Polyampholytes as low toxic efficient cryoprotective agents with antifreeze protein properties

Biomaterials. 2009 Sep;30(27):4842-9. doi: 10.1016/j.biomaterials.2009.05.025. Epub 2009 Jun 9.


Dimethyl sulfoxide (DMSO) has been used for several decades as the most efficient cryoprotective agent (CPA) for many types of cells and tissues in spite of its cytotoxicity and its effects on differentiation. Here we report that polyampholytes with an appropriate ratio of amino and carboxyl groups show higher cryopreservation efficiency and lower cytotoxicity than DMSO. Culture medium solutions of epsilon-poly-L-lysine (PLL) with more than 50 mol% of amino groups carboxylated showed excellent post-thaw survival efficiency of 95% murine L929 cells, and rat mesenchymal stem cells fully retained the potential for differentiation without serum. We also found that carboxylated PLLs showed antifreeze protein properties, such as ice recrystallization inhibition, which may contribute to successful cryopreservation by membrane protection. Thus, these polyampholytes can replace DMSO as new materials for CPAs in various preserving functions and will also be useful in studies elucidating the mechanisms of cryopreservation.

MeSH terms

  • Animals
  • Antifreeze Proteins / metabolism*
  • Buffers
  • Cell Differentiation / drug effects
  • Cell Proliferation / drug effects
  • Cell Shape / drug effects
  • Cell Survival / drug effects
  • Cryopreservation
  • Cryoprotective Agents / toxicity*
  • Mesenchymal Stem Cells / cytology
  • Mesenchymal Stem Cells / drug effects
  • Mice
  • Microscopy, Confocal
  • Polylysine / chemistry
  • Polylysine / toxicity*
  • Rats


  • Antifreeze Proteins
  • Buffers
  • Cryoprotective Agents
  • Polylysine