Cryopreservation is widely used in the preservation of blood, embryos, semen and many other biological applications. However, crystallization can damage cells and other valuable tissues.

Researchers experimented with various types of cryoprotectants, one of which is ethylene glycol that is used in automobile radiators to prevent them from freezing. Scientists developed a new way of mimicking the freezing process using cryoprotectants to preserve cells and tissues without crystallization and with low toxicity.

When cells are first exposed to tiny concentrations of cryoprotectants and they are given enough time to bloat, the cells can then be preserved ice-free by adding large amounts of cryoprotectants quickly. This process is called ice-free cryopreservation or vitrification, which could lead to overall low toxicity in the preserved cells or tissues.

The new procedure results in 80 percent strong cell survival post-vitrification compared to the 10 percent survival rate using the conventional method.

"This could be an important step toward the preservation of more complex tissues and structures," said associate professor Adam Higgins from the Oregon State University School of Chemical, Biological and Environmental Engineering.

Higgins added that vitrification's biggest and only problem is the toxicity that comes from using cryoprotectants. The findings help address the limiting factor and could lead to the identification of cryoprotectants that are even less toxic. The researchers hope that the process could lead to more complex and even complete organ vitrification.

Looking forward, widespread applications of vitrification can progress the medical field of tissue regeneration. In this field, tissues and even organs can be grown in a lab using stem cells. With the aid of vitrification, newly grown tissues can be made in small batches, stored and later transplanted. Vital organs from donors could be preserved as a routine until a perfect match is located. In theory, a normal person could have the option of growing a heart or any vital organ from stem cells, preserved and stored until such time that the need for a transplant arises.

"Our results demonstrate the potential for rational design of minimally toxic vitrification procedures and pave the way for extension of our optimization approach to other adherent cell types as well as more complex systems such as tissues and organs," the researchers wrote in the study published in the journal PLOS ONE on Nov. 25.

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