Suppression of the NLRP3 Inflammasome through Activation of the Transient Receptor Potential Channel Melastatin 2 Promotes Osteogenesis in Tooth Extraction Sockets of Periodontitis.

This study explored the role of transient receptor potential channel melastatin 2 (TRPM2)-mediated activation of NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome in osteogenesis during healing of tooth extraction sockets. Tooth extraction socket tissue samples were collected from patients with or without periodontitis. In a TRPM2 knockout mouse model of socket healing, mice with or without periodontitis and their wild-type littermates were used for comparing the socket healing phenotypes. Micro-computed tomography imaging, three-dimensional reconstruction of the sockets, and hematoxylin and eosin staining for histopathologic analysis were performed. Immunofluorescence, immunohistochemistry, and Western blot analysis were used for evaluation of protein expression; the mRNA levels were evaluated by quantitative RT-PCR. Osteogenic, chondrogenic, and adipogenic differentiation potential of human bone marrow mesenchymal stem cells (BMMSCs) was evaluated. Calcium deposition was evaluated using Alizarin Red S staining. NLRP3 and CASP1 were up-regulated in tooth sockets of periodontitis patients. NLRP3 knockdown promoted the osteogenic differentiation of maxillary BMMSCs under inflammatory conditions. TRPM2 was up-regulated in the tooth extraction socket tissue of periodontitis. Inhibiting TRPM2 expression mitigated the NLRP3 inflammasome and its deleterious effect on osteogenesis. Activation of the TRPM2 ion channel regulated osteogenesis of BMMSCs under inflammatory conditions via Ca2+ influx, the mitochondrial dynamics, and pyroptosis. Targeting the TRPM2/Ca2+/NLRP3 axis could be beneficial in the healing process of the tooth extraction sockets of patients with periodontitis.

Enhanced osteogenesis by addition of cancellous bone chips at xenogenic bone augmentation: In vitro and in vivo experiments.

OBJECTIVES: To investigate and compare the influence of deproteinized bovine bone mineral (DBBM) combined with autologous cortical (CorBC) or cancellous bone chips (CanBC) as bone grafts on guided bone regeneration (GBR) in vivo and in vitro. MATERIALS AND METHODS: Defects were created in the mandibular buccal alveolar ridges in dogs and randomly filled with 3 groups of bone grafts: DBBM, DBBM + CorBC, or DBBM + CanBC. Osteogenesis was evaluated by sequential fluorescent labeling and histological analysis. Moreover, rat bilateral calvaria defects were randomly grafted with DBBM, DBBM + CorBC, or DBBM + CanBC. A blank group was included as control. Defect healing was assessed by histological staining, micro-CT, and quantitative polymerase chain reaction. In vitro migration, proliferation, and osteogenic differentiation assays were performed by stimulating rat bone marrow mesenchymal stem cells (rBMSCs) with cortical (CorBCM) or cancellous bone conditioned medium (CanBCM) to unveil the cellular mechanism. RESULTS: In the canine model, the augmented sites of DBBM + CanBC exhibited higher mineralized tissue proportion than the other two groups (DBBM: 0.61 ± 0.03 versus DBBM + CorBC: 0.69 ± 0.07 versus DBBM + CanBC: 0.86 ± 0.06; p < .05). In the rat model, the BV/TV value of DBBM + CanBC (0.51 ± 0.01) was higher than those of DBBM + CorBC (0.41 ± 0.02), DBBM (0.31 ± 0.01), and Control (0.10 ± 0.01; p < .01). Further radiological, histological and transcriptional results showed similar trends. In vitro experiments revealed that CorBCM and especially CanBCM could enhance rBMSCs migration, proliferation, and osteogenic differentiation. CONCLUSION: In vivo and in vitro experiments verified favorable synergistic effect of mixing autologous bone chips with DBBM on osteogenesis. Furthermore, CanBC presented more powerful osteogenic effect than CorBC.

LAMA5-inspired adhesive dodecapeptide facilitates efficient dentine regeneration: An in vitro and in vivo study.

AIM: The primary goal of this study was to investigate the potential effects of A5G81 in inducing reparative dentine (RD) formation both in vitro and in vivo. METHODOLOGY: Cell adhesion was observed by crystal violet staining and quantified by Sodium Dodecyl Sulphate (SDS) extraction. Cell proliferation was investigated using Cell Counting Kit-8 (CCK-8) assay. Spreading of cytoskeleton was visualized using immunofluorescence staining. Protein expression level of Akt signalling pathway was compared in a human Akt pathway phosphorylation array. Genes that were up or downregulated by A5G81 were identified by RNA sequencing. The mRNA expression of odontoblastic markers was detected by quantitative real-time polymerase chain reaction (qPCR). Moreover, mineralization of human dental pulp cells (hDPCs) was visualized by alizarin red staining and quantified using cetylpyridinium chloride (CPC). A direct pulp-capping model was established in SD rats and the RD formation at 2 weeks after operation was observed using HE staining. RESULTS: A5G81 (optimal coating concentration: 0.5 mg/mL) promoted hDPCs adhesion and proliferation to a level that was similar to Type I collagen (COL-1). Meanwhile, A5G81 activated Akt signalling pathway, albeit to a lesser extent than COL-1. An inhibition test indicated that A5G81 induced hDPCs adhesion by activating PI3K pathway. A5G81 induced the expression of ECM remodelling genes and odontoblastic genes, which were demonstrated by RNA-seq and qPCR, respectively. In addition, A5G81 efficiently accelerated the mineralization of hDPCs in both immobilized and soluble forms, a property that makes it more applicable in dental clinic. Finally, the pulp-capping study in rats suggested that use of A5G81 could successfully induce the formation of RD within 2 weeks. CONCLUSION: Coating of A5G81 to non-tissue culture-treated polystyrene facilitates spreading, proliferation and differentiation of hDPCs, resulting in rapid RD formation in artificially exposed pulp.

Triggering receptor expressed on myeloid cells-2 stimulates osteoclast differentiation and bone loss in periodontitis.

OBJECTIVE: To investigate the expression of triggering receptor expressed on myeloid cells 2 (TREM-2) in the healthy and diseased tissue, including gingivitis or periodontitis, and then to assess whether it has an impact on the development of periodontitis. METHODS AND MATERIALS: The gingival tissues from healthy controls, gingivitis, and periodontitis underwent hematoxylin-eosin and immunohistochemical staining, and the association of TREM-2 expression or TREM-2+ cell counts with clinical parameters was assessed. An anti-TREM-2 antibody was used to block the osteoclastogenesis in vitro and during the experimental periodontitis by injection into the gingiva. The relative gene expression of TREM-2 in different gingival tissues was analyzed by quantitative PCR. RESULTS: In the gingival tissues of periodontitis, TREM-2 expression and TREM-2+ cell counts were significantly higher than those of gingivitis and healthy controls (p<0.05). In the group of periodontitis showing moderate signs, the gingival tissues displayed significantly lower TREM-2 expression, in contrast with the group with advanced periodontal symptoms (p < 0.05). Consistently, blocking TREM-2 significantly decreased osteoclast formation both in vitro and in vivo (p < 0.05). CONCLUSION: Increased TREM-2 expression and TREM-2+ cells were positively associated with the development of periodontitis. Osteoclast differentiation and stimulating alveolar bone loss were partly relied on TREM-2, which could be a target to be blocked for attenuating osteoclastogenesis in periodontitits.

Preoperative incidence and risk factors of deep vein thrombosis in patients with an isolated patellar fracture.

PURPOSE: This study aimed to investigate the incidence, location, and related factors of preoperative deep venous thrombosis (DVT) in patients with isolated patellar fractures. METHODS: Patients with an isolated patellar fracture, admitted between January 2013 and December 2019 at our institution, were retrospectively analyzed. Upon admission, patients underwent routine Doppler ultrasound scanning (DUS) of the bilateral lower extremities to detect DVT; those with DVT were assigned to the case group and those without DVT to the control group. Patients in both groups did not perform preoperative off-bed weight-bearing exercises. Data on demographics, comorbidities, and laboratory test results upon admission were extracted. Variables were evaluated between the two groups using univariate analyses, and independent risk factors associated with DVT were identified by logistic regression analysis. RESULTS: During the study period, 827 patients were included, of whom 5.8% (48/827) were found to have preoperative DVT. In DVT patients, 85.4%(41/48) were injured, 8.3%(4/48) were not injured, and 6.3%(3/48) were lower limbs. Multivariate analysis showed that male (male vs. female, odds ratio, OR = 2.25), delayed from injury to DUS (in each day, OR = 1.29), and elevated plasma D-dimer level (> 0.5 µg/mL, OR = 2.47) were independent risk factors associated with DVT. CONCLUSIONS: Despite the low prevalence of DVT after an isolated patellar fracture, this study underscores the importance of identifying those with a high risk of DVT, especially those with multiple identifiable factors, and encourage the early targeted use of anti-thromboembolic agents to reduce DVT occurrence.

Preoperative incidence and risk factors of deep venous thrombosis in patients with isolated femoral shaft fracture.

BACKGROUND: Preoperative deep vein thrombosis (DVT) of the lower extremities delays surgery in patients with femoral shaft fractures and impairs functional recovery. However, studies on preoperative DVT in patients with femoral shaft fractures are still rare. This study was aimed to retrospectively analyze the preoperative incidence, location and risk factors associated with DVT in patients with femoral shaft fractures. METHODS: Data of patients with femoral shaft fractures and treated with surgery at the Third Hospital of Hebei Medical University were retrospectively collected from January 2013 to December 2019. The information collected included demographic data, comorbidities, injury-related data and laboratory tests. Patients were divided into DVT and non-DVT groups. Univariate and multivariate logistic regression analyses were performed to determine independent risk factors. RESULTS: A total of 432 patients were included in this study, of whom 114 (26.4%) patients were diagnosed with preoperative DVT (all asymptomatic) and injured extremities of 78.1% (89/114) were investigated. Multivariate analysis showed that older age (increase in each 10 years), delay time from injury to operation (in each day), FIB > 4 g/L were independent risk factors for preoperative DVT. CONCLUSION: Patients with femoral shaft fractures (especially the elderly and patients with the above-mentioned conditions) are at the risk of DVT right from admission to surgery hence should be intensively monitored and provided with prompt treatment to prevent DVT.

Biomechanical study on the stability and strain conduction of intertrochanteric fracture fixed with proximal femoral nail antirotation versus triangular supporting intramedullary nail.

OBJECTIVES: Based on the features of the three-dimensional spatial structure of the proximal femoral trabeculae, we developed a bionic triangular supporting intramedullary nail (TSIN) for the treatment of the femoral intertrochanteric fracture. The current study aimed to compare the mechanical stability and restoration of mechanical conduction between proximal femoral nail antirotation (PFNA) and TSIN to fix the intertrochanteric fractures. METHODS: Firstly, five sets of PFNA and TSIN with the same size were selected and fixed on a biomechanical testing machine, and strain gauges were pasted on the main nail, lag screw, and supporting screw to load to the vertical load to 600 N, and the displacement and strain values were recorded. Secondly, formalin-preserved femurs were selected, and the left and right femurs of the same cadaver were randomly divided into two groups to prepare intertrochanteric femur fractures (AO classification 31-A1), which were fixed with PFNA (n = 15) and TSIN (n = 15), respectively. Sixteen sites around the fracture line were chosen to paste strain gauges and loaded vertically to 600 N, and then, the fracture fragment displacement and strain values were recorded. Finally, a 10,000-cycle test ranging from 10 to 600 N was conducted, and the cycle number and displacement value were recorded. RESULTS: The overall displacement of PFNA was 2.17 ± 0.18 mm, which was significantly greater than the displacement of the TSIN group (1.66 ± 0.05 mm, P < 0.05) under a vertical load of 600 N. The strain below the PFNA lag screw was 868.29 ± 147.85, which was significantly greater than that of the TSIN (456.02 ± 35.06, P < 0.05); the strain value at the medial side of the PFNA nail was 444.00 ± 34.23, which was significantly less than that of the TSIN (613.57 ± 108.00, P < 0.05). Under the vertical load of 600 N, the displacement of the fracture fragments of the PFNA group was 0.95 ± 0.25 mm, which was significantly greater than that of the TSIN group (0.41 ± 0.09 mm, P < 0.05). The femoral specimens in the PFNA group showed significantly greater strains at the anterior (1, 2, and 4), lateral (7, 9, and 10), posterior (11), and medial (15 and 16) sites than those in the TSIN group (all P < 0.05). In the cyclic compression experiment, the displacements of the PFNA group at 2000, 4000, 6000, 8000, and 10,000 cycles were 1.38 mm, 1.81 mm, 2.07 mm, 2.64 mm, and 3.58 mm, respectively, which were greater than the corresponding displacements of the TSIN group: 1.01 mm, 1.48 mm, 1.82 mm, 2.05 mm, and 2.66 mm (P8000 = 0.012, P10000 = 0.006). CONCLUSIONS: The current study showed that TSIN had apparent advantages in stability and stress conduction. TSIN enhanced the stability of intertrochanteric fractures, particularly in superior fracture fragments, improved stress conduction, reduced the stress in the anterior and medial femur, and restored the biomechanical properties of the femur.

Finite element analysis of biomechanical effects of residual varus/valgus malunion after femoral fracture on knee joint.

OBJECTIVE: Post-operative femoral shaft fractures are often accompanied by a residual varus/valgus deformity, which can result in osteoarthritis in severe cases. The purpose of this study was to investigate the biomechanical effects of residual varus/valgus deformities after middle and lower femoral fracture on the stress distribution and contact area of knee joint. METHODS: Thin-slice CT scanning of lower extremities and MRI imaging of knee joints were obtained from a healthy adult male to establish normal lower limb model (neutral position). Then, the models of 3°, 5°, and 10° of varus/valgus were established respectively by modifying middle and lower femur of normal model. To validate the modifying, a patient-specific model, whose BMI was same to former and had 10° of varus deformity of tibia, was built and simulated under the same boundary conditions. RESULT: The contact area and maximum stress of modified models were similar to those of patient-specific model. The contact area and maximum stress of medial tibial cartilage in normal neutral position were 244.36 mm2 and 0.64 MPa, while those of lateral were 196.25 mm2 and 0.76 MPa. From 10° of valgus neutral position to 10° of varus, the contact area and maximum stress of medial tibial cartilage increased, and the lateral gradually decreased. The contact area and maximum stress of medial meniscus in normal neutral position were 110.91 mm2 and 3.24 MPa, while those of lateral were 135.83 mm2 and 3.45 MPa. The maximum stress of medial tibia subchondral bone in normal neutral position was 1.47 MPa, while that of lateral was 0.65 MPa. The variation trend of medial/lateral meniscus and subchondral bone was consistent with that of tibial plateau cartilage in the contact area and maximum stress. CONCLUSION: This study suggested that varus/valgus deformity of femur had an obvious effect on the contact area and stress distribution of knee joint, providing biomechanical evidence and deepening understanding when performing orthopedic trauma surgery or surgical correction of the already existing varus/valgus deformity.

Heterogeneity of fibroblasts from radicular cyst influenced osteoclastogenesis and bone destruction.

AIM: To analyze the heterogeneity of fibroblasts isolated from the fibrous capsules of radicular cysts and explore the effects of fibroblast subsets on bone destruction. METHODOLOGY: Radicular cysts were divided into groups according to varying perilesional sclerosis identified by radiograph. Colony-forming units (CFUs) were isolated from the fibrous capsules of cysts, by which Trap + MNCs were induced, and the expression of osteoclastogenesis-related genes was compared among groups by real-time PCR. The variances in gene profiles of CFUs were identified by principal component analysis, and then, CFUs were divided into subsets using cluster analysis. The induction of Trap + MNCs and related gene expression was compared among subsets, and osteoclastogenic induction was blocked by IST-9 or bevacizumab. The fibroblast subsets in cysts were investigated by retrospective immunostaining with IST-9, VEGF-A, and CD34. A fibroblast subset that underwent gene editing by CRISPR/Cas was injected into the site of bone defects in animal models, and the in vivo effects on osteoclastogenesis were investigated. RESULTS: The fibroblast CFUs isolated from radicular cysts with perilesional unsclerotized cysts induced more Trap + MNCs than those with perilesional sclerotic cysts (p < .05). Most fibroblast CFUs from unsclerotized cysts belonged to Cluster 2, which induced more Trap + MNCs (p < .05) and highly expressed genes facilitating osteoclastogenesis; these results were different from those of Cluster 1 (p < .05), in which most CFUs were isolated from perilesional sclerotic cysts or controls (p < .05). The high expression of EDA + FN and VEGF-A was investigated in both the fibroblasts of Cluster 2 and the fibrous capsules of unsclerotized cysts (p < .05), and the number of Trap + MNCs induced by Cluster 2 was decreased by treatment with IST-9 and bevacizumab (p < .05). Consistently, EDA exon exclusion significantly decreased the osteoclastogenic induction of fibroblasts from Cluster 2 in vivo (p < .05). CONCLUSION: The fibrous capsules of radicular cysts contain heterogeneous fibroblasts that can form subsets exhibiting different effects on osteoclastogenesis. The subset, which depending on the autocrine effects of EDA + FN on VEGF-A, mainly contributes to the osteoclastogenesis and bone destruction of radicular cysts. The regulation of the proportion of subsets is a possible strategy for artificially interfering with osteoclastogenesis.

Bevacizumab or fibronectin gene editing inhibits the osteoclastogenic effects of fibroblasts derived from human radicular cysts.

Fibronectin (FN) is a main component of extracellular matrix (ECM) in most adult tissues. Under pathological conditions, particularly inflammation, wound healing and tumors, an alternatively spliced exon extra domain A (EDA) is included in the FN protein (EDA+FN), which facilitates cellular proliferation, motility, and aggressiveness in different lesions. In this study we investigated the effects of EDA+FN on bone destruction in human radicular cysts and explored the possibility of editing FN gene or blocking the related paracrine signaling pathway to inhibit the osteoclastogenesis. The specimens of radicular cysts were obtained from 20 patients. We showed that the vessel density was positively associated with both the lesion size (R = 0.49, P = 0.001) and EDA+FN staining (R = 0.26, P = 0.022) in the specimens. We isolated fibroblasts from surgical specimens, and used the CRISPR/Cas system to knockout the EDA exon, or used IST-9 antibody and bevacizumab to block EDA+FN and VEGF, respectively. Compared to control fibroblasts, the fibroblasts from radicular cysts exhibited significantly more Trap+MNCs, the relative expression level of VEGF was positively associated with both the ratio of EDA+FN/total FN (R = 0.271, P = 0.019) and with the number of Trap+MNCs (R = 0.331, P = 0.008). The knockout of the EDA exon significantly decreased VEGF expression in the fibroblasts derived from radicular cysts, leading to significantly decreased osteoclastogenesis; similar results were observed using bevacizumab to block VEGF, but block of EDA+FN with IST-9 antibody had no effect. Furthermore, the inhibitory effects of gene editing on Trap+MNC development were restored by exogenous VEGF. These results suggest that EDA+FN facilitates osteoclastogenesis in the fibrous capsule of radicular cysts, through a mechanism mediated by VEGF via an autocrine effect on the fibroblasts. Bevacizumab inhibits osteoclastogenesis in radicular cysts as effectively as the exclusion of the EDA exon by gene editing.

The fibroblast of radicular cyst facilitate osteoclastogenesis via the autocrine of Fibronectin containing extra domain A.

OBJECTIVE: To investigate the alternative spliced isoforms of Fibronectin (FN) in the stroma of radicular cysts and analyze the associations between these isoforms and the osteoclastogenic effects of fibroblasts. METHODS AND MATERIALS: The specimens of radicular cysts were stained with immunohistochemistry, and the associations between each FN isoform and clinical parameters were assessed. The fibroblasts isolated from cysts or jaw bone were cultured to induce the Trap + MNCs. In the conditioned medium, the Fibronectin containing extra domain A (EDA + FN) was neutralized by antibody IST-9, and the EDA exon of fibroblasts was knockout by CRISPR/Cas system, for assessing the osteoclastogenic effects. The mRNA level of FN isoforms and the osteoclastogenesis-related genes were analyzed by quantitive PCR. RESULTS: EDA + FN staining was positively associated with the size of the lesions (p < 0.05). In contrast with the controls, the ratio of EDA + FN/total FN in the fibroblasts from radicular cysts was significantly higher (p < 0.05), and positively associate with Trap + MNCs counting, it was consistent with increased expression of COX-2, IL-6, IL-17, and the RANKL/OPG (p < 0.05). The Trap + MNCs counting and osteoclastogenesis-related genes were decreased by IST-9 blocking and EDA exon knockout in fibroblasts, but the blockage of the interaction between EDA + FN and pre-osteoclasts exhibited little effects on Trap + MNCs formation. CONCLUSION: The microenvironment of the fibrous capsule of radicular cysts facilitates the splicing of EDA exon, it endues EDA + FN with autocrine effects on fibroblast itself, and it increases the expression of osteoclastogenesis-related genes, by which the osteoclastogenesis in radicular cysts could be initiated.

Paired-Related Homeobox 1-Positive Cells Are Needed for Osseointegration.

PURPOSE: To explore the contribution of paired-related homeobox 1-positive cells to the implant-induced osseointegration process in adult alveolar bone and the potential underlying mechanisms. MATERIALS AND METHODS: Cre recombinase-induced lineage tracing and cell ablation were conducted in a murine dental implant model. Scratch and transwell assays were used to assess MC3T3-E1 cell migration after paired-related homeobox 1 overexpression. Single-cell RNA sequencing were applied to identify potential genes involved in pairedrelated homeobox 1-positive cells-driven osteogenesis. RESULTS: Paired-related homeobox 1- positive cells were observed to accumulate in the peri-implant area in a time-dependent manner. The number of these cells were found to reach its maximum on day 14. Osseointegration in mice were noticeably impaired after ablation of paired-related homeobox 1-positive cells. Further, it was discovered that paired-related homeobox 1 promotes MC3T3- E1 cell migration, a process which is indispensable for sound healing of peri-implant tissue. Finally, Semaphorin 3C was detected exclusively and abundantly expressed by paired-related homeobox 1-positive cells. Knockdown of semaphorin 3C in paired-related homeobox 1- positive cells significantly weakened their osteogenic potential. CONCLUSION: Our data suggest that paired-related homeobox 1-positive cells contribute to the osseointegration process under stress stimulation and semaphorin 3C may play a critical role in paired-related homeobox 1- positive cell-driven osteogenesis. Paired-related homeobox 1 could significantly promote MC3T3-E1 cell migration.

The detection of Gper1 as an important gene promoting jawbone regeneration in the context of estrogen deficiency.

Numerous studies have demonstrated that estrogen deficiency inhibit the proliferation and differentiation of pre-osteoblasts in skeleton by affecting osteogenic signaling, lead to decreased bone mass and impaired regeneration. To explore the mechanisms maintaining bone regeneration under estrogen deficiency, we randomly selected 1102 clinical cases, in which female patients aged between 18 and 75 have underwent tooth extraction in Stomatological Hospital of Tongji University, there is little difference in the healing effect of extraction defects, suggesting that to some extent, the regeneration of jawbone is insensitive to the decreased estrogen level. To illuminate the mechanisms promoting jawbone regeneration under estrogen deficiency, a tooth extraction defect model was established in the maxilla of female rats who underwent ovariectomy (OVX) or sham surgery, and jawbone marrow stromal cells (BMSCs) were isolated for single-cell sequencing. Further quantitative PCR, RNA interference, alizarin red staining, immunohistochemistry and western blotting experiments demonstrated that in the context of ovariectomy, maxillary defects promoted G protein-coupled estrogen receptor 1 (Gper1) expression, stimulate downstream cAMP/PKA/pCREB signaling, and facilitate cell proliferation, and thus provided sufficient progenitors for osteogenesis and enhanced the regeneration capacity of the jawbone. Correspondingly, the heterozygous deletion of the Gper1 gene attenuated the phosphorylation of CREB, led to decreased cell proliferation, and impaired the restoration of maxillary defects. This study demonstrates the importance of Gper1 in maintaining jawbone regeneration, especially in the context of estrogen deficiency.

Leptin receptor (+) stromal cells respond to periodontitis and attenuate alveolar bone repair via CCRL2-mediated Wnt inhibition.

The impaired bone healing in tooth extraction sockets due to periodontitis presents a major obstacle to restoring oral health. The mechanisms regulating the osteogenic capacity of jawbone-derived stromal cells in the periodontitis microenvironment remain elusive. Leptin receptor (LepR) expressing stromal cells, which largely overlap with Cxcl12-abundant reticular (CAR) cells in bone tissue, rapidly proliferate and differentiate into bone-forming cells during extraction socket healing to support alveolar bone repair. In this study, we identify that CCRL2 is significantly expressed and inhibits osteogenesis in LepR+/CAR cells of alveolar bones with periodontitis. The Ccrl2-KO mice exhibit significant improvements in bone healing in extraction sockets with periodontitis. Specifically, the binding of CCRL2 to SFRP1 on the surface of LepR+/CAR cells can amplify the suppressive effect of SFRP1 on Wnt signaling under inflammation, thus hindering the osteogenic differentiation of LepR+/CAR cells and resulting in poor bone healing in extraction sockets with periodontitis. Together, we clarify that the CCRL2 receptor of LepR+/CAR cells can respond to periodontitis and crosstalk with Wnt signaling to deteriorate extraction socket healing.

The impaired bone healing in tooth extraction sockets due to periodontitis presents a major obstacle to restoring oral health. Alterations in the cellular activity of LepR+/CAR cells, an essential stromal cell population for extraction socket healing, in the periodontitis microenvironment have yet to be determined. In this study, we identify that CCRL2, as a potent agent of inflammation-bone crosstalk, is significantly expressed and inhibits osteogenesis in LepR+/CAR cells of alveolar bones with periodontitis. Specifically, the binding of CCRL2 to SFRP1 on the surface of LepR+/CAR cells can amplify the suppressive effect of SFRP1 on the Wnt/ß-catenin signaling under inflammation, thus hindering the osteogenic differentiation of LepR+/CAR cells and resulting in poor bone healing in tooth extraction sockets with periodontitis.

A Controlled Variable Study of the Biomechanical Properties of the Proximal Femur before and after Cancellous Bone Removal.

OBJECTIVE: The biomechanical characteristics of proximal femoral trabeculae are closely related to the occurrence and treatment of proximal femoral fractures. Therefore, it is of great significance to study its biomechanical effects of cancellous bone in the proximal femur. This study examines the biomechanical effects of the cancellous bone in the proximal femur using a controlled variable method, which provide a foundation for further research into the mechanical properties of the proximal femur. METHODS: Seventeen proximal femoral specimens were selected to scan by quantitative computed tomography (QCT), and the gray values of nine regions were measure to evaluated bone mineral density (BMD) using Mimics software. Then, an intact femur was fixed simulating unilateral standing position. Vertical compression experiments were then performed again after removing cancellous bone in the femoral head, femoral neck, and intertrochanteric region, and data were recorded. According to the controlled variable method, the femoral head, femoral neck, and intertrochanteric trabeculae were sequentially removed based on the axial loading of the intact femur, and the displacement and strain changes of the femur samples under axial loading were recorded. Gom software was used to measure and record displacement and strain maps of the femoral surface. RESULTS: There was a statistically significant difference in anteroposterior displacement of cancellous bone destruction in the proximal femur (p < 0.001). Proximal femoral bone mass explained 77.5% of the strength variation, in addition proximal femoral strength was mainly affected by bone mass at the level of the upper outer, lower inner, lower greater trochanter, and lesser trochanter of the femoral head. The normal stress conduction of the proximal femur was destroyed after removing cancellous bone, the stress was concentrated in the femoral head and lateral femoral neck, and the femoral head showed a tendency to subside after destroying cancellous bone. CONCLUSION: The trabecular removal significantly altered the strain distribution and biomechanical strength of the proximal femur, demonstrating an important role in supporting and transforming bending moment under the vertical load. In addition, the strength of the proximal femur mainly depends on the bone density of the femoral head and intertrochanteric region.

Biomechanical comparison of the therapeutic effect of a novel proximal femoral bionic intramedullary nail and traditional inverted triangle hollow screw on femoral neck fracture.

OBJECTIVE: A novel Proximal Femoral Bionic Nail (PFBN) has been developed by a research team for the treatment of femoral neck fractures. This study aims to compare the biomechanical properties of the innovative PFBN with those of the conventional Inverted Triangular Cannulated Screw (ITCS) fixation method through biomechanical testing. METHODS: Sixteen male femoral specimens preserved in formalin were selected, with the donors' age at death averaging 56.1 ± 6.3 years (range 47-64 years), and a mean age of 51.4 years. The femurs showed no visible damage and were examined by X-rays to exclude diseases affecting bone quality such as tumors, severe osteoporosis, and deformities. The 16 femoral specimens were randomly divided into an experimental group (n = 8) and a control group (n = 8). All femurs were prepared with Pauwels type III femoral neck fractures, fixed with PFBN in the experimental group and ITCS in the control group. Displacement and stress limits of each specimen were measured through cyclic compression tests and failure experiments, and vertical displacement and strain values under a 600 N vertical load were measured in all specimens through vertical compression tests. RESULTS: In the vertical compression test, the average displacement at the anterior head region of the femur was 0.362 mm for the PFBN group, significantly less than the 0.480 mm for the ITCS group (p < 0.001). At the fracture line area, the average displacement for the PFBN group was also lower than that of the ITCS group (0.196 mm vs. 0.324 mm, p < 0.001). The difference in displacement in the shaft area was smaller, but the average displacement for the PFBN group (0.049 mm) was still significantly less than that for the ITCS group (0.062 mm, p = 0.016). The situation was similar on the posterior side of the femur. The average displacements in the head area, fracture line area, and shaft area for the PFBN group were 0.300 mm, 0.168 mm, and 0.081 mm, respectively, while those for the ITCS group were 0.558 mm, 0.274 mm, and 0.041 mm, with significant differences in all areas (p < 0.001). The average strain in the anterior head area for the PFBN group was 4947 µm/m, significantly less than the 1540 µm/m for the ITCS group (p < 0.001). Likewise, in the fracture line and shaft areas, the average strains for the PFBN group were significantly less than those for the ITCS group (p < 0.05). In the posterior head area, the average strain for the PFBN group was 4861 µm/m, significantly less than the 1442 µm/m for the ITCS group (p < 0.001). The strain conditions in the fracture line and shaft areas also showed the PFBN group was superior to the ITCS group (p < 0.001). In cyclic loading experiments, the PFBN fixation showed smaller maximum displacement (1.269 mm vs. 1.808 mm, p < 0.001), indicating better stability. In the failure experiments, the maximum failure load that the PFBN-fixated fracture block could withstand was significantly higher than that for the ITCS fixation (1817 N vs. 1116 N, p < 0.001). CONCLUSION: The PFBN can meet the biomechanical requirements for internal fixation of femoral neck fractures. PFBN is superior in biomechanical stability compared to ITCS, particularly showing less displacement and higher failure resistance in cyclic load and failure experiments. While there are differences in strain performance in different regions between the two fixation methods, overall, PFBN provides superior stability.

Clinical research-When it matters.

Clinical research runs through the entire progress of the science and technology which has been currently and previously applied to the medical field. It has gradually developed into a standardized procedure and played an important role in understanding the etiology and characteristics of diseases. Clinical research assess the effectiveness and safety of new/improved diagnostic or therapeutic technologies, implants, instruments, or drug applications, to discover new data and improve potential deficiencies in previous medical knowledge.

Effects of Implant Diameter on Implant Stability and Osseointegration in the Early Stage in a Dog Model.

Purpose: To determine the optimal implant diameter under limited bone width by comparing the effects of implants with different diameters on implant stability, peri-implant bone stability, and osseointegration. In addition, to evaluate the reliability of resonance frequency analysis (RFA) in detecting osseointegration and marginal bone level (MBL). Materials and Methods: Mandibular premolars and first molars of seven beagle dogs were extracted. After 8 weeks, their mandibular models and radiographic information were collected to fabricate implant templates. Implant sites were randomly divided into three groups according to diameter: Ø3.3, Ø4.1, and Ø4.8 mm. Implant stability quotient (ISQ) measurement and radiographic evaluation were performed after surgery (baseline) and at 4, 8, and 12 weeks. Three dogs were euthanized at 4 weeks to observe osteogenesis and implant-tissue interface biology. Four dogs were euthanized at 12 weeks to observe osseointegration. Hard tissue sections were prepared to analyze osteogenesis (fluorescence double labeling) and osseointegration (methylene blue-acid fuchsin staining). Results: At baseline and at 4, 8, and 12 weeks, the ISQ values of Ø4.1- and Ø4.8-mm implants did not differ (P > .05), but both had higher values than the Ø3.3-mm implants (P < .05). The mean marginal bone resorption (MBR) associated with Ø3.3-, Ø4.1-, and Ø4.8-mm implants was 0.65 ± 0.58 mm, 0.37 ± 0.28 mm, and 0.73 ± 0.37 mm, respectively. The buccal MBR of Ø4.8-mm implants was significantly higher than that of Ø4.1-mm implants (P < .05). The bone-to-implant contact (BIC) percentage at 12 weeks did not differ for any group (P > .05). The correlation coefficients between the ISQ and MBL of the Ø3.3-, Ø4.1-, and Ø4.8-mm implants were -0.84 (P < .01), -0.90 (P < .001), and -0.93 (P < .001), respectively, while that between the ISQ and BIC was 0.15 (P > .05). Conclusions: During the early healing stage, the performance of Ø4.1- and Ø4.8-mm implants in terms of implant stability was better than that of Ø3.3-mm implants. Implant diameter may not influence BIC percentage. RFA can be used to evaluate implant stability and MBL but is not suitable to assess the degree of osseointegration.

Urine PD-L1 is a tumor tissue candidate substitute and is associated with poor survival in muscle-invasive bladder cancer patients.

Programmed death molecule ligand 1 (PD-L1) expression in urothelial carcinoma is a predictive marker used to guide immunotherapy. As expression of PD-L1 may be heterogeneous in the tumor tissue space, it cannot be accurately determined by immunohistochemical analysis. In this study, we examined PD-L1 protein levels in preoperative urine samples from bladder cancer patients, evaluated the prevalence of PD-L1 in urine, examined the usefulness of urine as a surrogate for PD-L1 expression in tumors, and compared PD-L1 expression in postoperative pathological sections. We found that PD-L1 in urine and tumor tissue correlated well and that it may be able to some extent serve as a surrogate for tissues in bladder cancer and thus predict risk of recurrence in muscle-invasive bladder cancer (MIBC) patients. Our findings reveal the clinical relevance of urine PD-L1 as a noninvasive prognostic indicator for immunotherapy and offer clinical translational suggestions for eventual development of a prognostic model for immunotherapy for bladder cancer.

Biomechanical properties and clinical significance of cancellous bone in proximal femur: A review.

Trabecular bone plays an important role in the load-bearing capacity of the femur. Understanding the structural characteristics, biomechanics, and mechanical conduction of the trabecular bone is of great value in studying the mechanism of fractures and formulating surgical plans. The past decade has witnessed unprecedented progress in imaging, biomechanics and finite element analysis techniques, translating into a better understanding of trabecular bone. This article reviews the research progress achieved over the years regarding femoral trabecular bone, especially on factors influencing the strength of the proximal femoral cancellous bone and cancellous bone microfractures and provides a comprehensive overview of the latest findings on proximal femoral trabecular bone and their clinical significance.