Effects of passage and cryopreservation on neurotrophic factor secretion from choroid plexus epithelial cells

The aim of the present study was to evaluate the effects of passage and cryopreservation of choroid plexus epithelial cells on their secretion of neurotrophic factors. Choroid plexus epithelial cells were cryopreserved and thawed following primary culture or passage cultured for up to two passages. The supernatant of primary, first/second passage and cryopreserved-thawed choroid plexus epithelial cells was collected when cells reached 80-90% confluence. ELISA was used to quantify brain-derived neurotrophic factor (BDNF), glial cell-derived neurotrophic factor (GDNF), nerve growth factor (NGF) and ciliary neurotrophic factor (CNTF) levels in the cell supernatant. First passage and cryopreserved-thawed cells secreted less BDNF and CNTF compared with primary cultured cells and increased levels of these two factors compared with second passage cells, and increased levels of GDNF and NGF compared with primary cultured and second passage cells (all P<0.05). Therefore, first passage culture decreased BDNF and CNTF secretion but increased NGF and GDNF compared with primary culture; second passage culture diminished neurotrophic factor secretion compared with first passage culture; and cryopreservation did not weaken the function of choroid plexus epithelial cells in secreting BDNF, GDNF, NGF and CNTF. The current study demonstrates that first passage and cryopreserved-thawed choroid plexus epithelial cells have an enhanced function to secrete neurotrophic factors including BDNF, GDNF, NGF and CNTF.