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The standard culture method for neural stem cells cannot prevent the attachment of neurospheres, which eventually result in differentiation. This study developed a new method for long-term neural stem cell cultivation. In the antiattachment group, neural stem cells were cultured in flasks coated with 1.5% agarose gel. As a control, cells were cultured in plastic flasks. The 5-bromine-deoxyuridine incorporation assay was used to determine the S-phase labeling index of both groups. The methyl thiazolyl tetrazolium (MTT) colorimetric assay was used to determine the total cell vitality. After a 3-mo culture, the spontaneous differentiation of stem cells was studied using immunocytochemistry for neuroepithelial stem cell protein. We found that neural stem cells grew rapidly in the antiattachment flasks. There was no statistically significant difference between the two groups in terms of the S-phase labeling index or MTT assay. When cultured for 3 mo in vitro, many more cells differentiated in the control than in the antiattachment group (32.05 vs. 0.64%, P<0.01). Moreover, the neural stem cells in the antiattachment group remained multipotent. Therefore, flasks coated with agarose gel are suitable for long-term neural stem cell culture.
Peroxisome proliferator-activated receptor γ (PPARγ) is a key transcription factor for adipocyte differentiation. Preadipocyte differentiation into adipocytes from precursors in blood vessels is an important issue related to atherosclerotic cardiovascular disease; however, it has been poorly studied because of lack of experimental models. Our aim was to evaluate the potential of primary outgrowths derived from rat aortic rings as a model for studying the preadipocyte differentiation from aortic precursors induced by thiazolidinediones, which are exogenous ligands for PPARγ. Cell outgrowths derived from rat aortic rings were cultured and incubated with rosiglitazone at 1–1,000 nM; presence of lipid droplets was evaluated by oil red O staining. Rosiglitazone at 100 nM exerted a clear adipogenic effect inferred from the cells filled with fine and medium size lipidic droplets; this effect was extreme at 1,000 nM with cells showing lipidic macrodroplets. These results showed that cultures derived from aortic rings are a useful model for studying arterial preadipocyte differentiation.
Angiopoietin-1 (Ang1) is an essential molecule for blood vessel formation. In an effort to produce large quantities of Ang1, recombinant Chinese hamster ovary (rCHO) cells expressing a high level of recombinant human Ang1 protein (rhAng1) with an amino terminal FLAG-tag were constructed by transfecting the expression vector into dihydrofolate reductase-deficient CHO cells and subsequent gene amplification in a medium containing step-wise increments of methotrexate, such as 0.02, 0.08, and 0.32 μM. The rhAng1 secreted from rCHO cells was purified at a purification yield of 18.4% from the cultured medium using an anti-FLAG M2 agarose affinity gel. SDS-PAGE and Western blot analyses showed that rCHO cells secret rhAng1 as heterogeneous multimers. Moreover, rhAng1 expressed in rCHO cells is biologically active in vitro as demonstrated by its ability to bind to the Tie2 receptor and to phosphorylate Tie2. Therefore, the rhAng1 produced from CHO cells could be useful for clarifying the biological effects of exogenous rhAng1 in the future.
We developed a highly sensitive and convenient method of nested polymerase chain reaction (PCR) targeted to mitochondrial deoxyribonucleic acid (DNA) to identify animal species quickly in cultured cells. Fourteen vertebrate species, including human, cynomolgus monkey, African green monkey, mouse, rat, Syrian hamster, Chinese hamster, guinea pig, rabbit, dog, cat, cow, pig, and chicken, could be distinguished from each other by nested PCR. The first PCR amplifies mitochondrial DNA fragments with a universal primer pair complementary to the conserved regions of 14 species, and the second PCR amplifies the DNA fragments with species-specific primer pairs from the first products. The species-specific primer pairs were designed to easily distinguish 14 species from each other under standard agarose gel electrophoresis. We further developed the multiplex PCR using a mixture of seven species-specific primer pairs for two groups of animals. One was comprised of human, mouse, rat, cat, pig, cow, and rabbit, and the other was comprised of African green monkey, cynomolgus monkey, Syrian hamster, Chinese hamster, guinea pig, dog, and chicken. The sensitivity of the PCR assay was at least 100 pg DNA/reaction, which was sufficient for the detection of each species of DNA. Furthermore, the nested PCR method was able to identify the species in the interspecies mixture of DNA. Thus, the method developed in this study will provide a useful tool for the authentication of animal species.
Many mechanisms involved in the pathogenesis of chronic enteropathies or host–pathogen interactions in canine intestine have not been elucidated so far. Next to the clinical and in vivo research tools, an in vitro model of canine intestinal cell culture would be very helpful for studies at the cellular level. Therefore, the purpose of this study was to establish and characterize a primary canine duodenal epithelial cell culture. Neonatal duodenum was disrupted with trypsin-ethylenediaminetetraacetic acid (EDTA) and the mucosa scraped off and digested with collagenase and dispase. After centrifugation on a 2% sorbitol gradient, the cells were incubated at 37° C in OptiMEM supplemented with Primocin, epidermal growth factor, insulin, hydrocortisone, and 10% fetal calf serum (FCS). After 24 h, the FCS concentration was reduced to 2.5%, and the temperature decreased to 33° C. With this method, the cultures were growing to confluent monolayers within 5–6 d and remained viable for an average of 2 wk. Their epithelial nature was confirmed by electron microscopy and immunofluorescence staining using antibodies directed against specific cytokeratins, desmosomes, and tight junctions. The intestinal cells proliferated, as evidenced by immunolabeling with a Ki-67 antibody, and cryptal cell subpopulations could be identified. Furthermore, alkaline phosphatase and sucrase activity were detected.
In vitro cell culture models have been proposed to analyze some of the complex structural and functional characteristics involved in astroglial changes after neural injury in vivo. This report contributes to analyze the proposed hypothesis that an experimentally induced discontinuity of a confluent cellular culture could represent a useful model for the analysis of the processes involved in a neural lesion. For this purpose, it was decided to characterize astroglial proliferation and dye coupling state after a “scratch wound” applied to confluent, astrocyte-enriched cell cultures, obtained from several rat brain regions. Proliferation was assessed in terms of bromodeoxyuridine nuclear incorporation as a function of lesion width, serum deprivation, time after confluence, brain region origin, postlesional culture medium changes and agitation, and after application of a gap-junction uncoupling agent. The proliferative reaction after injury was neither cell type-specific nor brain region specific, nor was significantly affected by neither of the above-mentioned variables. Furthermore, injury failed to significantly affect the astroglial dye coupling state. Results suggest that the proliferative response observed under present conditions would depend on the disruption of contact inhibition rather than on astroglial mitogenic signals released from the wound and operating by either extracellular or cell coupling mechanisms. Present results question the validity of astrocyte-enriched cell cultures as an experimental model of neural tissue injury in vivo, as they do not appear to reproduce fundamental characteristics expressed in situ.
A total of 13 insect cell lines spanning 4 orders (Lepidoptera, Coleoptera, Diptera, and Homoptera) were tested for their ability to replicate the nonoccluded virus Hz-1. Only the Lepidopteran cell lines supported replication of the virus with TN-CL1 and BCIRL-HZ-AM1 producing the highest titers of 2.4×108 tissue culture infective dose (TCID)50/ml and 2.0×108 TCID50/ml, respectively. A codling moth cell line (CP-169) was the only Lepidopteran cell line that did not replicate the virus and transfection of this cell line with Hz-1 DNA failed to replicate the virus. Also, transfection with DNA from a recombinant baculovirus carrying the red fluorescent protein gene (AcMNPVhsp70 Red) was not expressed in CP-169 cells. The replication cycle of Hz-1 in BCIRL-HZ-AM1 cells showed that this virus replicated rapidly starting at 16 h postinoculation (p.i.) and reaching a peak titer of 1.0×108 TCID50/ml 56 h postinoculation. Hz-1 when compared with several other baculoviruses has the widest in vitro host spectrum.