2-N, 6-O-sulfated chitosan-assisted BMP-2 immobilization of PCL scaffolds for enhanced osteoinduction

- Electrospun PCL fiber scaffold was superfical doped with 2-N, 6-O-sulfated chitosan.
- The binding efficiency of BMP-2 was improved, as well as prolonged releasing behavior.
- Enhancd osteogenic activity can be acquired ascribed to synergistic effect of 26SCS.

The aim of this study was to develop a 2-N, 6-O-sulfated chitosan (26SCS) modified electrospun fibrous PCL scaffold for bone morphogenetic protein-2 (BMP-2) delivery to improve osteoinduction. The PCL scaffold was modified by an aminolysis reaction using ethylenediamine (ED) and 26SCS was immobilized via electrostatic interactions (PCL-N-S). Scaffolds were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contact angle measurements. In vitro BMP-2 adsorption and release kinetics indicated that modified PCL-N-S scaffolds showed higher levels of binding of BMP-2 (about 30-100 times), moderative burst release (about one third), and prolonged releasing time compared to the unmodified PCL scaffold. The bioactivity of released BMP-2 determined by alkaline phosphatase (ALP) activity assay was maintained and improved 8- 12 times with increasing concentration of immobilized 26SCS on the scaffolds. In vitro studies demonstrated that bone marrow mesenchymal stem cells (BMSCs) attached more readily to the PCL-N-S scaffolds with increased spreading. In conclusion, 26SCS modified PCL scaffolds can be a potent system for the sustained and bioactive delivery of BMP-2.

Limited self-regenerating capacity of human body makes the reconstruction of critical size bone defect a significant challenge. Although bone morphogenetic protein-2 (BMP-2) is an important differentiation factor inducing bone regeneration, it's short half-life in vivo and potent side effect at high dosage still show lots of concerns in the clinical use. Herein, modification of electrospun PCL scaffolds was presented through immobilizing of sulfated chitosan (26SCS). The modified scaffolds effectively improve the binding capacity of BMP-2 and exhibited an enhanced bioactivity and sustained release in vitro. Thus, the use of 26SCS modified PCL scaffolds combined with BMP-2 could be a useful scaffold for tissue engineering for osteogenesis.88