Cryopreservation of placental biopsies for mitochondrial respiratory analysis.

Mitochondrial function is required to support energetically-demanding processes in the placenta. As such, a compromise in mitochondrial function could severely impact fetal growth and development. Respirometry is a highly useful method for studying mitochondrial function, but is not possible in freeze-thawed mitochondria, which become uncoupled. We have developed a novel method that permits respiratory analysis of cryopreserved placental tissue. We studied mitochondrial function in 7 normal human placentas, analysing both fresh and cryopreserved samples. We found no impairments in respiration following cryopreservation in the delivery suite, with enhanced coupling, as indicated by higher respiratory control ratios, than in fresh placental samples transported to the laboratory on ice.