Aminated 3D Printed Polystyrene Maintains Stem Cell Proliferation and Osteogenic Differentiation

As 3D printing becomes more common and the technique is used to build culture platforms, it is imperative to develop surface treatments for specific responses. The advantages of aminating and oxidizing polystyrene (PS) for human mesenchymal stem cell (hMSC) proliferation and osteogenic differentiation are investigated. We find that ammonia (NH(3)) plasma incorporates amines while oxygen plasma adds carbonyl and carboxylate groups. Across 2D, 3D, and 3D dynamic culture, we find that the NH(3)- treated surfaces encouraged cell proliferation. Our results show that the NH(3)-treated scaffold was the only treatment allowing dynamic proliferation of hMSCs with little evidence of osteogenic differentiation. With osteogenic media, particularly in 3D culture, we find the NH(3) treatment encouraged greater and earlier expression of RUNX2 and ALP. The NH(3)-treated PS scaffolds support hMSC proliferation without spontaneous osteogenic differentiation in static and dynamic culture. This work provides an opportunity for further investigations into shear profiling and coculture within the developed culture system toward developing a bone marrow niche model. IMPACT STATEMENT: Surface treatment can be leveraged to enhance human mesenchymal stem cell response when transitioning polystyrene from a 2D to a 3D culture substrate. Understanding how the underlying surface chemistry influences the adhered cells could help build complex culture environments, with multiple cell types and work toward more biomimetic models of the bone marrow niche. Toward this goal, it is imperative to establish how the cells respond under static and dynamic culture and ensure the scaffolds support osteogenesis under typical induction conditions.