THE EFFECT OF PORE GEOMETRY ON IN VITRO EXTRACELLULAR MATRIX
FORMATION IN 3D-PRINTED CALCIUM PHOSPHATE-BASED SCAFFOLDS
Ehsan Sadeghian Dehkord1, Bingbing Liang1, Liesbet Geris1, 2, 3
1GIGA In silico medicine, Biomechanics research unit, University of Liège, Belgium 2 Prometheus, The R&D division for skeletal tissue engineering, KU Leuven, Belgium 3 Department of Mechanical Engineering, Biomechanics Section, KU Leuven, Belgium e.sadeghian@uliege.be
INTRODUCTION
Porous scaffolds are widely used to support the regeneration of bone tissue. These structures are developed as interconnected matrices for adhesion and proliferation of the migrating cells. Recent advances show that in addition to the biological factors (biocompatibility and bioactivity), the macroscopic geometry of the porous scaffold also influence the biological interactions with the host organism and contribute in the kinetics of tissue growth. In particular, the geometrical features of scaffold pores have been shown to be an important factor determining the scaffold’s in vivo behaviour (Kerckhofs et al., 2016). However, a rigorous method to optimize porous scaffolds for bone regeneration has not been developed. Computer modelling can help to integrate existing knowledge on the effect of various scaffold features and ultimately propose optimize designs. In this study, we investigate the effect of pore shape and pore size on the cell viability and ECM growth pattern in the calcium phosphate (CaP)-based 3D-printed scaffolds.
METHODS
Three different CaP-based biomaterials (Hydroxyapatite, Tri-calcium phosphate and Biphasic calcium phosphate) were 3D printed in disc shape scaffolds in the size of a well of a 24-well plate. The basic shapes of pores including hexagon, circle, square and triangle with three different sizes of pore diameter (2 mm, 1 mm and 0.7 mm) were randomly distributed over the disc. In the in vitro study, each scaffold was seeded with immortalized bone marrow mesenchymal stem cells (hTERT-BMMSCs) and cultured in growth medium for 3 weeks. Cell viability and kinetics of neotissue (cell + ECM) pore filling were evaluated using Live-Dead viability/cytotoxicity staining after 10 and 21 days for the different pores geometries.
RESULTS AND DISCUSSION
Live-Dead staining provides quantitative information on the cell behavior in the in vitro culture demonstrating the importance of pore morphology (i.e. shape and size) in different CaP-based bone biomaterials. Qualitatively, the experiments also show curvature-based growth by hTERT-BMMSCs for all pore geometries.
CONCLUSION
This experiment confirms that the previously developed predictive models describing neotissue growth in titanium scaffolds can be used for CaP-based scaffolds. With these basic experiments, the model can be calibrated for CaP-based scaffolds and used to design a scaffold geometry maximizing bone tissue ingrowth after in vivo implantation.
