Polycaprolactone-Coated3D Printed Tricalcium PhosphateScaffolds for Bone Tissue Engineering: In Vitro Alendronate Release Behavior and LocalDelivery Effect on In Vivo Osteogenesis

摘要

The aim of this work was to evaluate the effect of in vitro alendronate (AD) release behavior through polycaprolactone (PCL) coating on in vivo bone formation using PCL-coated 3D printed interconnected porous tricalcium phosphate (TCP) scaffolds. Higher AD and Ca²⁺ ion release was observed at lower pH (5.0) than that at higher pH (7.4). AD and Ca²⁺ release, surface morphology, and phase analysis after release indicated a matrix degradation dominated AD release caused by TCP dissolution. PCL coating showed its effectiveness for controlled and sustained AD release. Six different scaffold compositions, namely, (i) TCP (bare TCP), (ii) TCP + AD (AD-coated TCP), (iii) TCP + PCL (PCL-coated TCP), (iv) TCP + PCL + AD, (v) TCP + AD + PCL, and (vi) TCP + AD + PCL + AD were tested in the distal femoral defect of Sprague–Dawley rats for 6 and 10 weeks. An excellent bone formation inside the micro and macro pores of the scaffolds was observed from histomorphology. Histomorphometric analysis revealed maximum new bone formation in TCP + AD + PCL scaffolds after 6 weeks. No adverse effect of PCL on bioactivity of TCP and in vivo boneformation was observed. All scaffolds with AD showed higher bone formationand reduced TRAP (tartrate resistant acid phosphatase) positive cellsactivity compared to bare TCP and TCP coated with only PCL. Bare TCPscaffolds showed the highest TRAP positive cells activity followedby TCP + PCL scaffolds, whereas TCP + AD scaffolds showed the lowestTRAP activity. A higher TRAP positive cells activity was observedin TCP + AD + PCL compared to TCP + AD scaffolds after 6 weeks. Ourresults show that in vivo local AD delivery fromPCL-coated 3DP TCP scaffolds could further induce increased earlybone formation.