title: Effect of cryoprotectant solution and of cooling rate on crystallization temperature in cryopreserved Hypericum perforatum cell suspension cultures.
abstract: BACKGROUND
  The increasing demand for hypericins and hyperforins, the unique pharmaceuticals found in the Hypericum genus, requires the development of effective tools for long-term storage of cells and tissues with unique biochemical profiles.
  
  
  OBJECTIVE
  To determine the temperature of crystallization (T(C)) and of ice formation of 14 cryoprotectant mixtures (CMs) for their use in cryoprotection of H. perforatum L. cell suspensions and to evaluate the impact of the lowest Tc on post-cryogenic recovery.
  
  
  METHODS
  T(C) was determined by real-time microscopy of ice formation during slow cooling to -196° C and heating to 20° C.
  
  
  RESULTS
  Exposure of cells to CMs CM2 (PVS3) containing sucrose and glycerol or CM12 and CM13 containing sucrose, glycerol, dimethylsulfoxide and ethylene glycol decreased T(C) below -60° C, prevented intracellular crystallization and considerably reduced both the size of crystals and the rate of extracellular ice propagation.
  
  
  CONCLUSIONS
  The selected CMs proved suitable for cryopreservation of H. perforatum cell suspensions with the maximum of 58 % post-thaw recovery.
authors.affiliation: Institute of Biology and Ecology, Faculty of Science, P. J. Safarik University in Kosice, Manesova, Slovakia.
authors.forename: Anna
authors.initials: A
authors.lastname: Misianiková
authors.affiliation: Institute of Biology and Ecology, Faculty of Science, P. J. Safarik University in Kosice, Manesova, Slovakia.
authors.forename: Daniela
authors.initials: D
authors.lastname: Zubrická
authors.affiliation: Institute of Biology and Ecology, Faculty of Science, P. J. Safarik University in Kosice, Manesova, Slovakia.
authors.forename: Linda
authors.initials: L
authors.lastname: Petijová
authors.affiliation: Institute of Biology and Ecology, Faculty of Science, P. J. Safarik University in Kosice, Manesova, Slovakia. katarina.brunakova@upjs.sk.
authors.forename: Katarina
authors.initials: K
authors.lastname: Brunákova
authors.affiliation: Institute of Biology and Ecology, Faculty of Science, P. J. Safarik University in Kosice, Manesova, Slovakia.
authors.forename: Eva
authors.initials: E
authors.lastname: Cellárová
mesh_terms: D002478:Cells, Cultured; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents / Q000737:chemistry*; D003460:Crystallization; D020902:Hypericum; D012996:Solutions / Q000737:chemistry; D013696:Temperature
chemical_list: D003451:Cryoprotective Agents; D012996:Solutions