In vitro osteogenesis of hMSCs on collagen membranes embedded within LEGO®-inspired 3D printed PCL constructs for mandibular bone repair

Abstract The field of bone tissue engineering aims to develop an effective and aesthetical bone graft substitute capable of repairing large mandibular defects. However, graft failure resulting from necrosis and insufficient integration with native tissue due to lack of oxygen and nutrient transportation remains a concern. To overcome these drawbacks, this study aims to develop a 3D printed polycaprolactone (PCL) layered construct with a LEGO®-inspired interlocking mechanism enabling spatial distribution of biological components. To highlight its in vitro osteogenic potential, human mesenchymal stromal cells (hMSCs) are cultured onto Bio-Gide® Compressed collagen (Col) membranes, which are embedded within the layered construct for 28 days. The osteogenic response is assessed through the measurement of proliferation, relevant markers for osteogenesis including alkaline phosphatase (ALP) activity, expression of transcriptional genes (SP7, RUNX2/SOX9) as well matrix-related genes (COL1A1, ALPL IBSP, SPP1), osteoprotegerin (OPG) secretion. In vitro osteogenic differentiation results showed increased levels of these osteogenic markers, indicating the layered construct's potential to support osteogenesis. In this study, a novel workflow of 3D printing a patient-specific LEGO®-inspired layered construct that can spatially deliver biological elements was successfully demonstrated. These layered constructs have the potential to be employed as a bone tissue engineering strategy, with particular focus on the repair of large mandibular defects.