Scientists have been laboring to detect cancer and a host of other diseases in people using promising new biomarkers called "exosomes." Indeed, Popular Science magazine named exosome-based cancer diagnostics one of the 20 breakthroughs that will shape the world this year. Exosomes could lead to less invasive, earlier detection of cancer, and sharply boost patients' odds of survival.
"Exosomes are minuscule membrane vesicles — or sacs — released from most, if not all, cell types, including cancer cells," said Yong Zeng, assistant professor of chemistry at the University of Kansas. "First described in the mid-'80s, they were once thought to be 'cell dust,' or trash bags containing unwanted cellular contents. However, in the past decade scientists realized that exosomes play important roles in many biological functions through capsuling and delivering molecular messages in the form of nucleic acids and proteins from the donor cells to affect the functions of nearby or distant cells. In other words, this forms a crucial pathway in which cells talk to others."
While the average piece of paper is about 100,000 nanometers thick, exosomes run just 30 to 150 nanometers in size. Because of this, exosomes are hard to separate out and test, requiring multiple-step ultracentrifugation — a tedious and inefficient process requires long stretches in the lab, according to scientists.
"There aren't many technologies out there that are suitable for efficient isolation and sensitive molecular profiling of exosomes," said Zeng. "First, current exosome isolation protocols are time-consuming and difficult to standardize. Second, conventional downstream analyses on collected exosomes are slow and require large samples, which is a key setback in clinical development of exosomal biomarkers."
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