Osteogenic effectiveness of photo-immobilized bone morphogenetic protein-2 using different azidophenyl-natural polymer carriers in rat calvarial defect model

Sequential deacetylation/self-gelling chitin hydrogels and scaffolds functionalized with fucoidan for enhanced BMP-2 loading and sustained release

Bone morphogenetic protein 2 (BMP-2) is a potent osteoinductive factor that promotes bone formation. A major obstacle to the clinical application of BMP-2 is its inherent instability and complications caused by its rapid release from implants. Chitin based materials have excellent biocompatibility and mechanical properties, making them ideal for bone tissue engineering applications. In this study, a simple and easy method was developed to spontaneously form deacetylated β-chitin (DAC-β-chitin) gels at room temperature through a sequential deacetylation/self-gelation process. The structural transformation of β-chitin to DAC-β-chitin leads to the formation of self-gelling DAC-β-chitin, from which hydrogels and scaffolds were prepared. Gelatin (GLT) accelerated the self-gelation of DAC-β-chitin and increased the pore size and porosity of the DAC-β-chitin scaffold. The DAC-β-chitin scaffolds were then functionalized with a BMP-2-binding sulfate polysaccharide, fucoidan (FD). Compared with β-chitin scaffolds, FD-functionalized DAC-β-chitin scaffolds showed higher BMP-2 loading capacity and more sustainable release of BMP-2, and thus had better osteogenic activity for bone regeneration.

Strategies to Control or Mimic Growth Factor Activity for Bone, Cartilage, and Osteochondral Tissue Engineering

Growth factors play a critical role in tissue repair and regeneration. However, their clinical success is limited by their low stability, short half-life, and rapid diffusion from the delivery site. Supraphysiological growth factor concentrations are often required to demonstrate efficacy but can lead to adverse reactions, such as inflammatory complications and increased cancer risk. These issues have motivated the development of delivery systems that enable sustained release and controlled presentation of growth factors. This review specifically focuses on bioconjugation strategies to enhance growth factor activity for bone, cartilage, and osteochondral applications. We describe approaches to localize growth factors using noncovalent and covalent methods, bind growth factors via peptides, and mimic growth factor function with mimetic peptide sequences. We also discuss emerging and future directions to control spatiotemporal growth factor delivery to improve functional tissue repair and regeneration.

LncRNA ENST00000563492 promoting the osteogenesis-angiogenesis coupling process in bone mesenchymal stem cells (BMSCs) by functions as a ceRNA for miR-205-5p

Pain, physical dysfunction, and mental disorders caused by bone nonunion bring great burden to patients. Bone mesenchymal stem cells (BMSCs) isolated from bone nonunion patients with poor proliferation and osteogenic ability are compared with that from normal bone-healing patients. Long noncoding RNAs (lncRNAs) are a class of RNAs that are more than 200 nucleotides in length, lack an open-reading frame encoding a protein, and have little or no protein-coding function, and could regulate gene expression, which is involved in the regulation of important life activities, such as growth, development, aging, and death at epigenetic, transcriptional, and post-transcriptional levels. In this study, we intended to investigate the difference of lncRNA expression between patients with nonunion and normal fracture healing. Our result found that lncRNA ENST00000563492 was downregulated in bone nonunion tissues. LncRNA ENST00000563492 promotes osteogenic differentiation of BMSCs through upregulating the expression of CDH11. On the other hand, LncRNA ENST0000563492 could improve the osteogenesis–angiogenesis coupling process through enhancing the expression of VEGF during osteogenic differentiation of BMSCs. LncRNA ENST00000563492 functions as a ceRNA for miR-205-5p that was targeting CDH11 and VEGF. LncRNA ENST00000563492 could promote the osteogenesis of BMSCs in vivo. Our result indicated that lncRNA ENST00000563492 may be a new target for bone nonunion.