Cyclic tensile strain combined with icariin promotes the osteogenic differentiation of adipose-derived stem cells

Abstract

Objective To study the roles of icariin and cyclic tensile strain (CTS) in promoting the osteogenic differentiation of adipose-derived stem cells (ASCs) and the molecular mechanisms involved. Methods ASCs were isolated from Sprague-Dawley rats and treated either with icariin (10-7 mol/L) or with 1000 μ, 2000 μ or 3000 μ of CTS for 7 days, or with icariin plus CTS at 2000 μ for three days. Alkaline phosphatase (ALP) activity was detected after 3 and 7 days of intervention. Western blotting was performed to detect the expression of Runt-related transcriptional factor 2 (Runx2), Yes-associated protein (YAP) and connective tissue growth factor (CTGF) after the third day of the intervention. A reverse transcription polymerase chain reaction was performed at 7 days to detect the expression of osteopontin (OPN) and collagen 1a and after 3 days to detect the expression of the YAP target gene, CTGF and ankyrin repeating domain 1 (Ankrd1). Results Icariin and CTS at 1000 μ, 2000 μ or 3000 μ could all significantly promote the expression of ALP protein. CTS at 2000 μ was the most effective. The co-treatment with icariin and CTS significantly promoted ALP protein expression compared with icariin or CTS treatment alone. It also significantly promoted the expression of Runx2 and CTGF protein. Icariin or CTS (2000 μ) alone could not promote the expression of YAP protein, but icariin combined with CTS (2000 μ) promoted it significantly. Either icariin or CTS (2000 μ) could significantly promote ALP activity after 3 and 7 days, but icariin combined with CTS had the most obvious effect. Both icariin and CTS (2000 μ) could also significantly promote the expression of the osteogenesis-related genes OPN and collagen 1a, as well as the YAP targeted genes CTGF and Ankrd1. However, the combination of icariin and CTS had the greatest effect in promoting the expression of OPN mRNA, collagen 1a mRNA, CTGF mRNA and ankrd1 mRNA. Conclusion Icariin and CTS co-treatment may promote osteogenic differentiation of ASCs via activating YAP expression. Key words: Icariin; Cyclic tensile strain; Adipose-derived stem cells; Osteogenic differentiation