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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

Imaging-based Quantification of Photosensitizer Uptake, Localization and Photobleaching. Overview of PDT treatment parameters and the capabilities of the imaging-based approach. The “Change in PS” column denotes pixel-by-pixel subtraction of post-treatment from pre-treatment photosensitizer fluorescence images. The most intense pixels in these images correspond to the pixels that were the most photobleached by PDT. Green and red pixels in fluorescence images in the “Imaging Based Viability Assessment” column denote live and dead characteristics of the nodules, respectively. All data presented here was collected from day 12 AsPC-1 cultures that were allowed to uptake photosensitizer for 4 hours. All scale bars are 350 μm.
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Figure 1: Imaging-based Quantification of Photosensitizer Uptake, Localization and Photobleaching. Overview of PDT treatment parameters and the capabilities of the imaging-based approach. The “Change in PS” column denotes pixel-by-pixel subtraction of post-treatment from pre-treatment photosensitizer fluorescence images. The most intense pixels in these images correspond to the pixels that were the most photobleached by PDT. Green and red pixels in fluorescence images in the “Imaging Based Viability Assessment” column denote live and dead characteristics of the nodules, respectively. All data presented here was collected from day 12 AsPC-1 cultures that were allowed to uptake photosensitizer for 4 hours. All scale bars are 350 μm.

Mentions: Figure 1 gives an overview of the parameters involved in a given PDT treatment as well as the capabilities of our imaging-based technique. PS fluorescence images are displayed based on a 12-bit colormap to easily identify areas of high pixel intensity. As expected, the No Treatment group contains no photosensitizer fluorescence (each image is nearly black) while the viability assessment image contains bright green nodules, signifying their health. Photobleaching of the photosensitizer can be qualitatively observed as a decrease in mean pixel intensity when comparing the pre- and post-treatment PS colormaps for a PDT treatment in which a fluence of 10 J/cm2 was delivered continuously.


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)

Imaging-based Quantification of Photosensitizer Uptake, Localization and Photobleaching. Overview of PDT treatment parameters and the capabilities of the imaging-based approach. The “Change in PS” column denotes pixel-by-pixel subtraction of post-treatment from pre-treatment photosensitizer fluorescence images. The most intense pixels in these images correspond to the pixels that were the most photobleached by PDT. Green and red pixels in fluorescence images in the “Imaging Based Viability Assessment” column denote live and dead characteristics of the nodules, respectively. All data presented here was collected from day 12 AsPC-1 cultures that were allowed to uptake photosensitizer for 4 hours. All scale bars are 350 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3475211&req=5

Figure 1: Imaging-based Quantification of Photosensitizer Uptake, Localization and Photobleaching. Overview of PDT treatment parameters and the capabilities of the imaging-based approach. The “Change in PS” column denotes pixel-by-pixel subtraction of post-treatment from pre-treatment photosensitizer fluorescence images. The most intense pixels in these images correspond to the pixels that were the most photobleached by PDT. Green and red pixels in fluorescence images in the “Imaging Based Viability Assessment” column denote live and dead characteristics of the nodules, respectively. All data presented here was collected from day 12 AsPC-1 cultures that were allowed to uptake photosensitizer for 4 hours. All scale bars are 350 μm.
Mentions: Figure 1 gives an overview of the parameters involved in a given PDT treatment as well as the capabilities of our imaging-based technique. PS fluorescence images are displayed based on a 12-bit colormap to easily identify areas of high pixel intensity. As expected, the No Treatment group contains no photosensitizer fluorescence (each image is nearly black) while the viability assessment image contains bright green nodules, signifying their health. Photobleaching of the photosensitizer can be qualitatively observed as a decrease in mean pixel intensity when comparing the pre- and post-treatment PS colormaps for a PDT treatment in which a fluence of 10 J/cm2 was delivered continuously.

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