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Photoinduced effects of m-tetrahydroxyphenylchlorin loaded lipid nanoemulsions on multicellular tumor spheroids

View Article: PubMed Central - PubMed

ABSTRACT

Background: Photosensitizers are used in photodynamic therapy (PDT) to destruct tumor cells, however, their limited solubility and specificity hampers routine use, which may be overcome by encapsulation. Several promising novel nanoparticulate drug carriers including liposomes, polymeric nanoparticles, metallic nanoparticles and lipid nanocomposites have been developed. However, many of them contain components that would not meet safety standards of regulatory bodies and due to difficulties of the manufacturing processes, reproducibility and scale up procedures these drugs may eventually not reach the clinics. Recently, we have designed a novel lipid nanostructured carrier, namely Lipidots, consisting of nontoxic and FDA approved ingredients as promising vehicle for the approved photosensitizer m-tetrahydroxyphenylchlorin (mTHPC).

Results: In this study we tested Lipidots of two different sizes (50 and 120 nm) and assessed their photodynamic potential in 3-dimensional multicellular cancer spheroids. Microscopically, the intracellular accumulation kinetics of mTHPC were retarded after encapsulation. However, after activation mTHPC entrapped into 50 nm particles destroyed cancer spheroids as efficiently as the free drug. Cell death and gene expression studies provide evidence that encapsulation may lead to different cell killing modes in PDT.

Conclusions: Since ATP viability assays showed that the carriers were nontoxic and that encapsulation reduced dark toxicity of mTHPC we conclude that our 50 nm photosensitizer carriers may be beneficial for clinical PDT applications.

Electronic supplementary material: The online version of this article (doi:10.1186/s12951-016-0221-x) contains supplementary material, which is available to authorized users.

No MeSH data available.


Light microscopy of CAL-33 spheroids incubated for 24 h with 3.67, 7.34 and 14.69 µM mTHPC or 50/120 nm M-Lipidots after light irradiation with 3440 lx for 20 min
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Fig5: Light microscopy of CAL-33 spheroids incubated for 24 h with 3.67, 7.34 and 14.69 µM mTHPC or 50/120 nm M-Lipidots after light irradiation with 3440 lx for 20 min

Mentions: The PDT effects mediated by M-Lipidots or free mTHPC were investigated in CAL-33 spheroids (Figs. 5, 6). Our microscopic analyses showed that PDT with both free mTHPC and 50 nm M-Lipidots induced a pronounced and comparable destruction of the spheroids (Fig. 5). Although the size reduction was difficult to microscopically measure under conditions of high destruction, the results correlated with the respective ATP luciferase viability assays (Fig. 6b). The 50 nm Lipidots as well as free mTHPC reduced spheroid sizes by 100 % at higher concentrations (p < 0.001). However, after PDT with 120 nm M-Lipidots, even at the highest concentration (14.69 µM), only mild phototoxic effects were visible with size reductions by only 34 % (Figs. 5, 6a, p < 0.001). These limited PDT effects of 120 nm M-Lipidots could also be confirmed by ATP luciferase viability assays (Fig. 6b). Viability after PDT with the highest concentration (14.69 µM) was 1.8 % with mTHPC, 6.6 % with the 50 nm particles and 66.2 % with the 120 nm particles (p < 0.001).Fig. 5


Photoinduced effects of m-tetrahydroxyphenylchlorin loaded lipid nanoemulsions on multicellular tumor spheroids
Light microscopy of CAL-33 spheroids incubated for 24 h with 3.67, 7.34 and 14.69 µM mTHPC or 50/120 nm M-Lipidots after light irradiation with 3440 lx for 20 min
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5015221&req=5

Fig5: Light microscopy of CAL-33 spheroids incubated for 24 h with 3.67, 7.34 and 14.69 µM mTHPC or 50/120 nm M-Lipidots after light irradiation with 3440 lx for 20 min
Mentions: The PDT effects mediated by M-Lipidots or free mTHPC were investigated in CAL-33 spheroids (Figs. 5, 6). Our microscopic analyses showed that PDT with both free mTHPC and 50 nm M-Lipidots induced a pronounced and comparable destruction of the spheroids (Fig. 5). Although the size reduction was difficult to microscopically measure under conditions of high destruction, the results correlated with the respective ATP luciferase viability assays (Fig. 6b). The 50 nm Lipidots as well as free mTHPC reduced spheroid sizes by 100 % at higher concentrations (p < 0.001). However, after PDT with 120 nm M-Lipidots, even at the highest concentration (14.69 µM), only mild phototoxic effects were visible with size reductions by only 34 % (Figs. 5, 6a, p < 0.001). These limited PDT effects of 120 nm M-Lipidots could also be confirmed by ATP luciferase viability assays (Fig. 6b). Viability after PDT with the highest concentration (14.69 µM) was 1.8 % with mTHPC, 6.6 % with the 50 nm particles and 66.2 % with the 120 nm particles (p < 0.001).Fig. 5

View Article: PubMed Central - PubMed

ABSTRACT

Background: Photosensitizers are used in photodynamic therapy (PDT) to destruct tumor cells, however, their limited solubility and specificity hampers routine use, which may be overcome by encapsulation. Several promising novel nanoparticulate drug carriers including liposomes, polymeric nanoparticles, metallic nanoparticles and lipid nanocomposites have been developed. However, many of them contain components that would not meet safety standards of regulatory bodies and due to difficulties of the manufacturing processes, reproducibility and scale up procedures these drugs may eventually not reach the clinics. Recently, we have designed a novel lipid nanostructured carrier, namely Lipidots, consisting of nontoxic and FDA approved ingredients as promising vehicle for the approved photosensitizer m-tetrahydroxyphenylchlorin (mTHPC).

Results: In this study we tested Lipidots of two different sizes (50 and 120&nbsp;nm) and assessed their photodynamic potential in 3-dimensional multicellular cancer spheroids. Microscopically, the intracellular accumulation kinetics of mTHPC were retarded after encapsulation. However, after activation mTHPC entrapped into 50&nbsp;nm particles destroyed cancer spheroids as efficiently as the free drug. Cell death and gene expression studies provide evidence that encapsulation may lead to different cell killing modes in PDT.

Conclusions: Since ATP viability assays showed that the carriers were nontoxic and that encapsulation reduced dark toxicity of mTHPC we conclude that our 50&nbsp;nm photosensitizer carriers may be beneficial for clinical PDT applications.

Electronic supplementary material: The online version of this article (doi:10.1186/s12951-016-0221-x) contains supplementary material, which is available to authorized users.

No MeSH data available.