Delineating the Cellular Mechanisms Associated with Skin Electroporation

Area of Science:

• Immunology
• Dermatology
• Biotechnology

Background:

• Electroporation (EP) significantly enhances DNA vaccine efficacy by improving plasmid DNA (pDNA) transfection in skin cells.
• EP's physical insult activates innate immune pathways, potentially mediating an adjuvant effect that boosts vaccine responses.

Purpose of the Study:

• To investigate the mechanisms of the adjuvant effect of intradermal electroporation (EP), focusing on cell death pathways induced by the procedure itself, independent of plasmid DNA delivery.
• To characterize the temporal and spatial patterns of apoptotic and necrotic cell death in the skin following intradermal EP.

Main Methods:

• Utilized the CELLECTRA®-3P intradermal electroporation device to deliver electrical pulses to the skin.
• Employed the terminal deoxynucleotidyl transferase nick-end labeling (TUNEL) assay to detect apoptosis.
• Used a propidium iodide assay to detect in vivo necrotic cell death.
• Assessed calreticulin expression on skin cells post-EP.

Main Results:

• Apoptosis was detected as early as 1 hour post-EP, peaking at 4 hours, primarily in the epidermal region near electrode needles.
• Necrotic cell death was concentrated in the epidermal region adjacent to the electrode.
• Upregulation of calreticulin expression was observed on skin cells following EP, marking them for immune cell uptake.

Conclusions:

• Intradermal EP induces distinct apoptotic and necrotic cell death pathways in the skin, independent of plasmid DNA delivery.
• These cell death mechanisms and associated calreticulin expression likely contribute to the adjuvant effect of EP in DNA vaccination.
• Understanding these EP-induced events provides insight into optimizing DNA vaccine delivery strategies.