Adhesion, proliferation and osteogenic differentiation of mesenchymal stem cells in 3D printed poly-ε-caprolactone/hydroxyapatite scaffolds combined with bone marrow clots

Mesenchymal stem cells (MSCs), a stem cell population capable of multi-lineage differentiation, bound to porous biomaterial scaffolds, are widely used for bone tissue regeneration. However, there is evidence to suggest that MSC collection from bone marrow and expansion in vitro may result in phenotypic changes including a loss of differentiation potential and cell senescence. The aim of the present study was to find a facile and efficient approach to enable MSC adhesion and proliferation to scaffolds with osteogenic differentiation. Unprocessed bone marrow blood from the condyle of the distal femur in the rabbits were added to three-dimensional (3D) printed porous poly-ε-caprolactone/hydroxyapatite (PCL/HA) scaffolds with bone marrow clots (MC) formed, using two different methods for Group A (MC enriched scaffolds) and Group B (MC combined scaffolds), and then were cultured in osteogenic medium for 4 weeks. The scaffolds were assessed macroscopically and microscopically. Scaffold bioactivity and the proliferation and osteogenic differentiation of seeded MSCs were measured. Higher cellular viability and greater cell numbers in the scaffolds at later phases of culture were observed in Group B compared with Group A. In addition, Group B was associated with greater osteoinductivity, alkaline phosphatase activity and bony nodule formation, as assessed using scanning electron microscopy. Furthermore, reverse transcription-quantitative polymerase chain reaction analysis revealed that more osteogenic differentiation was present in Group B, compared with Group A. MC combined scaffolds proved to be a highly efficient, reliable and simple novel method for MSC adhesion, proliferation and differentiation. The MC combined PCL-HA multi-scale porosity scaffold may represent a candidate for future bone regeneration studies.