Rabbits kept alive by oxygen injections

June 28, 2012

Am injected microparticle (yellow) can hand off oxygen molecules to red blood cells (red) to carry throughout the body (credit: D. Kunkel/Dennis Kunkel Microscopy Inc., D. Bell/Harvard University, J. Kheir/Boston Children’s Hospital, C. Porter/Chris Porter Illustration)

Rabbits with blocked windpipes have been kept alive for up to 15 minutes without a single breath, after researchers injected oxygen-filled microparticles into the animals’ blood, Nature News reports.

The development is reminescent of a hypothetical concept called respirocytes proposed by Robert A. Freiatas, Jr. —  microscopic, artificial red blood cells that can emulate the function of its organic counterpart, only with 200 times the efficiency, so as to supplement or replace the function of much of the human body’s normal respiratory system.

Oxygenating the blood by bypassing the lungs in this way could save the lives of people with impaired breathing or obstructed airways, says John Kheir, a cardiologist at the Children’s Hospital Boston in Massachusetts, who led the team.

In the past, doctors have tried to treat low levels of oxygen in the blood, or hypoxaemia, and related conditions such as cyanosis, by injecting free oxygen gas directly into the bloodstream. They had varying degrees of success, says Kheir.

The particles are injected directly into the bloodstream, where they mingle with circulating red blood cells. The oxygen diffuses into the cells within seconds of contact, says Kheir.

Injected rabbits survived for up to 15 minutes without breathing, and had normal blood pressure and heart rate. They showed no indication of heart, lung or liver damage caused by oxygen deprivation, or of pulmonary embolisms.

The microcapsules are easy and cheap to make, says Kheir. They effectively self-assemble when the lipid components are exposed to intense sound waves in an oxygen environment — a process known as sonication.

If it works in large animal trials that are currently underway and moves to human clinical trials, the therapy could eventually be used on anyone with a lung infection, asthma attack, or blocked airway.