procedure. After washing and solubilizing the inclusion bodies, rhBMP-2 was refolded and dimerized at concentrations up to 100 mg l−1 by means of a simple dilution method with yields exceeding 50%. Finally, a one-step purification procedure based on affinity chromatography was implemented to isolate the rhBMP-2 dimer. With the established renaturation and purification protocols, yields of more than 10 mg rhBMP-2 dimer per gram cell dry weight were obtained corresponding to 750 mg rhBMP-2 dimer per liter of culture broth. The purified rhBMP-2 dimer showed biological activity equivalent to CHO produced rhBMP-2 as tested by the induction of alkaline phosphatase activity in C2C12 cells.

The effect of ambient pH on production and glycosylation of glucoamylase (GAM) and on the generation of a morphological mutant produced by Aspergillus niger strain B1 (a transformant containing an additional 20 copies of the homologous GAM glaA gene) was studied. We have shown that a change in the pH from 4 to 5.4 during continuous cultivation of the A. niger B1 strain instigates or accelerates the spontaneous generation of a morphological mutant (LB). This mutant strain produced approx. 50% less extracellular protein and GAM during both chemostat and batch cultivation compared to another strain with parental-type morphology (PS). The intracellular levels of GAM were also lower in the LB strain. In addition, cultivation of the original parent B1 strain in a batch-pulse bioreactor at pH 5.5 resulted in a 9-fold drop in GAM production and a 5-fold drop in extracellular protein compared to that obtained at pH 4. Glycosylation analysis of the glucoamylases purified from shake-flask cultivation showed that both principal forms of GAM secreted by the LB strain possessed enhanced galactosylation (2-fold), compared to those of the PS. Four diagnostic methods (immunostaining, mild methanolysis, mild acid hydrolysis and beta-galactofuranosidase digestion) provided evidence that the majority of this galactose was of the furanoic conformation. The GAMs produced during batch-pulse cultivation at pH 5.5 similarly showed an approx. 2-fold increase in galactofuranosylation compared to pH 4. Interestingly, in both cases the increased galactofuranosylation appears primarily restricted to the O-linked glycan component. Ambient pH therefore regulates both GAM production and influences its glycosylation.