INTRODUCTION: Poly(trimethylene carbonate) (PTMC) based resin loaded with nano-hydroxyapatite (nHA) were recently produced to create implants using stereolithography (SLA)[1, 2]. In this study, 3D macroporous scaffolds with self-arrangement of HA particles were fabricated and assessed for their osteopromotive effect in vitro and in vivo.
METHODS: PTMC-methacrylate resin mixed with nHA at 0, 20 and 40% w/w were prepared and used for films and scaffolds fabrication using SLA. Following fabrication, micro-architecture of scaffolds was characterized using backscattered-electron on scanning electron microscopy and microtomography.
In vitro, human bone marrow stromal cells (hMSCs) were seeded on films and cultivated for 4 weeks in osteogenic media and differentiation was assessed by quantification of alkaline phosphatase activity (ALP) and by mineral deposition using alizarin red staining (ARS).
In vivo experiment was conducted by creating 4 calvarial defects of 6 mm Ø on rabbits and the defects were either left empty (control group) or PTMC and PTMC/nHA at 20 and 40% w/w scaffolds were inserted in the cavities. Following 6 weeks of implantation, osseointegration was assessed by X-ray and by histology (Giemsa-Eosin staining).
RESULTS: In vitro hMSCs expressed high ALP and ARS when cultivated on PTMC 20 and PTMC 40. In vivo, the incorporation of 20 and 40% of nHA in PTMC significantly increased osseointegration of the implant compared to PTMC only. BSE-SEM and tomography investigations revealed that SLA process was responsible to an anisotropic 3D self-arrangement of nHA particles, resulting in a 10 to 30 µm thick layer enriched in nHA, corralling the PTMC matrices.
DISCUSSION & CONCLUSIONS:
For the first time, we reported the fabrication of PTMC/nHA-based SLA scaffolds for bone repair. This composite biomaterial exhibited excellent biocompatibility and osteopromotive effect. As perspective of this work, the possibility to control the spatial repartition of particles in composite materials opens exciting venues of research.