Characteristics and osteogenic potential of scaffolds with controlled pore geometry obtained by FDM 3D printing technology from resorbable bioplastics

In the field of tissue engineering, the architecture of a scaffold plays a critical role in determining how cells behave and how new tissue structures are formed. In this study, we have for the first time developed and compared four different types of 3D printed scaffolds made from biodegradable polymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate). These scaffolds varied in terms of their internal channel topologies, which included triangular, square, and hexagonal geometry, as well as a configuration based on the Hilbert curve. The scaffolds were fabricated via the process of 3D printing using the method of fused deposition modeling, based on pre-designed computer models. The investigation into the proliferation, metabolic activity, and osteogenic differentiation of human mesenchymal stem cells (MSCs) revealed a substantial impact of scaffold architecture on the dynamics of channel closure. Initially, MSCs tended to adhere and proliferate in regions of high curvature, such as corners of triangular channels or bends of the Hilbert curve-shaped channels. The cells on the scaffolds with a triangular structure of pores exhibited a higher level of metabolic activity and a faster rate of channel closure compared to other structures. At the later stages of cultivation, all types of channels were fully colonized by cells, with no indication of a decrease in metabolic activity. Analysis of osteogenic differentiation revealed that all scaffolds facilitate the differentiation of MSCs into osteoblasts; however, on day 14 of cultivation, slightly lower alkaline phosphatase activity was observed on scaffolds with square-shaped channels. On day 28 of cultivation, the scaffolds with the Hilbert curve geometry of channels demonstrated the highest degree of mineralization. Our research is a step forward in the exploration of the design and 3D printing of polyhydroxyalkanoate-based scaffolds with different cell-stimulating geometries for restoration of critical-size bone defects. This research contributes to the development of innovative functional materials.