Electrical Pulses / HMGB1 Cancer Research Results

Electrical Pulses (Pulsed Electric Field therapies; PEF) are a bioelectromagnetic modality in oncology that delivers brief, high-voltage (or high-field) pulses to tissue to permeabilize membranes and/or ablate tumors. Clinically relevant categories commonly discussed:
(1) Reversible electroporation for drug/ion delivery (Electrochemotherapy, ECT; Calcium electroporation),
(2) Irreversible electroporation ablation (IRE; e.g., NanoKnife-type approaches), and
(3) Nanosecond PEF (nsPEF) aimed at intracellular targets.
Primary mechanisms (ranked):
1) Membrane electroporation → rapid loss of ionic homeostasis / enhanced transport (ECT) or irreversible disruption (IRE).
2) Ca²⁺ dysregulation (influx + organelle Ca²⁺ stress) → mitochondrial depolarization, ER stress, apoptosis/necrosis spectrum (pulse-width dependent).
3) Stress biology (ROS↑, inflammatory/DAMP signaling) → immunogenic cell death signals and microenvironment remodeling (often secondary/adaptive).
PK/Bioavailability relevance: systemic PK is mainly relevant only for ECT (bleomycin/cisplatin timing, tissue exposure); field-based effects themselves are local and device/geometry-limited rather than concentration-limited.
In-vitro vs systemic exposure: not concentration-driven (electric field–driven); however, many in-vitro protocols use idealized field homogeneity not achievable in heterogeneous tumors without image-guided electrode placement.
Clinical evidence: ECT and IRE have substantial human use (ECT for cutaneous/superficial tumors; IRE for selected solid tumors near critical structures). nsPEF remains mostly preclinical/early human and is still device- and protocol-evolving.

In nsPEF systems the main engineering challenge is not current or power, but:
  -generating fast rise times
  -maintaining transmission line impedance
  -preventing pulse distortion at the electrodes
Other important aspects of nsPEF
  -mainly an electric field effect: 
     -Membrane breakdown typically occurs around 0.5–1 V across the membrane,
      which corresponds to ~10–50 kV/cm fields in tissue.
  -ns pulses terminate before plasma channels develop.
  -impedance mismatch and cable dispersion is important
  -nsPEF often induces programmed cell death rather than thermal ablation
The hallmark of nsPEF is simultaneous targeting of multiple intracellular pathways, particularly:
  -Calcium signaling (Ca²⁺ release)
  -Mitochondrial apoptosis (ΔΨm↓, Caspase-9↑, Caspase-3↑)
  -ROS stress pathways
Research might show cancer cells have some greater sensitivity to nsPEF, 
but nsPEF affects both normal and cancer cells

Electrical Pulses / PEF Oncology Modality — Ranked Mechanistic Axes