Supercooling methods for preservation of biological samples
The present invention provides methods for cryopreserving a population of cells with improved cell viability. In some aspects, the method comprises contacting a population of cells with a peptoid polymer comprising one or more polar peptoid monomers, e.g., formulated in a cryoprotectant solution, and cooling the population of cells at a temperature of from 0° C. to about −20° C. for a time period of at least about 3 hours to produce a population of supercooled cells. The supercooling methods of the present invention provide excellent post-thaw cell survival and recovery. In certain embodiments, the population of cells is present in a tissue or an organ that is cryopreserved by performing the supercooling methods of the present invention.
1. A method for preserving a population of cells, the method comprising:
(a) contacting a population of cells with a solution comprising a peptoid polymer or a salt thereof comprising one or more polar peptoid monomers; and
(b) cooling the solution to a temperature of from 0° C. to about −20° C. for a time period of at least about 3 hours to produce a population of preserved cells,
wherein the peptoid polymer is present in an amount sufficient to reduce or inhibit ice crystal formation at the temperature,
wherein the solution comprising the preserved cells is unfrozen at the temperature, and
wherein at least about 50% of the population of preserved cells survive after warming to above 0° C.
2. The method of claim 1 , wherein the temperature is from about −5° C. to about −20° C.
3. The method of claim 1 , wherein the time period is at least about 8 or 16 hours.
4. The method of claim 1 , wherein the time period is from about 2 to about 5 days.
5. The method of claim 1 , wherein the time period is at least about 72 hours.
6. The method of claim 1 , wherein at least about 50% of the population of preserved cells survive after warming to 37° C.
7. The method of claim 1 , wherein the population of cells is present in a tissue, an engineered tissue, or an organ.
8. The method of claim 1 , wherein the population of cells is selected from the group consisting of primary cells, heart cells, liver cells, lung cells, kidney cells, pancreatic cells, gastric cells, intestinal cells, muscle cells, skin cells, neural cells, blood cells, immune cells, fibroblasts, genitourinary cells, bone cells, stem cells, sperm cells, oocytes, embryonic cells, epithelial cells, endothelial cells, and a combination thereof.
9. The method of claim 1 , wherein the peptoid polymer comprises at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, or more polar peptoid monomers.
10. The method of claim 1 , wherein at least 2 of the polar peptoid monomers have a side chain that comprises an independently selected optionally substituted C 1-18 hydroxyalkyl group.
11. The method of claim 10 , wherein the C 1-18 hydroxyalkyl group is an independently selected optionally substituted C 1-6 hydroxyalkyl group.
12. The method of claim 1 , wherein the peptoid polymer is a peptoid-peptide hybrid or a salt thereof comprising the peptoid polymer and one or more amino acids, wherein the one or more amino acids are located at one or both ends of the peptoid polymer and/or between one or more peptoid monomers.
13. The method of claim 1 , wherein the peptoid polymer salt is selected from the group consisting of a hydrochloride salt, acetate salt, sulfate salt, phosphate salt, maleate salt, citrate salt, mesylate salt, nitrate salt, tartrate salt, gluconate salt, and a combination thereof.
14. The method of claim 1 , wherein the population of preserved cells is in a liquid, ice-free suspension at the temperature.