The Toll-like receptor ligand, CpG oligodeoxynucleotides, regulate proliferation and osteogenic differentiation of osteoblast

Relevant Properties and Potential Applications of Sericin in Bone Regeneration

The potential of sericin, a protein derived from silkworms, is explored in bone graft applications. Sericin's biocompatibility, hydrophilic nature, and cost-effectiveness make it a promising candidate for enhancing traditional graft materials. Its antioxidant, anti-inflammatory, and UV-resistant properties contribute to a healthier bone-healing environment, and its incorporation into 3D-printed grafts could lead to personalized medical solutions. However, despite these promising attributes, there are still gaps in our understanding. The precise mechanism through which sericin influences bone cell growth and healing is not fully understood, and more comprehensive clinical trials are needed to confirm its long-term biocompatibility in humans. Furthermore, the best methods for incorporating sericin into existing graft materials are still under investigation, and potential allergic reactions or immune responses to sericin need further study.

Metal-polyDNA nanoparticles reconstruct osteoporotic microenvironment for enhanced osteoporosis treatment

Current clinical approaches to osteoporosis primarily target osteoclast biology, overlooking the synergistic role of bone cells, immune cells, cytokines, and inorganic components in creating an abnormal osteoporotic microenvironment. Here, metal-polyDNA nanoparticles (Ca-polyCpG MDNs) composed of Ca2+ and ultralong single-stranded CpG sequences were developed to reconstruct the osteoporotic microenvironment and suppress osteoporosis. Ca-polyCpG MDNs can neutralize osteoclast-secreted hydrogen ions, provide calcium repletion, promote remineralization, and repair bone defects. Besides, the immune-adjuvant polyCpG in MDNs could induce the secretion of osteoclastogenesis inhibitor interleukin-12 and reduce the expression of osteoclast function effector protein to inhibit osteoclast differentiation, further reducing osteoclast-mediated bone resorption. PPi4- generated during the rolling circle amplification reaction acts as bisphosphonate analog and enhances bone targeting of Ca-polyCpG MDNs. In ovariectomized mouse and rabbit models, Ca-polyCpG MDNs prevented bone resorption and promoted bone repair by restoring the osteoporotic microenvironment, providing valuable insights into osteoporosis therapy.

PEEK and Hyaluronan-Based 3D Printed Structures: Promising Combination to Improve Bone Regeneration

Hybrid bone substitute made up of a 3D printed polyetheretherketone (PEEK) scaffold coated with methacrylated hyaluronic acid (MeHA)-hydroxyapatite (HAp) hydrogel is the objective of the present work. Development and characterization of the scaffold and of the MeHA-HAp after its infiltration and UV photocrosslinking have been followed by analyses of its biological properties using human mesenchymal stem cells (MSCs). Interconnected porous PEEK matrices were produced by fused deposition modeling (FDM) characterized by a reticular pattern with 0°/90° raster orientation and square pores. In parallel, a MeHA-HAp slurry has been synthesized and infiltrated in the PEEK scaffolds. The mechanical properties of the coated and pure PEEK scaffold have been evaluated, showing that the inclusion of MeHA-HAp into the lattice geometry did not significantly change the strength of the PEEK structure with Young's modulus of 1034.9 ± 126.1 MPa and 1020.0 ± 63.7 MPa for PEEK and PEEK-MeHA-HAp scaffolds, respectively. Human MSCs were seeded on bare and coated scaffolds and cultured for up to 28 days to determine the adhesion, proliferation, migration and osteogenic differentiation. In vitro results showed that the MeHA-HAp coating promotes MSCs adhesion and proliferation and contributes to osteogenic differentiation and extracellular matrix mineralization. This study provides an efficient solution for the development of a scaffold combining the great mechanical performances of PEEK with the bioactive properties of MeHA and HAp, having high potential for translational clinical applications.

Physiology-Inspired Multilayer Nanofibrous Membranes Modulating Endogenous Stem Cell Recruitment and Osteo-Differentiation for Staged Bone Regeneration

Bone regeneration involves a cascade of sophisticated, multiple-staged cellular and molecular events, where early-phase stem cell recruitment mediated by chemokines and late-phase osteo-differentiation induced by pro-osteogenic factors play the crucial roles. Herein, enlightened by a bone physiological and regenerative mechanism, the multilayer nanofibrous membranes (PLLA@SDF-1α@MT01) consisting of PLLA/MT01 micro-sol electrospun nanofibers as intima and PLLA/PEG/SDF-1α electrospun nanofibers as adventitia are fabricated through micro-sol electrospinning and manual multi-layer stacking technologies. In vitro releasing profiles show that PLLA@SDF-1α@MT01 represents the rapid release of stromal cell-derived SDF-1α (SDF-1α) in the outer layers, while with long-term sustained release of MT01 in the inner layer. Owing to interconnected porosity like the natural bone extracellular matrix and improved hydrophilia, PLLA@SDF-1α@MT01 manifests good biocompatibility both in vitro and in vivo. Furthermore, PLLA@SDF-1α@MT01 can promote bone marrow mesenchymal stem cells (BMSCs) migration by amplifying the SDF-1α/CXCR4 axis and stimulating BMSCs osteo-differentiation via activating the MAPK pathway in vitro. PLLA@SDF-1α@MT01, with a programmed dual-delivery system, exhibits the synergetic promotion of bone regeneration and vascularization by emulating key characteristics of the staged bone repair in vivo. Overall, PLLA@SDF-1α@MT01 that mimics the endogenous cascades of bone regeneration can enrich the physiology-mimetic staged regenerative strategy and represent a promising tissue-engineered scaffold for the bone defect.

Identification of a Novel Osteogenetic Oligodeoxynucleotide (osteoDN) That Promotes Osteoblast Differentiation in a TLR9-Independent Manner

Dysfunction of bone-forming cells, osteoblasts, is one of the causes of osteoporosis. Accumulating evidence has indicated that oligodeoxynucleotides (ODNs) designed from genome sequences have the potential to regulate osteogenic cell fate. Such osteogenetic ODNs (osteoDNs) targeting and activating osteoblasts can be the candidates of nucleic acid drugs for osteoporosis. In this study, the ODN library derived from the Lacticaseibacillus rhamnosus GG genome was screened to determine its osteogenetic effect on murine osteoblast cell line MC3T3-E1. An 18-base ODN, iSN40, was identified to enhance alkaline phosphatase activity of osteoblasts within 48 h. iSN40 also induced the expression of osteogenic genes such as Msx2, osterix, collagen type 1α, osteopontin, and osteocalcin. Eventually, iSN40 facilitated calcium deposition on osteoblasts at the late stage of differentiation. Intriguingly, the CpG motif within iSN40 was not required for its osteogenetic activity, indicating that iSN40 functions in a TLR9-independent manner. These data demonstrate that iSN40 serves as a novel osteogenetic ODN (osteoDN) that promotes osteoblast differentiation. iSN40 provides a potential seed of the nucleic acid drug that activating osteoblasts for osteoporosis therapy.

PAMPs and DAMPs as the Bridge Between Periodontitis and Atherosclerosis: The Potential Therapeutic Targets

Atherosclerosis is a chronic artery disease characterized by plaque formation and vascular inflammation, eventually leading to myocardial infarction and stroke. Innate immunity plays an irreplaceable role in the vascular inflammatory response triggered by chronic infection. Periodontitis is a common chronic disorder that involves oral microbe-related inflammatory bone loss and local destruction of the periodontal ligament and is a risk factor for atherosclerosis. Periodontal pathogens contain numerous pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharide, CpG DNA, and Peptidoglycan, that initiate the inflammatory response of the innate immunity depending on the recognition of pattern-recognition receptors (PRRs) of host cells. The immune-inflammatory response and destruction of the periodontal tissue will produce a large number of damage-associated molecular patterns (DAMPs) such as neutrophil extracellular traps (NETs), high mobility group box 1 (HMGB1), alarmins (S100 protein), and which can further affect the progression of atherosclerosis. Molecular patterns have recently become the therapeutic targets for inflammatory disease, including blocking the interaction between molecular patterns and PRRs and controlling the related signal transduction pathway. This review summarized the research progress of some representative PAMPs and DAMPs as the molecular pathological mechanism bridging periodontitis and atherosclerosis. We also discussed possible ways to prevent serious cardiovascular events in patients with periodontitis and atherosclerosis by targeting molecular patterns.

In vitro and in silico anti-osteoporosis activities and underlying mechanisms of a fructan, ABW90-1, from Achyranthes bidentate

Achyranthes bidentata is a traditional Chinese medicine used to treat osteoporosis. AB90, a crude saccharide from A. bidentata, showed excellent osteoprotective effects in ovariectomized rats, and ABW90-1, an oligosaccharide purified from AB90, stimulated significant differentiation of osteoblasts. However, the osteogenic effects and underlying mechanisms of ABW90-1 have remained unknown. In the present study, we found that ABW90-1 significantly promoted ALP activity, mineralization, and the expression of osteogenic markers in MC3T3-E1 cells. ABW90-1 showed strong binding with the WNT signaling complex and BMP2 based on number of interactions, hydrogen bond length, and binding energy in silico. ABW90-1 significantly increased the expression of active-β-catenin, p-GSK-3β, LEF-1, BMP2, and p-SMAD1. Importantly, the osteogenic effects of ABW90-1 were partially suppressed by DKK-1 and Noggin, which are specific inhibitors of the WNT and BMP signaling pathways, respectively. Collectively, these findings suggest that ABW90-1 has osteogenic effects through crosstalk between WNT/β-catenin and BMP2/SMAD1 signaling pathways.

Immunomodulation in the Treatment of Periodontitis: Progress and Perspectives

Periodontitis is one of the most common dental diseases. Compared with healthy periodontal tissues, the immune microenvironment plays the key role in periodontitis by allowing the invasion of pathogens. It is possible that modulating the immune microenvironment can supplement traditional treatments and may even promote periodontal regeneration by using stem cells, bacteria, etc. New anti-inflammatory therapies can enhance the generation of a viable local immune microenvironment and promote cell homing and tissue formation, thereby achieving higher levels of immune regulation and tissue repair. We screened recent studies to summarize the advances of the immunomodulatory treatments for periodontitis in the aspects of drug therapy, microbial therapy, stem cell therapy, gene therapy and other therapies. In addition, we included the changes of immune cells and cytokines in the immune microenvironment of periodontitis in the section of drug therapy so as to make it clearer how the treatments took effects accordingly. In the future, more research needs to be done to improve immunotherapy methods and understand the risks and long-term efficacy of these methods in periodontitis.