DARPA's Spleen-on-a-Chip Solves Sepsis

Blood poisoning is the number one cause of death among critical care patients in the US, killing more than 200,000 people annually. However, a radical new treatment option could transform the way we treat sepsis and save thousands of lives every year.

Sepsis, also known as blood poisoning, is the result of your immune system overreacting to blood-borne pathogens causing widespread inflamation, vessel leakage, which can lead to multiple-organ shutdown, shock, and sometimes death. Even those who live through the ordeal are often left hobbled by amputations or damaged organs.

The normal response against sepsis is the administration of wide-ranging antibiotics to help fight the infection while stabilizing the patient's blood pressure, performing mechanical ventilation or dialysis as needed. The system developed by The Wyss Institute for Biologically Inspired Engineering at Harvard University, on the other hand, physically traps and removes pathogens using nanotechnology.

The system was recently awarded a $9.25 million grant from DARPA to further spur its development and works much like the spleen, helping filter dead cells and pathogens from the blood supply. You can live without the spleen, sure, but it plays an important role in managing your body's supply of red blood cells and available iron as well as maintaining a reserve of monocytes, which help quell infections and grow into macrophages.

DARPA's Spleen-on-a-Chip Solves Sepsis

The magnetic nanobeads utilized by Harvard's system work much the same way as macrophages, binding and trapping foreign bodies. The patient's blood is first blended with these nanobeads, which are coated in synthetic opsonin—a protein that acts as a chemical fly paper against a wide range of bacteria, virii, and fungi. The mixed blood flows through the patient, collecting foreign invaders along the way, then through a series of magnetized microtubules located in an external device. The nanobeads are attracted to the walls of the tubules, which remain behind (along with their captured pathogens) while the freshly-cleaned blood then returns to the patient. To prevent the blood from clotting in these tiny mechanical capillaries, the team developed a super-hydrophobic coating called Spleen-on-a-Chip Fluidic Separation (SLIPS) coating. Lining the interiors of the capillaries with this substance prevents blood cells from gaining any purchase, thereby preventing clots.

"In just a few years we have been able to develop a suite of new technologies, and to integrate them to create a powerful new device that could potentially transform the way we treat sepsis," said Wyss founding director and project leader, Dr. Don Ingber, in a press release. However much more work must be done before this technology is ready to advance from animal trials to human.

[Wikipedia - Harvard - Science Space Robots - NIH - Images: Wyss Institute]