| Backgroud and ObjectiveUtilizing bone graft materials to repair periodontal bone defects is a main method for the periodontal regeneration. Autogenous bone is always considered as the gold standard for bone graft materials and dental extraction inside the mouth is one source of autogenous bone. The newborn tissue obtained from extraction sockets in the early healing stages contains plentiful osteogenesis associated cells and bioactive factors, which is expected to become a better periodontal bone graft material than the mature autogenous bone. The objective of this study was to observe the discrepant effects of mature alveolar bone namely proper alveolar bone (PAB) and the extraction socket-derived early healing tissue (ESEHT) on the migration, proliferation and osteogenic differentiation of mouse bone marrow-derived stromal cell lines (ST2 cells), in order to provide theoretical basis for the clinical application of ESEHT by essentially probing into its biological activity, as well as its cellular biological basis of promoting osteogenesis.Materials and MethodsEESHT from the two-week healing extraction sockets and PAB from the interdental septa or surrounding socket walls were acquired from beagle dogs. ESEHT and PAB were separately co-cultured with ST2 cells using a Transwell system. The cells cultured with no material were considered as blank control groups. The chemotaxis of ST2 cells after 24h of co-culturing with tissue was detected.1,3,5, 7days later, the proliferation and alkaline phosphatase (ALP) activity of ST2 cells were measured. Real-time fluorescent quantitative reverse transcription polymerase chain reaction (RT-PCR) and Western Blot were used to detect the gene and protein expression of osteogenesis related factors BSP and Runx2. The formation of calcium nodules were observed by 1% alizarin red staining after 28 days of co-culture.ResultsST2 cells showed positive chemotaxis to ESEHT and PAB (P< 0.05), but there was no significant difference between themselves (P>0.05). The results of CCK-8 test showed that ESEHT and PAB could obviously promote the efficiency of cell proliferation since 3 days of co-culture when compared with the blank control group, and ESEHT exerted significantly higher proliferative activity than PAB on the 7th day (P< 0.05). The ALP activity of ST2 cells in ESEHT group was higher than that in blank control group with significant difference (P<0.05) after 1d of incubation and also significantly higher than that in PAB group at 3d,5d and 7d (P<0.05). The results of RT-PCR and Western Blot showed that the level of BSP and Runx2 both in gene and protein expressions at 7 days was sequenced as follows:ESEHT> PAB> control, while there was no significant difference among the three groups on the day 14,21. After co-cultured for 28 days,1% alizarin red staining showed that more calcium nodules were formed in ESEHT and PAB groups than the control group.ConclusionThe newborn healing tissue obtained from extraction sockets at 2 weeks showed better effects of migration, proliferation and osteogenic differentiation on ST2 cells than mature alveolar bone on the whole, which indicates that ESEHT is potentially expected to become a more advantageous periodontal bone graft material than mature autogenous bone. |
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