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Surface engineering of macrophages with nanoparticles to generate a cell-nanoparticle hybrid vehicle for hypoxia-targeted drug delivery.

Holden CA, Yuan Q, Yeudall WA, Lebman DA, Yang H - Int J Nanomedicine (2010)

Bottom Line: Nanoparticles immobilized on the cell surface provide numerous new sites for anticancer drug loading, hence potentially minimizing the toxic effect of anticancer drugs on the viability and hypoxia-targeting ability of the macrophage vehicles.Further, a reducing agent, sodium cyanoborohydride, was applied to reduce Schiff bases to stable secondary amine linkages.The distribution of nanoparticles on the cell surface was confirmed by fluorescence imaging, and it was found to be dependent on the stability of the linkages coupling nanoparticles to the cell surface.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, School of Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA.

ABSTRACT
Tumors frequently contain hypoxic regions that result from a shortage of oxygen due to poorly organized tumor vasculature. Cancer cells in these areas are resistant to radiation- and chemotherapy, limiting the treatment efficacy. Macrophages have inherent hypoxia-targeting ability and hold great advantages for targeted delivery of anticancer therapeutics to cancer cells in hypoxic areas. However, most anticancer drugs cannot be directly loaded into macrophages because of their toxicity. In this work, we designed a novel drug delivery vehicle by hybridizing macrophages with nanoparticles through cell surface modification. Nanoparticles immobilized on the cell surface provide numerous new sites for anticancer drug loading, hence potentially minimizing the toxic effect of anticancer drugs on the viability and hypoxia-targeting ability of the macrophage vehicles. In particular, quantum dots and 5-(aminoacetamido) fluorescein-labeled polyamidoamine dendrimer G4.5, both of which were coated with amine-derivatized polyethylene glycol, were immobilized to the sodium periodate-treated surface of RAW264.7 macrophages through a transient Schiff base linkage. Further, a reducing agent, sodium cyanoborohydride, was applied to reduce Schiff bases to stable secondary amine linkages. The distribution of nanoparticles on the cell surface was confirmed by fluorescence imaging, and it was found to be dependent on the stability of the linkages coupling nanoparticles to the cell surface.

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Quantitative analysis of the distribution of fluorescence intensity in representative cells. A) Control 1; B) Control 2; C) Macrophage–T-dendrimer hybrid; D) Macrophage–S-dendrimer hybrid. The treatment conditions are detailed in Figure 6.Notes: Original magnification, ×630.
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f7-ijn-5-025: Quantitative analysis of the distribution of fluorescence intensity in representative cells. A) Control 1; B) Control 2; C) Macrophage–T-dendrimer hybrid; D) Macrophage–S-dendrimer hybrid. The treatment conditions are detailed in Figure 6.Notes: Original magnification, ×630.

Mentions: It is apparent that fluorescently labeled nanoparticles were taken into the macrophages after each treatment. Qualitatively, there is a uniform distribution of fluorescence throughout the untreated control groups, suggesting cellular uptake pathways are responsible for this occurrence. Following surface modification, a pronounced ring of fluorescence is observed towards the cell surface. Quantitative analysis of the distribution of nanoparticle fluorescence was attempted with the intensity profile generated by ImageJ software (Figure 7). Since all confocal images were taken under identical image acquisition settings, the fluorescence intensity profiles generated allowed us to quantitatively analyze fluorescence distribution in individual cells based on their relative fluorescence intensity. For each group, three representative cells were chosen and analyzed. Individual cells were measured three times from different orientations with each orientation approximately bisecting midlines. From each profile, intensity values were recorded from fluorescence peaks at the two cell boundaries and from a fluorescence peak near the midline of each trace. The results are summarized in Table 1. The results from the intensity traces show that for a nanoparticle incubation of one minute, there is 20.8% more fluorescence at the cell boundaries versus the cell center. For an overnight incubation, there was an even distribution of fluorescent intensity where the cell walls exhibited a fluorescence value that was 99.8% of the fluorescence of the midpoint of the slice. Surface modification drastically increased the ratio of fluorescence between the cell walls versus the cell interior. The macrophage–T-nanoparticle hybrids showed an 85.2% increase in fluorescence near the cell exterior, whereas the macrophage–S-nanoparticle hybrids showed a 94.4% increase in cell wall fluorescence. Based on these measurements we show that there is markedly more fluorescence near the cell surface for surface-treated groups, whereas there is an even distribution of nanoparticles in the control groups.


Surface engineering of macrophages with nanoparticles to generate a cell-nanoparticle hybrid vehicle for hypoxia-targeted drug delivery.

Holden CA, Yuan Q, Yeudall WA, Lebman DA, Yang H - Int J Nanomedicine (2010)

Quantitative analysis of the distribution of fluorescence intensity in representative cells. A) Control 1; B) Control 2; C) Macrophage–T-dendrimer hybrid; D) Macrophage–S-dendrimer hybrid. The treatment conditions are detailed in Figure 6.Notes: Original magnification, ×630.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2819902&req=5

f7-ijn-5-025: Quantitative analysis of the distribution of fluorescence intensity in representative cells. A) Control 1; B) Control 2; C) Macrophage–T-dendrimer hybrid; D) Macrophage–S-dendrimer hybrid. The treatment conditions are detailed in Figure 6.Notes: Original magnification, ×630.
Mentions: It is apparent that fluorescently labeled nanoparticles were taken into the macrophages after each treatment. Qualitatively, there is a uniform distribution of fluorescence throughout the untreated control groups, suggesting cellular uptake pathways are responsible for this occurrence. Following surface modification, a pronounced ring of fluorescence is observed towards the cell surface. Quantitative analysis of the distribution of nanoparticle fluorescence was attempted with the intensity profile generated by ImageJ software (Figure 7). Since all confocal images were taken under identical image acquisition settings, the fluorescence intensity profiles generated allowed us to quantitatively analyze fluorescence distribution in individual cells based on their relative fluorescence intensity. For each group, three representative cells were chosen and analyzed. Individual cells were measured three times from different orientations with each orientation approximately bisecting midlines. From each profile, intensity values were recorded from fluorescence peaks at the two cell boundaries and from a fluorescence peak near the midline of each trace. The results are summarized in Table 1. The results from the intensity traces show that for a nanoparticle incubation of one minute, there is 20.8% more fluorescence at the cell boundaries versus the cell center. For an overnight incubation, there was an even distribution of fluorescent intensity where the cell walls exhibited a fluorescence value that was 99.8% of the fluorescence of the midpoint of the slice. Surface modification drastically increased the ratio of fluorescence between the cell walls versus the cell interior. The macrophage–T-nanoparticle hybrids showed an 85.2% increase in fluorescence near the cell exterior, whereas the macrophage–S-nanoparticle hybrids showed a 94.4% increase in cell wall fluorescence. Based on these measurements we show that there is markedly more fluorescence near the cell surface for surface-treated groups, whereas there is an even distribution of nanoparticles in the control groups.

Bottom Line: Nanoparticles immobilized on the cell surface provide numerous new sites for anticancer drug loading, hence potentially minimizing the toxic effect of anticancer drugs on the viability and hypoxia-targeting ability of the macrophage vehicles.Further, a reducing agent, sodium cyanoborohydride, was applied to reduce Schiff bases to stable secondary amine linkages.The distribution of nanoparticles on the cell surface was confirmed by fluorescence imaging, and it was found to be dependent on the stability of the linkages coupling nanoparticles to the cell surface.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, School of Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA.

ABSTRACT
Tumors frequently contain hypoxic regions that result from a shortage of oxygen due to poorly organized tumor vasculature. Cancer cells in these areas are resistant to radiation- and chemotherapy, limiting the treatment efficacy. Macrophages have inherent hypoxia-targeting ability and hold great advantages for targeted delivery of anticancer therapeutics to cancer cells in hypoxic areas. However, most anticancer drugs cannot be directly loaded into macrophages because of their toxicity. In this work, we designed a novel drug delivery vehicle by hybridizing macrophages with nanoparticles through cell surface modification. Nanoparticles immobilized on the cell surface provide numerous new sites for anticancer drug loading, hence potentially minimizing the toxic effect of anticancer drugs on the viability and hypoxia-targeting ability of the macrophage vehicles. In particular, quantum dots and 5-(aminoacetamido) fluorescein-labeled polyamidoamine dendrimer G4.5, both of which were coated with amine-derivatized polyethylene glycol, were immobilized to the sodium periodate-treated surface of RAW264.7 macrophages through a transient Schiff base linkage. Further, a reducing agent, sodium cyanoborohydride, was applied to reduce Schiff bases to stable secondary amine linkages. The distribution of nanoparticles on the cell surface was confirmed by fluorescence imaging, and it was found to be dependent on the stability of the linkages coupling nanoparticles to the cell surface.

Show MeSH
Related in: MedlinePlus