Macroporous poly(lactic acid) construct supporting the osteoinductive porous chitosan-based hydrogel for bone tissue engineering

Poor mechanical performance of porous chitosan-hydroxyapatite systems is the main limitation in bone tissue engineering. If we merge good mechanical performance of poly(lactic acid) construct with osteoinductive and bioresorbable properties of chitosan-hydroxyapatite porous hydrogel, we can obtain a material that meets necessary requirement for bone tissue substituent. With this in mind, we propose the combination of 3D printing technique and the thermally-induced phase separation method for simultaneous modification of biological properties of poly(lactic acid) and load-bearing properties of chitosan-hydroxyapatite porous hydrogel. 3D printed poly(lactic acid), PLA, construct has been used as a mechanical support with very large pore diameter of 960 +/- 50 mu m allowing enough free space (similar to 60% of porosity) to form porous composite hydrogel by freeze gelation. In situ formation of hydroxyapatite within chitosan hydrogel has ensured higher human mesenchymal stem cell osteogenesis during 21 days of culture. Positive modification of poly(lactic acid) has been simultaneously utilized to improve the compressive strength of composite hydrogel which has been confirmed by Young's modulus ranging from lower values reported for cancellous bone in dry state. Considering positive osteogenic signal accompanied with suitable mechanical properties, our scaffolds have shown good potential as bone tissue substituent. (C) 2016 Elsevier Ltd. All rights reserved.