Normothermic Machine Perfusion

The idea of machine perfusion for the preservation of organs and tissues has been around since the 1800’s. Several early working models were produced, including ones by Alexis Carrel and Charles Lindbergh in 1935 and Belzer in the mid 1900’s. However, without the advanced technology required for success, the idea lapsed. Cold storage methods that provided a simpler option of preservation and are still routinely used today.

OCS system
A liver is set up on the Organ Care System.

However, although the liver transplant waiting list grows each year, the number of viable donor organs available has not stayed the same. As a result, many patients die while waiting for a liver transplant. This scarcity of donor livers necessitates the increased use of organs previously considered non-viable, such as organs from older or DCD donors or from donors with Fatty Liver Disease.These livers are more prone to damage during cold storage and the prolonged time outside of the body this preservation method entails. Normothermic machine perfusion is a promising alternative preservation method to allow for the successful utilization of less robust organs. Normothermic machine perfusion utilizes a perfusion apparatus to keep a liver at physiological conditions outside the body. Temperature and pH are controlled while the liver is perfused with an oxygenated pulsatile blood flow. The liver functions as it does in the body, even producing bile.

Surgeon preps a liver
Liver prep

The machine is taken to the donor site where the organ is procured and then used to transport the organ to the recipient, substantially decreasing the cold storage time. Organ function, including enzyme and lactate levels, can be constantly monitored. Dr. MacConmara leads the UT Southwestern branch of the clinical trial of the Organ Care System, a normothermic machine perfusion system developed by TransMedics. The Organ Care System has already been approved for use in heart and lung transplants.