OBJECTIVE To explore the cytotoxicity, labeled time, marking rate, and effect on adhesion of quantum dot 655 (QD655) labeled rat bone marrow mesenchymal stem cells (BMSCs) in vitro, and to confirm its feasibility for stem cell labeling and tracer means for rat.
Methods: BMSCs were collected from the femur and tibia bone marrow cavity of a 2-week-old SD rat, cultured and identified. The 3rd passage of BMSCs were incubated with QD655 as the experimental group according to the recommended concentration of the markers. The cells were not labeled by QD655 as control group. The cell survival rate after QD655 labeling was detected by trypan-blue exclusion. The effect of QD655 on cell proliferation was observed by MTT. The osteogenic differentiation potential was identified by Alizarin red staining, alkaline phosphatase (ALP) staining, and real-time fluorogenic quantitative PCR. At immediately, 1, 2, 4, and 6 weeks, fluorescent microscopy was used to observe the labeled rate and scanning electron microscope was used to observe the cell adhesion to scaffold (bioglass/collagen composite).
Results: The cell survival rates were more than 90% in both experimental group and control group, showing no significant difference (P > 0.05). There was no significant difference in the cell proliferation between 2 groups (P > 0.05). Alizarin red staining and ALP staining showed positive results. Real-time fluorogenic quantitative PCR result showed that the mRNA expression levels of osteopontin, osteocalcin, collagen type I, ALP, and BMP-2 in the experimental group was significantly higher than those in the control group. The labeled rates were 96.50% +/- 1.59%, 93.30% +/- 1.51%, 72.40% +/- 2.90%, 40.10% + 3.60%, and 10.00% +/- 1.70% immediately, 1, 2, 4, and 6 weeks after labeling, respectively. The labeled rate in the control group was 0. Scanning electron microscope showed a good distribution of fusiform or polygonal cells in the pores of scaffold.
Conclusion: QD655 can be used as a labeling marker for BMSCs. Rat BMSCs labeled with QD655 is of high efficiency and safety.