Shape-fitting collagen-PLA composite promotes osteogenic differentiation of porcine adipose stem cells

Abstract

Craniomaxillofacial bone defects can occur as a result of congenital, post-oncologic, and highenergy impact conditions. The scale and irregularity of such defects motivate new biomaterials to promote regeneration of the damaged bone. We have recently described a mineralized collagen scaffold capable of instructing stem cell osteogenic differentiation and new bone infill in the absence of traditional osteogenic supplements. Herein, we report the integration of a millimeterscale reinforcing poly (lactic acid) frame fabricated via 3D-printing into the mineralized collagen scaffold with micron-scale porosity to form a multi-scale mineralized collagen-PLA composite. We describe modifications to the PLA frame design to increase the compressive strength (Young's Modulus, ultimate stress and strain) of the composite. A critical challenge beyond increasing the compressive strength of the collagen scaffold is addressing challenges inherent with the irregularity of clinical defects. As a result, we examined the potential for modifying the frame architecture to render the composite with increased compressive strength in one axis or radial compressibility and shape-fitting capacity in an orthogonal axis. A library of mineralized collagen-PLA composites was mechanically characterized via compression testing and push-out test to describe mechanical performance and shape-fitting capacity. We also report in vitro comparison of the bioactivity of porcine adipose derived stem cells in the mineralized collagen-PLA composite versus the mineralized collagen scaffold via metabolic activity, gene expression, and functional matrix synthesis. The results suggest that incorporation of the PLA reinforcing frame does not negatively influence the osteoinductive nature of the mineralized collagen scaffold. Together, these

Sequential sequestrations increase the incorporation and retention of multiple growth factors in mineralized collagen scaffolds

“…cell penetration, diffusive biotransport), all scaffold variants show sub-optimal mechanical performance. While beyond the scope of this project, we have described methods to increase the mechanical stability of a cell activity optimized scaffolds via the inclusion of 3D printed polymeric meshes 49,69 . Based on these results, we did not use extended mSBF treatments prior to sequestration in subsequent experiments and instead focused on repeated mSBF treatments during sequestration.…”

Stiffness of Nanoparticulate Mineralized Collagen Scaffolds Triggers Osteogenesis via Mechanotransduction and Canonical Wnt Signaling

“…So while individual cells experience a microscale mechanical defined by E s , the bulk performance of the scaffold E* is dictated by the high porosity necessary to support penetration, metabolic health, and tissue biosynthesis. To address the need to improve macroscale mechanical performance without sacrificing porosity, we have recently reported approaches to integrate a millimeter-scale reinforcing poly (lactic acid) (PLA) frame fabricated via 3Dprinting into the mineralized collagen scaffold to form a multi-scale mineralized collagen-PLA composite (27). This composite shows significant increased macroscale mechanical performance (Young's Modulus, ultimate stress, ultimate strain) that is dictated by the PLA frame design, but osteogenic activity dictated by the scaffold.…”

Mineralized collagen scaffolds fabricated with amniotic membrane matrix increase osteogenesis under inflammatory conditions

“…All handling steps were done utilizing sterile techniques. Before seeding with cells, hydration followed previously described methods (43). Briefly, scaffolds underwent a soaking period in 100% ethanol, then multiple washes in PBS and crosslinked with a carbodiimide chemistry.…”