Abstract:

BACKGROUND: Zinc has effects on DNA polymerase and RNA polymerase by direct and indirect action, and plays important roles in DNA duplication, RNA transcription, proliferation and differentiation of cells. Some studies have verified that zinc at a suitable concentration has effects on promoting the proliferation of neurons and osteoblasts.
OBJECTIVE: To explore effects of zinc on DNA and protein content as well as reproductive cycle of human umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) using flow cytometry, and to investigate zinc at a suitable concentration effects on UCB-MSCs.
METHODS: UCB-MSCs were isolated and cultured in vitro by the density gradient centrifugation. At the third passage, BMSCs in the control group were incubated with DMEM/F12 containing fetal bovine serum. BMSCs in the zinc group were incubated in above-mentioned DMEM, supplemented with zinc sulfate. The final concentration of zinc was 0.5, 1.5, 2.5, 3.5, 4.5 and 5.5 mg/L. BMSCs were incubated for 21 days. Cell surface antigen expression was observed. MTT assay was used to detect cell activity. Flow cytometry was utilized to measure DNA content, protein content and reproductive cycle.
RESULTS AND CONCLUSION: Cells were positive for CD29 and CD44. Zinc had dose-effect relationship on promotion of BMSC activity. Cell activity was significantly higher in the 0.5-4.5 mg/L zinc group compared with the control group (P < 0.01), especially at 2.5 mg/L. At 7, 14 and 21 days, BMSC DNA content and protein content significantly increased in the 2.5 mg/L zinc group compared with the control group (P < 0.01). Cell percentage in the S and G₂+M phases and cell proliferation index significantly increased, but cell percentage in the G₀/G₁ phases decreased significantly (P < 0.01). These indicate that zinc (0.5-4.5 mg/L) has the effect of promoting the rat BMSC proliferation, DNA reproduction and protein synthesis, and the 2.5 mg/L is the optimal concentration.