Researchers have developed a new treatment method that shows promise for Chagas' disease — which can contribute to heart disease and is caused by a tropical parasite found primarily in Latin America — by using nanotechnology to deliver the drug directly to affected tissues in an effort to eliminate the severe side effects associated with available medications.
The technology stands to benefit millions of people who are affected by Chagas' disease, which is designated as a neglected tropical disease by the World Health Organization because it persists under conditions of poverty. The researchers have applied for a patent and the application was published Feb. 25 by the U.S. Patent and Trademark Office.
The new intravenous treatment, which has been tested in mice but not in humans, is part of a growing movement in pharmaceutical science toward nanomedicine, which uses drug delivery systems on a molecular scale to cure illnesses more efficiently and safely. While most medicines flow through the body uncontrolled after dosage, which can result in unintended side effects, nanomedicine systems package the treatment so it can travel inertly to the affected parts of the body, only becoming active in infected or damaged tissues.
Nanomedicine is a developing technology, but one that has already found success when applied to other illnesses, including heart disease, cancer and glaucoma. It's also being used to develop vaccines for tuberculosis and HIV and was even instrumental in designing the current COVID-19 mRNA vaccine.
"We are currently designing and testing new nanocarriers for neonatal vaccines, a new COVID-19 vaccine, cell/organ transplantation and for a novel endometriosis nanotherapy," said inventor Evan Scott, an associate professor of biomedical engineering at Northwestern University.
However, this is the first nanomedicine treatment for Chagas' disease, also known as American trypanosomiasis, which affects up to 7 million people worldwide, according to the WHO. Chagas' disease disproportionately affects Latin America, particularly areas with widespread poverty. This has to do in part with how the parasite is transmitted: through the bites of kissing bugs, which thrive in poor rural communities.
"The housing we have here in the States is not so suitable for these insects," said co-inventor David Engman, a retired chair of pathology at Cedars Sinai Medical Center in Los Angeles and former professor of pathology at Northwestern, where he first met Scott. "They prefer more rudimentary housing like mud or thatch huts. And while overall that type of housing is decreasing throughout the world, in these highly endemic regions a little hut can have 10,000 or 20,000 of these insects. And it's not just people they bite, it's chickens and other animals around them."
The work behind the patent application was funded by the National Institutes of Health and the National Science Foundation.
With symptoms that tend to be nonspecific and resemble the flu, acute Chagas' disease often comes and goes unnoticed. However, around 5% to 10% of people who contract the disease, generally young children or infants, die from the acute phase of illness.
However, for most people, the larger danger lies in it going untreated. In the long term, up to 40% of people infected with Chagas' disease develop heart damage. Many also develop chronic digestive complications. These dangers often emerge 30 or 40 years after an initial childhood infection. They can be mitigated if the infection is treated — but for some, the treatment is worse than the disease. Medications can cause severe and persistent nausea, vertigo, rashes, numbness of the limbs and weight loss.
"The problem is that the current drugs available are effective, but they're very toxic and so often people can't even tolerate the treatment regimen because of this toxicity," Engman said. "That's where this technology comes in, using nanotechnology to package drugs in such a way that they can be delivered while protecting tissues it can damage inadvertently."
The team hopes that the novel treatment will help more people living with this illness decide to seek treatment, even for long-term asymptomatic infections, something that is largely out of the question with current treatments.
"About two-thirds of people with this infection live their lives fully, and die of other causes completely either unaware of being infected or not having any clinical manifestation of disease," Engman said. "So the question then is, is it always effective to treat someone?"
This question is far more easily answered in the affirmative if treatment itself may help prevent the long-term risks of the disease without dangerous side effects.
While the treatment has currently only been tested in mice, the inventors are optimistic that their invention will contribute to better global health once it is finalized.
"With continuing changes in our climate, the insect vectors that carry Chagas' disease have spread from South [America] into many states across the U.S.," Scott said. "It takes many years for Chagas' disease to result in severe heart conditions, so we hope that our nanotherapy will be ready in time to help prevent future Chagas' disease cases."
He added, "It is important to think ahead with regard to infectious disease and public health, so that we have relevant treatments ready when needed."
The application for the patent, "Compositions and Methods of Using Propylene Sulfide-Based Polymers for Treatment of Chagas Disease," was filed July 29, 2020, to the U.S. Patent and Trademark Office. It was published Feb. 25, 2021 with the application number 2021/0052498. The earliest priority date was July 29, 2020. The inventors of the pending patent are Evan A. Scott, Northwestern University; Sijia Yi, Merck & Co.; Nicholas Karabin, Phosphorex Inc.; and Xiaomo Li, Cedars-Sinai Medical Center.
Parola Analytics provided technical research for this story.