What if chemotherapy drugs could be squirted directly onto breast tumors from tiny reservoirs inside the body in short bursts, on demand?
They can, thanks to a self-healing gel that amounts to a miniature drug vial that can be opened and closed via ultrasound.
David J. Mooney, PhD, a core faculty member at Harvard University’s Wyss Institute for Biologically Inspired Engineering, led the team that developed the technique. As quoted in a Harvard news release, he explained the achievement:
Our approach counters the current paradigm of sustained drug release and offers a double whammy. We have shown that we can use the hydrogels repeatedly and turn the drug pulses on and off at will, and that the drug bursts in concert with the baseline low-level drug delivery seems to be particularly effective in killing cancer cells.
Dr. Mooney is also the Robert P. Pinkas Family Professor of Bioengineering at the Harvard School of Engineering and Applied Sciences (SEAS). He is senior author of an article about the research that was published online last week in Proceedings of the National Academy of Sciences.
Using injectable gels to deliver slow, steady doses of chemotherapy directly to a cancer site isn’t new. Nor is using ultrasound to administer a more concentrated drug dose. But such a drug pulse has been a one-shot deal because the ultrasound destroyed the gel carrier. The new technique uses a gel held together with calcium ions. When hit with ultrasound, the bonds break, releasing some of the drug the gel carries. But as long as there is calcium in the surrounding tissue, the bonds re-form, and the gel self-heals.
The key, the researchers found, is to use the correct intensity of ultrasound. “We were able to trigger our system with a level of ultrasound that was much lower than high-intensity focused ultrasound that is used clinically to heat and destroy tumors,” said co-lead author Cathal Kearney, PhD. Dr. Kearney was a postdoctoral fellow at SEAS at the time of the research. He is now a senior research fellow at the Royal College of Surgeons in Ireland.
The researchers tested their technique using the breast cancer drug mitoxantrone in mice with implanted human breast cancer tumors. Over six months, the mice that received a low-level sustained release of the drug plus a daily concentrated pulse triggered by ultrasound did much better than mice that got the sustained release alone. Their tumors virtually stopped growing, and they lived an average of 80 days longer.
The gel technique could also be used for other drugs and additional substances, such as proteins designed to spur tissue regeneration and condensed plasmid DNA for use in gene therapy.
* * *
A chiropractic college must make accommodations for blind students even though they have to find someone to read X-rays for them, says the Iowa Supreme Court. For details, see our Facebook page.
Related CME seminar (up to 39.25 AMA PRA Category 1 credits™): Comprehensive Review of Breast Imaging