Basic study on cryopreservation of rat calvarial osteoblasts with different cryoprotectants

Cryopreservation is a method adopted for storage of autologous skulls. Herein, this current research sought to explore the effects of different cryoprotectants on the biological characteristics of rat calvarial osteoblasts after cryopreservation. Neonatal Sprague-Dawley rats were selected and their skull tissues were isolated. The skull tissues were allocated into the refrigerating-3M, refrigerating-6M, M199-3M, M199-6M, povidone iodine-3M, and povidone iodine-6M groups according to the usage of cryoprotectants and treatment time (month) and the fresh group. Osteoblasts were isolated from skull tissues in each group through digestion. The histomorphology of the skull was evaluated by H&E staining and cell morphology was observed by microscopy. The viability, proliferation, apoptosis, and osteogenic activity of osteoblasts were assessed by trypan blue staining, MTT, flow cytometry, and alkaline phosphatase (ALP) staining. The skull histomorphology and osteoblast morphology were similar between the fresh and refrigerating groups. Osteoblast viability was weakened after cryopreservation. The longer the refrigeration time, the lower the number of living cells and the higher the apoptosis rate. However, cryopreservation using different cryoprotectants did not evidently affect osteoblast proliferation and ALP activity. Different cryoprotectants show no apparent effect on the osteogenic activity of rat calvarial osteoblasts after cryopreservation.