2023, Vol. 27 ›› Issue (8): 1193-1198

Calcium phosphate cement/poly(lactic-co-glycolic acid) degradation products promote osteoclast differentiation of mouse monocytes

Long Guiyue1, Li Dongdong1, Liao Hongbing2   

Abstract: BACKGROUND: Preliminary studies found that calcium phosphate cement/poly(lactic-co-glycolic acid) composite can accelerate the process of bone remodeling, and the effect of its degradation products on the differentiation of mononuclear osteoclasts needs further study.
OBJECTIVE: To observe the effect of calcium phosphate cement/poly(lactic-co-glycolic acid) degradation products on the differentiation of mouse RAW264.7 monocytes and osteoclasts.
METHODS: The experiment was divided into blank control group, glycolic acid group, and calcium phosphate cement/poly(lactic-co-glycolic acid) group. According to the experimental group assignment, the prepared solution and 50 μg/L ligand of nuclear factor κB receptor activator were added to complete medium to prepare media with different conditions. Mouse RAW264.7 cells were cultured for 5 days to induce their differentiation. Cell counting kit-8 assay was used to analyze the effect of different culture media on cell proliferation. RT-PCR and western blot assay were used to detect the changes of gene and protein expression levels of nuclear factor of activated T-cells cytoplasmic 1, matrix metalloproteinase-9, nuclear factor κB receptor activator and tartrate-resistant acid phosphatase activated by osteoclast differentiation-related factors in mouse RAW264.7 monocytes. The osteoclast-like cells were identified by tartrate-resistant acid phosphatase staining.
RESULTS AND CONCLUSION: Cell counting kit-8 assay results showed that the cells were in a rapid growth period within 72 hours, and then began to decline after 96 hours. The results of RT-PCR and western blot assay showed that the expression levels of nuclear factor of activated T-cells cytoplasmic 1, nuclear factor-κB receptor activator and tartrate-resistant acid phosphatase mRNA and protein expression levels of nuclear factor-1 and nuclear factor-κB receptor activator in activated T cells in calcium phosphate cement/poly(lactic-co-glycolic acid) group were significantly higher than those in glycolic acid group and control group (P < 0.05). There was no significant difference in gene and protein expression levels of matrix metalloproteinase-9 between glycolic acid group and calcium phosphate cement/poly(lactic-co-glycolic acid) group, but it was higher than that of the control group (P < 0.01). Tartrate-resistant acid phosphatase staining results showed that the number of osteoclast-like cells in the calcium phosphate cement/poly(lactic-co-glycolic acid) group was significantly higher than that in the control group and the glycolic acid group (P < 0.05). Overall, these results indicate that the microenvironment formed by the degradation products of calcium phosphate cement/poly(lactic-co-glycolic acid) can promote the osteoclast differentiation of mouse RAW264.7 monocytes.
Key words: calcium phosphate cement/poly(lactic-co-glycolic acid) copolymer, monocyte, osteoclast differentation, matrix metalloproteinase-9, nuclear factor of activated T-cells cytoplasmic 1, nuclear factor-κB receptor activator