Synergistic Effect of Whitlockite Scaffolds Combined with Alendronate to Promote Bone Regeneration

Impact of Cerium Doping on the Osteogenic Properties of a 3D Biomimetic Piezoelectric Scaffold with Sustained Mg2+ Release

Background

In the realm of bone tissue engineering, the role of biomimetic piezoelectric scaffolds made from whitlockite (WH) nanoparticles is increasingly recognized. WH, the second most abundant mineral in human bone, possesses piezoelectric properties and the capacity to release magnesium ions (Mg2+), both of which are vital for osteogenic differentiation. This study investigates the osteogenic effects of cerium (Ce) doping on three-dimensional biomimetic piezoelectric scaffolds composed of whitlockite (WH) nanoparticles.

Methods

WH nanoparticles with varying Ce concentrations were synthesized and scaffolds were prepared using a freeze-drying process with sodium alginate as the matrix. In vitro experiments with human bone marrow mesenchymal stem cells (hBMSCs) assessed cell proliferation and differentiation, while animal studies employed a rat calvarial defect model to evaluate new bone formation and mineralization.

Results

Our findings revealed that Ce doping modifies the crystallinity and electrical properties of WH nanoparticles, thereby affecting their osteogenic potential. In vitro studies indicated that scaffolds with a Ce/Ca ratio of 0.06 significantly boosted osteogenic marker expression. Furthermore, animal studies confirmed that Ce-doped WH scaffolds, especially those with the 0.06 ratio, markedly improved both new bone formation and mineralization.

Conclusion

The study demonstrates that Ce doping can significantly enhance the osteogenic properties of WH-based scaffolds, with the optimal Ce/Ca ratio of 0.06 being particularly effective in promoting bone formation. This research provides a promising approach for the development of advanced materials in bone tissue engineering.

Biocompatibility Evaluation of Ampicillin-Loaded Whitlockite for Bone Regeneration

Introduction Whitlockite (WH), a rare phosphate mineral within the apatite group, shows potential for bone regeneration owing to its superior composition and biocompatibility compared to hydroxyapatite. It can serve as a carrier for bioactive molecules, gradually releasing them to stimulate bone growth and expedite healing. This study aims to assess the biocompatibility of antibiotic-loaded WH, focusing on ampicillin, for bone regeneration applications. Methodology WH particles loaded with varying concentrations of ampicillin (10 and 25 mM) underwent biocompatibility assessments using the MTT assay. One gram of particles was incubated in 10 mL of culture medium for 24 and 48 hours. Experimental groups included control, WH, WH with ampicillin at 10 mM (WH+A10), WH with ampicillin at 25 mM (WH+A25), and positive control treated with 0.1% Triton X detergent. Subsequently, after a three-day culture period, RunX2 gene expression, indicative of osteoblastic differentiation, was quantified using real-time PCR analysis. Results Our research evaluated the bioactivity of WH particles treated with human osteoblastic cells using the MTT assay. While 10 mM ampicillin-loaded WH showed no significant difference in metabolic activity at both 24 and 48 hours, 25 mM ampicillin-loaded WH exhibited a slight reduction in metabolic activity at 24 hours, which normalized by 48 hours. Additionally, we assessed osteogenic potential and showed a significant increase in RunX2 expression with ampicillin-loaded WH, indicating sustained osteogenic properties. Conclusions Our study underscores the promising biocompatibility of WH particles by retaining their osteogenic properties even when, loaded with ampicillin, offering a potential avenue for future bone regeneration strategies.

BMP-2-immobilized PCL 3D printing scaffold with a leaf-stacked structure as a physically and biologically activated bone graft

Although three-dimensional (3D) printing techniques are used to mimic macro- and micro-structures as well as multi-structural human tissues in tissue engineering, efficient target tissue regeneration requires bioactive 3D printing scaffolds. In this study, we developed a bone morphogenetic protein-2 (BMP-2)-immobilized polycaprolactone (PCL) 3D printing scaffold with leaf-stacked structure (LSS) (3D-PLSS-BMP) as a bioactive patient-tailored bone graft. The unique LSS was introduced on the strand surface of the scaffold via heating/cooling in tetraglycol without significant deterioration in physical properties. The BMP-2 adsorbed on3D-PLSS-BMPwas continuously released from LSS over a period of 32 d. The LSS can be a microtopographical cue for improved focal cell adhesion, proliferation, and osteogenic differentiation.In vitrocell culture andin vivoanimal studies demonstrated the biological (bioactive BMP-2) and physical (microrough structure) mechanisms of3D-PLSS-BMPfor accelerated bone regeneration. Thus, bioactive molecule-immobilized 3D printing scaffold with LSS represents a promising physically and biologically activated bone graft as well as an advanced tool for widespread application in clinical and research fields.

Large-Scale Green Synthesis of Magnesium Whitlockite from Environmentally Benign Precursor

Magnesium whitlockite (Mg-WH) powders were synthesized with remarkable efficiency via the dissolution-precipitation method by employing an environmentally benign precursor, gypsum. Under optimized conditions, each 5.00 g of initial gypsum yielded an impressive amount of 3.00 g (89% yield) of Mg-WH in a single batch. Remarkably, no XRD peaks attributable to impurity phases were observed, indicating the single-phase nature of the sample. FT-IR analysis confirmed the presence of the PO43- and HPO42- groups in the obtained Mg-WH phase. The SEM-EDX results confirmed that Mg-WH crystals with homogeneous Ca, Mg, P, and O distributions were obtained. In previously published research papers, the synthesis of Mg-WH has been consistently described as a highly intricate process due to material formation within a narrow pH and temperature range. Our proposed synthesis method is particularly compelling as it eliminates the need for meticulous monitoring, presenting a notable improvement in the quest for a more convenient and efficient Mg-WH synthesis. The proposed procedure not only emphasizes the effectiveness of the process, but also highlights its potential to meet significant demands, providing a reliable solution for large-scale production needs in various promising applications.

Bisphosphonate-incorporated coatings for orthopedic implants functionalization

Bisphosphonates (BPs), the stable analogs of pyrophosphate, are well-known inhibitors of osteoclastogenesis to prevent osteoporotic bone loss and improve implant osseointegration in patients suffering from osteoporosis. Compared to systemic administration, BPs-incorporated coatings enable the direct delivery of BPs to the local area, which will precisely enhance osseointegration and bone repair without the systemic side effects. However, an elaborate and comprehensive review of BP coatings of implants is lacking. Herein, the cellular level (e.g., osteoclasts, osteocytes, osteoblasts, osteoclast precursors, and bone mesenchymal stem cells) and molecular biological regulatory mechanism of BPs in regulating bone homeostasis are overviewed systematically. Moreover, the currently available methods (e.g., chemical reaction, porous carriers, and organic material films) of BP coatings construction are outlined and summarized in detail. As one of the key directions, the latest advances of BP-coated implants to enhance bone repair and osseointegration in basic experiments and clinical trials are presented and critically evaluated. Finally, the challenges and prospects of BP coatings are also purposed, and it will open a new chapter in clinical translation for BP-coated implants.

Emerging nano-scale delivery systems for the treatment of osteoporosis

Osteoporosis is a pathological condition characterized by an accelerated bone resorption rate, resulting in decreased bone density and increased susceptibility to fractures, particularly among the elderly population. While conventional treatments for osteoporosis have shown efficacy, they are associated with certain limitations, including limited drug bioavailability, non-specific administration, and the occurrence of adverse effects. In recent years, nanoparticle-based drug delivery systems have emerged as a promising approach for managing osteoporosis. Nanoparticles possess unique physicochemical properties, such as a small size, large surface area-to-volume ratio, and tunable surface characteristics, which enable them to overcome the limitations of conventional therapies. These nanoparticles offer several advantages, including enhanced drug stability, controlled release kinetics, targeted bone tissue delivery, and improved drug bioavailability. This comprehensive review aims to provide insights into the recent advancements in nanoparticle-based therapy for osteoporosis. It elucidates the various types of nanoparticles employed in this context, including silica, polymeric, solid lipid, and metallic nanoparticles, along with their specific processing techniques and inherent properties that render them suitable as potential drug carriers for osteoporosis treatment. Furthermore, this review discusses the challenges and future suggestions associated with the development and translation of nanoparticle drug delivery systems for clinical use. These challenges encompass issues such as scalability, safety assessment, and regulatory considerations. However, despite these challenges, the utilization of nanoparticle-based drug delivery systems holds immense promise in revolutionizing the field of osteoporosis management by enabling more effective and targeted therapies, ultimately leading to improved patient outcomes.

Peculiarities of the formation, structural and morphological properties of zinc whitlockite (Ca18Zn2(HPO4)2(PO4)12) synthesized via a phase transformation process under hydrothermal conditions

In the present work, the formation of zinc whitlockite via a dissolution–precipitation process was investigated in detail. The influence of medium pH, reaction time, temperature and concentration of precursors on the formation of the material was studied.