Icariin-Releasing 3D-Printed Scaffolds for in Situ Regeneration of Cleft Bone

Objectives: Three-quarters of cleft lip and cleft palate patients require alveolar cleft osteoplasty using an autologous graft derived from the iliac crest, and ~46% of the patients develop acute or chronic graft disturbances post-surgically. Previous studies have tested 3D-printed scaffolds embedded with cells for cleft grafts with suboptimal outcomes. Here, we explored the potential of 3D-printed scaffolds with controlled delivery of small molecule, icariin (ICA), to promote cleft bone regeneration through recruitment and activation of endogenous stem/progenitor cells.
Methods: Polycaprolactone (PCL) scaffolds embedded with 0.1 – 0.3% of ICA were prepared per our well-established protocol, followed by 3D-printing scaffolds (3 mm x 0.7mm; 200 ~ 250 µm interstrand microchannels). Mechanical tests were performed, and in vitro efficacy in bone formation was tested using mesenchymal stem/progenitor cells. For in vivo, a rat model of the cleft defect was established. Briefly, 3 mm x 1 mm circular defect was created at the center region of the upper incisor socket, between the anterior and posterior inner borders of the incisor. The ICA/PCL scaffolds were implanted in the defect via press-fitting and the soft tissues were closed by suturing.
Results: The 3D-printed ICA/PCL scaffolds significantly enhanced in vitro bone formation, with notable variances depending on the loading doses and release kinetics. The most promising outcome was observed in 0.3% ICA/PCL scaffolds with 2-hr NaOH surface treatment. Consistently, RT-qPCR analysis showed the increased expressions of COL1A1, IBSP, and BGLAP in 0.3% ICA/PCL with 2- & 3-hr NaOH treatments as compared to the other groups. We achieved reproducible and stable press-fitting implantation of ICA/PCL scaffolds into the rat cleft defects. We are currently following up with in vivo bone regeneration outcomes, regarding initial cell recruitment, differentiation, integration with host tissue, and matrix turnover.
Conclusions: Icariin-embedded 3D-printed PCL scaffolds may have the potential to facilitate bone regeneration after alveolar cleft osteoplasty.