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Image-Based Quantification of Benzoporphyrin Derivative Uptake, Localization, and Photobleaching in 3D Tumor Models, for Optimization of PDT Parameters.

Glidden MD, Celli JP, Massodi I, Rizvi I, Pogue BW, Hasan T - Theranostics (2012)

Bottom Line: While the systematic optimization of these treatment parameters can be complex, it also provides multiple avenues for enhancement of PDT efficacy under diverse treatment conditions, provided that a rational framework is established to quantify the impact of parameter selection upon treatment response.We use this approach to visualize and quantify the uptake, localization, and photobleaching of the PS benzoporphyrin derivative monoacid ring-A (BPD) in a range of treatment conditions with varying uptake times as well as continuous and fractionated light delivery regimens in 3D cultures of AsPC-1 and PANC-1 cells.Quantification of the spatial profile of cell killing within multicellular nodules revealed that these conditions also achieve the highest depth of cytotoxicity along the radial axis of 3D nodules.

View Article: PubMed Central - PubMed

Affiliation: 1. Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA 02114, USA; ; 2. Department of Physics, University of Massachusetts Boston, Boston, MA 02125, USA;

ABSTRACT
Photodynamic therapy (PDT) is a light-based treatment modality in which wavelength specific activation of a photosensitizer (PS) generates cytotoxic response in the irradiated region. PDT response is critically dependent on several parameters including light dose, PS dose, uptake time, fluence rate, and the mode of light delivery. While the systematic optimization of these treatment parameters can be complex, it also provides multiple avenues for enhancement of PDT efficacy under diverse treatment conditions, provided that a rational framework is established to quantify the impact of parameter selection upon treatment response. Here we present a theranostic technique, combining the inherent ability of the PS to serve simultaneously as a therapeutic and imaging agent, with the use of image-based treatment assessment in three dimensional (3D) in vitro tumor models, to comprise a platform to evaluate the impact of PDT parameters on treatment outcomes. We use this approach to visualize and quantify the uptake, localization, and photobleaching of the PS benzoporphyrin derivative monoacid ring-A (BPD) in a range of treatment conditions with varying uptake times as well as continuous and fractionated light delivery regimens in 3D cultures of AsPC-1 and PANC-1 cells. Informed by photobleaching patterns and correlation with cytotoxic response, asymmetric fractionated light delivery at 4 hours BPD uptake was found to be the most effective regimen assessed. Quantification of the spatial profile of cell killing within multicellular nodules revealed that these conditions also achieve the highest depth of cytotoxicity along the radial axis of 3D nodules. The framework introduced here provides a means for systematic assessment of PDT treatment parameters in biologically relevant 3D tumor models with potential for broader application to other systems.

No MeSH data available.


Related in: MedlinePlus

Uptake Dependent Treatment Response for AsPC-1 Cultures (Fractionated Irradiation). (A) Variable treatment response with uptake time for a constant 10J/cm2 light dose delivered continuously (33s on/0s off) and with increasing rest-period asymmetry (33s on/33s off, 33s on/66s off, etc.) for day 12 AsPC-1 nodules. Fractionation schedules are reported as seconds on/seconds off. Reported p-values are subscript symbolized as the comparison between groups with two different dark intervals for clarity. (B) Correlation of mean residual BPD to mean viability in day 12 AsPC-1 nodules with 4 hours of BPD uptake. Mean residual BPD was normalized to the BPD-only control.
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Figure 4: Uptake Dependent Treatment Response for AsPC-1 Cultures (Fractionated Irradiation). (A) Variable treatment response with uptake time for a constant 10J/cm2 light dose delivered continuously (33s on/0s off) and with increasing rest-period asymmetry (33s on/33s off, 33s on/66s off, etc.) for day 12 AsPC-1 nodules. Fractionation schedules are reported as seconds on/seconds off. Reported p-values are subscript symbolized as the comparison between groups with two different dark intervals for clarity. (B) Correlation of mean residual BPD to mean viability in day 12 AsPC-1 nodules with 4 hours of BPD uptake. Mean residual BPD was normalized to the BPD-only control.

Mentions: Figure 4 shows the change in treatment response of 10 J/cm2 delivered continuously and fractionated (symmetric and asymmetric regimens) with uptake time in day 12 AsPC-1 cultures. Fractionation schedules are reported as seconds on/seconds off (33/0 denotes continuous irradiation, no rest period). Reported p-values are subscript symbolized as the comparison between groups with two different dark intervals for clarity. At only 1.5 hours of verteporfin uptake, there is no discernable difference between any fractionation schedule and continuous irradiation. However, a significant benefit from symmetric fractionation is observed at 4 hours. A two-tailed student t-test reveals that comparing no dark interval (0s off, continuous irradiation) to symmetric (33s off) and asymmetric fractionation (99s off) at 1.5 hours uptake results in p-values of p0-33=0.572 and p0-99=0.531, respectively. The result of this same comparison at 4 hours uptake is p0-33=0.004 and p0-99<0.001. At 4 hours uptake, symmetric fractionation (33s on/33s off) does provide a modest enhancement, and increasingly asymmetric fractionation (33s on/99s off) provides even more. To determine why this occurs, we measured the mean photobleaching at 4 hours uptake in day 12 AsPC-1 cultures for 10 J/cm2 33s/0s and 33s/99s, and then correlated that to mean cytotoxic response. Figure 4B shows the result of this analysis and that the enhancement between continuous irradiation and asymmetric fractionation is present and significant (pV=0.016), but that there is an insignificant difference between the mean residual BPD in the wells (pBPD=0.115). From this data, it is clear that, in comparison to the absence of a dark interval, a statistically significant and greater cytotoxic response is obtained by fractionating delivered light. However, the reason for this enhancement cannot be readily elucidated by using mean field methods to quantify residual BPD or photobleaching.


Image-Based Quantification of Benzoporphyrin Derivative Uptake, Localization, and Photobleaching in 3D Tumor Models, for Optimization of PDT Parameters.

Glidden MD, Celli JP, Massodi I, Rizvi I, Pogue BW, Hasan T - Theranostics (2012)

Uptake Dependent Treatment Response for AsPC-1 Cultures (Fractionated Irradiation). (A) Variable treatment response with uptake time for a constant 10J/cm2 light dose delivered continuously (33s on/0s off) and with increasing rest-period asymmetry (33s on/33s off, 33s on/66s off, etc.) for day 12 AsPC-1 nodules. Fractionation schedules are reported as seconds on/seconds off. Reported p-values are subscript symbolized as the comparison between groups with two different dark intervals for clarity. (B) Correlation of mean residual BPD to mean viability in day 12 AsPC-1 nodules with 4 hours of BPD uptake. Mean residual BPD was normalized to the BPD-only control.
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Related In: Results  -  Collection

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Figure 4: Uptake Dependent Treatment Response for AsPC-1 Cultures (Fractionated Irradiation). (A) Variable treatment response with uptake time for a constant 10J/cm2 light dose delivered continuously (33s on/0s off) and with increasing rest-period asymmetry (33s on/33s off, 33s on/66s off, etc.) for day 12 AsPC-1 nodules. Fractionation schedules are reported as seconds on/seconds off. Reported p-values are subscript symbolized as the comparison between groups with two different dark intervals for clarity. (B) Correlation of mean residual BPD to mean viability in day 12 AsPC-1 nodules with 4 hours of BPD uptake. Mean residual BPD was normalized to the BPD-only control.
Mentions: Figure 4 shows the change in treatment response of 10 J/cm2 delivered continuously and fractionated (symmetric and asymmetric regimens) with uptake time in day 12 AsPC-1 cultures. Fractionation schedules are reported as seconds on/seconds off (33/0 denotes continuous irradiation, no rest period). Reported p-values are subscript symbolized as the comparison between groups with two different dark intervals for clarity. At only 1.5 hours of verteporfin uptake, there is no discernable difference between any fractionation schedule and continuous irradiation. However, a significant benefit from symmetric fractionation is observed at 4 hours. A two-tailed student t-test reveals that comparing no dark interval (0s off, continuous irradiation) to symmetric (33s off) and asymmetric fractionation (99s off) at 1.5 hours uptake results in p-values of p0-33=0.572 and p0-99=0.531, respectively. The result of this same comparison at 4 hours uptake is p0-33=0.004 and p0-99<0.001. At 4 hours uptake, symmetric fractionation (33s on/33s off) does provide a modest enhancement, and increasingly asymmetric fractionation (33s on/99s off) provides even more. To determine why this occurs, we measured the mean photobleaching at 4 hours uptake in day 12 AsPC-1 cultures for 10 J/cm2 33s/0s and 33s/99s, and then correlated that to mean cytotoxic response. Figure 4B shows the result of this analysis and that the enhancement between continuous irradiation and asymmetric fractionation is present and significant (pV=0.016), but that there is an insignificant difference between the mean residual BPD in the wells (pBPD=0.115). From this data, it is clear that, in comparison to the absence of a dark interval, a statistically significant and greater cytotoxic response is obtained by fractionating delivered light. However, the reason for this enhancement cannot be readily elucidated by using mean field methods to quantify residual BPD or photobleaching.

Bottom Line: While the systematic optimization of these treatment parameters can be complex, it also provides multiple avenues for enhancement of PDT efficacy under diverse treatment conditions, provided that a rational framework is established to quantify the impact of parameter selection upon treatment response.We use this approach to visualize and quantify the uptake, localization, and photobleaching of the PS benzoporphyrin derivative monoacid ring-A (BPD) in a range of treatment conditions with varying uptake times as well as continuous and fractionated light delivery regimens in 3D cultures of AsPC-1 and PANC-1 cells.Quantification of the spatial profile of cell killing within multicellular nodules revealed that these conditions also achieve the highest depth of cytotoxicity along the radial axis of 3D nodules.

View Article: PubMed Central - PubMed

Affiliation: 1. Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA 02114, USA; ; 2. Department of Physics, University of Massachusetts Boston, Boston, MA 02125, USA;

ABSTRACT
Photodynamic therapy (PDT) is a light-based treatment modality in which wavelength specific activation of a photosensitizer (PS) generates cytotoxic response in the irradiated region. PDT response is critically dependent on several parameters including light dose, PS dose, uptake time, fluence rate, and the mode of light delivery. While the systematic optimization of these treatment parameters can be complex, it also provides multiple avenues for enhancement of PDT efficacy under diverse treatment conditions, provided that a rational framework is established to quantify the impact of parameter selection upon treatment response. Here we present a theranostic technique, combining the inherent ability of the PS to serve simultaneously as a therapeutic and imaging agent, with the use of image-based treatment assessment in three dimensional (3D) in vitro tumor models, to comprise a platform to evaluate the impact of PDT parameters on treatment outcomes. We use this approach to visualize and quantify the uptake, localization, and photobleaching of the PS benzoporphyrin derivative monoacid ring-A (BPD) in a range of treatment conditions with varying uptake times as well as continuous and fractionated light delivery regimens in 3D cultures of AsPC-1 and PANC-1 cells. Informed by photobleaching patterns and correlation with cytotoxic response, asymmetric fractionated light delivery at 4 hours BPD uptake was found to be the most effective regimen assessed. Quantification of the spatial profile of cell killing within multicellular nodules revealed that these conditions also achieve the highest depth of cytotoxicity along the radial axis of 3D nodules. The framework introduced here provides a means for systematic assessment of PDT treatment parameters in biologically relevant 3D tumor models with potential for broader application to other systems.

No MeSH data available.


Related in: MedlinePlus