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Study of the efficacy of antimalarial drugs delivered inside targeted immunoliposomal nanovectors.

Urbán P, Estelrich J, Adeva A, Cortés A, Fernàndez-Busquets X - Nanoscale Res Lett (2011)

Bottom Line: The results obtained indicate that immunoliposome encapsulation of chloroquine and fosmidomycin improves by tenfold the efficacy of antimalarial drugs.An average of five antibody molecules per liposome significantly improves in cell cultures the performance of immunoliposomes over non-functionalized liposomes as drug delivery vessels.Increasing the number of antibodies on the liposome surface correspondingly increases performance, with a reduction of 50% parasitemia achieved with immunoliposomes encapsulating 4 nM chloroquine and bearing an estimated 250 BM1234 units.

View Article: PubMed Central - HTML - PubMed

Affiliation: Nanobioengineering Group, Institute for Bioengineering of Catalonia, Baldiri Reixac 10-12, Barcelona, E08028, Spain. xfernandez_busquets@ub.edu.

ABSTRACT
Paul Ehrlich's dream of a 'magic bullet' that would specifically destroy invading microbes is now a major aspect of clinical medicine. However, a century later, the implementation of this medical holy grail continues being a challenge in three main fronts: identifying the right molecular or cellular targets for a particular disease, having a drug that is effective against it, and finding a strategy for the efficient delivery of sufficient amounts of the drug in an active state exclusively to the selected targets. In a previous work, we engineered an immunoliposomal nanovector for the targeted delivery of its contents exclusively to Plasmodium falciparum-infected red blood cells [pRBCs]. In preliminary assays, the antimalarial drug chloroquine showed improved efficacy when delivered inside immunoliposomes targeted with the pRBC-specific monoclonal antibody BM1234. Because difficulties in determining the exact concentration of the drug due to its low amounts prevented an accurate estimation of the nanovector performance, here, we have developed an HPLC-based method for the precise determination of the concentrations in the liposomal preparations of chloroquine and of a second antimalarial drug, fosmidomycin. The results obtained indicate that immunoliposome encapsulation of chloroquine and fosmidomycin improves by tenfold the efficacy of antimalarial drugs. The targeting antibody used binds preferentially to pRBCs containing late maturation stages of the parasite. In accordance with this observation, the best performing immunoliposomes are those added to Plasmodium cultures having a larger number of late form-containing pRBCs. An average of five antibody molecules per liposome significantly improves in cell cultures the performance of immunoliposomes over non-functionalized liposomes as drug delivery vessels. Increasing the number of antibodies on the liposome surface correspondingly increases performance, with a reduction of 50% parasitemia achieved with immunoliposomes encapsulating 4 nM chloroquine and bearing an estimated 250 BM1234 units. The nanovector prototype described here can be a valuable platform amenable to modification and improvement with the objective of designing a nanostructure adequate to enter the preclinical pipeline as a new antimalarial therapy.

No MeSH data available.


Related in: MedlinePlus

Confocal fluorescence microscopy study of the subcellular localization of BM1234. Early trophozoites (A), late trophozoites (B), and schizonts (C). Monoclonal antibody BM1234 was added to acetone/methanol-fixed P. falciparum cultures of the 3D7 strain, and its binding was detected by confocal fluorescence microscopy using a secondary antibody (green). DAPI (nuclei, in blue) and hemozoin fluorescence (pink) are used to indicate pRBCs. The RBC plasma membrane is shown in red. The four upper panels correspond to a single confocal section and are overlaid in the lower left panel. The lower right panel shows two perpendicular cross sections throughout the stack of images.
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Figure 5: Confocal fluorescence microscopy study of the subcellular localization of BM1234. Early trophozoites (A), late trophozoites (B), and schizonts (C). Monoclonal antibody BM1234 was added to acetone/methanol-fixed P. falciparum cultures of the 3D7 strain, and its binding was detected by confocal fluorescence microscopy using a secondary antibody (green). DAPI (nuclei, in blue) and hemozoin fluorescence (pink) are used to indicate pRBCs. The RBC plasma membrane is shown in red. The four upper panels correspond to a single confocal section and are overlaid in the lower left panel. The lower right panel shows two perpendicular cross sections throughout the stack of images.

Mentions: The preferential binding of BM1234 to trophozoites and schizonts suggested a differential subcellular localization of the corresponding antigen throughout the intraerythrocytic cycle of P. falciparum. This antibody had been selected for its binding to external features of pRBCs [25], which was a necessary condition for the targeting of these cells in vivo. When pRBCs are fixed with acetone/methanol prior to immunocytochemistry, BM1234 is observed to bind internal pRBC structures also (Figure 5). These are likely corresponding to regions in the endomembrane system built by Plasmodium that delineate the trafficking of the BM1234 antigen from its synthesis towards its final location in the pRBC plasma membrane. Alternatively, they could also represent internalization routes of externally exposed antigens. As expected, the subcellular localization of BM1234 antigens is changing during the intraerythrocytic cycle. A dominant spotted pattern in early trophozoites (Figure 5A) is consistent with the binding to pRBC intracellular membranous structures termed Maurer's clefts. In late trophozoites (Figure 5B) and especially in schizonts (Figure 5C), BM1234 binds structures on the periphery of the pRBC.


Study of the efficacy of antimalarial drugs delivered inside targeted immunoliposomal nanovectors.

Urbán P, Estelrich J, Adeva A, Cortés A, Fernàndez-Busquets X - Nanoscale Res Lett (2011)

Confocal fluorescence microscopy study of the subcellular localization of BM1234. Early trophozoites (A), late trophozoites (B), and schizonts (C). Monoclonal antibody BM1234 was added to acetone/methanol-fixed P. falciparum cultures of the 3D7 strain, and its binding was detected by confocal fluorescence microscopy using a secondary antibody (green). DAPI (nuclei, in blue) and hemozoin fluorescence (pink) are used to indicate pRBCs. The RBC plasma membrane is shown in red. The four upper panels correspond to a single confocal section and are overlaid in the lower left panel. The lower right panel shows two perpendicular cross sections throughout the stack of images.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3285703&req=5

Figure 5: Confocal fluorescence microscopy study of the subcellular localization of BM1234. Early trophozoites (A), late trophozoites (B), and schizonts (C). Monoclonal antibody BM1234 was added to acetone/methanol-fixed P. falciparum cultures of the 3D7 strain, and its binding was detected by confocal fluorescence microscopy using a secondary antibody (green). DAPI (nuclei, in blue) and hemozoin fluorescence (pink) are used to indicate pRBCs. The RBC plasma membrane is shown in red. The four upper panels correspond to a single confocal section and are overlaid in the lower left panel. The lower right panel shows two perpendicular cross sections throughout the stack of images.
Mentions: The preferential binding of BM1234 to trophozoites and schizonts suggested a differential subcellular localization of the corresponding antigen throughout the intraerythrocytic cycle of P. falciparum. This antibody had been selected for its binding to external features of pRBCs [25], which was a necessary condition for the targeting of these cells in vivo. When pRBCs are fixed with acetone/methanol prior to immunocytochemistry, BM1234 is observed to bind internal pRBC structures also (Figure 5). These are likely corresponding to regions in the endomembrane system built by Plasmodium that delineate the trafficking of the BM1234 antigen from its synthesis towards its final location in the pRBC plasma membrane. Alternatively, they could also represent internalization routes of externally exposed antigens. As expected, the subcellular localization of BM1234 antigens is changing during the intraerythrocytic cycle. A dominant spotted pattern in early trophozoites (Figure 5A) is consistent with the binding to pRBC intracellular membranous structures termed Maurer's clefts. In late trophozoites (Figure 5B) and especially in schizonts (Figure 5C), BM1234 binds structures on the periphery of the pRBC.

Bottom Line: The results obtained indicate that immunoliposome encapsulation of chloroquine and fosmidomycin improves by tenfold the efficacy of antimalarial drugs.An average of five antibody molecules per liposome significantly improves in cell cultures the performance of immunoliposomes over non-functionalized liposomes as drug delivery vessels.Increasing the number of antibodies on the liposome surface correspondingly increases performance, with a reduction of 50% parasitemia achieved with immunoliposomes encapsulating 4 nM chloroquine and bearing an estimated 250 BM1234 units.

View Article: PubMed Central - HTML - PubMed

Affiliation: Nanobioengineering Group, Institute for Bioengineering of Catalonia, Baldiri Reixac 10-12, Barcelona, E08028, Spain. xfernandez_busquets@ub.edu.

ABSTRACT
Paul Ehrlich's dream of a 'magic bullet' that would specifically destroy invading microbes is now a major aspect of clinical medicine. However, a century later, the implementation of this medical holy grail continues being a challenge in three main fronts: identifying the right molecular or cellular targets for a particular disease, having a drug that is effective against it, and finding a strategy for the efficient delivery of sufficient amounts of the drug in an active state exclusively to the selected targets. In a previous work, we engineered an immunoliposomal nanovector for the targeted delivery of its contents exclusively to Plasmodium falciparum-infected red blood cells [pRBCs]. In preliminary assays, the antimalarial drug chloroquine showed improved efficacy when delivered inside immunoliposomes targeted with the pRBC-specific monoclonal antibody BM1234. Because difficulties in determining the exact concentration of the drug due to its low amounts prevented an accurate estimation of the nanovector performance, here, we have developed an HPLC-based method for the precise determination of the concentrations in the liposomal preparations of chloroquine and of a second antimalarial drug, fosmidomycin. The results obtained indicate that immunoliposome encapsulation of chloroquine and fosmidomycin improves by tenfold the efficacy of antimalarial drugs. The targeting antibody used binds preferentially to pRBCs containing late maturation stages of the parasite. In accordance with this observation, the best performing immunoliposomes are those added to Plasmodium cultures having a larger number of late form-containing pRBCs. An average of five antibody molecules per liposome significantly improves in cell cultures the performance of immunoliposomes over non-functionalized liposomes as drug delivery vessels. Increasing the number of antibodies on the liposome surface correspondingly increases performance, with a reduction of 50% parasitemia achieved with immunoliposomes encapsulating 4 nM chloroquine and bearing an estimated 250 BM1234 units. The nanovector prototype described here can be a valuable platform amenable to modification and improvement with the objective of designing a nanostructure adequate to enter the preclinical pipeline as a new antimalarial therapy.

No MeSH data available.


Related in: MedlinePlus