In vitro evaluation of 3D-printed PCL/forsterite scaffolds with aligned collagen and demineralized bone matrix for cranial bone regeneration

Developing an appropriate scaffold for cranioplasty applications remains challenging due to the high mechanical strength, controlled degradation, and support for cell migration and proliferation. Despite their common use, traditional materials such as titanium implants, bone allografts, hydroxyapatite, and poly methyl methacrylate have limitations that hinder their effectiveness. Achieving both robust mechanical performance and favorable biological properties in a single scaffold remains a significant challenge. In this study, we introduce a novel fabrication approach that combines 3D printing and directional freeze-casting to create a hybrid scaffold with enhanced structural and biological properties. A composite of polycaprolactone (PCL) and forsterite (FO) was 3D-printed to provide mechanical stability. Meanwhile, collagen and demineralized bone matrix (DBM) were freeze-cast into the pores to form radially aligned microchannels. This design enhances the biological properties and promotes cell migration by mimicking the native extracellular matrix architecture. Our results showed that adding 10 % forsterite to PCL increased the Young's modulus to 100 MPa, with 12 % degradation after one month of immersion in phosphate-buffered saline (PBS). The radially oriented collagen-DBM network supported a 2.4-fold increase in cell proliferation. Furthermore, the in vitro cell migration assay demonstrated enhanced cellular infiltration in aligned versus randomly structured scaffolds. Integrating a directional microstructure, chemical cues from ion release and DBM particles, along with a mechanically robust platform, offers a promising strategy for bone regeneration and cranioplasty applications.