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Porous silicon nanoparticles for cancer photothermotherapy.

Hong C, Lee J, Zheng H, Hong SS, Lee C - Nanoscale Res Lett (2011)

Bottom Line: Also, the cell deaths were mostly due to necrosis but partly due to late apoptosis.Tumors have not recurred at all in the PSi/NIR treatment groups thereafter.Both the in vitro cell test and in vivo animal test results suggest that thermotherapy based on PSi in combination with NIR laser irradiation is an efficient technique to selectively destroy cancer cells without damaging the surrounding healthy cells.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Materials Science and Engineering, Inha University, 253 Yonghyeon-dong, Incheon, 402-751, Republic of Korea. cmlee@inha.ac.kr.

ABSTRACT
The in vitro cell tests and in vivo animal tests were performed to investigate the feasibility of the photothermal therapy based on porous silicon (PSi) in combination with near-infrared (NIR) laser. According to the Annexin V- fluorescein isothiocyanate Apoptosis assay test results, the untreated cells and the cells exposed to NIR laser without PSi treatment had a cell viability of 95.6 and 91.3%, respectively. Likewise, the cells treated with PSi but not with NIR irradiation also had a cell viability of 74.4%. Combination of these two techniques, however, showed a cell viability of 6.7%. Also, the cell deaths were mostly due to necrosis but partly due to late apoptosis. The in vivo animal test results showed that the Murine colon carcinoma (CT-26) tumors were completely resorbed without nearly giving damage to surrounding healthy tissue within 5 days of PSi and NIR laser treatment. Tumors have not recurred at all in the PSi/NIR treatment groups thereafter. Both the in vitro cell test and in vivo animal test results suggest that thermotherapy based on PSi in combination with NIR laser irradiation is an efficient technique to selectively destroy cancer cells without damaging the surrounding healthy cells.

No MeSH data available.


Related in: MedlinePlus

In vivo animal test results. Photographs of the tumors of the mice treated differently 24 h after treatment: (a) neither PSi nor laser treatment (control), (b) PSi treatment only, (c) NIR laser treatment only (NIR laser irradiation 4 times for 2 min at 1.5 W/cm2 each time with a time interval of 2 min), and (d) PSi treatment (PSi concentration = 0.7 g/L) followed by laser treatment (for 20 min at 600 mW/cm2).
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Figure 5: In vivo animal test results. Photographs of the tumors of the mice treated differently 24 h after treatment: (a) neither PSi nor laser treatment (control), (b) PSi treatment only, (c) NIR laser treatment only (NIR laser irradiation 4 times for 2 min at 1.5 W/cm2 each time with a time interval of 2 min), and (d) PSi treatment (PSi concentration = 0.7 g/L) followed by laser treatment (for 20 min at 600 mW/cm2).

Mentions: The in vitro cell test results show the photothermal effect of the thermotherapy based on PSi combined with laser on cell death, but it does not guarantee that the thermotherapy can inhibit tumor growth. To confirm that the photothermal effect of PSi combined with NIR laser could efficiently destroy tumor cells without giving damage to surrounding healthy cells, we attempted in vivo therapeutic examinations against Balb/c mice bearing (CT-26) on their backs. When the tumors were grown up to a volume of approximately 100 mm3, PSi/EtOH:PEG solution (0.7 g/L, 100 μL) were then injected directly into the tumor regions. A mouse ready for the irradiation was located under the focal lens through which NIR laser could be focused to have a power density of 1.5 W/cm2 and irradiated 4 times for 2 min each time with a time interval of 2 min. This intermittent laser irradiation was designed to minimize the damage of the healthy tissues adjacent to the tumor tissues. As shown in Figure 5, the mouse treated with a PSi/EtOH:PEG solution and NIR laser irradiation shows perfect tumor destruction 25 days after the treatments. It appears that the tumor has shrinked to almost zero volume at day 5 post-treatment. The tumescent part formed on the laser-treated region is not the shrinked tumor but looks like a kind of water blister formed by thermal energy from PSi nanoparticles. Finally, the tumor has completely disappeared at day 25 post-treatment although the complete disappearance of the tumor is not clearly observable owing to the regrown fur. Comparison of the tumor site between the four groups treated differently, however, more clearly indicates the complete destruction of the tumor in the group treated both PSi and laser. It is worthy of noting that the surface structures including the epidermis and subcutaneous tissue got no damage such as carbonization at all. It is common that an esker or a black skin burn mark forms and it falls off many days after treatment in PTT. Even no such marks were observed on the mice in the group treated both PSi and laser. The intact surface structures suggest that the treatment parameters including the power intensity of the laser and the PSi concentration of the PSi/EtOH:PEG solution was adequate. It is well known that the degree of damage of the surface structures in PTT strongly depends on the treatment parameters. The mice given both PSi and laser treatments remained healthy without any recurrence of tumors and side effects for more than 3 months. In contrast, the other three groups including the control group, the group treated only with PSi, and that treated only with NIR laser show significant growth of tumors after the treatment. The size of the tumors in these groups is in a range of 1.1-1.5 cm at day 5 post-treatment. The tumors grew continuously to be 1.8-2.7 cm in diameter at day 25 post-treatment. The same kind of in vivo animal tests were repeated for another two sets of mouse groups and similar results were obtained, implying that these results are very reproducible. Figure 6 compares the tumor growth rate between the four different experimental mouse groups. The tumors in the mice treated with both PSi and laser show almost zero volume change, whereas the tumors in the other three groups continued to grow until they died (Table 1).


Porous silicon nanoparticles for cancer photothermotherapy.

Hong C, Lee J, Zheng H, Hong SS, Lee C - Nanoscale Res Lett (2011)

In vivo animal test results. Photographs of the tumors of the mice treated differently 24 h after treatment: (a) neither PSi nor laser treatment (control), (b) PSi treatment only, (c) NIR laser treatment only (NIR laser irradiation 4 times for 2 min at 1.5 W/cm2 each time with a time interval of 2 min), and (d) PSi treatment (PSi concentration = 0.7 g/L) followed by laser treatment (for 20 min at 600 mW/cm2).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211409&req=5

Figure 5: In vivo animal test results. Photographs of the tumors of the mice treated differently 24 h after treatment: (a) neither PSi nor laser treatment (control), (b) PSi treatment only, (c) NIR laser treatment only (NIR laser irradiation 4 times for 2 min at 1.5 W/cm2 each time with a time interval of 2 min), and (d) PSi treatment (PSi concentration = 0.7 g/L) followed by laser treatment (for 20 min at 600 mW/cm2).
Mentions: The in vitro cell test results show the photothermal effect of the thermotherapy based on PSi combined with laser on cell death, but it does not guarantee that the thermotherapy can inhibit tumor growth. To confirm that the photothermal effect of PSi combined with NIR laser could efficiently destroy tumor cells without giving damage to surrounding healthy cells, we attempted in vivo therapeutic examinations against Balb/c mice bearing (CT-26) on their backs. When the tumors were grown up to a volume of approximately 100 mm3, PSi/EtOH:PEG solution (0.7 g/L, 100 μL) were then injected directly into the tumor regions. A mouse ready for the irradiation was located under the focal lens through which NIR laser could be focused to have a power density of 1.5 W/cm2 and irradiated 4 times for 2 min each time with a time interval of 2 min. This intermittent laser irradiation was designed to minimize the damage of the healthy tissues adjacent to the tumor tissues. As shown in Figure 5, the mouse treated with a PSi/EtOH:PEG solution and NIR laser irradiation shows perfect tumor destruction 25 days after the treatments. It appears that the tumor has shrinked to almost zero volume at day 5 post-treatment. The tumescent part formed on the laser-treated region is not the shrinked tumor but looks like a kind of water blister formed by thermal energy from PSi nanoparticles. Finally, the tumor has completely disappeared at day 25 post-treatment although the complete disappearance of the tumor is not clearly observable owing to the regrown fur. Comparison of the tumor site between the four groups treated differently, however, more clearly indicates the complete destruction of the tumor in the group treated both PSi and laser. It is worthy of noting that the surface structures including the epidermis and subcutaneous tissue got no damage such as carbonization at all. It is common that an esker or a black skin burn mark forms and it falls off many days after treatment in PTT. Even no such marks were observed on the mice in the group treated both PSi and laser. The intact surface structures suggest that the treatment parameters including the power intensity of the laser and the PSi concentration of the PSi/EtOH:PEG solution was adequate. It is well known that the degree of damage of the surface structures in PTT strongly depends on the treatment parameters. The mice given both PSi and laser treatments remained healthy without any recurrence of tumors and side effects for more than 3 months. In contrast, the other three groups including the control group, the group treated only with PSi, and that treated only with NIR laser show significant growth of tumors after the treatment. The size of the tumors in these groups is in a range of 1.1-1.5 cm at day 5 post-treatment. The tumors grew continuously to be 1.8-2.7 cm in diameter at day 25 post-treatment. The same kind of in vivo animal tests were repeated for another two sets of mouse groups and similar results were obtained, implying that these results are very reproducible. Figure 6 compares the tumor growth rate between the four different experimental mouse groups. The tumors in the mice treated with both PSi and laser show almost zero volume change, whereas the tumors in the other three groups continued to grow until they died (Table 1).

Bottom Line: Also, the cell deaths were mostly due to necrosis but partly due to late apoptosis.Tumors have not recurred at all in the PSi/NIR treatment groups thereafter.Both the in vitro cell test and in vivo animal test results suggest that thermotherapy based on PSi in combination with NIR laser irradiation is an efficient technique to selectively destroy cancer cells without damaging the surrounding healthy cells.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Materials Science and Engineering, Inha University, 253 Yonghyeon-dong, Incheon, 402-751, Republic of Korea. cmlee@inha.ac.kr.

ABSTRACT
The in vitro cell tests and in vivo animal tests were performed to investigate the feasibility of the photothermal therapy based on porous silicon (PSi) in combination with near-infrared (NIR) laser. According to the Annexin V- fluorescein isothiocyanate Apoptosis assay test results, the untreated cells and the cells exposed to NIR laser without PSi treatment had a cell viability of 95.6 and 91.3%, respectively. Likewise, the cells treated with PSi but not with NIR irradiation also had a cell viability of 74.4%. Combination of these two techniques, however, showed a cell viability of 6.7%. Also, the cell deaths were mostly due to necrosis but partly due to late apoptosis. The in vivo animal test results showed that the Murine colon carcinoma (CT-26) tumors were completely resorbed without nearly giving damage to surrounding healthy tissue within 5 days of PSi and NIR laser treatment. Tumors have not recurred at all in the PSi/NIR treatment groups thereafter. Both the in vitro cell test and in vivo animal test results suggest that thermotherapy based on PSi in combination with NIR laser irradiation is an efficient technique to selectively destroy cancer cells without damaging the surrounding healthy cells.

No MeSH data available.


Related in: MedlinePlus