3D-printing of Reinforced Skeleton for Bone Tissue Engineering

Objectives: Bone tissue engineering (BTE) has been widely used for restoring damaged or disordered bones. The scaffolds that have been used for BTE are chiefly composed of porous biodegradable materials which can improve cell adhesion. In the present research, 3D-printed polycaprolactone (PCL) scaffolds were embedded with gelatin foam for BTE.
Methods: The PCL scaffolds were 3D-printed using Envision-Tech 3D-Bioplotter. The optimized parameters include, but are not limited to, temperature, speed, and pressure which were set on 130^oC, 1-2.5 mm/s, and 1-2 bar. The scaffolds were then chemically treated for better attachment with the gelatin foam. The scaffolds were functionalized with 1-6 hexanediamine solution (10% wt in Iso-propyl alcohol) at 40^oC for 3 h, washed with deionized water (DI), and then dried in a vacuum oven overnight. Next, the scaffolds were post-treated with glutaraldehyde solution (2.5% wt in PBS) at room temperature for 12 h. The scaffolds were then repeatedly washed with copious amount of DI and buffer phosphate and dried in a vacuum oven for 48 h. For incorporation of the scaffolds with gelatin foam, a solution of porcine gelatin (10% wt in PBS) was prepared through mechanical mixing at 1500 rpm for 15 min. Subsequently, the scaffolds were immersed into gelatin foam and put into a -70^oC freezer. The scaffolds were then lyophilized, cross-linked, washed with DI and lyophilized again to get rid of the solvent. The attachment of gelatin and aminolyzed PCL was confirmed by FTIR spectra. The morphology of the scaffolds was evaluated using 3D-laser microscope. Biocompatibility of the scaffolds, cell attachment and proliferation were examined against dental pulp stem cells (DPSCs).
Results: The images revealed that the scaffolds were surrounded with gelatin foam indicating proper physical attachment between the foam and scaffolds. The FTIR results showed that gelatin molecules were also chemically attached to the constructs. The in vitro study demonstrated that the scaffolds have no significant cytotoxicity towards DPSCs and presented exceptional cell attachment and proliferation in the presence of embedded gelatin foam.
Conclusions: Incorporation of gelatin foam into the 3D-printed PCL scaffolds can significantly improve the adhesion and proliferation of stem cells for bone tissue engineering applications.