Enhanced osteoprogenitor elongated collagen fiber matrix formation by bioactive glass ionic silicon dependent on Sp7 (osterix) transcription

• Published in: Journal of biomedical materials research. Part A 2016-10, Vol.104 (10), p.2604-2615
• Main Authors: Varanasi, Venu G., Odatsu, Tetsurou, Bishop, Timothy, Chang, Joyce, Owyoung, Jeremy, Loomer, Peter M.
• Format: Article
• Language: English
• Subjects: Animals; bioactive glass; Biocompatibility; Biocompatible Materials - pharmacology; Biomedical materials; bone regeneration; Bone Regeneration - drug effects; Cell Line; Ceramics - chemistry; Ceramics - pharmacology; collagen type I; Collagen Type I - genetics; Collagens; Density; Extracellular Matrix - genetics; Formations; Gene expression; Gene Expression Regulation - drug effects; Glass; Intercellular Signaling Peptides and Proteins - genetics; Ions - pharmacology; magnesium; Markers; Mice; Osteoblasts - cytology; Osteoblasts - drug effects; Osteoblasts - metabolism; Osteogenesis - drug effects; RNA, Small Interfering - genetics; silicon; Silicon - chemistry; Silicon - pharmacology; Sp7 Transcription Factor; Transcription Factors - genetics; Transcriptional Activation - drug effects
• ISSN: 1549-3296; 1552-4965
• DOI: 10.1002/jbm.a.35795

Bioactive glasses release ions, those enhance osteoblast collagen matrix synthesis and osteogenic marker expression during bone healing. Collagen matrix density and osteogenic marker expression depend on osteogenic transcription factors, (e.g., Osterix (OSX)). We hypothesize that enhanced expression and formation of collagen by Si4+ depends on enhanced expression of OSX transcription. Experimental bioactive glass (6P53‐b) and commercial BioglassTM (45S5) were dissolved in basal medium to make glass conditioned medium (GCM). ICP‐MS analysis was used to measure bioactive glass ion release rates. MC3T3‐E1 cells were cultured for 20 days, and gene expression and extracellular matrix collagen formation was analyzed. In a separate study, siRNA was used to determine the effect of OSX knockdown on impacting the effect of Si4+ on osteogenic markers and matrix collagen formation. Each bioactive glass exhibited similar ion release rates for all ions, except Mg2+ released by 6P53‐b. Gene expression results showed that GCM markedly enhanced many osteogenic markers, and 45S5 GCM showed higher levels of expression and collagen matrix fiber bundle density than 6P53‐b GCM. Upon knockdown of OSX transcription, collagen type 5, alkaline phosphatase, and matrix density were not enhanced as compared to wild type cells. This study illustrates that the enhancement of elongated collagen fiber matrix formation by Si± depends on OSX transcription. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2604–2615, 2016.