Understanding the influence of phosphorylation and polysialylation of gelatin on mineralization and osteogenic differentiation

Post-translational modifications such as phosphorylation and sialylation impart crucial functions such as mineral deposition and osteogenic differentiation to non-collagenous bone matrix proteins. In this work, the influence of phosphorylation and polysialylation of gelatin on mineralization in simulated body fluid (SBF) and on osteogenic differentiation of mesenchymal stem cells (MSC) was studied. It was observed that increase in phosphorylation could be directly correlated with the mineralization ability of phosphorylated gelatin in SBF. The total calcium and phosphate deposited increased with increase in degree of phosphorylation and was >3 fold higher on the highest degree of phosphorylation. Whereas, polysialylation did not have any significant influence on mineral deposition in SBF. On the other hand, when MSCs were cultured on polysialylated surfaces they showed relatively higher cell elongation with 1.5 fold higher cell aspect ratio, higher alkaline phosphatase activity and 3 fold higher mineral deposition when compared to control and phosphorylated gelatin surfaces. In conclusion, phosphorylation and polysialylation of gelatin show a significant influence on mineralization and osteogenic differentiation respectively which can be advantageously used for bone tissue engineering. (C) 2016 Elsevier B.V. All rights reserved.