Bioactive-glass ceramic with two crystalline phases (BioS-2P) for bone tissue engineering

Update on the use of 45S5 bioactive glass in the treatment of bone defects in regenerative medicine

Bone regeneration is a critical area in regenerative medicine, particularly in orthopedics, demanding effective biomedical materials for treating bone defects. 45S5 bioactive glass (45S5 BG) is a promising material because of its osteoconductive and bioactive properties. As research in this field continues to advance, keeping up-to-date on the latest and most successful applications of this material is imperative. To achieve this, we conducted a comprehensive search on PubMed/MEDLINE, focusing on English articles published in the last decade. Our search used the keywords "bioglass 45S5 AND bone defect" in combination. We found 27 articles, and after applying the inclusion criteria, we selected 15 studies for detailed examination. Most of these studies compared 45S5 BG with other cement or scaffold materials. These comparisons demonstrate that the addition of various composites enhances cellular biocompatibility, as evidenced by the cells and their osteogenic potential. Moreover, the use of 45S5 BG is enhanced by its antimicrobial properties, opening avenues for additional investigations and applications of this biomaterial.

Mussel-inspired cortical bone-adherent bioactive composite hydrogels promote bone augmentation through sequential regulation of endochondral ossification

Endochondral ossification (ECO) plays an integral part in bone augmentation, which undergoes sequential processes including mesenchymal stem cells (MSC) condensation, chondrocyte differentiation, chondrocyte hypertrophy, and mineralized bone formation. Thus, accelerating these steps will speed up the osteogenesis process through ECO. Herein, inspired by the marine mussels' adhesive mechanism, a bioactive glass-dopamine (BG-Dopa) hydrogel was prepared by distributing the micro-nano BG to aldehyde modified hyaluronic acid with dopamine-modified gelatin. By in vitro and in vivo experiments, we confirm that after implanting in the bone augmentation position, the hydrogel can adhere to the cortical bone surface firmly without sliding. Moreover, the condensation and hypertrophy of stem cells were accelerated at the early stage of ECO. Whereafter, the osteogenic differentiation of the hypertrophic chondrocytes was promoted, which lead to accelerating the late stage of ECO process to achieve more bone augmentation. This experiment provides a new idea for the design of bone augmentation materials.

Effect of the secretome of mesenchymal stem cells overexpressing BMP-9 on osteoblast differentiation and bone repair

The secretome present in the conditioned medium (CM) of mesenchymal stem cells (MSCs) is a promising tool to be used in therapies to promote bone regeneration. Considering the high osteogenic potential of the bone morphogenetic protein 9 (BMP-9), we hypothesized that the secretome of MSCs overexpressing BMP-9 (MSCsBMP-9 ) enhances the osteoblast differentiation of MSCs and the bone formation in calvarial defects. CM of either MSCsBMP-9 (CM-MSCsBMP-9 ) or MSCs without BMP-9 overexpression (CM-MSCsVPR ) were obtained at different periods. As the CM-MSCsBMP-9 generated after 1 h presented the highest BMP-9 concentration, CM-MSCsBMP-9 and CM-MSCsVPR were collected at this time point and used to culture MSCs and to be injected into mouse calvarial defects. The CM-MSCsBMP-9 enhanced the osteoblast differentiation of MSC by upregulating RUNX2, alkaline phosphatase (ALP) and osteopontin protein expression, and ALP activity, compared with CM-MSCsVPR . The CM-MSCsBMP-9 also enhanced the bone repair of mouse calvarial defects, increasing bone volume, bone volume/total volume, bone surface, and trabecular number compared with untreated defects and defects treated with CM-MSCsVPR or even with MSCsBMP-9 themselves. In conclusion, the potential of the MSCBMP-9 -secretome to induce osteoblast differentiation and bone formation shed lights on novel cell-free-based therapies to promote bone regeneration of challenging defects.

Bioactive glass-ceramic for bone tissue engineering: an in vitro and in vivo study focusing on osteoclasts

Despite the crucial role of osteoclasts in the physiological process of bone repair, most bone tissue engineering strategies have focused on osteoblast-biomaterial interactions. Although Biosilicate® with two crystalline phases (BioS-2P) exhibits osteogenic properties and significant bone formation, its effects on osteoclasts are unknown. This study aimed to investigate the in vitro and in vivo effects of BioS-2P on osteoclast differentiation and activity. RAW 264.7 cells were cultured in osteoclastogenic medium (OCM) or OCM conditioned with BioS-2P (OCM-BioS-2P), and the cell morphology, viability, and osteoclast differentiation were evaluated. BioS-2P scaffolds were implanted into rat calvarial defects, and the bone tissue was evaluated using tartrate-resistant acid phosphatase (TRAP) staining and RT-polymerase chain reaction (PCR) after 2 and 4 weeks to determine the gene expressions of osteoclast markers and compare them with those of the bone grown in empty defects (Control). OCM-BioS-2P favored osteoclast viability and activity, as evidenced by an increase in the TRAP-positive cells and matrix resorption. The bone tissue grown on BioS-2P scaffolds exhibited higher expression of the osteoclast marker genes (Ctsk, Mmp 9, Rank) after 2 and 4 weeks and the RankL/Opg ratio after 2 weeks. Trap gene expression was lower at 2 weeks, and a higher number of TRAP-stained areas were observed in the newly formed bone on BioS-2P scaffolds at both 2 and 4 weeks compared to the Controls. These results enhanced our understanding of the role of bioactive glass-ceramics in bone repair, and highlighted their role in the modulation of osteoclastic activities and promotion of interactions between bone tissues and biomaterials.

A new bioactive glass with extremely high crystallization temperature and outstanding biological performance

In this work, a new bioactive glass was designed, prepared by means of a melt-quenching route and characterized in terms of both thermal properties and biological performance. The main objective was to obtain a novel product with high temperature of crystallization in view of possible thermal treatments, as well as remarkable biological responsiveness. Thermal behavior was investigated by heating microscopy, differential thermal analysis (DTA) and sintering tests. The glass displayed a very high crystallization temperature and the samples remained completely amorphous after sintering. Bioactivity was evaluated by means of Simulated Body Fluid (SBF) assay, which is a widely used method to preliminary investigate samples' reactivity in vitro; the glass showed a strong apatite forming ability. Additionally, in order to exclude cytotoxic effects, biocompatibility was verified according to ISO standard 10993. Finally, the biological potential of the new glass was tested by using an innovative 3D cellular model, that mimicked the potential clinical application of a given biomaterial. Human bone marrow mesenchymal stem cells (BM-MSCs) were employed to study the performance of bioactive glass granules in such 3D cellular model. The results showed that the bioactive glass supported human BM-MSCs adhesion, colonization and bone differentiation. Thus, this new bioactive glass looks particularly promising for orthopedic applications, bone tissue engineering and regenerative medicine, especially when a thermal treatment is necessary for the production of specific devices.

Human Mesenchymal Stem Cell Combined with a New Strontium-Enriched Bioactive Glass: An ex-vivo Model for Bone Regeneration

A 3D cellular model that mimics the potential clinical application of a biomaterial is here applied for the first time to a bioactive glass, in order to assess its biological potential. A recently developed bioactive glass (BGMS10), whose composition contained strontium and magnesium, was produced in the form of granules and fully investigated in terms of biocompatibility in vitro. Apart from standard biological characterization (Simulated Body Fluid (SBF) testing and biocompatibility as per ISO10993), human bone marrow mesenchymal stromal/stem cells (BM-MSCs) were used to investigate the performance of the bioactive glass granules in an innovative 3D cellular model. The results showed that BGMS10 supported human BM-MSCs adhesion, colonization, and bone differentiation. Thus, bioactive glass granules seem to drive osteogenic differentiation and thus look particularly promising for orthopedic applications, bone tissue engineering and regenerative medicine.

Cell Therapy: Effect of Locally Injected Mesenchymal Stromal Cells Derived from Bone Marrow or Adipose Tissue on Bone Regeneration of Rat Calvarial Defects

Treatment of large bone defects is a challenging clinical situation that may be benefited from cell therapies based on regenerative medicine. This study was conducted to evaluate the effect of local injection of bone marrow-derived mesenchymal stromal cells (BM-MSCs) or adipose tissue-derived MSCs (AT-MSCs) on the regeneration of rat calvarial defects. BM-MSCs and AT-MSCs were characterized based on their expression of specific surface markers; cell viability was evaluated after injection with a 21-G needle. Defects measuring 5 mm that were created in rat calvaria were injected with BM-MSCs, AT-MSCs, or vehicle-phosphate-buffered saline (Control) 2 weeks post-defect creation. Cells were tracked by bioluminescence, and 4 weeks post-injection, the newly formed bone was evaluated by µCT, histology, nanoindentation, and gene expression of bone markers. BM-MSCs and AT-MSCs exhibited the characteristics of MSCs and maintained their viability after passing through the 21-G needle. Injection of both BM-MSCs and AT-MSCs resulted in increased bone formation compared to that in Control and with similar mechanical properties as those of native bone. The expression of genes associated with bone formation was higher in the newly formed bone induced by BM-MSCs, whereas the expression of genes involved in bone resorption was higher in the AT-MSC group. Cell therapy based on local injection of BM-MSCs or AT-MSCs is effective in delivering cells that induced a significant improvement in bone healing. Despite differences observed in molecular cues between BM-MSCs and AT-MSCs, both cells had the ability to induce bone tissue formation at comparable amounts and properties. These results may drive new cell therapy approaches toward complete bone regeneration.

Effect of cell therapy with allogeneic osteoblasts on bone repair of rat calvaria defects

BACKGROUND AIMS

Regenerative medicine strategies based on cell therapy are considered a promising approach to repair bone defects. The aims of this study were to evaluate the effect of subculturing on the osteogenic potential of osteoblasts derived from newborn rat calvaria and the effect of these osteoblasts on bone repair of rat calvaria defects.

METHODS

Cells were obtained from 50 newborn rat calvaria, and primary osteoblasts (OB) were compared with first passage (OB-P1) in terms of osteogenic potential by assaying cell proliferation, alkaline phosphatase (ALP) activity, extracellular matrix mineralization and gene expression of the osteoblastic markers RUNX2, ALP, osteocalcin and bone sialoprotein. Then, 5-mm calvaria defects were created in 24 Wistar rats, and after 2 weeks, they were locally injected with 50 µL of phosphate-buffered saline containing either 5 × 10⁶ osteoblasts (OB-P1, n = 12) or no cells (control, n = 12). Four weeks post-injection, the bone formation was evaluated by micro-computed tomography and histological analyses. Data were compared by analysis of variance, followed by the Student-Newman-Keuls's test or Student's t-test (P ≤ 0.05).

RESULTS

OB-P1 showed high proliferation and ALP activity, and despite the reduced gene expression of osteoblastic markers and extracellular matrix mineralization compared with OB, they displayed osteogenic potential, being a good choice for injection into calvaria defects. The micro-tomographic and histological data showed that defects treated with OB-P1 presented higher bone formation compared with control defects.

DISCUSSION

Our results indicate that cells derived from newborn rat calvaria retain osteoblastic characteristics after subculturing and that these osteoblasts stimulate bone repair in a rat calvaria defect model.