Osteoprogenitor Cells Research Articles

Craniomaxillofacial morphology in a murine model of ephrinB1 conditional deletion in osteoprogenitor cells

ObjectiveEFNB1 mutation causes craniofrontonasal dysplasia (CFND), a congenital syndrome associated with craniomaxillofacial anomalies characterised by coronal craniosynostosis, orbital hypertelorism, and midface dysplasia. The aim of this murine study was to investigate the effect of the EfnB1 conditional gene deletion in osteoprogenitor cells on the craniomaxillofacial skeletal morphology. DesignThe skulls of male and female mice, in which EfnB1 was deleted by Cre (a site-specific DNA recombinase) under the control of the Osterix (Osx) promoter (EfnB1OB-/-), were compared to those without EfnB1 deletion (Osx:Cre control) at two ages (4 and 8 weeks; n = 6 per group). The three-dimensional micro-computed tomography reconstructions were prepared to calculate 17 linear measurements in the cranial vault (brain box), midface and mandible. Coronal and sagittal sutures from the 8-week-old mice were also subjected to histological examination. ResultsEfnB1OB-/- mice displayed significantly larger cranial height, larger interorbital and nasal widths, smaller maxillary width than controls by 8 weeks (p < 0.05), but mandibular size was not significantly different (p > 0.05). Binomial testing showed significantly smaller EfnB1OB-/- skulls at 4 weeks but larger at 8 weeks (p < 0.05). Histological examination revealed increased bony fusion and fibrous connective tissue deposition at the coronal suture of EfnB1OB-/- mice compared with controls. ConclusionsCraniofacial phenotype of the murine model of EfnB1 deletion in osteoprogenitor cells partially represents the human CFND phenotype, with implications for better understanding mechanisms involved in skeletal morphogenesis and malocclusion.

Chemical Compounds Released from Specific Osteoinductive Bioactive Materials Stimulate Human Bone Marrow Mesenchymal Stem Cell Migration.

In this work, a poly(L-lactide-co-glycolide) (PLGA)-based composite was enriched with one of the following sol-gel bioactive glasses (SBG) at 50 wt.%: A1—40 mol% SiO2, 60 mol% CaO, CaO/SiO2 ratio of 1.50; S1—80 mol% SiO2, 20 mol% CaO, CaO/SiO2 ratio of 0.25; A2—40 mol% SiO2, 54 mol% CaO, 6 mol% P2O5, CaO/SiO2 ratio of 1.35; S2—80 mol% SiO2,16 mol% CaO, 4 mol% P2O5, CaO/SiO2 ratio of 0.20. The composites and PLGA control sheets were then soaked for 24 h in culture media, and the obtained condition media (CM) were used to treat human bone marrow stromal cells (hBMSCs) for 72 h. All CMs from the composites increased ERK 1/2 activity vs. the control PLGA CM. However, expressions of cell migration-related c-Fos, osteopontin, matrix metalloproteinase-2, C-X-C chemokine receptor type 4, vascular endothelial growth factor, and bone morphogenetic protein 2 were significantly increased only in cells treated with the CM from the A1/PLGA composite. This CM also significantly increased the rate of human BMSC migration but did not affect cell metabolic activity. These results indicate important biological markers that are upregulated by products released from the bioactive composites of a specific chemical composition, which may eventually prompt osteoprogenitor cells to colonize the bioactive material and accelerate the process of tissue regeneration.

Hydrophilic implants generated using a low-cost dielectric barrier discharge plasma device at the time of placement exhibit increased osseointegration in an animal pre-clinical study: An effect that is sex-dependent

ObjectivesIncreased wettability of titanium and titanium alloy surfaces due to processing and storage methods increases osteoprogenitor cell differentiation and osseointegration compared to microroughness alone. Implants that are exposed to air have a hydrophobic surface due to adsorption of atmospheric hydrocarbons, which can limit overall implant success. Dielectric barrier discharge plasma (DBD) is one method to increase surface hydrophilicity. Although current DBD methods yield a hydrophilic surface, adsorbed hydrocarbons rapidly restore hydrophobicity. We demonstrated that application of DBD to implants previously packaged in a vacuum, generates a hydrophilic surface that supports osteoblastic differentiation in vitro and this can be done immediately prior to use. In the present study, we tested the hypothesis that DBD treatment to alter surface wettability at the time of implant placement will improve osseointegration in vivo. Materials and methodsTwenty male and sixteen female rabbits were used in a preclinical trans-axial femur model of osseointegration. Control and DBD treatment implants were inserted randomized per hind limb in each rabbit (1 implant/hind-limb). At 6 weeks post-surgery, bone-to-implant contact, adjacent bone volume, and torque to failure were assessed by micro-CT, calcified histology, and mechanical testing. ResultsDBD plasma treatment of vacuum-sealed implants increased surface wettability and did not change surface chemistry or roughness. Peak torque and torsional energy, and bone-to-implant contact increased with DBD treatment in males. In contrast, female rabbits showed increased osseointegration equal to DBD treated male implants regardless of DBD plasma treatment. ConclusionDBD treatment is an effective method to enhance osseointegration by increasing surface wettability; however, this response is sex dependent. In healthy female patients, DBD treatment may not be necessary but in older patients or patients with compromised bone, this treatment could be an effective measure to ensure implant success.

Mouse LGR6 regulates osteogenesis in vitro and in vivo through differential ligand use.

Leucine-rich repeat containing G-protein-coupled receptor 6 (LGR6) is a marker of osteoprogenitor cells and is dynamically expressed during in vitro osteodifferentation of mouse and human mesenchymal stem cells (MSCs). While the Lgr6 genomic locus has been associated with osteoporosis in human cohorts, the precise molecular function of LGR6 in osteogenesis and maintenance of bone mass are not yet known. In this study, we performed in vitro Lgr6 knockdown and overexpression experiments in murine osteoblastic cells and find decreased Lgr6 levels results in reduced osteoblast proliferation, differentiation, and mineralization. Consistent with these data, overexpression of Lgr6 in these cells leads to significantly increased proliferation and osteodifferentiation. To determine whether these findings are recapitulated in vivo, we performed microCT and ex vivo osteodifferentiation analyses using our newly generated CRISPR-Cas9 mediated Lgr6 mouse knockout allele (Lgr6-KO). We find that ex vivo osteodifferentiation of Lgr6-KO primary MSCs is significantly reduced, and 8week-old Lgr6-KO mice have less trabecular bone mass as compared to Lgr6 wildtype controls, indicating that Lgr6 is necessary for normal osteogenesis and bone mass. Towards mechanism, we analyzed in vitro signaling in the context of two LGR6 ligands, RSPO2 and MaR1. We find that RSPO2 stimulates LGR6-mediated WNT/β-catenin signaling whereas MaR1 stimulates LGR6-mediated cAMP activity, suggesting two ligand-dependent functions for LGR6 receptor signaling during osteogenesis. Collectively, this study reveals that Lgr6 is necessary for wildtype levels of proliferation and differentiation of osteoblasts, and achieving normal bone mass.

TGF-1 biomarker level evaluation on fracture healing in a murine model with a bone defect after stromal vascular fraction application.

Aim Bone defect is a challenge even for experienced orthopaedic surgeons and it is a significant cause of morbidity in patients and a source of high economic burden in health care. A severe bone defect is a condition whereby the bone tissue cannot undergo natural healing despite surgical stabilization and requires further surgical intervention. Stromal vascular fraction (SVF) is a heterogeneous cell population derived from adipose tissue that results from minimal manipulation of the adipose tissue itself. TGF is essential in maintaining and expanding mesenchymal stem cells or progenitors of osteoblasts. Furthermore, TGF-β signalling also triggers osteoprogenitor cell proliferation, early differentiation, and maintenance of osteoblasts in the bone healing process. The aim of this study was to determine the effect of administering SVF on bone defects' healing process assessed based on the TGF- β1. Methods This was an animal study involving twelve Wistar strain Rattus norvegicus. They were divided into three groups: negative group (normal rats), positive group (rats with bone defect without SVF application), and SVF group (rats with bone defect with SVF application). After 30 days, the rats were sacrificed, the TGF- β1 biomarker was evaluated (quantified using ELISA). Results TGF- β1 biomarker expressions were higher in the group with SVF application than in the group without SVF application. All comparisons of the SVF group and positive control group showed significant differences (p=0,000), respectively. Conclusion Giving SVF application could aid the healing process in a murine model with bone defect, marked by an increased level of TGF- β1.

Biodegradable Hydrogel Beads Combined with Calcium Phosphate Bone Cement for Bone Repair: In Vitro and In Vivo Characterization.

This study evaluated the in vitro characterizations of biodegradable hydrogel beads with calcium phosphate bone cement (CPC). Commercial fast-setting CPC and hydrogel beads were compared with 25%-volume hydrogel in CPC (C/0.25) in vivo. The histological behaviors and absorption rates of CPC only, hydrogel beads, and hydrogel/CPC composite were measured and compared at 4, 8, and 12 weeks. The results indicated that the C/0.25 composite can be molded and does not disintegrate when immersed in the solution, but this delays the phase transition of the CPC into the product in the early reaction process. The osteoprogenitor D1 cell affinity of the C/0.25 composite was equally competitive with that of the CPC-only. Adding hydrogel beads to CPC did not inhibit cell proliferation as well as differentiation of osteoprogenitor cells. In vivo histological evaluations did not indicate any significant difference in the CPC-only, hydrogel-only, and C/0.25 composite after 4 weeks of implantation; however, significantly less residue was observed in the C/0.25 composite relative to the CPC-only after 8 weeks. After 12 weeks of hydrogel beads implantation, the hydrogel degraded substantially, creating vacancies that were subsequently occupied by a large amount of soft tissue. New bone was formed in large quantities in the C/0.25; therefore, the C/0.25 composite is a promising option for a wide range of dental, craniofacial, and orthopedic applications.

Impaired Bone Fracture Healing in Type 2 Diabetes Is Caused by Defective Functions of Skeletal Progenitor Cells.

The mechanisms of obesity and type 2 diabetes (T2D)-associated impaired fracture healing are poorly studied. In a murine model of T2D reflecting both hyperinsulinemia induced by high-fat diet and insulinopenia induced by treatment with streptozotocin, we examined bone healing in a tibia cortical bone defect. A delayed bone healing was observed during hyperinsulinemia as newly formed bone was reduced by -28.4±7.7% and was associated with accumulation of marrow adipocytes at the defect site +124.06±38.71%, and increased density of SCA1+ (+74.99±29.19%) but not Runx2+ osteoprogenitor cells. We also observed increased in reactive oxygen species production (+101.82±33.05%), senescence gene signature (≈106.66±34.03%), and LAMIN B1- senescent cell density (+225.18±43.15%), suggesting accelerated senescence phenotype. During insulinopenia, a more pronounced delayed bone healing was observed with decreased newly formed bone to -34.9±6.2% which was inversely correlated with glucose levels (R2 = 0.48, P < .004) and callus adipose tissue area (R2 = .3711, P < .01). Finally, to investigate the relevance to human physiology, we observed that sera from obese and T2D subjects had disease state-specific inhibitory effects on osteoblast-related gene signatures in human bone marrow stromal cells which resulted in inhibition of osteoblast and enhanced adipocyte differentiation. Our data demonstrate that T2D exerts negative effects on bone healing through inhibition of osteoblast differentiation of skeletal stem cells and induction of accelerated bone senescence and that the hyperglycemia per se and not just insulin levels is detrimental for bone healing.

Dmp1 Lineage Cells Contribute Significantly to Periosteal Lamellar Bone Formation Induced by Mechanical Loading But Are Depleted from the Bone Surface During Rapid Bone Formation.

ABSTRACTPrevious work has shown that osteoprogenitor cells (Prx1+) and pre‐osteoblasts (Osx+) contribute to mechanical loading‐induced bone formation. However, the role of mature Dmp1‐expressing osteoblasts has not been reported. In this study we assessed the contribution of osteoblast lineage cells to bone formation at an early time point following mechanical loading (day 8 from onset of loading). We labeled Osx‐expressing and Dmp1‐expressing cells in inducible Osx and Dmp1 reporter mice (iOsx‐Ai9, iDmp1‐Ai9), respectively, 3 weeks before loading. Mice were then loaded daily for 5 days (days 1–5) and were dosed with 5‐ethynyl‐2′‐deoxyuridine (EdU) in their drinking water until euthanasia on day 8. Mice were loaded to lamellar and woven bone inducing stimulation (−7 N/1400 με, −10 N/2000 με) to assess differences in these processes. We found varied responses in males and females to the loading stimuli, inducing modest lamellar (females, −7 N), moderate lamellar (males, −10 N), and robust woven (females, −10 N) bone. Overall, we found that preexisting (ie, lineage positive) Osx‐expressing and Dmp1‐expressing cells contribute largely to the bone formation response, especially during modest bone formation, while our results stuggest that other (non‐lineage–positive) cells support the sustained bone formation response during rapid bone formation. With moderate or robust levels of bone formation, a decrease in preexisting Osx‐expressing and Dmp1‐expressing cells at the bone surface occurred, with a near depletion of Dmp1‐expressing cells from the surface in female mice loaded to −10 N (from 52% to 11%). These cells appeared to be replaced by lineage‐negative cells from the periosteum. We also found a dose response in proliferation, with 17% to 18% of bone surface cells arising via proliferation in modest lamellar, 38% to 53% in moderate lamellar, and 59% to 81% in robust woven bone formation. In summary, our results show predominant contributions by preexisting Osx and Dmp1 lineage cells to loading‐induced lamellar bone formation, whereas recruitment of earlier osteoprogenitors and increased cell proliferation support robust woven bone formation. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

ОЦЕНКА КЛИНИКО-БИОХИМИЧЕСКОГО АНАЛИЗА КРОВИ СОБАК С УЧЕТОМ ПРИМЕНЕНИЯ ОСТЕОБИОКОМПОЗИТА ДЛЯ УСКОРЕНИЯ КОНСОЛИДАЦИИ

To date, it is quite important to prevent antibacterial contamination, osteoconductivity and osteoinductivity of the processes of reparative regeneration of bone tissue with the help of coatings for implants, as well as a variety of pharmacological drugs administered systemically or pointwise into the fracture zone. This is necessary to prevent degenerative-dystrophic changes in the osteoarticular system (false joint, arthrosis, resorption, sequestration, slow consolidation, non-fusion, osteoporosis, reduced vascularization), acute and chronic infectious lesions, joint blockage, deformity of tubular bones and disability. This article reflects the studies of clinical and biochemical blood analysis of three groups of animals (dogs) using the developed biocomposite injected into the intramedullary canal with a simulated transverse fracture of the middle third of the radius diaphysis. The components of the composite are used as: a matrix that compensates for parts of the destroyed bone, accelerates the processes of renewal of structural parts of cells, tissues at various stages of organization, while it has a stimulating effect on leuko- and erythropoiesis, as well as the process of phagocytosis, bone formation, prompting osteoprogenitor cells to proliferate and differentiate into osteoblasts. Also, due to the presence of a semi-synthetic broad-spectrum antibiotic (penicillin series), it has a bactericidal effect as a result of inhibition of bacterial cell wall synthesis. It is also worth noting that the developed composite is safely absorbed and biointegrated without reaction to a foreign body. Based on the conducted studies, a group of authors, taking into account the clinical and biochemical analysis, confirmed the absence of inflammatory, allergic, aplastic, hepatotoxic and nephrotoxic reactions from the macro- and micro-organism of animals.

Bioglass: A New Era in Modern Dentistry

AbstractThe function of biomaterials has been to replace infected or injured tissues. The first used biomaterials were bioinert, thus minimizing formation of scar tissue at the interface with host tissues. Bioglass was discovered in 1969. Larry Hench developed Bioglass 45S5, which was the earliest synthetic substance that was bonded chemically with bone. In recent researches it has appeared that Bioglass bonds with bone more readily than other bioceramics; it also indicated that the osteogenic properties are due to stimulation of osteoprogenitor cells by the dissolution products formed from Bioglass. Bioglass is chemically calcium sodium phosphosilicate, which is capable of forming an active chemical bond with the tissues. Bioglass is particularly biocompatible which, when placed in body cavity or on reacting with body stimulating factors, induces hydroxyapatite formation. This paper reviews Bioglass as a material of modern dentistry and its various applications in modern dentistry. It also discusses its composition, methods of preparation, and mechanism of action, along with its advantages and disadvantages.

Preparation and Physicochemical Evaluation of Hydroxyapatite-gelatin Nanoparticles

One of the promising fields of research is tissue engineering that can facilitate available therapeutic methods. Nanosized hydroxyapatite (HA) is one of the key elements in mineral bone. It is possible to affect the surrounding osteoprogenitor cells using nano-sized HA and through this improve bone repair through changing paracrine signaling. The present paper is an attempt to prepare and evaluate physicochemical properties of hydroxyapatite-gelatin nanoparticles. To this end, two sizes were prepared including S100 and S150 using standard chemical precipitation. To characterize the size and morphology of the synthesized powders, X-ray diffraction and Brunauer-Emmett-Teller (BET) surface area were determined using Autosrob-IQ2-MP. To measure the calcium ions released by HANPs, an inductively coupled plasma optical emission spectrometer (ICP-OES) was used. The collected data was analyzed in SPSS 19.0. In the case of S100, the hydrodynamic diameter based on DLS analyses was equal to 626.10±14.95nm; this figure for S150 was equal to 262.33±46.5. There was a larger specific surface area in S100 compared to S150; in addition, S100 had wider diffraction peaks, which is in agreement with small and poorly crystalline crystals. On the other hand, the diffraction peaks of S150 were sharper, which means that the crystallinity was higher in S150. In addition, HANPs of all sizes had degradability and HANPs with smaller sizes (S100) degraded faster compared to larger-sized S150. The pH level of the control, S100, and S150 was 7.24±0.01, and 7.26±0.02 so that there was no significant difference between them. Nanoparticle size is a key factor in the biological environment, which provides a reference for HANPs in biomedical uses.

A New Type of COP: The Role of Circulating Osteoprogenitor (COP) Cells in Health and Disease

Circulating osteogenic progenitor (COP) cells are a population of cells in the peripheral blood with the capacity for bone formation and broader differentiation into mesoderm-like cells in vitro. While some of their biological characteristics are documented in vitro, their role in the aging process and the pathogenesis of musculoskeletal diseases remains yet to be thoroughly evaluated. This translational session will go from bench to bedside, reviewing the current evidence on COP cells. In this session, we will provide an overview of the role of COP cells in the aging process and a number of physiological and pathological conditions and identify areas for future research. In addition, we will suggest possible areas for clinical utilization in the management of musculoskeletal diseases, which include novel diagnostic and therapeutic uses.

Evaluation of Cytotoxicity and Biocompatibility of Ti2AlC in Rabbits

Background: The Titanium and its alloys are suitable for dental implant and medical applications. Biocompatibility of the materials is a major factor in determining the success of the implant and has a great impact on their rate of osseointegration. The aim of this study was to evaluate the biocompatibility and cytotoxicity of Ti2AlC in comparison to CPTi &amp; Ti6Al7Nb in rabbits. Materials and Methods: 10 male New Zealand White rabbits, weighing (2-2.5 kg), aged (10-12 months) were used in this study. Cylindrical implants were prepared from the study materials (CPTi, Ti6Al7Nb and Ti2AlC) with (8mm) height and (3mm) diameter for the evaluation of tissue response and disc specimens were prepared with (6 mm) diameter and (2 mm) thickness for evaluation of cytotoxicity MTT test. A histological study was performed at 2 &amp; 6 weeks post- surgical implant insertion. Results: Histological findings show that Ti2AlC has enhanced proliferation of osteo-progenitor cell and reported mature bone formation at 6 weeks. Moreover, Ti2AlC has recorded a higher percentage for viable cells by MTT test in comparison to CPTi and Ti6Al7Nb. Conclusion: The new Ti2AlC dental implant is considered biocompatible and has showed a better bone formation than the CPTi and Ti6Al7Nb materials at 2 &amp; 6 weeks.

Bioactive Coatings Loaded with Osteogenic Protein for Metallic Implants.

Osteoconductive and osteoinductive coatings represent attractive and tunable strategies towards the enhanced biomechanics and osseointegration of metallic implants, providing accurate local modulation of bone-to-implant interface. Composite materials based on polylactide (PLA) and hydroxyapatite (HAp) are proved beneficial substrates for the modulation of bone cells’ development, being suitable mechanical supports for the repair and regeneration of bone tissue. Moreover, the addition of osteogenic proteins represents the next step towards the fabrication of advanced biomaterials for hard tissue engineering applications, as their regulatory mechanisms beneficially contribute to the new bone formation. In this respect, laser-processed composites, based on PLA, Hap, and bone morphogenetic protein 4(BMP4), are herein proposed as bioactive coatings for metallic implants. The nanostructured coatings proved superior ability to promote the adhesion, viability, and proliferation of osteoprogenitor cells, without affecting their normal development and further sustaining the osteogenic differentiation of the cells. Our results are complementary to previous studies regarding the successful use of chemically BMP-modified biomaterials in orthopedic and orthodontic applications.

Stability of dental implants with sandblasted and acid-etched (SLA) and modified (SLActive) surfaces during the osseointegration period.

Background. The surface properties of implants are effective factors for increasing the osseointegration and activity of osteoprogenitor cells. This study compared the stability of dental implants with sandblasted and acid-etched (SLA) and modified surfaces (SLActive) using the resonance frequency analysis (RFA). Methods. In a split-mouth design, 50 dental implants with either SLA surface properties (n=25) or modified (SLActive) surface properties (n=25) were placed in the mandibles of 12 patients with a bilateral posterior edentulous area. Implant stability was measured using RFA (Osstell) at implant placement time and every week for 1, 2, and 3 months before the conventional loading time. Results. One week following the implantation, implant stability increased from 70 to 77.67 for SLA and from 71.67 to 79 for SLActive (P < 0.05). Stability improved each week except in the 4th week in SLActive surface measurements. No significant differences were observed between the groups at 2 and 3 months (P > 0.05). Conclusions. For both implant surfaces, increased stability was observed over time, with no significant differences between the groups.

Wnt Pathway Inhibitor Delays Fracture Healing by Targeting Ephrin B1 (EFNB1) in Osteoprogenitor Cells

Our study assessed the role of Wnt signaling inhibitor (SM04690) in fracture healing and the underlying mechanism. Sprague Dawley (SD) rats were used to establish a fracture model which was then separated into SM04690 group which received SM04690 (50 mg/kg) by intraperitoneal injection once a day for one week, and control group which received saline once a day. After rats were sacrificed, the fractured femurs were harvested to measure femoral strength by stress testing, bone density and volume by CT. Femurs were sliced for immunohistochemical staining. Mesenchymal stem cells (MSCs), endothelial cells, osteoprogenitor cells and osteoblasts were detected by flow cytometer and EFNB1 expression was detected by immunoblotting and PCR. In addition, MSCs were treated with SM04690 (5 uM), followed by detection of EFNB1 expression. SM04690 treatment significantly inhibited EFNB1 expression and reduced bone volume and callus volume as well as decreased ultimate load of bones. Immunohistochemical staining and flow cytometry analysis showed no difference of osteoclast numbers at the fracture site between two groups, but proportion of osteoclasts in the cartilage tissue of SM04690 group was significantly decreased. In addition, the number of osteoblasts, osteoprogenitor cells and endothelial cells was significantly decreased after treatment. Under the conditions favoring osteogenic differentiation, the production of minerals by osteogenic cells was significantly decreased along with upregulated TAZ phosphorylation and downregulated Osterix in SM04690 group. In conclusion, SM04690 delays fracture healing by inhibiting EpRunB1 in osteoprogenitor cells.

WNT16 elevation induced cell senescence of osteoblasts in ankylosing spondylitis

BackgroundWNT16 is critical for bone homeostasis, but the effect of WNT16 in ankylosing spondylitis (AS) is still unknown. Here, we investigated whether WNT16 influences bone formation and pathophysiological changes of AS in an in vitro model.MethodsThe bone tissue from the facet joints was obtained from seven disease control and seven AS patients. Primary osteoprogenitor cells of the facet joints were isolated using an outgrowth method. Isolated osteoprogenitor cells from both control and AS tissues were analyzed by microarray, RT-qPCR, immunoblotting, and immunohistochemistry. The bone-forming activity of osteoprogenitor cells was assessed by various in vitro assays. β-galactosidase staining and senescence-associated secretory phenotype (SASP) using RT-qPCR were used to assess cell senescence.ResultsIn microarray analysis, WNT16 expression was significantly elevated in AS osteoprogenitor cells compared to the control. We also validated that WNT16 expression was elevated in AS-osteoprogenitor cells and human AS-bone tissues. WNT16 treatment inhibited bone formation in AS-osteoprogenitor cells but not in the control. Intriguingly, AS-osteoprogenitor cells were stained markedly with β-galactosidase for cell senescence in WNT16 treatment. Furthermore, in an H2O2 stress-induced premature senescence condition, WNT16 treatment increased cell senescence in AS-osteoprogenitor cells and WNT16 treatment under the H2O2 stress condition showed an increase in p21 protein and SASP mRNA expression. The WNT16-induced SASP expression in AS-osteoprogenitor cells was reduced in WNT16 knockdown cultures.ConclusionWNT16 is highly expressed in AS and WNT16 treatment facilitated cell senescence in AS-osteoprogenitor cells during osteoblast differentiation accompanied by suppression of bone formation. The identified role of WNT16 in AS could influence bone loss in AS patients.

MiRNA-Nanofiber, the Next Generation of Bioactive Scaffolds for Bone Regeneration: A Review.

Scaffold-based bone tissue engineering has been introduced as an alternative treatment option for bone grafting due to limitations in the allograft. Not only physical conditions but also biological conditions such as gene expression significantly impact bone regeneration. Scaffolds in composition with bioactive molecules such as miRNA mimics provide a platform to enhance migration, proliferation, and differentiation of osteoprogenitor cells for bone regeneration. Among scaffolds, fibrous structures showed significant advantages in promoting osteogenic differentiation and bone regeneration via delivering bioactive molecules over the past decade. Here, we reviewed the bone and bone fracture healing considerations for the impact of miRNAs on bone regeneration. We also examined the methods used to improve miRNA mimics uptake by cells, the fabrication of fibrous scaffolds, and the effective delivery of miRNA mimics using fibrous scaffold and their processes for bone development. Finally, we offer our view on the principal challenges of miRNA mimics delivery by nanofibers for bone tissue engineering.

Effects of immune cells on mesenchymal stem cells during fracture healing.

In vertebrates, bone is considered an osteoimmune system which encompasses functions of a locomotive organ, a mineral reservoir, a hormonal organ, a stem cell pool and a cradle for immune cells. This osteoimmune system is based on cooperatively acting bone and immune cells, cohabitating within the bone marrow. They are highly interdependent, a fact that is confounded by shared progenitors, mediators, and signaling pathways. Successful fracture healing requires the participation of all the precursors, immune and bone cells found in the osteoimmune system. Recent evidence demonstrated that changes of the immune cell composition and function may negatively influence bone healing. In this review, first the interplay between different immune cell types and osteoprogenitor cells will be elaborated more closely. The separate paragraphs focus on the specific cell types, starting with the cells of the innate immune response followed by cells of the adaptive immune response, and the complement system as mediator between them. Finally, a brief overview on the challenges of preclinical testing of immune-based therapeutic strategies to support fracture healing will be given.

Traumatized periosteum: Its histology, viability, and clinical significance.

The periosteum covers the surface of long bone except at the joints. During fracture fixation, we found the periosteum is ragged and damaged. Our objective is to determine the microscopic picture of traumatized periosteum in terms of the degree of damage, cell type, stromal tissue, and vascularity. Periosteum of 1cm*1cm is harvested at 1cm, 3cm, and 5cm proximal and distal to fracture site following fracture of a long bone in 20 humans. Ragged and damaged periosteum mainly consists of an outer fibrous layer with many hemorrhagic tissue and neovascularization. Osteoprogenitor cells were seen only in 12 out of 97 samples, mostly harvested 5 cm from the fracture site. The innermost layer of the periosteum remains attached to the bone surface after separating the fibrous layer following a fracture. The use of a periosteal elevator on the bone surface further damages the inner layer of the periosteum. Using a scalpel to separate the periosteum or merely pulling it away from the bone surface will decrease damage to the inner cambium layer. Fracture reduction can be achieved by indirect means at least 5 cm away from the fracture site.