The method for transporting organs like hearts, lungs, and kidneys has remained relatively the same for decades and has included the same two basic components: Ice and the ice chest.
The traditional process: An organ is quickly taken from the recovery site, placed on a bed of crushed ice within an insulated carrier, and is flushed with a cold preservation solution – one that keeps the tissue at 4 °C all the way to the transplant site.
The ice-chest arrangement preserves a heart for 4-6 hours, but that small window of time can mean the difference between a healthy organ and a rejected one.
A self-contained system called ULiSSES™ – winner of Tech Briefs Media Group's 'Create the Future' Design Contest this year – extends the life of organs to 24 hours, circulating oxygen instead of calling for the ice.
With ULiSSES, the recovered organ is stored in a container and is attached to an oxygenation head. An oxygen-rich solution maintains the basic metabolic functions of the organ so that it stays in a healthy and viable condition for longer periods of time.
Through gas pressure, the nutrient-rich fluid is pulsed into the organ – a process called perfusion – and then vented into a canister within the device. The solution is recycled and returned to the upper part of the system where it is reoxygenated, filtered, and sent back through the tissue again and again.
ULiSSES does not require a mechanical pump, motor, or battery. Harvested energy from the expanding oxygen recirculates the preservation fluid, also called perfusate – a convenient, efficient feature, according to Leonid Bunegin, Chief Scientific Officer at the award-winning San Antonio, TX-based manufacturer Vascular Perfusion Solutions . Bunegin is also an associate professor of anesthesiology at UT Health San Antonio.
The system fits into an airplane's overhead compartment on an airplane, simplifying transport to the transplant hospital.
"Overall, ULiSSES is distinguished by its portability, affordability, and ease of use," Bunegin told Tech Briefs.
In the edited interview below, Prof. Bunegin offers a closer look at the device and its life-saving potential.
Tech Briefs: How did this technology idea come about? Was there a kind of moment of inspiration?
Prof. Leonid Bunegin: In 1980, it was scarcely 15 years since the first successful heart transplant had occurred. It dawned on me that the technology for transporting humans to the Moon and back had already been developed. Why were we still transporting our most precious cargo, namely, hearts and other organs for transplantation, just like it was the day’s catch from the coast?
Recognizing that separating organs from the body also separated them from their oxygen supply suggested that preservation technology should circulate an oxygenated solution through the tissue in order to maintain its access to oxygen. My research using high-frequency ventilation led me to the idea that a perfusion device could be configured to harvest energy from compressed oxygen to both power perfusion and oxygenate the perfusate.
Tech Briefs: What are the limitations of today's organ transport methods?
Prof. Bunegin: First, as soon as the tissue is separated from the body it begins to die due to a lack of oxygen.
Second, when the tissue is placed on ice, the portion in contact with the ice becomes frost-bitten, which induces injury.
Third, any delay in transporting the tissue results in additional tissue deterioration, to the extent that many organs are rejected because of poor quality.
Fourth, because the tissue is transported as rapidly as possible, optimal matching between the donor and recipient often doesn’t occur. Consequently, higher doses of immunosuppressants are required in order to prevent rejection.
Other limitations include high transportation costs, emergency surgery that can occur at any hour of the day or night, and long recovery periods in the ICU, all of which drive up the overall cost of transplantation.
Tech Briefs: Why do you think the transport method hasn’t changed all that much?
Prof. Bunegin: Transporting the organ from the recovery site to the transplant site has not changed much primarily because the current method of cold of storage is simple – requiring only the organ, ice, and an ice chest. Additionally, the engineering mind-set for machine perfusion was and still is locked into using a pump, which needs a motor, which needs a power supply, which results in a larger, heavier, and less transportable device.
Tech Briefs: Can you help readers visualize the technology? What is it, and how does it work exactly? Can you take us through an example of how it’s used?
Prof. Bunegin: The ULiSSESTM device is in every respect a heart-lung machine for organs and tissues. It consists of two parts: a fluid-filled container in which the organ is stored, and an oxygenation head to which the organ is attached.
Within the head is an oxygenator attached to a simplified pump. The recovered organ is attached to one end of the oxygenator via the arterial vessel, so that both the oxygenator and organ can be lowered onto the container, which has previously been filled with a preservation solution. Joining the two parts forms the organ storage compartment. A switch operates as an actuator to provide pulsatile operation with a suitable output pressure.
Pressure pulses applied to the pump push oxygenated perfusate through the organ. Perfusate exits via the vein into the organ storage compartment until the pressure in the organ storage chamber reaches a selected level. Feedback allows excess pressure to be vented, and the pressure differential forces fluid in the storage compartment through the oxygenator. CO2 is removed, oxygenation occurs, and the next cycle begins. The system is placed in an insulated case that can fit into the overhead compartment on an airplane, for simplified transport to the transplant hospital.
Tech Briefs: From a technology perspective, what is innovative, do you think?
Prof. Bunegin: The innovation is that the oxygenator and the pump are integrated to achieve three functions simultaneously. The first is to drive perfusate though the attached limb of organ, the second is to prevent retrograde flow though the oxygenator, and the third is to oxygenate and remove CO2 from the perfusate.
Additionally, the combination of the oxygenator/pump mechanism with a switch operating in a pulsatile fashion provides a mechanism that harvests the energy from the expanding oxygen to recirculate the preservation perfusate.
Tech Briefs: What is most exciting to you about this technology?
Prof. Bunegin: The most exciting aspect of this technology is that it has the capacity to provide sufficient oxygen to organs and tissues at room temperature, satisfying metabolic requirements for more than 24 hours. That means the tissue remains healthy throughout the preservation period, yielding high-quality organs for transplantation. This in turn leads to higher organ utilization and more opportunities for transplantation. Overall, ULiSSES is distinguished by its portability, affordability and ease of use.
Tech Briefs: Where has this been tested?
Prof. Bunegin: Thus far, the device has been tested in various animal models using kidneys, hearts, colons, and skeletal muscle. Through the U.S. Army Institute of Surgical research in San Antonio, we will have access to porcine limbs and organs, and diseased human limbs for additional testing. Moreover, our company Vascular Perfusion Solutions will be conducting studies in porcine hearts and kidneys in order to gather data for FDA submission and clearance.
Tech Briefs: What’s next?
Prof. Bunegin: Additional directions into which ULiSSES can expand include regenerative medicine, and organ banking. Simply switching the preservation solution to a nutrient solution, ULiSSES can function as a bioreactor for tissue regeneration. By switching to a surfactant solution, ULiSSES can effectively decellularize vascularized tissue to form extracellular matrices for tissue regeneration. And given the right environment, we may even be able to preserve limbs and organs for a much longer time, perhaps leading to banks of organs that are available to those who need them on-demand.
What do you think? Share your questions and comments below.