In vivo cell culture

Cell culture (in vitro) Whole animal (in vivo) Cell culture (in vitro) Whole ahimal (in vivo)... 

Several methods have been developed for the experimental investigation of the process and for the quantitative description of mucoadhesion. These methods can be classified into the following groups i) methods based on measuring viscosity [99-102], ii) separation of the substrate and the adhesive with microscales based on horizontal or vertical force measurement [94,95,103-105], the most up to-date means of which is the so-called texture analyser [106], iii) in vitro or in vivo cell culture examinations [107-109], and iv) animal experiments [94,105,110]. 

In vivo Cell Culture Assays with Drug-Loaded Targeted-Nanodroplets... 

In this in vitro system, the presence of serum in cell culture medium is not necessary, but the type of transwell is important (the total amount of H-triglycerides secreted was two-fold higher when using 3 pm versus 1 pm pore size transwells), and oleic acid supplementation is required for the formation and secretion of CMs as well as the transport of 3-carotene through Caco-2 cells. Finally, the presence of Tween 40 does not affect CM synthesis and secretion in this in vitro cell culture system. Thus, CMs secreted by Caco-2 cells were characterized as particles rich in newly synthesized H-triglycerides (90% of total secreted) containing apolipoprotein B (30% of total secreted) and H-phospholipids (20% of total secreted) and with an average diameter of 60 nm. These characteristics are close to those of CMs secreted in vivo by enterocytes. ... 

Another limitation is that there is no quantitative relationship between active drug transport in the cell culture models and in vivo e.g. [92, 93]. The reason may be that the expression level of the transporter in Caco-2 cells is not comparable to that in vivo or that there is a difference in effective surface area (see Section 4.3.2.2 below). One solution to this problem is to determine the apparent transport constants, Km and Vmax, for each transporter and subsequently, to determine a scaling factor. However, this is not readily done. In addition these studies are further complicated by the lack of specific substrates. For example, there are almost no specific substrates for the drug efflux transporters [18]. Therefore, other epithelial... 

When applying any of these models it is crucial to understand the main transport mechanisms as well as the metabolic route and characterization of the activity of the transporter/enzyme involved. It is well recognized that the activities of carrier-mediated processes in Caco-2 cells are considerably lower than in vivo [20, 42, 48] therefore, it is crucial to extrapolate in vitro cell culture data to the in vivo situation with great care [18, 20, 42, 48], This is especially important when carrier-mediated processes are involved, as evidenced by a recent report which showed significant differences in gene expression levels for transporters, channels and metabolizing enzymes in Caco-2 cells than in human duodenum [48], If an animal model is used, then potential species differences must also be considered [18, 20, 45],... 

Paine, A. J. and Hockin, L. J. (1980). Nutrient imbalance causes the loss of cytochrome P-450 in liver cell culture formulation of culture media which maintain cytoch rome P-450 at in vivo concentrations. Biochem. Pharmacol. 29 3215-3218. 

Ethical issues as well as difficulty in obtaining enough human nasal tissue specimens have called for the need to use alternative in vitro and in vivo methods. Various in vivo animal models and in vitro excised tissue models have been described in the literature for nasal drug transport studies. However, due to the difficulty in both controlling the experimental conditions in in vivo animal models and obtaining intact excised tissue samples, in vitro cell culture models are also being actively developed. 

Phenotypic resistance assays directly measure the ability of HlV-1 to replicate in a cell culture in the presence of different antiretroviral drug concentrations. This process is similar to that used to determine antibiotic resistance and is, therefore, more familiar to most clinicians. The recombinant virus, composed of a virus s reverse transcripfase and protease genes, is inserted into a standard reference strain of virus. The recombinant virus is then tested in vitro for fhe amount of drug needed to inhibit virus replication by 50%, relative to the amount of drug needed to inhibit a reference strain of virus. Phenotypic resistance testing is limited by the fact that it is conducted in vitro and not in vivo. 

This study showed that hydroquinone was glycosated by the barley to form arbutln and was therefore effectively detoxified. If the equilibrium of the detoxification mechanism of a plant is sensitive to an oversupply of the toxic and detoxified compound, an oversupply of a detoxified compound could produce equilibrium amounts of the toxic compound. Cell culture bloassay (Table II) showed that hydroquinone is not significantly detoxified in vivo in leafy spurge, indicating the succeptiblllty of the plant to low levels of hydroquinone which could originate from an oversupply of arbutln. The observed toxicity of -benzoquinone in the cell cultures and seed bloassays also indicates that oxidation processes affecting hydroquinone will not detoxify the compound vivo. 

Dichloromethane induced DNA single-strand breaks in mammalian cell cultures, but inconclusive or negative effects were reported for induction of gene mutations. It did not induce unscheduled DNA synthesis either in vivo in rodents or in human fibroblast cultures. It was genotoxic in fungi but not in Drosophila in the sex-linked recessive lethal assay. 

Trichloroethane covalently bound to DNA, RNA and protein in mice and rats but did not induce micronuclei or abnormal sperm head morphology in mice in vivo. It induced chromosomal aberrations and cell transfonnation in mammalian cell cultures and it showed inconclusive evidence of sister chromatid exchange induction. It did not induce unscheduled DNA synthesis or gene mutation in mammalian cells in vitro. 

The chemopreventive and chemotherapeutic potential of resveratrol has been extensively investigated in different in vivo models of tumorigenesis and in vitro cell culture systems [Aggarwal et ah, 2004 Kundu and Surh, 2004]. Repeated topical application of resveratrol significantly reduced the incidence and the... 

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