We missed this interesting medical development back in February. So here it is. Boris Rubinsky, a UC Berkeley researcher and professor, has shown that microsecond electrical pulses can punch nanoscale holes in the target cells’ membranes without causing any damage to the tissue scaffolding. This irreversible electroporation technique (IRE), as he calls it, has proven successful in a large animal study and can be used in minimally invasive surgical treatments of tumors. Here’s more from UC Berkeley:
The study on pigs, the first large animal trial for the irreversible electroporation (IRE) technique, is described in the February issue of the journal Technology in Cancer Research and Treatment. IRE was developed at the University of California, Berkeley, which holds a number of patents on the technology.
“I’ve been working in this area of minimally invasive surgery for 30 years now,” said Boris Rubinsky, UC Berkeley professor of bioengineering and mechanical engineering and lead author of the paper. “I truly think that this will be viewed as one of the most important advances in the treatment of tumors in years. I am very excited about the potential of this technique. It may have tremendous applications in many areas of medicine and surgery.”
Irreversible electroporation uses electrical pulses that are slightly longer and stronger than reversible electroporation. With IRE, the holes in the cell membrane do not reseal, causing the cell to lose its ability to maintain homeostasis and die.
The researchers say that IRE overcomes the limitations of current minimally invasive surgical techniques that use extreme heat, such as hyperthermia or radiofrequency, or extreme cold, such as cryosurgery, to destroy cells.
They point out that temperature damage to cells also causes structural damage to proteins and the surrounding connective tissue. For liver cancer, the bile duct is at risk for damage. For prostate cancer, the urethra and surrounding nerve tissue is often affected.
Electroporation, on the other hand, acts just on the cell membrane, leaving collagen fibers and other vascular tissue structures intact. The researchers said that leaving the tissue’s “scaffolding” in place allows healthy cells to regrow far more quickly than if everything in the region was destroyed.
In the new study, the researchers set out to demonstrate that the IRE technique could produce reliable and predictable results in a large animal model. They performed the IRE surgical technique on 14 healthy female pigs under general anesthesia, using the same procedures as if the patients were human.
They used ultrasound imaging to guide the 18 gauge stainless steel electrodes to target areas in the pigs’ livers. The researchers applied 2,500 volts in eight 100-microsecond pulses spaced 100 microseconds apart to create lesions in the livers. They found that the lesions were immediately apparent as dark spots on the ultrasound images, giving real-time feedback during the procedure. The livers were then examined 24 hours, three days, seven days and 14 days after surgery.
“All of the vessels, down to the microvasculature, remain intact with IRE treatment, so the healing process is amazing,” said Onik, who performed the surgery for the study. “Where it might take a year for a cryosurgery lesion to resolve, IRE lesions resolved in two weeks. That has major implications in terms of monitoring what you’re doing and knowing that the cancer has been killed.”