Self-assembled composite matrix in a hierarchical 3-D scaffold for bone tissue engineering

It is of high clinical relevance in bone tissue engineering that scaffolds promote a high seeding efficiency of cells capable of osteogenic differentiation, such as human bone marrow-derived mesenchymal stem cells (hMSCs). We evaluated the effects of a novel polycaprolactone (PCL) scaffold on hMSC seeding efficiency, proliferation, distribution and differentiation. Porous PCL meshes prepared by fused deposition modeling (FDM) were embedded in matrix of hyaluronic acid, methylated collagen and terpolymer via polyelectrolyte complex coacervation. Scaffolds were cultured statically and dynamically in osteogenic stimulation medium for up to 28 days. Compared to naked PCL scaffolds, embedded scaffolds provided a higher cell seeding efficiency (t-test, P<0.05), a more homogeneous cell distribution and more osteogenically differentiated cells, verified by a more pronounced gene expression of the bone markers alkaline phosphatase, osteocalcin, bone sialoprotein I and bone sialoprotein II. Dynamic culture resulted in higher amounts of DNA (day 14 and day 21) and calcium (day 21 and day 28), compared to static culture. Dynamic culture and the embedding synergistically enhanced the calcium deposition of hMSC on day 21 and day 28. This in vitro study provides evidence that hybrid scaffolds made from natural and synthetic polymers improve cellular seeding efficiency, proliferation, distribution and osteogenic differentiation.