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A genetically-encoded KillerRed protein as an intrinsically generated photosensitizer for photodynamic therapy

Zi-Xian Liao1, Yu-Chun Li, Hsiang-Ming Lu

  • 1Department of Chemical Engineering and Institute of Biomedical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC.

Biomaterials
|October 12, 2013
PubMed

Insights

This study explores genetically encoded KillerRed protein as a biodegradable photosensitizer for photodynamic therapy (PDT). Intracellular expression of KillerRed offers a potential solution to prolonged skin reactions associated with external photosensitizers.

Area of Science:

  • Biomedical Engineering
  • Photochemistry
  • Cell Biology

Background:

  • Photodynamic therapy (PDT) faces challenges with external photosensitizers causing prolonged skin reactions due to slow clearance.
  • Developing safe and effective photosensitizers is crucial for advancing PDT treatments.

Purpose of the Study:

  • To investigate the intracellular expression of a membrane-targeted KillerRed protein as a biodegradable photosensitizer for PDT.
  • To evaluate the efficacy and safety of genetically encoded KillerRed in PDT applications.

Main Methods:

  • Delivery of pKillerRed-mem using chitosan (CS) and poly(γ-glutamic acid) (γPGA) complexes for intracellular expression.
  • Observation of KillerRed expression at cellular membranes via fluorescence microscopy.
  • Assessment of reactive oxygen species (ROS) production upon green-light irradiation.
  • Evaluation of cell viability, cytotoxicity, apoptosis, and anti-proliferation effects.

Main Results:

  • Successful intracellular expression of membrane-targeted KillerRed protein was achieved.
  • KillerRed-positive cells generated excessive reactive oxygen species (ROS) upon green-light exposure.
  • ROS mediated KillerRed-induced cytotoxicity, apoptosis, and anti-proliferation.
  • Phototoxic reactions diminished over time, indicating intracellular degradability.

Conclusions:

  • Genetically encoded KillerRed protein functions as an effective and biodegradable photosensitizer for PDT.
  • This approach offers a promising alternative to external photosensitizers, potentially reducing side effects.
  • KillerRed holds potential for targeted destruction of diseased cells in PDT treatments.
Keywords:
Degradable photosensitizerFluorescence proteinGene therapyPhotocytotoxicityReactive oxygen species

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