Jaidev L. Chakka (1), Timothy Acri (1), Noah Z. Laird (1), Ling Zhong (2), Kyungsup Shin (3), Satheesh Elangovan (4), Aliasger K. Salem (1)
RSC Advances, 11, March 2021: 13282–13291. DOI: 10.1039/d1ra01193f

Abstract

Bone is a highly vascularized organ and the formation of new blood vessels is essential to regenerate large critical bone defects. In this study, polylactic acid (PLA) scaffolds of 20–80% infill were three-dimensionally (3D) printed using a fused deposition modeling based 3D printer. The PLA scaffolds were coated with polydopamine (PDA) and then were surface-functionalized with polyethyleneimine (PEI) and VEGF-encoding plasmid DNA (pVEGF) nanoplexes (PLA-PDA-PEI-pVEGF). The PLA-PDA-PEI-pVEGF scaffolds with 40% infill demonstrated higher encapsulation efficiency and sustained release of pVEGF than scaffolds with 20, 60 and 80% infill and were therefore used for in vitro and in vivo studies. The PLA-PDA-PEI-pVEGF increased the translation and secretion of VEGF and BMP-2. The PLA-PDA-PEI-pVEGF also yielded a 2- and 4.5-fold change in VEGF and osteocalcin gene expression in vitro, respectively. A tube formation assay using human umbilical vascular endothelial cells (HUVECs) showed a significant increase in tube length when exposed to the PLA-PDA-PEI-pVEGF scaffold, in comparison to PLA and PLA-PDA scaffolds. The PLA-PDA-PEI-pVEGF scaffold in an in vivo rat calvarial critical bone defect model demonstrated 1.6-fold higher new bone formation compared to the PLA-PDA scaffold. H&E and Masson's trichrome staining of bone sections also revealed that the PLA-PDA-PEI-pVEGF scaffold facilitated the formation of more blood vessels in the newly formed bone compared to the PLA and PLA-PDA scaffold groups. Thus, PLA-PDA-PEI-pVEGF might be a potential 3D printed gene activated scaffold for bone regeneration in clinical situations.

How Our Software Was Used

Dragonfly was used to calculate bone volume per total volume.

Author Affiliation

(1) Department of Pharmaceutics and Experimental Therapeutics, College of Pharmacy, University of Iowa, Iowa City, IA-52242, USA.
(2) Department of Experimental Research, Sun Yat-sen University, Guangzhou, PR China.
(3) Department of Orthodontics, College of Dentistry and Dental Clinics, University of Iowa, Iowa City, IA-52242, USA.
(4) Department of Periodontics, College of Dentistry and Dental Clinics, University of Iowa, Iowa City, IA-52242, USA.