Effect of extracellular matrix on bone healing with 3D printed Polylactic acid/Bioglass scaffolds

3YFAW ORAL COMMUNICATION CLINICAL INNOVATIONS

Background: One of the most effective ways of treating tooth loss is by using dental implants. Considering bone deficiencies, almost every second dental implant surgery needs bone grafting. Attempts are made to create personalized composite 3D printed bone scaffolds, which exhibit superior therapeutic results than traditional bone grafts. These 3D printed scaffolds may be modified with the extracellular matrix (ECM) for better osteoinductivity.

Aim/Hypothesis: This study aimed to evaluate the effect in vivo of 3D printed polylactic acid (PLA) and Bioglass 45S5 (BG) scaffolds, which were enhanced with dental pulp stem cells (DPSC) or their produced ECM and compare the results with Geistlich Bio-Oss^® substitute.

Materials and Methods: Bone regeneration was evaluated using a critical-size Wistar rat's calvarial defect model. Twelve male and twelve female rats were evenly divided into three groups. Negative control and Bio-Oss formed the first group, PLA and PLA/BG – the second, PLA/BG cellularized with DPSC and PLA/BG ECM scaffolds – the third. PLA/BG filament was created with hot-melt extrusion equipment at the ratio of 9:1. All scaffolds were fabricated using a 3D printer. DPSC were isolated from the incisors of adult Wistar rats. The defects were evaluated by micro-computer tomography (micro-CT) and histology eight weeks after surgery. Approval of the Ethics Committee and permission for the experimentation was received from the State Food and Veterinary Service of Lithuania, No G2-40, 2016-03-18. Data are presented as mean with single SD. Differences were considered statistically significant when the p-value was less than 0.05.

Results: Qualitative histological evaluation showed new bone formation in all groups. PLA/BG scaffolds in five Wistar rats caused soft tissue dystrophic mineralization. Pronounced inflammation reaction was found during biodegradation in the PLA group. Results obtained from micro-CT showed the highest volume of bone formation in the PLA/BG (5.95 with 3.38), PLA/BG ECM (5.34 with 2.22), and Bio-Oss (4.04 with 0.44) groups. However, there was no statistically significant difference between the experimental groups and Bio-Oss. Statistically significantly more bone regenerated in PLA/BG, PLA/BG ECM, and Bio-Oss groups than in negative control. Quantitative histology showed gender-specific differences in all experimental groups.

Conclusions and Clinical Implications: The bone-forming ability was comparable between the Bio-Oss, PLA/BG, and PLA/BG ECM scaffolds. PLA/BG and PLA/BG ECM scaffolds have the potential of being used in bone tissue engineering. However, due to the increased cost of the ECM procedure, further research is needed to analyse the effect of BG on soft tissue dystrophic mineralization and the impact of different PLA/BG ratio for osteoregeneration.

Acknowledgements: The authors report no conflicts of interest related to this study. This research was supported by the Research Council of Lithuania, Grant No. MIP-15552.

Keywords: biocomposite scaffolds, PLA/BG scaffolds, bone regeneration, extracellular matrix, dental pulp stem cells.