October 9, 2017
A recent study by biological engineers at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, demonstrated a significant advancement in the preservation of particular types of medicines, known as protein expression systems, for field applications — enabling those medicines to be stored and reconstituted on site in adverse conditions. The research, performed by David Karig and co-authors Seneca Bessling, Peter Thielen, Sherry Zhang and Joshua Wolfe, was recently published in a Journal of the Royal Society Interface article, “Preservation of Protein Expression Systems at Elevated Temperatures for Portable Therapeutic Production.”
Researchers have been trying to match the increasing need for portable protein expression systems, but these efforts have either required specialized storage for stability or involved difficult procedures for reconstituting. In addition, research has not shown long-term stability above room temperature, which is essential for many applications, including transportation to and storage in warm climates.
Karig, an APL research project manager, developed a method for preserving “cell-free” protein expression reagents. Cell-free protein expression systems consist of living-cell extracts that contain machinery for producing new proteins, along with several reagents that help to fuel protein expression. Typically, these components are unstable above freezing temperatures.
“Our method allows protein expression systems to withstand months of heat stress under atmospheric conditions,” said Karig. “The resulting ability to efficiently produce proteins with reagents that can be easily stored and distributed under harsh conditions overcomes many of the challenges associated with implementation of novel therapeutics in remote areas.”
This method enables the production of therapeutics on demand from dried, heat-tolerant reagents that consist of powdered cell extracts, water and DNA. Once mixed together, these reagents can create different therapeutics or vaccines depending on the type of DNA used. A key advantage of this method is that it solves the issue of cold-chain storage, which is costly in the developed world and nearly impossible in developing countries, where storing therapeutics at cold temperatures is impractical. In disaster scenarios, this method could facilitate fast distribution and production.
The article covers the procedures for preserving cell-free protein expression systems and demonstrates protein expression using reagents that have been stored for months at body temperature, 98.6 degrees F (37 degrees C).
To demonstrate the application potential of this capability, the researchers used heat-stressed, cell-free protein expression components to produce sufficient amounts of pyocin protein to kill Pseudomonas aeruginosa, a common pathogen that can cause disease in plants, animals and humans. This demonstration marks a step toward transportable, field-ready protein therapeutics.
“The pyocin production system provides an effective first-line treatment to prevent wound infections in combat environments or other remote locations where transport of lab-produced therapeutics would be infeasible,” Karig explained. “As the end of the age of antibiotics draws near, fieldable platforms like the one we present will be a necessary next step for low-cost storage, delivery, and production of novel medicines.”
Karig is a part of a team of APL synthetic biologists working on critical challenges for the nation and also leads a Multidisciplinary University Research Initiatives grant on understanding the human skin microbiome.
The Applied Physics Laboratory, a not-for-profit division of The Johns Hopkins University, meets critical national challenges through the innovative application of science and technology. For more information, visit www.jhuapl.edu.