In a first, rat organs successfully transplanted after 100-day storage

In fact, the official release highlights that roughly 20 percent of donated kidneys can't be transplanted because the organs cannot be kept on ice for an extended period of time. 

This is where the possibility of freezing the organ comes into play, although it comes with its own set of complications. This approach extends the storage duration of organs, but the ice crystals that form between cells might harm the tissue, rendering it worthless.

Another alternative for long-term storage is cryopreservation methods such as vitrification. Using chemicals, this approach enables quicker organ cooling at very low temperatures. However, this has the disadvantage of rewarming the organ, which often results in uneven heating.

The new 'warming' method 

To solve the uneven heating issues, the team has developed a specialized nano-warming process that warms the organ inside out. 

The new rewarming technique involves using iron oxide nanoparticles added to the cryoprotectant chemical. These nanoparticles, which act like tiny heaters, are dispersed throughout the organ’s blood vessels after applying magnetic fields. Thereby rewarming up the organ uniformly. 

The scientists demonstrated this approach effectively by cryogenically preserving rat kidneys for up to 100 days. The organ was then rewarmed without any damage before being transplanted into rats. 

The five rat recipients witnessed normal organ function after 30 days of receiving the kidneys. 

“This is the first time anyone has published a robust protocol for long-term storage, rewarming, and successful transplantation of a functional preserved organ in an animal,” said John Bischof, the study’s co-senior author, in an official release.  

Up next, the team will work to demonstrate the process using pig kidneys.

The research study has been published in the journal Nature Communications.

Study abstract:

Banking cryopreserved organs could transform transplantation into a planned procedure that more equitably reaches patients regardless of geographical and time constraints. Previous organ cryopreservation attempts have failed primarily due to ice formation, but a promising alternative is vitrification, or the rapid cooling of organs to a stable, ice-free, glass-like state. However, rewarming of vitrified organs can similarly fail due to ice crystallization if rewarming is too slow or cracking from thermal stress if rewarming is not uniform. Here we use “nanowarming,” which employs alternating magnetic fields to heat nanoparticles within the organ vasculature, to achieve both rapid and uniform warming, after which the nanoparticles are removed by perfusion. We show that vitrified kidneys can be cryogenically stored (up to 100 days) and successfully recovered by nanowarming to allow transplantation and restore life-sustaining full renal function in nephrectomized recipients in a male rat model. Scaling this technology may one day enable organ banking for improved transplantation.