Scaffold channel size influences stem cell differentiation pathway in 3-D printed silica hybrid scaffolds for cartilage regeneration
We report that 3D printed scaffold channel size can direct bone marrow derived stem cell differentiation. Treatment of articular cartilage trauma injuries, such as microfracture surgery, have limited success because durability is limited as fibrocartilage forms. A scaffold-assisted approach, combining microfracture with biomaterials has potential if the scaffold can promote articular cartilage production and share load with cartilage. Here, we investigated human bone marrow derived stromal cell (hBMSC) differentiation in 3-D printed poly(tetrahydrofuran)/poly(ε-caprolactone) hybrid scaffolds with specific channel sizes. Channel widths of ~220 μm provoked hBMSC differentiation down a chondrogenic path, with collagen Type II matrix prevalent, indicative of hyaline cartilage. When pores were larger (~500 μm) collagen Type I was dominant, indicating fibrocartilage. There was less matrix and voids in smaller channels (~100 μm). Our hypothesis is that a 200-250 μm pore channel width, in combination with the surface chemistry and stiffness of the scaffold, is optimal for cell-cell interactions to promote chondrogenic differentiation and enable the chondrocytes to maintain their phenotype. When pores were larger, cells were likely to use the scaffold walls as 2D substrates, leading to fibroblastic differentiation or dedifferentiation of chondrocytes, while poor mass transportation in scaffolds with 100 μm pores may have occurred.
- This article is part of the themed collection: 29th Annual Conference of the European Society for Biomaterials