Bimodal macroporous 3D scaffolds based on compatibilized PCL and PLA blend using PCL-PEG-PCL block copolymers and cellulose nanocrystals for osteogenic differentiation of hMSCs

In recent years, attempts were made to develop biomaterials using synthetic and natural polymers to induce osteogenesis of human mesenchymal stem cells (hMSCs). Poly(epsilon-caprolactone) (PCL) is one of the few synthetic polymers with the potential to differentiate hMSCs to bone. However, its potential is limited, attributed to its low strength; its fast crystallization rate also compromises its dimensional stability. Polylactic acid (PLA) is another synthetic biocompatible polymer with low crystallinity and high rigidity widely used in biomedical engineering. It's commonly added to PCL to limit its shrinkage. However, they are incompatible. Here, the PCL: PLA (70: 30) blend was prepared and three PCL-PEGx-PCL block copolymers (BCPs) and cellulose nanocrystals (CNCs) were employed to improve their compatibility. Bone is a natural porous structure and here, by limiting shrinkage of PCL, potential of the blends to yield stable three- dimensional (3D) scaffolds with interconnected pores was studied. Salt leaching and thermally- induced phase separation was used to produce 3D scaffolds. CNCs were efficient in tuning pore morphology through cell- wall stabilization once the optimal BCP improved the interfacial interaction and reduced the viscosity. The results showed the blends possessed osteoinductive potential. However, the CNC nanocomposites were quite successful at intensifying biomineralization process.