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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

Determination of Nodule-by-nodule Photobleaching. Progression from pre- and post-treatment and photobleaching difference map images to evaluation of the photobleaching pixel intensity profiles of selected nodules (circled in blue) for day 12 AsPC-1 cultures receiving 1.5 hours and 4 hours uptake and 10 J/cm2 of light delivered (A) continuously or (B) asymmetrically fractionated. All scale bars are 350 μm.
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Figure 5: Determination of Nodule-by-nodule Photobleaching. Progression from pre- and post-treatment and photobleaching difference map images to evaluation of the photobleaching pixel intensity profiles of selected nodules (circled in blue) for day 12 AsPC-1 cultures receiving 1.5 hours and 4 hours uptake and 10 J/cm2 of light delivered (A) continuously or (B) asymmetrically fractionated. All scale bars are 350 μm.

Mentions: To determine why fractionation produces a larger cytotoxic response than continuous irradiation, we further leverage our imaging based approach to correlate spatial photobleaching patterns with uptake and light delivery parameters. Figure 5 summarizes the data extracted from treatments at 1.5 hours and 4 hours of uptake for day 12 AsPC-1 nodules. Photobleaching maps were generated for the continuous irradiation and 33s on/99s off regimens for both 1.5 hours and 4 hours of BPD uptake. Pixel intensity line scans of the photobleaching maps were taken from nodules that were determined to be of similar diameter along their minor axis (~200 μm) and aspect ratio. Each line profile presents two peaks on the periphery of the nodules while the acini cores contain a large dip in the pixel intensity. There is little difference in the distribution of photobleaching comparing only continuous and fractionated light delivery. However, the thickness of the photobleaching “depth” is dissimilar comparing 1.5 hours to 4 hours of BPD uptake. The width of the photobleaching peaks are ~10-40 μm for 1.5 hours uptake while peaks on similarly sized nodules are ~80-100 μm at 4 hours. Referring back to Figure 1, the depth of photobleaching roughly corresponds to regions of dead cells from the evaluation of cytotoxic response. This suggests that broader photobleaching peaks correspond to deeper penetration of cytotoxicity in the acini, as observed from the data in Figure 5.


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)

Determination of Nodule-by-nodule Photobleaching. Progression from pre- and post-treatment and photobleaching difference map images to evaluation of the photobleaching pixel intensity profiles of selected nodules (circled in blue) for day 12 AsPC-1 cultures receiving 1.5 hours and 4 hours uptake and 10 J/cm2 of light delivered (A) continuously or (B) asymmetrically fractionated. All scale bars are 350 μm.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 5: Determination of Nodule-by-nodule Photobleaching. Progression from pre- and post-treatment and photobleaching difference map images to evaluation of the photobleaching pixel intensity profiles of selected nodules (circled in blue) for day 12 AsPC-1 cultures receiving 1.5 hours and 4 hours uptake and 10 J/cm2 of light delivered (A) continuously or (B) asymmetrically fractionated. All scale bars are 350 μm.
Mentions: To determine why fractionation produces a larger cytotoxic response than continuous irradiation, we further leverage our imaging based approach to correlate spatial photobleaching patterns with uptake and light delivery parameters. Figure 5 summarizes the data extracted from treatments at 1.5 hours and 4 hours of uptake for day 12 AsPC-1 nodules. Photobleaching maps were generated for the continuous irradiation and 33s on/99s off regimens for both 1.5 hours and 4 hours of BPD uptake. Pixel intensity line scans of the photobleaching maps were taken from nodules that were determined to be of similar diameter along their minor axis (~200 μm) and aspect ratio. Each line profile presents two peaks on the periphery of the nodules while the acini cores contain a large dip in the pixel intensity. There is little difference in the distribution of photobleaching comparing only continuous and fractionated light delivery. However, the thickness of the photobleaching “depth” is dissimilar comparing 1.5 hours to 4 hours of BPD uptake. The width of the photobleaching peaks are ~10-40 μm for 1.5 hours uptake while peaks on similarly sized nodules are ~80-100 μm at 4 hours. Referring back to Figure 1, the depth of photobleaching roughly corresponds to regions of dead cells from the evaluation of cytotoxic response. This suggests that broader photobleaching peaks correspond to deeper penetration of cytotoxicity in the acini, as observed from the data in Figure 5.

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