Effects of storage temperatures and times on cell viability of cryopreserved intervertebral disc

English Keywords:Intervertebral disc  Cryopreserve  Cytoactive  Survival ratio of cell

English Abstract:

  【Abstract】 Objective：To investigate effects of different storage temperatures and times on cell viability of cryopreserved intervertebral disc and to obtain the optimal storage condition.Method：72 fresh canine intervertebral discs were divided into control group（group A，n=8），-80℃ group（group B，n=32） and -196℃ group（group C，n=32）.The intervertebral discs in group B and C were immerged into the freezing preservation medium and stored in -80℃ low temperature refrigerator and liquid nitrogen respectively.At each time-point of the 2md week，2nd month，6th month and 12th month，the survival ratio of different position at disc was detected by EB/FDA，the proteoglycans（PG） content of nucleus pulposus （NP） tissue was detected by DMMB，and the collagen content was detected by hydroxyproline.Result：The survival ratio of cell in group A was higher than that in group B and C at any time-points.Moreover，the survival ratios of cell in group B and C remained in a lower level.At 2th week and 2th month，the survival ratio in outer layer annulus fibrosus did not differ significantly in group B and C（P>0.05）.At the 6th month and 12th month，the survival ratio in outer layer annulus fibrosus in group B was higher than that in group C（P<0.05）.The survival ratio in inner layer annulus fibrosus and nucleus pulposus in group B was higher than that in group C at any time-point（P<0.05）.The PG content reduced gradually in 2-month storage.While from the 2nd to 12th storage month，the PG content in group C was higher than that in group B（P<0.05）.The collagen content in both groups showed no difference（P>0.05）.Conclusion：Both the ratio of cell survival and PG content of intervertebral disc stored in liquid nitrogen are higher than those in -80℃.During 1 year storage in liquid nitrogen，the ratio of cell survival and PG content maintain stably，which is suitable for allogenic transplantation.