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Differential stress reaction of human colon cells to oleic-acid-stabilized and unstabilized ultrasmall iron oxide nanoparticles.

Schütz CA, Staedler D, Crosbie-Staunton K, Movia D, Chapuis Bernasconi C, Kenzaoui BH, Prina-Mello A, Juillerat-Jeanneret L - Int J Nanomedicine (2014)

Bottom Line: Induction of an autophagic response was observed in the two cell lines for both NPs but not free OA, while the other stress responses were cell- and NP-specific.The formation of lipid vacuoles/droplets was demonstrated in HT29 and CaCo₂ cells exposed to OA-USPIO NPs but not to NS-USPIO NPs, and to a much lower level in cells exposed to equimolar concentrations of free OA.Therefore, the induction of lipid vacuoles in colon cells exposed to OA utilized as a stabilizer for USPIO NPs is higly amplified compared to free OA, and is not observed in the absence of this lipid in NS-USPIO NPs.

View Article: PubMed Central - PubMed

Affiliation: Centre Hospitalier Universitaire Vaudois (CHUV), UNIL, Switzerland.

ABSTRACT
Therapeutic engineered nanoparticles (NPs), including ultrasmall superparamagnetic iron oxide (USPIO) NPs, may accumulate in the lower digestive tract following ingestion or injection. In order to evaluate the reaction of human colon cells to USPIO NPs, the effects of non-stabilized USPIO NPs (NS-USPIO NPs), oleic-acid-stabilized USPIO NPs (OA-USPIO NPs), and free oleic acid (OA) were compared in human HT29 and CaCo2 colon epithelial cancer cells. First the biophysical characteristics of NS-USPIO NPs and OA-USPIO NPs in water, in cell culture medium supplemented with fetal calf serum, and in cell culture medium preconditioned by HT29 and CaCo₂ cells were determined. Then, stress responses of the cells were evaluated following exposure to NS-USPIO NPs, OA-USPIO NPs, and free OA. No modification of the cytoskeletal actin network was observed. Cell response to stress, including markers of apoptosis and DNA repair, oxidative stress and degradative/autophagic stress, induction of heat shock protein, or lipid metabolism was determined in cells exposed to the two NPs. Induction of an autophagic response was observed in the two cell lines for both NPs but not free OA, while the other stress responses were cell- and NP-specific. The formation of lipid vacuoles/droplets was demonstrated in HT29 and CaCo₂ cells exposed to OA-USPIO NPs but not to NS-USPIO NPs, and to a much lower level in cells exposed to equimolar concentrations of free OA. Therefore, the induction of lipid vacuoles in colon cells exposed to OA utilized as a stabilizer for USPIO NPs is higly amplified compared to free OA, and is not observed in the absence of this lipid in NS-USPIO NPs.

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OA-USPIO NPs and NS-USPIO NPs, but not free oleic acid, inhibit lipid synthesis in human colon cells.Notes: HT29 cells (A) or CaCo2 cells (B) were exposed to NS-USPIO NPs, OA-USPIO NPs (50 μg iron/mL), or free OA (23 μM) for 24 hours, then the synthesis of lipids by the cells was determined by the incorporation of [14C]sodium acetate (acetate). Results are expressed as percentage of acetate incorporation in exposed cells compared to unexposed cells and are the means ± SD of the triplicate of two independent experiments. Statistical significance was assessed using a Student’s t-test. *P<0.05; ***P<0.001.Abbreviations: NPs, nanoparticles; NS-NPs, NS-USPIO NPs; NS-USPIO NPs, non-stabilized USPIO NPs; OA, oleic acid; OA-NPs, OA-USPIO NPs; OA-USPIO NPs, oleic-acid-stabilized USPIO NPs; SD, standard deviation; USPIO, ultrasmall superparamagnetic iron oxide.
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f7-ijn-9-3481: OA-USPIO NPs and NS-USPIO NPs, but not free oleic acid, inhibit lipid synthesis in human colon cells.Notes: HT29 cells (A) or CaCo2 cells (B) were exposed to NS-USPIO NPs, OA-USPIO NPs (50 μg iron/mL), or free OA (23 μM) for 24 hours, then the synthesis of lipids by the cells was determined by the incorporation of [14C]sodium acetate (acetate). Results are expressed as percentage of acetate incorporation in exposed cells compared to unexposed cells and are the means ± SD of the triplicate of two independent experiments. Statistical significance was assessed using a Student’s t-test. *P<0.05; ***P<0.001.Abbreviations: NPs, nanoparticles; NS-NPs, NS-USPIO NPs; NS-USPIO NPs, non-stabilized USPIO NPs; OA, oleic acid; OA-NPs, OA-USPIO NPs; OA-USPIO NPs, oleic-acid-stabilized USPIO NPs; SD, standard deviation; USPIO, ultrasmall superparamagnetic iron oxide.

Mentions: Then we evaluated the effect of oleic acid, either free or USPIO-NPs-associated, on the metabolism and handling of lipids in the human colon cells. Both NS-USPIO NPs and OA-USPIO NPs, but not free oleic acid, decreased the incorporation of acetate in CaCo2 cells, but not in HT29 cells (Figure 7). OA-USPIO NPs decreased acetate incorporation significantly more than NS-USPIO NPs, suggesting a selective interference with lipid metabolism in these cells. Therefore, we examined the effects of NS-USPIO NPs, OA-USPIO NPs, and free oleic acid on the aspect of cells when examined under light microscopy (Figure 8). In cells exposed to NS-USPIO NPs, high amounts of the iron oxide cores of NPs could be seen inside cells in the TEM images (Figure 8, black arrows), while only low amounts of the iron oxide cores could be detected by TEM in cells exposed to OA-USPIO NPs, which are internalized at much lower levels than NS-USPIO NPs. However, TEM images demonstrated the presence of a high amount of vacuoles in cells exposed to OA-USPIO NPs, and of a much lower amount of vacuoles in cells exposed to free oleic acid (Figure 8, white arrows). The lipidic nature of these vacuoles was demonstrated by histological staining with Oil-Red-O, a fat-soluble red-colored dye which allows visualizing and evaluating lipids in cells (Figure 9). In cells exposed to OA-USPIO NPs, many red-colored vacuoles were observed, while in cells exposed to an equimolar concentration of free oleic acid achieved in OA-USPIO NPs, only rare lipid vacuoles were observed. Thus, the Oil-Red-O histological staining strongly supported a lipidic nature for the vacuoles observed in TEM images. Thus the OA-USPIO NPs, despite their poor cellular uptake, were inducing a cell reaction suggesting an effect of the oleic acid stabilizer in the cell metabolism.


Differential stress reaction of human colon cells to oleic-acid-stabilized and unstabilized ultrasmall iron oxide nanoparticles.

Schütz CA, Staedler D, Crosbie-Staunton K, Movia D, Chapuis Bernasconi C, Kenzaoui BH, Prina-Mello A, Juillerat-Jeanneret L - Int J Nanomedicine (2014)

OA-USPIO NPs and NS-USPIO NPs, but not free oleic acid, inhibit lipid synthesis in human colon cells.Notes: HT29 cells (A) or CaCo2 cells (B) were exposed to NS-USPIO NPs, OA-USPIO NPs (50 μg iron/mL), or free OA (23 μM) for 24 hours, then the synthesis of lipids by the cells was determined by the incorporation of [14C]sodium acetate (acetate). Results are expressed as percentage of acetate incorporation in exposed cells compared to unexposed cells and are the means ± SD of the triplicate of two independent experiments. Statistical significance was assessed using a Student’s t-test. *P<0.05; ***P<0.001.Abbreviations: NPs, nanoparticles; NS-NPs, NS-USPIO NPs; NS-USPIO NPs, non-stabilized USPIO NPs; OA, oleic acid; OA-NPs, OA-USPIO NPs; OA-USPIO NPs, oleic-acid-stabilized USPIO NPs; SD, standard deviation; USPIO, ultrasmall superparamagnetic iron oxide.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4114909&req=5

f7-ijn-9-3481: OA-USPIO NPs and NS-USPIO NPs, but not free oleic acid, inhibit lipid synthesis in human colon cells.Notes: HT29 cells (A) or CaCo2 cells (B) were exposed to NS-USPIO NPs, OA-USPIO NPs (50 μg iron/mL), or free OA (23 μM) for 24 hours, then the synthesis of lipids by the cells was determined by the incorporation of [14C]sodium acetate (acetate). Results are expressed as percentage of acetate incorporation in exposed cells compared to unexposed cells and are the means ± SD of the triplicate of two independent experiments. Statistical significance was assessed using a Student’s t-test. *P<0.05; ***P<0.001.Abbreviations: NPs, nanoparticles; NS-NPs, NS-USPIO NPs; NS-USPIO NPs, non-stabilized USPIO NPs; OA, oleic acid; OA-NPs, OA-USPIO NPs; OA-USPIO NPs, oleic-acid-stabilized USPIO NPs; SD, standard deviation; USPIO, ultrasmall superparamagnetic iron oxide.
Mentions: Then we evaluated the effect of oleic acid, either free or USPIO-NPs-associated, on the metabolism and handling of lipids in the human colon cells. Both NS-USPIO NPs and OA-USPIO NPs, but not free oleic acid, decreased the incorporation of acetate in CaCo2 cells, but not in HT29 cells (Figure 7). OA-USPIO NPs decreased acetate incorporation significantly more than NS-USPIO NPs, suggesting a selective interference with lipid metabolism in these cells. Therefore, we examined the effects of NS-USPIO NPs, OA-USPIO NPs, and free oleic acid on the aspect of cells when examined under light microscopy (Figure 8). In cells exposed to NS-USPIO NPs, high amounts of the iron oxide cores of NPs could be seen inside cells in the TEM images (Figure 8, black arrows), while only low amounts of the iron oxide cores could be detected by TEM in cells exposed to OA-USPIO NPs, which are internalized at much lower levels than NS-USPIO NPs. However, TEM images demonstrated the presence of a high amount of vacuoles in cells exposed to OA-USPIO NPs, and of a much lower amount of vacuoles in cells exposed to free oleic acid (Figure 8, white arrows). The lipidic nature of these vacuoles was demonstrated by histological staining with Oil-Red-O, a fat-soluble red-colored dye which allows visualizing and evaluating lipids in cells (Figure 9). In cells exposed to OA-USPIO NPs, many red-colored vacuoles were observed, while in cells exposed to an equimolar concentration of free oleic acid achieved in OA-USPIO NPs, only rare lipid vacuoles were observed. Thus, the Oil-Red-O histological staining strongly supported a lipidic nature for the vacuoles observed in TEM images. Thus the OA-USPIO NPs, despite their poor cellular uptake, were inducing a cell reaction suggesting an effect of the oleic acid stabilizer in the cell metabolism.

Bottom Line: Induction of an autophagic response was observed in the two cell lines for both NPs but not free OA, while the other stress responses were cell- and NP-specific.The formation of lipid vacuoles/droplets was demonstrated in HT29 and CaCo₂ cells exposed to OA-USPIO NPs but not to NS-USPIO NPs, and to a much lower level in cells exposed to equimolar concentrations of free OA.Therefore, the induction of lipid vacuoles in colon cells exposed to OA utilized as a stabilizer for USPIO NPs is higly amplified compared to free OA, and is not observed in the absence of this lipid in NS-USPIO NPs.

View Article: PubMed Central - PubMed

Affiliation: Centre Hospitalier Universitaire Vaudois (CHUV), UNIL, Switzerland.

ABSTRACT
Therapeutic engineered nanoparticles (NPs), including ultrasmall superparamagnetic iron oxide (USPIO) NPs, may accumulate in the lower digestive tract following ingestion or injection. In order to evaluate the reaction of human colon cells to USPIO NPs, the effects of non-stabilized USPIO NPs (NS-USPIO NPs), oleic-acid-stabilized USPIO NPs (OA-USPIO NPs), and free oleic acid (OA) were compared in human HT29 and CaCo2 colon epithelial cancer cells. First the biophysical characteristics of NS-USPIO NPs and OA-USPIO NPs in water, in cell culture medium supplemented with fetal calf serum, and in cell culture medium preconditioned by HT29 and CaCo₂ cells were determined. Then, stress responses of the cells were evaluated following exposure to NS-USPIO NPs, OA-USPIO NPs, and free OA. No modification of the cytoskeletal actin network was observed. Cell response to stress, including markers of apoptosis and DNA repair, oxidative stress and degradative/autophagic stress, induction of heat shock protein, or lipid metabolism was determined in cells exposed to the two NPs. Induction of an autophagic response was observed in the two cell lines for both NPs but not free OA, while the other stress responses were cell- and NP-specific. The formation of lipid vacuoles/droplets was demonstrated in HT29 and CaCo₂ cells exposed to OA-USPIO NPs but not to NS-USPIO NPs, and to a much lower level in cells exposed to equimolar concentrations of free OA. Therefore, the induction of lipid vacuoles in colon cells exposed to OA utilized as a stabilizer for USPIO NPs is higly amplified compared to free OA, and is not observed in the absence of this lipid in NS-USPIO NPs.

Show MeSH
Related in: MedlinePlus