Advances in cell cryopreservation take a cue from nature

Deep in a freezer Japan, stash of tiny but exceptionally hardy micro-animals called tardigrades offered an even more surprising revelation. When thawed from their Rip Van Winkle–like slumber after 31 years, the seemed none worse for wear and began to reproduce. Inspired by natural processes that preserve features mummified tissue or permit full revival cells, tissues, entire organisms, scientists are exploring how improve cryopreservation both therapeutic research purposes. “Nature is best engineer,” says Xiaoming He, PhD, professor bioengineering at University Maryland Baltimore. Freezing drying similarly remove liquid water, organisms such as can protect themselves against both. His laboratory others conducting bio-inspired understand certain species able whether adapting some approaches surmount host drawbacks linked standard methods human cells tissues. Although organic solvent dimethyl sulfoxide (DMSO) helps stem during cooling process, its toxicity requires extensive washing procedure upon thawing still result harm recipients. Clinicians using growing range therapies, whereas cancer becoming promising new chemotherapeutic targets. How consistently biological integrity increasingly routine long-term banking critical line inquiry. Allison Hubel, mechanical engineering director Biopreservation Core Resource Minnesota Minneapolis, sees 3 main challenges. The first recovering many viable possible. An example frozen umbilical cord blood. “You can't go back ask baby more,” she says. second challenge ensuring consistent outcome with particularly treatments which they act living drug. “If you don't have outcome, know dose,” third avoiding DMSO-related adverse reactions neurological problems potentially life-threatening complications, including heart kidney failure. Feridoun Karimi-Busheri, scientist Department Oncology Alberta Edmonton, Canada, saw limitations firsthand his time cell program biopharmaceutical company NovaRx Corp San Diego, California, decade ago. Dr. Karimi-Busheri technician noticed traits lung preserved DMSO appeared change were thawed. laboratory's follow-up used proteomics analysis on periods 1 week year show characteristics indeed changing over time. impact, felt wide variety physical trigger apoptosis necrosis. Other pathways may turn off drop low activity levels. “That seriously damage functions we not see because test them,” he points recent study Blood Advances cautionary tale.1 Australian researchers found cryopreserving hematopoietic progenitor bone marrow peripheral blood donors—a necessity COVID-19 pandemic due disruptions transplant centers, reduced donor availability, travel restrictions—significantly cells' quality. team analyzed 305 products cryopreserved 9 laboratories across Australia. calculated median postthaw recovery rate 76%, was deemed “generally acceptable,” documented rates 6% cases. Prolonged storage times, higher white counts, complex manipulation before all associated “significant risk” poor product Together colleagues China, He investigating potential trehalose, disaccharide glucose, replacement. Tardigrades make trehalose major part combination strategy surviving extreme environmental conditions. sugar biocompatible body, humans cannot naturally it transport into cells. As solution, created nanoparticles delivery vesicles efficiently mammalian cells.2 Once subjected cold temperatures, disassemble release inside Importantly, treated this way protected temperatures comparable DMSO. One hypothesis trehalose's cryoprotective abilities suggests form hydrogen bonds proteins, lipids, other molecules within allow any conformational changes induced absence water become reversible. A separate posits prevent formation ice crystals instead encourage viscous, glasslike state process vitrification. another research, He's experimenting alginate hydrogel, compound walls brown algae. hydrogel's 3-dimensional structure slow down cryopreservation, also trying resolve appear when begin thaw. Tiny grow larger destructive recrystallization, anew devitrification. To avoid thaw-related damage, nanowarming, magnetic field quickly heats up speed warming rate. Hubel's own inspired, large part, looking out window winter. “I thought, ‘How do trees survive winters?’” recalls. answer involves multiple compounds, sugars trehalose. has toolkit strategies stress,” However, each organism, tree tardigrade, adopt somewhat different strategy. Unlike past efforts find work every system, Hubel pursuing “fit purpose” approach takes differences account. strategy, focusing kinds compounds: sugars, alcohols, amino acids. Overall, her systematic experiments suggested disaccharides better than monosaccharides seems individual compounds. DMSO-free products, one mesenchymal stromal been developed startup company, BlueCube Bio, based Minnesota. In mouse without cryoprotectant agent all. Instead, ultrarapid superflash freezing, achieves 10,000 °C per avoids crystal damage.3 method well applications, caution drawbacks. object increases size, removes heat center less rapidly perimeter. That property means ultrafast freezing small volume oocytes, would be much useful difficult achieve high enough formation. believes increasing revelations helping shape cryobiology robust dynamic study. Looking ahead, move toward freeze preservation Also inspired nature, successful freeze-drying could effectively same seeds ambient temperatures.