Bioactive mineralized small intestinal submucosa acellular matrix/PMMA bone cement for vertebral bone regeneration

Comprehensive Overview of Interface Strategies in Implant Osseointegration

With the improvement of implant design and the expansion of application scenarios, orthopedic implants have become a common surgical option for treating fractures and end‐stage osteoarthritis. Their common goal is rapidly forming and long‐term stable osseointegration. However, this fixation effect is limited by implant surface characteristics and peri‐implant bone tissue activity. Therefore, this review summarizes the strategies of interface engineering (osteogenic peptides, growth factors, and metal ions) and treatment methods (porous nanotubes, hydrogel embedding, and other load‐release systems) through research on its biological mechanism, paving the way to achieve the adaptation of both and coordination between different strategies. With the transition of the osseointegration stage, interface engineering strategies have demonstrated varying therapeutic effects. Especially, the activity of osteoblasts runs almost through the entire process of osseointegration, and their physiological activities play a dominant role in bone formation. Furthermore, diseases impacting bone metabolism exacerbate the difficulty of achieving osseointegration. This review aims to assist future research on osseointegration engineering strategies to improve implant‐bone fixation, promote fracture healing, and enhance post‐implantation recovery.

Osteoporotic osseointegration: therapeutic hallmarks and engineering strategies

Osteoporosis is a systemic skeletal disease caused by an imbalance between bone resorption and formation. Current treatments primarily involve systemic medication and hormone therapy. However, these systemic treatments lack directionality and are often ineffective for locally severe osteoporosis, with the potential for complex adverse reactions. Consequently, treatment strategies using bioactive materials or external interventions have emerged as the most promising approaches. This review proposes twelve microenvironmental treatment targets for osteoporosis-related pathological changes, including local accumulation of inflammatory factors and reactive oxygen species (ROS), imbalance of mitochondrial dynamics, insulin resistance, disruption of bone cell autophagy, imbalance of bone cell apoptosis, changes in neural secretions, aging of bone cells, increased local bone tissue vascular destruction, and decreased regeneration. Additionally, this review examines the current research status of effective or potential biophysical and biochemical stimuli based on these microenvironmental treatment targets and summarizes the advantages and optimal parameters of different bioengineering stimuli to support preclinical and clinical research on osteoporosis treatment and bone regeneration. Finally, the review addresses ongoing challenges and future research prospects.

The application of small intestinal submucosa in tissue regeneration

The distinctive three-dimensional architecture, biological functionality, minimal immunogenicity, and inherent biodegradability of small intestinal submucosa extracellular matrix materials have attracted considerable interest and found wide-ranging applications in the domain of tissue regeneration engineering. This article presents a comprehensive examination of the structure and role of small intestinal submucosa, delving into diverse preparation techniques and classifications. Additionally, it proposes approaches for evaluating and modifying SIS scaffolds. Moreover, the advancements of SIS in the regeneration of skin, bone, heart valves, blood vessels, bladder, uterus, and urethra are thoroughly explored, accompanied by their respective future prospects. Consequently, this review enhances our understanding of the applications of SIS in tissue and organ repair and keeps researchers up-to-date with the latest research advancements in this area.

Preparation and efficacy of antibacterial methacrylate monomer-based polymethyl methacrylate bone cement containing N-halamine compounds

Introduction

Our objective in this study was to prepare a novel type of polymethyl methacrylate (PMMA) bone cement, analyze its material properties, and evaluate its safety and antibacterial efficacy.

Methods

A halamine compound methacrylate antibacterial PMMA bone cement containing an N-Cl bond structure was formulated, and its material characterization was determined with Fourier transform infrared spectroscopy (FT-IR) and 1H-NMR. The antibacterial properties of the material were studied using contact bacteriostasis and releasing-type bacteriostasis experiments. Finally, in vitro and in vivo biocompatibility experiments were performed to analyze the toxic effects of the material on mice and embryonic osteoblast precursor cells (MC3T3-E1).

Results

Incorporation of the antibacterial methacrylate monomer with the N-halamine compound in the new antibacterial PMMA bone cement significantly increased its contact and releasing-type bacteriostatic performance against Staphylococcus aureus. Notably, at 20% and 25% additions of N-halamine compound, the contact and releasing-type bacteriostasis rates of bone cement samples reached 100% (p < 0.001). Furthermore, the new antibacterial bone cement containing 5%, 10%, and 15% N-halamine compounds showed good biocompatibility in vitro and in vivo.

Conclusion

In this study, we found that the novel antibacterial PMMA bone cement with N-halamine compound methacrylate demonstrated good contact and releasing-type bacteriostatic properties against S. aureus. In particular, bone cement containing a 15% N-halamine monomer exhibited strong antibacterial properties and good in vitro and in vivo biocompatibility.

Surface functionalization of calcium magnesium phosphate cements with alginate sodium for enhanced bone regeneration via TRPM7/PI3K/Akt signaling pathway

Although calcium‑magnesium phosphate cements (CMPCs) have been widely applied to treating critical-size bone defects, their repair efficiency is unsatisfactory owing to their weak surface bioactivity and uncontrolled ion release. In this study, we lyophilized alginate sodium (AS) as a coating onto HAp/K-struvite (H@KSv) to develop AS/HAp/K-struvite (AH@KSv), which promotes bone regeneration. The compressive strength and hydrophilicity of AH@KSv significantly improved, leading to enhanced cell adhesion in vitro. Importantly, the SA coating enables continuous ions release of Mg2+ and Ca2+, finally leading to enhanced osteogenesis in vitro/vivo and different patterns of new bone ingrowth in vivo. Furthermore, these composites increased the expression levels of biomarkers of the TRPM7/PI3K/Akt signaling pathway via an equilibrium effect of Mg2+ to Ca2+. In conclusion, our study provides novel insights into the mechanisms of Mg-based biomaterials for bone regeneration.

Preclinical Evaluation of Bioactive Small Intestinal Submucosa-PMMA Bone Cement for Vertebral Augmentation

In vertebroplasty and kyphoplasty, bioinert poly(methyl methacrylate) (PMMA) bone cement is a conventional filler employed for quick stabilization of osteoporotic vertebral compression fractures (OVCFs). However, because of the poor osteointegration, excessive stiffness, and high curing temperature of PMMA, the implant loosens, the adjacent vertebrae refracture, and thermal necrosis of the surrounding tissue occurs frequently. This investigation addressed these issues by incorporating the small intestinal submucosa (SIS) into PMMA (SIS-PMMA). In vitro analyses revealed that this new SIS-PMMA bone cement had improved porous structure, as well as reduced compressive modulus and polymerization temperature compared with the original PMMA. Furthermore, the handling properties of SIS-PMMA bone cement were not significantly different from PMMA. The in vitro effect of PMMA and SIS-PMMA was investigated on MC3T3-E1 cells via the Transwell insert model to mimic the clinical condition or directly by culturing cells on the bone cement samples. The results indicated that SIS addition substantially enhanced the proliferation and osteogenic differentiation of MC3T3-E1 cells. Additionally, the bone cement's biomechanical properties were also assessed in a decalcified goat vertebrae model with a compression fracture, which indicated the SIS-PMMA had markedly increased compressive strength than PMMA. Furthermore, it was proved that the novel bone cement had good biosafety and efficacy based on the International Standards and guidelines. After 12 weeks of implantation, SIS-PMMA indicated significantly more osteointegration and new bone formation ability than PMMA. In addition, vertebral bodies with cement were also extracted for the uniaxial compression test, and it was revealed that compared with the PMMA-implanted vertebrae, the SIS-PMMA-implanted vertebrae had greatly enhanced maximum strength. Overall, these findings indicate the potential of SIS to induce efficient fixation between the modified cement surface and the host bone, thereby providing evidence that the SIS-PMMA bone cement is a promising filler for clinical vertebral augmentation.