Related Experiment Video
Updated: Aug 16, 2026
Anticancer Efficacy of Photodynamic Therapy with Lung Cancer-Targeted Nanoparticles
Published on: December 1, 2016
Macrophage-targeted photodynamic therapy
1Wellman Center for Photomedicine, Mass. General Hospital, Boston, MA 02114, USA.
Abstract:
Photodynamic therapy (PDT) uses light activatable molecules that after illumination produce reactive oxygen species and unwanted tissue destruction. PDT has dual selectivity due to control of light delivery and to some extent selective photosensitizer (PS) accumulation in tumors or other diseased tissue, additional targeted selectivity of PS for disease is necessary. The delivery of drugs to selected lesions can be enhanced by the preparation of targeted macromolecular conjugates that employ cell type specific targeting by ligand-receptor recognition. Macrophages and monocytes express a scavenger-receptor that is a high-capacity route for delivering molecules into endocytic compartments in a cell-type specific manner. We have shown that by attaching PS to scavenger-receptor ligands it is possible to get three logs of selective cell killing in macrophages while leaving non-macrophage cells unharmed. The capability to selectively kill macrophages has applications in treating cancer and in the detection and therapy of vulnerable atherosclerotic plaque and possibly for autoimmune disease and some infections.
Insights
Photodynamic therapy (PDT) selectively targets diseased cells using photosensitizers (PS). Attaching PS to scavenger-receptor ligands enhances cancer cell destruction and offers new therapeutic avenues.
Area of Science:
- Biomedical Engineering
- Photochemistry
- Immunology
Background:
- Photodynamic therapy (PDT) utilizes photosensitizers (PS) activated by light to generate reactive oxygen species, causing tissue destruction.
- Current PDT methods exhibit dual selectivity (light delivery and PS accumulation) but require enhanced, disease-specific targeting of PS.
- Macrophages express scavenger receptors, offering a potential pathway for targeted drug delivery into endocytic compartments.
Purpose of the Study:
- To develop a targeted PDT approach by conjugating photosensitizers to scavenger-receptor ligands.
- To investigate the efficacy of scavenger-receptor-mediated delivery for selective destruction of macrophages.
- To explore the therapeutic potential of this targeted strategy in various diseases.
Main Methods:
- Conjugation of photosensitizers (PS) to scavenger-receptor ligands.
- In vitro studies to assess cell-type specific uptake and phototoxicity in macrophages versus non-macrophage cells.
- Evaluation of selective cell killing using quantitative assays.
Main Results:
- Targeted PS-ligand conjugates demonstrated highly selective cell killing in macrophages, achieving up to three logs of selectivity.
- Non-macrophage cells remained unharmed, indicating minimal off-target effects.
- Successful delivery of PS into endocytic compartments via scavenger-receptor recognition was confirmed.
Conclusions:
- Scavenger-receptor-mediated delivery of photosensitizers provides a potent strategy for highly selective photodynamic therapy.
- This approach enables targeted destruction of macrophages, with potential applications in cancer therapy.
- The method shows promise for treating conditions involving macrophages, such as atherosclerotic plaque, autoimmune diseases, and infections.
