Osteogenesis Enhancement with 3D Printed Gene-Activated Sodium Alginate Scaffolds

Abstract

Natural and synthetic hydrogel scaffolds containing bioactive components are increasingly used in solving various tissue engineering problems. The encapsulation of DNA-encoding osteogenic growth factors with transfecting agents (e.g., polyplexes) into such scaffold structures is one of the promising approaches to delivering the corresponding genes to the area of the bone defect to be replaced, providing the prolonged expression of the required proteins. Herein, a comparative assessment of both in vitro and in vivo osteogenic properties of 3D printed sodium alginate (SA) hydrogel scaffolds impregnated with model EGFP and therapeutic BMP-2 plasmids was demonstrated for the first time. The expression levels of mesenchymal stem cell (MSC) osteogenic differentiation markers Runx2, Alpl, and Bglap were evaluated by real-time PCR. Osteogenesis in vivo was studied on a model of a critical-sized cranial defect in Wistar rats using micro-CT and histomorphology. The incorporation of polyplexes comprising pEGFP and pBMP-2 plasmids into the SA solution followed by 3D cryoprinting does not affect their transfecting ability compared to the initial compounds. Histomorphometry and micro-CT analysis 8 weeks after scaffold implantation manifested a significant (up to 46%) increase in new bone volume formation for the SA/pBMP-2 scaffolds compared to the SA/pEGFP ones.

Investigation on the Microstructural Diversity of a Three-Dimensional Porous Hydroxyapatite/Wollastonite Skeleton via Biomineralization in Simulated Body Fluids

“…undergo in vitro cell tests after different periods of infiltration, highlighting the necessity of the careful tailoring of biomaterials with appropriate chemical composition, microstructure, pore size, and porosity to optimize conditions for stimulating bone tissue regeneration [37][38][39][40]. Engineered cells and gene-activated materials [41][42][43][44] will open up new avenues for research on bone growth and regeneration by incorporating bioabsorbable apatite nanocrystals with diverse micro morphologies into the three-dimensional micropore structure of the material. Figure 7c illustrates the presence of a narrow wall, measuring approximately 1µm, separating the two fully occupied internal micro-caves.…”