Nanomaterials-based Cell Osteogenic Differentiation and Bone Regeneration

Nano-zinc oxide (nZnO) targets the AMPK-ULK1 pathway to promote bone regeneration

BACKGROUND

Nano-zinc oxide (nZnO) has attracted significant attention in bone tissue engineering due to its antibacterial properties, anti-inflammatory effects, biocompatibility, and chemical stability. Although numerous studies have demonstrated the enhancement of osteogenic differentiation by nZnO-modified tissue engineering materials, the underlying mechanisms remain poorly characterized.

METHODS

This study aimed to identify the molecular mechanisms how nZnO promoted osteogenic differentiation and bone regeneration using transcriptome analysis, drug intervention, and shRNA knockdown techniques, etc. First, the study evaluated the in vivo effects of gelatin methacryloyl (GelMA) containing nZnO on bone regeneration using a mouse calvarial defect model. The impact of nZnO exposure on the osteogenic differentiation of mesenchymal stem cells (MSCs) was then assessed. The combined treatment of nZnO and MSCs in GelMA for bone regeneration was assessed in the mouse calvarial defect model thereafter.

RESULTS

nZnO induced osteoblastic differentiation to promote bone regeneration. nZnO activated the AMP-dependent protein kinase (AMPK)-ULK1 signals to stimulate autophagosomes formation and facilitate autophagy flow, which was the essential pathway to induce osteogenic differentiation. The combined treatment of MSCs and nZnO significantly enhanced bone regeneration in calvarial defect mice. Conversely, AMPK inhibitor Compound C (C.C) reversed the effects on autophagy flow and osteogenic potentiality induced by nZnO.

CONCLUSIONS

These results highlight that nZnO can regulate bone regeneration by activating autophagy through the AMPK/ULK1 signaling pathway, which may provide a novel therapeutic strategy for addressing bone defects using nZnO.

3D-printed porous tantalum artificial bone scaffolds: fabrication, properties, and applications

Porous tantalum scaffolds offer a high degree of biocompatibility and have a low friction coefficient. In addition, their biomimetic porous structure and mechanical properties, which closely resemble human bone tissue, make them a popular area of research in the field of bone defect repair. With the rapid advancement of additive manufacturing, 3D-printed porous tantalum scaffolds have increasingly emerged in recent years, offering exceptional design flexibility, as well as facilitating the fabrication of intricate geometries and complex pore structures that similar to human anatomy. This review provides a comprehensive description of the techniques, procedures, and specific parameters involved in the 3D printing of porous tantalum scaffolds. Concurrently, the review provides a summary of the mechanical properties, osteogenesis and antibacterial properties of porous tantalum scaffolds. The use of surface modification techniques and the drug carriers can enhance the characteristics of porous tantalum scaffolds. Accordingly, the review discusses the application of these porous tantalum materials in clinical settings. Multiple studies have demonstrated that 3D-printed porous tantalum scaffolds exhibit exceptional corrosion resistance, biocompatibility, and osteogenic properties. As a result, they are considered highly suitable biomaterials for repairing bone defects. Despite the rapid development of 3D-printed porous tantalum scaffolds, they still encounter challenges and issues when used as bone defect implants in clinical applications. Ultimately, a concise overview of the primary challenges faced by 3D-printed porous tantalum scaffolds is offered, and corresponding insights to promote further exploration and advancement in this domain are presented.

Enhancing Bone Regeneration through CDC20-Loaded ZIF-8 Nanoparticles Wrapped in Erythrocyte Membranes with Targeting Aptamer

In the context of bone regeneration, nanoparticles harboring osteogenic factors have emerged as pivotal agents for modulating the differentiation fate of stem cells. However, persistent challenges surrounding biocompatibility, loading efficiency, and precise targeting ability warrant innovative solution. In this study, a novel nanoparticle platform founded upon the zeolitic imidazolate framework-8 (ZIF-8) is introduced. This new design, CDC20@ZIF-8@eM-Apt, involves the envelopment of ZIF-8 within an erythrocyte membrane (eM) cloak, and is coupled with a targeting aptamer. ZIF-8, distinguished by its porosity, biocompatibility, and robust cargo transport capabilities, constitutes the core framework. Cell division cycle protein 20 homolog (CDC20) is illuminated as a new target in bone regeneration. The eM plays a dual role in maintaining nanoparticle stability and facilitating fusion with target cell membranes, while the aptamer orchestrates the specific recruitment of bone marrow mesenchymal stem cells (BMSCs) within bone defect sites. Significantly, CDC20@ZIF-8@eM-Apt amplifies osteogenic differentiation of BMSCs via the inhibition of NF-κB p65, and concurrently catalyzes bone regeneration in two bone defect models. Consequently, CDC20@ZIF-8@eM-Apt introduces a pioneering strategy for tackling bone defects and associated maladies, opening novel avenues in therapeutic intervention.

CARM1 deficiency inhibits osteoblastic differentiation of bone marrow mesenchymal stem cells and delays osteogenesis in mice

Bone repair remains a clinical challenge due to low osteogenic capacity. Coactivator associated arginine methyltransferase 1 (CARM1) is a protein arginine methyltransferase that mediates arginine methylation and endochondral ossification. However, the roles of CARM1 in osteoblastic differentiation and bone remodeling have not been explored. In our study, heterozygous CARM1-knockout (KO) mice were generated using the CRISPR-Cas9 system and a model of femoral defect was created. At day 7 postsurgery, CARM1-KO mice exhibited obvious bone loss compared with wild type (WT) mice, as evidenced by reduced bone mineral density (BMD), bone volume/total volume (BV/TV), trabecular thickness (Tb.Th), and trabecular number (Tb.N), and increased trabecular separation (Tb.Sp). Deletion of CARM1 in mice lowered synthesis and accumulation of collagen at the injury sites. The alkaline phosphatase (ALP) activity and osteogenic-related gene expression were declined in CARM1-KO mice. To further understand the role of CARM1 in osteoblastic differentiation, bone marrow mesenchymal stem cells (BMSCs) were isolated from the tibia and femur of WT or CARM1-KO mice. CARM1 deletion decreased histone arginine methylation and inhibited osteoblastic differentiation and mineralization. The mRNA sequencing of CARM1-KO BMSCs revealed the possible regulatory molecules by CARM1, which could deepen our understanding of CARM1 regulatory mechanisms. These data could be of interest to basic researchers and provide the direction for future research into bone-related disorders.

Osteogenic differentiation of 3D-printed porous tantalum with nano-topographic modification for repairing craniofacial bone defects

Introduction: Congenital or acquired bone defects in the oral and cranio-maxillofacial (OCMF) regions can seriously affect the normal function and facial appearance of patients, and cause great harm to their physical and mental health. To achieve good bone defect repair results, the prosthesis requires good osteogenic ability, appropriate porosity, and precise three-dimensional shape. Tantalum (Ta) has better mechanical properties, osteogenic ability, and microstructure compared to Ti6Al4V, and has become a potential alternative material for bone repair. The bones in the OCMF region have unique shapes, and 3D printing technology is the preferred method for manufacturing personalized prosthesis with complex shapes and structures. The surface characteristics of materials, such as surface morphology, can affect the biological behavior of cells. Among them, nano-topographic surface modification can endow materials with unique surface properties such as wettability and large surface area, enhancing the adhesion of osteoblasts and thereby enhancing their osteogenic ability. Methods: This study used 3D-printed porous tantalum scaffolds, and constructed nano-topographic surface through hydrothermal treatment. Its osteogenic ability was verified through a series of in vitro and in vivo experiments. Results: The porous tantalum modified by nano-topographic surface can promote the proliferation and osteogenic differentiation of BMSCs, and accelerate the formation of new bone in the Angle of the mandible bone defect of rabbits. Discussion: It can be seen that 3D-printed nano-topographic surface modified porous tantalum has broad application prospects in the repair of OCMF bone defects.

Osteoimmunomodulatory Nanoparticles for Bone Regeneration

Treatment of large bone fractures remains a challenge for orthopedists. Bone regeneration is a complex process that includes skeletal cells such as osteoblasts, osteoclasts, and immune cells to regulate bone formation and resorption. Osteoimmunology, studying this complicated process, has recently been used to develop biomaterials for advanced bone regeneration. Ideally, a biomaterial shall enable a timely switch from early stage inflammatory (to recruit osteogenic progenitor cells) to later-stage anti-inflammatory (to promote differentiation and terminal osteogenic mineralization and model the microstructure of bone tissue) in immune cells, especially the M1-to-M2 phenotype switch in macrophage populations, for bone regeneration. Nanoparticle (NP)-based advanced drug delivery systems can enable the controlled release of therapeutic reagents and the delivery of therapeutics into specific cell types, thereby benefiting bone regeneration through osteoimmunomodulation. In this review, we briefly describe the significance of osteoimmunology in bone regeneration, the advancement of NP-based approaches for bone regeneration, and the application of NPs in macrophage-targeting drug delivery for advanced osteoimmunomodulation.

Design and development of biodegradable POSS-PCL-Zeolite (β) nano-scaffold for potential applications in bone regeneration

Side effects caused by bone fractures and restrictions on bone regeneration impose an enormous economic burden on the health system of society. To overcome these limitations, tissue engineering and cell-based therapies have been proposed as alternatives to induce and promote bone healing. Still, bone regeneration disadvantages, such as limited and painful surgery, the risk of infection, nerve injury, bleeding, and function damage, have led investigators to find an alternative therapy. In some studies, bone stimulants have prompted scientists to design scaffolds with appropriate physical structure with the possibility of cell adhesion and proliferation, which plays an influential role in the regeneration and repair of bone tissue. PCL nanofiber is an absorbing candidate for the formulation of biocompatible scaffolds used in tissue engineering. To overcome these negative aspects, improve the properties of PCL nanofibers, and based on the biocompatibility and superior mechanical properties of POSS, Polyhedral Oligomeric Silsesquioxane-Polycaprolactone-Zeolite (POSS-PCL-Zeolite) nanocomposite electrospun nanofiber scaffolds were fabricated in the present study. Nanohybrids and nanofibers structures were characterized by FTIR, HNMR, XRD, SEM, EDX, and DSC techniques. We used cellular and molecular assays, including DCFH ROS detection system, gene expression (RUNX-2, Osteocalcin, Nrf2, BAX, VEGF gens), and apoptotic to demonstrate the biocompatibility and induce bone differentiation of formulated POSS-PCL-Zeolite scaffolds. The results showed the biodegradability of POSS-PCL-Zeolite Nano-scaffold and supported the nesting of mesenchymal stem cells (MSCs) and induced bone differentiation by POSS-PCL-Zeolite Nano-scaffold.

Recent Advances in Enhancement Strategies for Osteogenic Differentiation of Mesenchymal Stem Cells in Bone Tissue Engineering

Although bone is an organ that displays potential for self-healing after damage, bone regeneration does not occur properly in some cases, and it is still a challenge to treat large bone defects. The development of bone tissue engineering provides a new approach to the treatment of bone defects. Among various cell types, mesenchymal stem cells (MSCs) represent one of the most promising seed cells in bone tissue engineering due to their functions of osteogenic differentiation, immunomodulation, and secretion of cytokines. Regulation of osteogenic differentiation of MSCs has become an area of extensive research over the past few years. This review provides an overview of recent research progress on enhancement strategies for MSC osteogenesis, including improvement in methods of cell origin selection, culture conditions, biophysical stimulation, crosstalk with macrophages and endothelial cells, and scaffolds. This is favorable for further understanding MSC osteogenesis and the development of MSC-based bone tissue engineering.

Forskolin-Loaded Halloysite Nanotubes as Osteoconductive Additive for the Biopolymer Tissue Engineering Scaffolds

Here we report the use of forskolin-modified halloysite nanotubes (HNTs) as a dopant for biopolymer porous hydrogel scaffolds to impart osteoinductive properties. Forskolin is a labdane diterpenoid isolated from the Indian Coleus plant. This small molecule is widely used as a supplement in molecular biology for cell differentiation. It has been reported in some earlier publications that forskolin can activate osteodifferentiation process by cyclic adenosine monophosphate (c-AMP) signalling activation in stem cells. In presented study it was demonstrated that forskolin release from halloysite-doped scaffolds induced the osteodifferentiation of equine mesenchymal stem cells (MSCs) in vitro without addition of any specific growth factors. The reinforcement of mechanical properties of cells and intercellular space during the osteodifferentiation was demonstrated using atomic force microscopy (AFM). These clay-doped scaffolds may find applications to accelerate the regeneration of horse bone defects by inducing the processes of osteodifferentiation of endogenous MSCs.