Induction of Bone Formation by 3D Biologically Active Scaffolds Containing RGD-NPs, BMP2, and NtMPCs

Abstract

It is demonstrated that nuclear transfer embryonic stem cells (NT-ESCs) can be transformed into mesenchymal progenitor cells (NtMPCs) via culture under appropriate conditions and it is proposed that NtMPCs can be used for bone regeneration instead of bone marrow-derived mesenchymal stem cells (BMSCs). In a 2-dimensional culture, NtMPCs undergo chondrogenic and adipogenic differentiation more readily than BMSCs upon culture in appropriate media. However, the osteogenic differentiation ability of NtMPCs is lower than that of BMSCs. 3-dimensional (3D) biologically active scaffolds (BAs) comprising poly(lactic-co-glycolic acid) (PLGA) microspheres are constructed to improve osteogenic differentiation. To generate BAs, nanoparticles containing an l-Arginyl-Glycyl-l-Aspartic acid (RGD) sequence (RGD-NPs) and dexamethasone (DEX), a drug used to control differentiation and inflammation, are simultaneously encapsulated by PLGA to form particles measuring 150–250 µm. After that, bone morphogenetic protein 2 (BMP2) is immobilized on the surface of polyethylenimine (PEI)-coated microspheres via formation of ionic bonds between O-sulfate and N-sulfate in heparin with lysine/arginine residues of BMP2. Gene expression profiling is performed via QuantSeq 3′ mRNA-sequencing in mice transplanted with BAs containing NtMPCs and BMSCs. Expression of the osteogenic differentiation-related genes collagen Type I Alpha 2 (COL1A2), Homeobox protein MSX-2 (MSX2), Runt-related transcription factor 2 (RUNX2), and bone morphogenetic protein 2 (BMP2) is 2–3-fold higher in mice transplanted with BAs containing NtMPCs than in mice transplanted with BAs containing BMSCs.