Hydroxyapatite Tricalcium Phosphate Research Articles

Engineered pre-dentin with well-aligned hierarchical mineralized collagen fibril bundles promote bio-root regeneration

Stem cell-mediated bio-root regeneration is an alternative tooth replacement strategy; however, physiologically functional bio-root regeneration with distinctive dentin structure remains challenging. In this study, the distinct arrangements of collagen fibril bundles were identified that account for hierarchical structural differences between dentin, cementum, and alveolar bone. Thus, an “engineered pre-dentin” was fabricated, which was a dentin hierarchical structure mimicking collagen (MC) scaffold, with well-aligned hierarchical mineralized collagen fibril bundles. The results revealed that it has a stronger effect on promoting biological root regeneration in nude mice and miniature pigs with dental pulp stem cell (DPSC) and periodontal ligament stem cell (PDLSC) sheets compared to hydroxyapatite tricalcium phosphate (HA/TCP). The success rate in the MC group was also higher than that in the HA/TCP group (67% and 33%, respectively). In conclusion, the hierarchical dentin-mimicking scaffold can enhance the regeneration of bio-roots, which provides a promising strategy for tooth regeneration.

Design of Laser Activated Antimicrobial Porous Tricalcium Phosphate-Hydroxyapatite Scaffolds for Orthopedic Applications.

The field of bone tissue engineering is steadily being improved by novel experimental approaches. Nevertheless, microbial adhesion after scaffold implantation remains a limitation that could lead to the impairment of the regeneration process, or scaffold rejection. The present study introduces a methodology that employs laser-based strategies for the development of antimicrobial interfaces on tricalcium phosphate-hydroxyapatite (TCP-HA) scaffolds. The outer surfaces of the ceramic scaffolds with inner porosity were structured using a femtosecond laser (λ = 800 nm; τ = 70 fs) for developing micropatterns and altering local surface roughness. The pulsed laser deposition of ZnO was used for the subsequent functionalization of both laser-structured and unmodified surfaces. The impact of the fs irradiation was investigated by Raman spectroscopy and X-ray diffraction. The effects of the ZnO-layered ceramic surfaces on initial bacterial adherence were assessed by culturing Staphylococcus aureus on both functionalized and non-functionalized scaffolds. Bacterial metabolic activity and morphology were monitored via the Resazurin assay and microscopic approaches. The presence of ZnO evidently decreased the metabolic activity of bacteria and led to impaired cell morphology. The results from this study have led to the conclusion that the combination of fs laser-structured surface topography and ZnO could yield a potential antimicrobial interface for implants in bone tissue engineering.

FGF2/HGF priming facilitates adipose-derived stem cell-mediated bone formation in osteoporotic defects

AimsThe activity of adipose-derived stem cells (ADSCs) is susceptible to the physiological conditions of the donor. Therefore, employing ADSCs from donors of advanced age or with diseases for cell therapy necessitates a strategy to enhance therapeutic efficacy before transplantation. This study aims to investigate the impact of supplementing Fibroblast Growth Factor 2 (FGF2) and Hepatocyte Growth Factor (HGF) on ADSC-mediated osteogenesis under osteoporotic conditions and to explore the underlying mechanisms of action. Main methodsAdipose-derived stem cells (ADSCs) obtained from ovariectomized (OVX) rats were cultured ex vivo. These cells were cultured in an osteogenic medium supplemented with FGF2 and HGF and subsequently autologously transplanted into osteoporotic femur defects using Hydroxyapatite-Tricalcium Phosphate. The assessment of bone formation was conducted four weeks post-transplantation. Key findingsOsteoporosis detrimentally affects the viability and osteogenic differentiation potential of ADSCs, often accompanied by a deficiency in FGF2 and HGF signaling. However, priming with FGF2 and HGF facilitated the formation of immature osteoblasts from OVX ADSCs in vitro, promoting the expression of osteoblastogenic proteins, including Runx-2, osterix, and ALP, during the early phase of osteogenesis. Furthermore, FGF2/HGF priming augmented the levels of VEGF and SDF-1α in the microenvironment of OVX ADSCs under osteogenic induction. Importantly, transplantation of OVX ADSCs primed with FGF2/HGF for 6 days significantly enhanced bone formation compared to non-primed cells. The success of bone regeneration was confirmed by the expression of type-1 collagen and osteocalcin in the bone tissue of the deficient area. SignificanceOur findings corroborate that priming with FGF2/HGF can improve the differentiation potential of ADSCs. This could be applied in autologous stem cell therapy for skeletal disease in the geriatric population.

Evaluation of osseous healing in induced mandibular defects grafted with biphasic calcium phosphate doped with silver and zirconium nanoparticles: An experimental study in dogs

ObjectiveEvaluation of the osteoconductive p otential of the nanocomposite tricalcium phosphate/hydroxyapatite (TCP/HA) bi-doped with zirconium (Zr) and silver (Ag) ions versus TCP/HA & 4AgTCP/HA in induced defects. MethodsFifteen dogs were divided into four groups in 12 weeks duration before euthanasia: 1-control, 2- TCP/HA, 3- TCP/HA doped with Ag and 4-TCP/HA bi-doped with Ag & Zr groups. Four surgically created defects were randomly allocated in each animal on the left and right mandibular sides, three defects were grafted with mentioned alloplasts and one empty control. Clinical, radiographic, and histological evaluations were performed for the newly formed bone. ResultsClinical results revealed no infection or inflammatory conditions. All graft groups revealed a significant increase (P<0.05) in mature bone mean density versus controls. TCP/HA bidoped with Ag and Zr group elucidated a highly significant increase (P <0.01) in mature bone density compared to other groups while the TCP/HA was statistically insignificant (P > 0.05) compared to the Ag-doped TCP/HA. The bactericidal action of both Zr and Ag nanoparticles was evident by antibacterial testing. ConclusionBi-doping of TCP/HA with Ag and Zr has a synergistic osteoconductive effect to enhance bone formation as an excellent modality for defective bone reconstruction. Histomorphometric investigation clarified that Ag and Zr doped TCP/HA stimulated osteogenesis and bone remodeling as compared to un-doped TCP/HA. Therefore, this nanocomposite has promising clinical significance in grafting maxillofacial bone defects for optimal healing compared to un-doped TCP/HA. Moreover, Zr and Ag nanoparticles are effective bactericidal materials with optimal biological safety on the animals.

3D-printed TCP-HA scaffolds delivering MicroRNA-302a-3p improve bone regeneration in a mouse calvarial model

ObjectiveTo demonstrate hydroxyapatite nanoparticles modified with cationic functional molecules. 3-aminopropyltriethoxysilane (HA-NPs-APTES) carrying microRNA-302a-3p (miR) in the 3D-printed tricalcium phosphate/Hydroxyapatite (TCP/HA) scaffold can increase healing of the critical-sized bone defect.Materials and methods3D-printed TCP/HA were modified with HA-NPs-APTES by two methods (M1, M2). The dispersion of particles was visualized by fluorescent microscopy. Biocompatibility of the scaffolds was tested by alizarin assay. Delivery of miR to the cells and osteogenic gene expression were evaluated by qPCR. After selecting best method (M2), scaffolds, scaffolds+HA-NPs-APTES with or without miR were implanted in 4 mm mouse calvarium defect (n = 4 per group). After 2,4 and 6 weeks, bone regeneration were evaluated by microCT and histology sections.ResultsBoth M1 and M2 scaffolds were biocompatible with cell adhesion on its surface. M2 scaffold showed significant increase of miR, suggesting successful delivery, resulted in downregulation of its target mRNA COUP-TFII, and upregulation of RUNX2 mRNA. Calvarium defect with M2 scaffold also showed significantly higher BV/TV and higher number of filled spaces at all time points. Histomorphometry demonstrated new bone formed at the center of the HA-NPs-APTES-miR scaffold earlier than controls.ConclusionTCP/HA scaffold modified with HA-NPs-APTES facilitated delivery of miR and enhanced bone regeneration.

Human Digested Dentin Matrix for Dentin Regeneration and the Applicative Potential in Vital Pulp Therapy

IntroductionHuman dentin is a natural acellular matrix with excellent reported biocompatibility. The aim was to fabricate a novel dentin matrix material from human dentin and investigate its applicative potential for vital pulp therapy. MethodsDigested dentin matrix extract (DDME) was fabricated using controlled enzymatic digestion under acidic conditions. The surfaces and biocompatibility of DDME were then investigated, with its effects on the odontogenic differentiation of human dental pulp cells (hDPCs) also studied. The ability of DDME to induce mineralization was assessed in a nude mouse model. The performance of DDME as a pulp capping agent was evaluated in an in situ rat model. The molecular mechanism was verified by mRNA sequencing. ResultsA novel type of dentin matrix material with a uniform size of 8 μm was fabricated. DDME had a similar band compared with grinded dentin matrix, with a smaller size, and more uneven surface, as detected by Fourier-transform infrared spectrometer and X-ray photoelectron spectroscopy. DDME at low concentrations did not affect hDPC viability or proliferation, but enhanced runt-related transcription factor 2, dentin matrix acidic phosphoprotein 1, and COL1A1 (collagen type I alpha 1 chain) expression in hDPCs in vitro. DDME was superior to HA-TCP (hydroxyapatite-tricalcium phosphate) in dentin-like mineralized tissue formation after subcutaneous transplantation. In the rat model of pulpotomy, DDME showed visible curative effects. The underlying mechanism may be the inhibition of Hippo signaling following DDME treatment. DDME promoted Yes-associated protein (YAP) 1 nuclear influx, thereby enhancing the expression of DMP-1 (dentin matrix acidic phosphoprotein 1), which was reversed by YAP inhibitor treatment. ConclusionsHuman DDME can be used as a biomaterial for dentin regeneration. The combined application of DDME and current pulp capping agents is a potential choice for vital pulp therapy.

Effects of peptides with different side groups on the surface mineralization process of bioceramic

The reference peptide's side groups (polylysine, PL(–NH2)) were changed to create the carboxy-grafted polylysine (PL-COOH), and Methyl-grafted polylysine (PL-CH3) peptides. The influence of polypeptides with different side groups on the surface mineralization behavior of hydroxyapatite/tricalcium phosphate (HA/TCP) biphasic ceramics was investigated using the static immersion mineralization method of simulated bodily fluid and the dynamic mineralization method based on quartz crystal microbalance (QCM-D) technology. Experiments revealed that changing the side groups of the peptides altered their secondary structure as well as the adsorption behavior on the substrate surface. Furthermore, the hydrophilicity and hydrophobicity of the substrate surface were altered by peptide adsorption. These structural and property changes impacted Ca2+ and PO43- concentrations, and thus governed biomineralization. This study will offer fresh perspectives on bone implant material surface design.

A dual osteoconductive-osteoprotective implantable device for vertical alveolar ridge augmentation

Repair of large oral bone defects such as vertical alveolar ridge augmentation could benefit from the rapidly developing additive manufacturing technology used to create personalized osteoconductive devices made from porous tricalcium phosphate/hydroxyapatite (TCP/HA)-based bioceramics. These devices can be also used as hydrogel carriers to improve their osteogenic potential. However, the TCP/HA constructs are prone to brittle fracture, therefore their use in clinical situations is difficult. As a solution, we propose the protection of this osteoconductive multi-material (herein called “core”) with a shape-matched “cover” made from biocompatible poly-ɛ-caprolactone (PCL), which is a ductile, and thus more resistant polymeric material. In this report, we present a workflow starting from patient-specific medical scan in Digital Imaging and Communications in Medicine (DICOM) format files, up to the design and 3D printing of a hydrogel-loaded porous TCP/HA core and of its corresponding PCL cover. This cover could also facilitate the anchoring of the device to the patient's defect site via fixing screws. The large, linearly aligned pores in the TCP/HA bioceramic core, their sizes, and their filling with an alginate hydrogel were analyzed by micro-CT. Moreover, we created a finite element analysis (FEA) model of this dual-function device, which permits the simulation of its mechanical behavior in various anticipated clinical situations, as well as optimization before surgery. In conclusion, we designed and 3D-printed a novel, structurally complex multi-material osteoconductive-osteoprotective device with anticipated mechanical properties suitable for large-defect oral bone regeneration.

Adipose-derived stem cells with miR-150-5p inhibition laden in hydroxyapatite/tricalcium phosphate ceramic powders promote osteogenesis via regulating Notch3 and activating FAK/ERK and RhoA

Adipose-derived mesenchymal stem cells (ADSCs) are multipotent stromal cells and play huge role in forming and repairing bone tissues. Emerging evidence shows that MicroRNAs (miRNAs) are involved in ADSCs differentiation. Here, we explored the role of miR-150-5p and its related mechanisms in ADSCs osteogenesis. Real-time PCR was used to determine miR-150-5p expression during ADSCs osteogenesis. miR-150-5p inhibitors, miR-150-5p ADV or short hairpin RNA (shRNA) of Notch3 were transfected to ADSCs for analyzing the effects on osteogenesis. The mixture of hydroxyapatite/tricalcium phosphate (HA/TCP) ceramic powders and transfected ADSCs was implanted into BALB/C nude mice. Micro-CT and histological methods were performed to evaluate the new bone formation. Compared with negative control (NC) and miR-150-5p overexpression, inhibition of miR-150-5p increased ADSCs osteogenesis by regulating Notch3. MiR-150-5p overexpression decreased the expression of pFAK, pERK1/2, and RhoA, while these were up-regulated when miR-150-5p was inhibited, or notch3 was silenced. Furthermore, miR-150-5p inhibition partially reversed the suppression effect of notch3 knockdown on osteogenesis in vitro and in vivo. This study demonstrated the critical function of miR-150-5p during osteogenesis. The combination of ADSCs with miR-150-5p inhibition and HA/TCP might be a promising strategy for bone damage repair. Statement of significanceOsteoporosis is a common chronic metabolic bone disease in humans. Bone tissue engineering based on mesenchymal stem cells, biomaterials, and growth factors, provides a promising way to treat osteoporosis and bone defects. ADSCs commonly differentiate into adipose cells, they can also differentiate into osteogenic cell lineages. Nucleic acids and protein have usually been considered as regulators of ADSCs osteogenic differentiation. In the current study, we demonstrated the combination of ADSCs with miR-150-5p inhibition and hydroxyapatite/tricalcium phosphate ceramic powders enhanced bone regeneration. Furthermore, miR-150-5p/Notch3 axis regulating osteogenesis via the FAK/ERK1/2 and RhoA pathway was assessed. The current study showed the application of ADSCs in bone regeneration might be a promising strategy for osteoporosis and bone damage repairing.

Bone Morphogenetic Protein as Bone Additive around Dental Implant and its Impact on Osseointegration: a Systematic Review.

Bone morphogenetic protein (BMP), a potential osteoinductive agent, was systematically reviewed for merits and demerits when used as a bone additive that was intervened during the surgical phase of dental implant placement; and suitable drug carriers that could withstand the functional load and deliver BMP at its lowest concentration. To identify the carriers and concentration of BMP acceptable during surgical phase of implant placement and evaluate its efficacy in bone gain and osseointegration. The study design was systematic review. Literature search as per PICO format was carried out within a time range from 2000 to July 2021. The review fol-lowed PRISMA guidelines and registered with the PROSPERO (CRD42020171667). The focus question included the population with an intra-oral implant placed in both animal and human models that were intervened with BMP-2 as an external additive biomaterial during the surgical phase. 2631 articles selected from the initial search were systematically filtered and yielded 16 articles that were qualitatively analysed. The inter-rater reliability and level of agreement were 93.71%, κ(Kappa)>0.81 re-spectively. Results revealed the collagen carrier was commonly used for BMP delivery but lacked the property to withstand functional load and sustained release. BMP concentration varied in the range of 0.215μg to 0.8mg and the study revealed significantly indifferent out-come with low dose compared to the highest dose. BMP supplement showed better osseointe-gration in comparison with non-supplemented sites during the early period (within 6 months). BMP at lower concentrations and with appropriate carriers, collagen sponge, hydroxyapatite/tricalcium phosphate (HA/TCP) with a bio ceramic bulking agent, and poly (D, L-lactide-co-glycolic acid) (PLGA) reinforced with gelatin/HA/TCP accelerated bone growth during the initial stages of healing. Further long-term clinical trials for dental implant, analysing the sustained release of BMP with biodegradable and load-bearing carriers should be considered.

Cytotoxicity of HA-TCP Scaffold on Human Umbilical Cord Mesenchymal Stem Cells using MTT Assay

Hydroxyapatite-tricalcium phosphate (HA-TCP) scaffold is a three-dimensional structure used to support bone regeneration. Ideally, the scaffold should be biocompatible, biodegradable, and non-toxic. The tissue engineering technique uses a combined stem cell and scaffold to repair the bone defect. To prove the non-toxic properties of the scaffold, a cytotoxicity test is needed for the human umbilical cord mesenchymal stem cell (HUCMSCs). In this study, 27 samples were divided into eight groups with a variantof scaffold HA-TCP doses ranging from 5–1000 μg. Each treatment group of scaffolds was covered in HUCMSCs. The samples were added by methyl-thiazol-tetrazolium (MTT) colorimetric assay, counted using an optical density (OD) formula, and observed by a microplate reader. The viability of the cells was observed by an inverted TMS microscope with 100x magnification. The MTT assay’s test shows that the HUCMSCs cell viability shed each variant of HA-TCP scaffold dose, did not show any toxic effect. The higher the OD value, the higher the viability. It has been found that there is no significant difference between the variable scaffold doses to the percentage viability of umbilical cord cells

Cytotoxicity of HA-TCP Scaffold on Human Umbilical Cord Mesenchymal Stem Cells using MTT Assay

Hydroxyapatite-tricalcium phosphate (HA-TCP) scaffold is a three-dimensional structure used to support bone regeneration. Ideally, the scaffold should be biocompatible, biodegradable, and non-toxic. The tissue engineering technique uses a combined stem cell and scaffold to repair the bone defect. To prove the non-toxic properties of the scaffold, a cytotoxicity test is needed for the human umbilical cord mesenchymal stem cell (HUCMSCs). In this study, 27 samples were divided into eight groups with a variantof scaffold HA-TCP doses ranging from 5–1000 μg. Each treatment group of scaffolds was covered in HUCMSCs. The samples were added by methyl-thiazol-tetrazolium (MTT) colorimetric assay, counted using an optical density (OD) formula, and observed by a microplate reader. The viability of the cells was observed by an inverted TMS microscope with 100x magnification. The MTT assay’s test shows that the HUCMSCs cell viability shed each variant of HA-TCP scaffold dose, did not show any toxic effect. The higher the OD value, the higher the viability. It has been found that there is no significant difference between the variable scaffold doses to the percentage viability of umbilical cord cells.

A Bioreactor for 3D In Vitro Modeling of the Mechanical Stimulation of Osteocytes.

The bone is a mechanosensitive organ that is also a common metastatic site for prostate cancer. However, the mechanism by which the tumor interacts with the bone microenvironment to further promote disease progression remains to be fully understood. This is largely due to a lack of physiological yet user-friendly models that limit our ability to perform in-depth mechanistic studies. Here, we report a tunable bioreactor which facilitates the 3D culture of the osteocyte cell line, MLO-Y4, in a hydroxyapatite/tricalcium phosphate (HA/TCP) scaffold under constant fluidic shear stress and tunable hydrostatic pressure within physiological parameters. Increasing hydrostatic pressure was sufficient to induce a change in the expression of several bone remodeling genes such as Dmp1, Rankl, and Runx2. Furthermore, increased hydrostatic pressure induced the osteocytes to promote the differentiation of the murine macrophage cell line RAW264.7 toward osteoclast-like cells. These results demonstrate that the bioreactor recapitulates the mechanotransduction response of osteocytes to pressure including the measurement of their functional ability in a 3D environment. In conclusion, the bioreactor would be useful for exploring the mechanisms of osteocytes in bone health and disease.

Multipotent stem cells from apical pulp of human deciduous teeth with immature apex

Isolation of high-quality human postnatal stem cells from accessible sources is an important goal for dental tissue engineering. Stem cells from developing organs are a better cell source but are hard to obtain. With extensive caries that are difficult to restore, the extracted deciduous tooth with an immature apex is a developing organ for investigation. In the present study, a cell population from the tip of apical pulp of human deciduous teeth with an immature apex was isolated and termed apical pulp-derived cells of deciduous teeth (De-APDCs). De-APDCs expressed STRO-1, CD44, CD90 and CD105 but not CD34 or CD45. Furthermore, De-APDCs demonstrated a significantly higher clonogenic and proliferative ability and osteo/dentinogenic differentiation capacity than dental pulp cells from exfoliated deciduous teeth (De-DPCs) (P < 0.05). Differentiation potential toward adipogenic, neurogenic and chondrogenic lineages was also observed in induced De-APDCs. In addition, after De-APDCs were seeded into hydroxyapatite/tricalcium phosphate (HA/TCP) scaffolds and transplanted into nude mice, they were able to regenerate dentin/pulp-like structures aligned with human odontoblast-like cells. In conclusion, De-APDCs, which are derived from a developing tissue, represent an accessible and prospective cell source for tooth regeneration.

Bone ingrowth observed in a cup removed during revision surgery for early dislocation after primary THA: A case report.

Introduction and importanceRecently cementless total hip arthroplasty (THA) has shown good long-term results with excellent stability resulted from the porous coating of the implant. A hydroxyapatite-tricalcium phosphate (HA-TCP) coating on the porous surface is expected to promote bone ingrowth and to improve initial fixation of the implant. Here we report a case of bone ingrowth observed in a cup removed during revision surgery for early dislocation, 37 days after primary THA using a porous coating cup with HA-TCP.Case presentationA 61-year-old woman who has bilateral osteoarthritis underwent same-day bilateral THA. Both sides used porous coating cups with HA-TCP. Line-to-line technique and screw fixation were utilized. Anterior dislocation of the left hip occurred on days 27 and 31, and we performed cup revision on day 37 after surgery. We noted bone-like tissue on the posterior surface of the cup and in a vacant screw hole. Bone tissue was also confirmed in pathological findings.Clinical discussionStudies in animals have confirmed early bone ingrowth about 4 weeks after surgery with HA-TCP coated implants. In humans, the earliest report of bone ingrowth in cups is for a cup without HA-TCP coating, detected 5 weeks after surgery. In the present case, we used a porous coating cup with HA-TCP, and bone ingrowth was confirmed at approximately the same time as for the previous case.ConclusionEarly clinical bone ingrowth was confirmed in an HA-TCP coated cup, occurring at about the same time after surgery as in previous reports.

Baghdadite Ceramics Prevent Senescence in Human Osteoblasts and Promote Bone Regeneration in Aged Rats.

Bone fractures and critical-sized bone defects present significant health threats for the elderly who have limited capacity for regeneration due to the presence of functionally compromised senescent cells. A wide range of synthetic materials has been developed to promote the regeneration of critical-sized bone defects, but it is largely unknown if a synthetic biomaterial (scaffold) can modulate cellular senescence and improve bone regeneration in aged scenarios. The current study investigates the interaction of Baghdadite (Ca3ZrSi2O9) ceramic scaffolds with senescent human primary osteoblast-like cells (HOBs) and its bone regeneration capacity in aged rats. A senescent HOB model was established by repeatedly passaging HOBs till passage 7 (P7). Compared to the clinically used hydroxyapatite/tricalcium phosphate (HA/TCP), Baghdadite prevented senescence induction in P7 HOBs and markedly negated the paracrine effect of P7 HOB secretomes that mediated the up-regulations of cellular senescence-associated gene expression levels in P2 HOBs. We further demonstrated that conditioned media extracted from Baghdadite corrected the dysfunctional mitochondria in P7 HOBs. In vivo, the bone regeneration capacity was enhanced when 3D printed Baghdadite scaffolds were implanted in a calvaria critical-sized bone defect model in both young and aged rats compared to HA/TCP scaffolds, but a better effect was observed in aged rats than in young rats. This study suggests that Baghdadite ceramic represents a novel and promising biomaterial approach to promote bone regeneration capacity in the elderly by providing an anti-senescent microenvironment.

Extracellular vesicles from deciduous pulp stem cells recover bone loss by regulating telomerase activity in an osteoporosis mouse model

BackgroundSystemic transplantation of stem cells from human exfoliated deciduous teeth (SHED) recovers bone loss in animal models of osteoporosis; however, the mechanisms underlying this remain unclear. Here, we hypothesized that trophic factors within SHED-releasing extracellular vesicles (SHED-EVs) rescue osteoporotic phenotype.MethodsEVs were isolated from culture supernatant of SHED. SHED-EVs were treated with or without ribonuclease and systemically administrated into ovariectomized mice, followed by the function of recipient bone marrow mesenchymal stem cells (BMMSCs) including telomerase activity, osteoblast differentiation, and sepmaphorine-3A (SEMA3A) secretion. Subsequently, human BMMSCs were stimulated by SHED-EVs with or without ribonuclease treatment, and then human BMMSCs were examined regarding the function of telomerase activity, osteoblast differentiation, and SEMA3A secretion. Furthermore, SHED-EV-treated human BMMSCs were subcutaneously transplanted into the dorsal skin of immunocompromised mice with hydroxyapatite tricalcium phosphate (HA/TCP) careers and analyzed the de novo bone-forming ability.ResultsWe revealed that systemic SHED-EV-infusion recovered bone volume in ovariectomized mice and improved the function of recipient BMMSCs by rescuing the mRNA levels of Tert and telomerase activity, osteoblast differentiation, and SEMA3A secretion. Ribonuclease treatment depleted RNAs, including microRNAs, within SHED-EVs, and these RNA-depleted SHED-EVs attenuated SHED-EV-rescued function of recipient BMMSCs in the ovariectomized mice. These findings were supported by in vitro assays using human BMMSCs incubated with SHED-EVs.ConclusionCollectively, our findings suggest that SHED-secreted RNAs, such as microRNAs, play a crucial role in treating postmenopausal osteoporosis by targeting the telomerase activity of recipient BMMSCs.

Effectiveness of Anadara granosa shell-Stichopus hermanni granules at accelerating woven bone formation fourteen days after tooth extraction

Background: Post-extraction complications can cause alveolar bone resorption. Hydroxyapatite-tricalcium phosphate (HA-TCP) is one potential bone graft material that can be synthesized from Anadara granosa shell. Another biomarine, Stichopus hermanni, contains hyaluronic acid which can accelerate bone formation on the fourteenth day. Purpose: This study aims to prove the effectiveness of Anadara granosa shell-Stichopus hermanni granules in weaving bone formation fourteen days after tooth extraction. Methods: Twenty-five male Wistar rats were divided into five groups. Their lower left incisor was extracted with gelatin being administered to the control group (C) and granule scaffold derived from Anadara granosa (AG) shell and Anadara granosa shell-Stichopus hermanni at concentrations of 0.4%-0.8%-1.6% (AGSH1-AGSH2-AGSH3) to the treatment group. This study developed a HA-TCP synthesized from Anadara granosa combined with whole Stichopus hermanni to create granule scaffolds by means of a freeze-dried method. The jaw was removed on the fourteenth day post-tooth extraction. Observation of HPA involved the use of an Image Raster®. The resulting data was subjected to analysis by ANOVA and tukey-HSD tests (p&lt;0.05). Results: Data showed the mean of C=0.157±0.078; AG=1.139±0.371; AGSH1=1.595±0.291; AGSH2=1.740±0.308; and AGSH3=1.638±0.286. Statistical analyses showed significant differences in the woven bone area (mm2) between C and the treatment groups AG;AGSH1;AGSH2; AGSH3; and between AG and the AGSH2 groups. Conclusions: Scaffold granules from Anadara granosa shells and Stichopus hermanni effectively accelerate the bone formation process with the most effective being Stichopus hermanni at a concentration of 0.8%.

Synthesis, microstructure and mechanical properties of tricalcium phosphate–hydroxyapatite (TCP/HA) composite ceramic

Tricalcium phosphate-hydroxyapatite (TCP/HA) is an important composite ceramic ubiquitously applied in biomedicine research. In this work, a novel design and synthesizing method for preparation of TCP/HA composites is proposed consisting in suspension mixing amorphous calcium phosphate (ACP) and hydroxyapatite (HA) ceramic powders with different weight ratios, and their compaction under a uniaxial pressure of 200 MPa and sintering at 1150 °C for 2 h. The obtained sintered bodies exhibited optimum hardness and fracture toughness of 5 GPa and 1.27 MPa m1/2, and values significantly improved as compared with those obtained with the traditional mechanical mixing method. The mechanical enhancement mechanism was mainly attributed to the good ACP and HA phase dispersion and ACP crystallization. SEM and HRTEM observations showed the suspension mixing method to allow amorphous spherical ACP and crystalline rod-like HA particles with size around 50 nm to uniformly disperse at the nano scale in the composite powder, which contributes to the excellent sinter ability. Furthermore, XRD results indicate that after sintering, nearly 100% of amorphous spherical ACP transformed to the crystalline β-TCP, which results in the nanoparticle shrinkage, porosity reduction and composite densification.

Hedgehog Signaling Inhibition by Smoothened Antagonist BMS-833923 Reduces Osteoblast Differentiation and Ectopic Bone Formation of Human Skeletal (Mesenchymal) Stem Cells.

Background Hedgehog (Hh) signaling is essential for osteoblast differentiation of mesenchymal progenitors during endochondral bone formation. However, the critical role of Hh signaling during adult bone remodeling remains to be elucidated. Methods A Smoothened (SMO) antagonist/Hedgehog inhibitor, BMS-833923, identified during a functional screening of a stem cell signaling small molecule library, was investigated for its effects on the osteoblast differentiation of human skeletal (mesenchymal) stem cells (hMSC). Alkaline phosphatase (ALP) activity and Alizarin red staining were employed as markers for osteoblast differentiation and in vitro mineralization capacity, respectively. Global gene expression profiling was performed using the Agilent® microarray platform. Effects on in vivo ectopic bone formation were assessed by implanting hMSC mixed with hydroxyapatite-tricalcium phosphate granules subcutaneously in 8-week-old female nude mice, and the amount of bone formed was assessed using quantitative histology. Results BMS-833923, a SMO antagonist/Hedgehog inhibitor, exhibited significant inhibitory effects on osteoblast differentiation of hMSCs reflected by decreased ALP activity, in vitro mineralization, and downregulation of osteoblast-related gene expression. Similarly, we observed decreased in vivo ectopic bone formation. Global gene expression profiling of BMS-833923-treated compared to vehicle-treated control cells, identified 348 upregulated and 540 downregulated genes with significant effects on multiple signaling pathways, including GPCR, endochondral ossification, RANK-RANKL, insulin, TNF alpha, IL6, and inflammatory response. Further bioinformatic analysis employing Ingenuity Pathway Analysis revealed significant enrichment in BMS-833923-treated cells for a number of functional categories and networks involved in connective and skeletal tissue development and disorders, e.g., NFκB and STAT signaling. Conclusions We identified SMO/Hedgehog antagonist (BMS-833923) as a powerful inhibitor of osteoblastic differentiation of hMSC that may be useful as a therapeutic option for treating conditions associated with high heterotopic bone formation and mineralization.