title: Beneficial effect of microinjected trehalose on the cryosurvival of human oocytes.
abstract: OBJECTIVE
  To determine the effectiveness of trehalose as an intracellular cryoprotectant for the cryopreservation of human oocytes.
  
  
  METHODS
  In vitro comparative study.
  
  
  METHODS
  Clinical and academic research environment at a medical school teaching hospital.
  
  
  METHODS
  Women undergoing in vitro fertilization (IVF).
  
  
  METHODS
  Discarded human oocytes, obtained from IVF patients, were randomly distributed into three groups: control group (no trehalose), extracellular trehalose group (0.5 M extracellular trehalose), and intracellular trehalose group (0.15 M intra- and 0.5 M extracellular trehalose). Trehalose was introduced into oocytes by microinjection. The oocytes in each group were cooled to different temperatures (i.e., -15 degrees C, -30 degrees C, and -60 degrees C) at rate of 1 degrees C/minute and thawed at ambient air temperature. Survival was examined after overnight culture.
  
  
  METHODS
  Survival of human oocytes cryopreserved in the presence and absence of trehalose.
  
  
  RESULTS
  The majority of oocytes in the intracellular trehalose group survived cooling to -15 degrees C (63%), -30 degrees C (53%), and -60 degrees C (66%). In contrast, only a small number of oocytes in both the control (13%) and extracellular trehalose group (22%) survived cooling to -15 degrees C, while all oocytes degenerated when cooled to -30 degrees C and -60 degrees C.
  
  
  CONCLUSIONS
  Small amounts of intracellular trehalose in the absence of any other cryoprotectant provide a significant protection against freeze-associated stresses. Our results suggest that sugars such as trehalose should be considered as intracellular cryoprotectants for cryopreservation of human oocytes.
authors.affiliation: Center for Engineering in Medicine and Surgical Services, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
authors.forename: Ali
authors.initials: A
authors.lastname: Eroglu
authors.forename: Mehmet
authors.initials: M
authors.lastname: Toner
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Toth
mesh_terms: D002470:Cell Survival / Q000187:drug effects*; D015925:Cryopreservation / Q000379:methods*; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods; D006801:Humans; D008845:Microinjections; D009865:Oocytes / Q000166:cytology* / Q000187:drug effects; D014199:Trehalose / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D014199:Trehalose