In vitro evaluation of freeze-drying chitosan-mineralized collagen/Mg–Ca alloy composites for osteogenesis

Magnesium (Mg) alloy with good mechanical properties and biodegradability is considered as one of the ideal bone repair materials. However, the rapid corrosion of Mg-based metals can pose harm to the function of an implant in clinical applications. In this study, micro-arc oxidation coating was prepared on the surface of the Mg–Ca matrix, then the chitosan and mineralized collagen (nano-hydroxyapatite/collagen; nHAC) were immobilized on the surface of the MAO/Mg–Ca matrix to construct the CS-nHAC/Mg–Ca composites of different component proportions (the ratio of CS to nHAC is 2:1, 1:1, and 1:2, respectively). The corrosion resistance, osteogenic activity, and angiogenic ability were extensively investigated. The results indicated that the CS-nHAC reinforcement materials can improve the corrosion resistance of the Mg matrix significantly and promote the proliferation and adhesion of mouse embryo osteoblast precursor cells (MC3T3-E1) and human umbilical vein endothelial cells (HUVECs). In addition, the CS-nHAC/Mg–Ca composites can not only promote the alkaline phosphatase (ALP) activity and extracellular matrix mineralization of MC3T3-E1 cells but also enhance the migration motility and vascular endothelial growth factor (VEGF) expression of HUVECs. Meanwhile, the 2CS-1nHAC/Mg–Ca composite exhibited the optimum function characteristics compared with other samples. Therefore, considering the improvement of corrosion resistance and biocompatibility, the CS-nHAC/Mg–Ca composites are expected to be a promising orthopedic implant.

Orthophosphate and Alkaline Phosphatase Induced the Formation of Apatite with Different Multilayered Structures and Mineralization Balance

Mineralized collagen is a natural organic-inorganic composite. The combination of organic collagen and inorganic apatite to form different nanostructures is the key to produce bone- substitutes with biomechanical properties that...

A Rapid and Convenient Approach to Construct Porous Collagen Membranes via Bioskiving and Sonication-Feasible for Mineralization to Induce Bone Regeneration

Porous mineralized collagen membranes efficiently promote bone regeneration. To generate them, we need to fabricate collagen membranes that are porous. However, the current fabrication method is primarily based on a bottom-up strategy, with certain limitations, such as a long manufacturing process, collagen denaturation, and failure to control fibril orientation. Using a top-down approach, we explore a novel method for constructing porous collagen membranes via the combined application of bioskiving and sonication. Numerous collagen membranes with well-aligned fibril structures were rapidly fabricated by bioskiving and then sonicated at 30, 60, 90, and 120 W for 20 min. This treatment allowed us to study the effect of power intensity on the physicochemical traits of collagen membranes. Subsequently, the prepared collagen membranes were immersed in amorphous calcium phosphate to evaluate the feasibility of mineralization. Additionally, the bioactivities of the membranes were assessed using preosteoblast cells. Tuning the power intensity was shown to modulate fibril orientation, and the porous membrane without denatured collagen could be obtained by a 20-min sonication treatment at 90 W. The prepared collagen membrane could also be further mineralized to enhance osteogenesis. Overall, this study offers a rapid and convenient approach for fabricating porous collagen membranes via bioskiving and sonication.

Bone Tissue Regeneration by Collagen Scaffolds with Different Calcium Phosphate Coatings: Amorphous Calcium Phosphate and Low-Crystalline Apatite

Surface-mineralized collagen sponges have attracted much attention as scaffolds for bone tissue engineering. Recently, we developed amorphous calcium phosphate (ACP) and low-crystalline apatite coating processes on collagen sponges. In the present study, we applied these coating processes to granular collagen sponges (referred to as Col) to compare the bone tissue regeneration capabilities of ACP-coated and apatite-coated Col (referred to as Col-ACP and Col-Ap, respectively) using a rat cranial bone defect model. According to micro-CT and histological analyses, Col-Ap enhanced bone tissue regeneration compared to Col, whereas Col-ACP did not. These results not only demonstrated the superior bone tissue regeneration capability of Col-Ap, but also indicated limitations of the in vitro simulated body fluid (SBF) test used in our previous study. Despite the apatite-forming ability of Col-ACP in SBF, it was ineffective in improving bone tissue regeneration in vivo, unlike Col-Ap, most likely due to the quick resorption of the ACP coating in the defect site. The present results clarified the importance of the coating stability in vivo and revealed that the low-crystalline apatite coating was more beneficial than the ACP coating in the fabrication of surface-mineralized collagen sponges for use as bone tissue engineering scaffolds.

Clinical efficacy of mineralized collagen (MC) versus anorganic bovine bone (Bio-Oss) for immediate implant placement in esthetic area: a single-center retrospective study

Background The purpose of this retrospective study was to evaluate the clinical efficacy of mineralized collagen (MC) versus anorganic bovine bone (Bio-Oss) for immediate implant placement in esthetic area. Methods Medical records of Department of Oral and Maxillofacial Surgery of Shandong Provincial Hospital were screened for patients who had been treated with immediate implant implantation in the esthetic area using either MC (Allgens®, Beijing Allgens Medical Science and Technology Co., Ltd., China) or Bio-Oss (Bio-Oss®, Geistlich Biomaterials, Wolhusen, Switzerland), between January 2018 and December 2019. All patients fulfilling the in-/exclusion criteria and following followed for a minimum period of 1 year after surgery were enrolled into the presented study. Implant survival rate, radiographic, esthetic and patient satisfactory evaluations were performed. Results Altogether, 70 patients were included in the study; a total of 80 implants were inserted. All implants had good initial stability. The survival rate of implants was 100% at 1-year follow-up. The differences in horizontal and vertical bone loss between the MC group (0.72 ± 0.26 mm, 1.62 ± 0.84 mm) and the Bio-Oss group (0.70 ± 0.52 mm, 1.57 ± 0.88 mm) were no significant difference statistically no significant 6 months after permanent restoration. Similar results occurred at 12 months after permanent restoration functional loaded. Clinical acceptability defined by pink esthetic score (PES) ≥ 6 (6.07 ± 1.62 vs. 6.13 ± 1.41) was not significantly different between groups. Patient satisfaction estimated by visual analog scale (VAS) was similar (8.56 ± 1.12 vs. 8.27 ± 1.44), and the difference was no significant difference between the two groups. Conclusions The biomimetic MC showed a similar behaviour as Bio-Oss not only in its dimensional tissues changes but also in clinical acceptability and patient satisfaction. Within the limitations of this study, these cases show that MC could be considered as an alternative bone graft in IIP

Bilayer Membrane Composed of Mineralized Collagen and Chitosan Cast Film Coated With Berberine-Loaded PCL/PVP Electrospun Nanofiber Promotes Bone Regeneration

Bone defects are difficult to repair and reconstruct as bone regeneration remains technically challenging, with exogenous factors required to accelerate this process. Biodegradable synthetic scaffolds are promising materials for stimulating bone tissue repair. In this study, we investigated whether a bilayer membrane that includes mineralized collagen (MC) and chitosan (CS) delivering berberine (BER)—a typical Chinese herbal monomer—could promote bone healing in a rat model. An MC/CS cast film was coated with polycaprolactone (PCL)/polyvinylpyrrolidone (PVP) electrospun nanofibers loaded with BER, yielding the BER@PCL/PVP-MC/CS bilayer membrane. The 3-dimensional structure had nanofibers of uniform diameter and showed good hydrophilicity; the bilayer membrane showed favorable mechanical properties. BER@PCL/PVP-MC/CS enhanced the proliferation and attachment of MC3T3-E1 cells in vitro and induced bone regeneration when implanted into a rat femoral bone defect. These findings provide evidence that BER@PCL/PVP-MC/CS has clinical potential for effective bone repair.