Organ Preservation Techniques and Future Directions

A review article published recently in Engineering examines the field of organ preservation, focusing on its history, current techniques, and future possibilities. The global shortage of donor organs remains a critical issue, with only about 10% of the demand for organ transplantation being met, according to the World Health Organization. This challenge is compounded by the limitations of existing preservation methods.

The two primary clinical approaches to organ preservation are static cold storage (SCS) and machine perfusion (MP). SCS involves storing organs at low temperatures (around 4 °C) in a preservation solution. While simple and cost-effective, it can only maintain organ viability for limited durations: 12–24 hours for kidneys, 6–8 hours for lungs, and 4–6 hours for hearts. Extended SCS use can lead to complications such as ATP depletion, metabolite buildup, and ischemia-reperfusion injury (IRI), which may result in organ damage.

Machine perfusion offers longer preservation times by supplying oxygen and nutrients continuously. Hypothermic machine perfusion (HMP) can sustain organs for several days, while normothermic machine perfusion (NMP), which mimics body temperature, has shown improved transplant outcomes in some cases. However, MP has limitations, such as non-anastomotic biliary strictures in liver transplants.

Cryopreservation techniques like vitrification are being explored as long-term solutions. Vitrification prevents ice crystal formation by replacing water in organs with solutes to create a glass-like state but requires high concentrations of cryoprotective agents (CPAs), which can be toxic. Researchers are investigating methods to reduce CPA toxicity and improve rewarming techniques.

The article also highlights preservation challenges for specific organs. For example, kidneys show promise with vitrification-based cryopreservation, while livers face high discard rates due to IRI. Hearts require strategies to address high ATP consumption, and lungs may benefit from ex vivo lung perfusion (EVLP). Intestine preservation remains difficult due to its bacterial content.

According to the paper, future research should focus on refining preservation strategies, reducing CPA toxicity, and enhancing rewarming methods to address the global organ shortage.