Mineralizing Coating on 3D Printed Scaffolds for the Promotion of Osseointegration

Abstract

Design and fabrication of implants that can perform better than autologous bone grafts remain an unmet challenge for the hard tissue regeneration in craniomaxillofacial applications. Here, we report an integrated approach combining additive manufacturing with supramolecular chemistry to develop acellular mineralizing 3D printed scaffolds for hard tissue regeneration. Our approach relies on an elastin-like recombinamer (ELR) coating designed to trigger and guide the growth of ordered apatite on the surface of 3D printed nylon scaffolds. Three test samples including a) uncoated nylon scaffolds (referred to as “Uncoated”), b) ELR coated scaffolds (referred to as “ELR only”), and c) ELR coated and in vitro mineralized scaffolds (referred to as “Pre-mineralized”) were prepared and tested for in vitro and in vivo performance. All test samples supported normal human immortalized mesenchymal stem cell adhesion, growth, and differentiation with enhanced cell proliferation observed in the “Pre-mineralized” samples. Using a rabbit calvarial in vivo model, ‘Pre-mineralized’ scaffolds also exhibited higher bone ingrowth into scaffold pores and cavities with higher tissue-implant integration. However, the coated scaffolds (“ELR only” and “Pre-mineralized”) did not exhibit significantly more new bone formation compared to “Uncoated” scaffolds. Overall, the mineralizing coating offers an opportunity to enhance integration of 3D printed bone implants. However, there is a need to further decipher and tune their immunologic response to develop truly osteoinductive/conductive surfaces.

Bioactive coatings on 3D printed polycaprolactone scaffolds for bone regeneration: a novel murine femur defect model for examination of the biomaterial capacity for repair

“…ELP coating of scaffolds was based on previous published methods [12]. In brief, lyophilized ELP powder was dissolved in a solvent mixture of DMF/DMSO (at 9/1 ratio, v/v) to prepare a 5% (w/v) ELP solution followed by addition of hexamethyl diisocyanate (HDI) crosslinker (cross-linker to lysine ratios of 12/1).…”

Bioactive coatings on 3D printed scaffolds for bone regeneration: Translation fromin vitrotoin vivomodels and the impact of material properties and growth factor concentration

“…3D printed nylon or PCL-TMA scaffolds were immersed in the ELP solution for 10–15 seconds and left to dry overnight at RT (22 °C) inside a glovebox (BELLE Technology, UK) maintained at a humidity <20%. Dry ELP coated scaffolds were washed several times with deionised water (dH 2 O) to remove excess HDI and were termed as ELP coated scaffolds [12].…”

“…To create ‘mineralised’ scaffolds, ELP coated scaffolds were incubated in the mineralizing solution (pH 6) at 37 °C for 16 days. Post mineralisation, scaffolds were washed several times with dH 2 O, air dried and stored at RT until use [12]. The ELP coating and mineralisation were confirmed on the PCL-TMA scaffold surface using scanning electron microscopy [12].…”

“…Post mineralisation, scaffolds were washed several times with dH 2 O, air dried and stored at RT until use [12]. The ELP coating and mineralisation were confirmed on the PCL-TMA scaffold surface using scanning electron microscopy [12].…”

Functionalization of 3D-Printed Titanium Scaffolds with Elastin-like Recombinamers to Improve Cell Colonization and Osteoinduction

“…In this context, the use of genetic engineering methodologies enables the design of highly complex functional proteins or polymeric proteins with several properties [ 17 ], such as elastin-like recombinamers (ELRs), which are synthetic proteins whose sequences are derived from certain peptides of natural elastin [ 18 , 19 ]. ELRs retain the elastin mechanical properties, thermo-responsiveness, non-immunogenicity, and excellent biocompatibility and present a strong tendency to self-assemble depending on the environmental conditions [ 20 ].…”