Silver nanoparticles promote osteogenic differentiation of human urine-derived stem cells at noncytotoxic concentrations

Abstract

Hui Qin,1,* Chen Zhu,2,* Zhiquan An,1 Yao Jiang,1 Yaochao Zhao,1 Jiaxin Wang,1 Xin Liu,1 Bing Hui,1 Xianlong Zhang,1 Yang Wang1 1Department of Orthopedics, Sixth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 2Department of Orthopaedic Surgery, Provincial Hospital Affiliated to Anhui Medical University, HeFei, People's Republic of China *These authors contributed equally to this work Abstract: In tissue engineering, urine-derived stem cells are ideal seed cells and silver nanoparticles (AgNPs) are perfect antimicrobial agents. Due to a distinct lack of information on the effects of AgNPs on urine-derived stem cells, a study was conducted to evaluate the effects of silver ions and AgNPs upon the cytotoxicity and osteogenic differentiation of urine-derived stem cells. Initially, AgNPs or AgNO3 were exposed to urine-derived stem cells for 24 hours. Cytotoxicity was measured using the Cell Counting kit-8 (CCK-8) test. The effects of AgNPs or AgNO3 at the maximum safety concentration determined by the CCK-8 test on osteogenic differentiation of urine-derived stem cells were assessed by alkaline phosphatase activity, Alizarin Red S staining, and the quantitative reverse transcription polymerase chain reaction. Lastly, the effects of AgNPs or AgNO3 on "urine-derived stem cell actin cytoskeleton organization" and RhoA activity were assessed by rhodamine-phalloidin staining and Western blotting. Concentration-dependent toxicity was observed starting at an AgNO3 concentration of 2 µg/mL and at an AgNP concentration of 4 µg/mL. At these concentrations, AgNPs were observed to promote osteogenic differentiation of urine-derived stem cells, induce actin polymerization and increase cytoskeletal tension, and activate RhoA; AgNO3 had no such effects. In conclusion, AgNPs can promote osteogenic differentiation of urine-derived stem cells at a suitable concentration, independently of silver ions, and are suitable for incorporation into tissue-engineered scaffolds that utilize urine-derived stem cells as seed cells. Keywords: silver nanoparticles, osteogenic differentiation, stem cell, cytotoxicity