The role of bone marrow on the mechanical properties of trabecular bone: a systematic review.

BACKGROUND: Accurate evaluation of the mechanical properties of trabecular bone is important, in which the internal bone marrow plays an important role. The aim of this systematic review is to investigate the roles of bone marrow on the mechanical properties of trabecular bone to better support clinical work and laboratory research. METHODS: A systematic review of the literature published up to June 2022 regarding the role of bone marrow on the mechanical properties of trabecular bone was performed, using PubMed and Web of Science databases. The journal language was limited to English. A total of 431 articles were selected from PubMed (n = 186), Web of Science (n = 244) databases, and other sources (n = 1). RESULTS: After checking, 38 articles were finally included in this study. Among them, 27 articles discussed the subject regarding the hydraulic stiffening of trabecular bone due to the presence of bone marrow. Nine of them investigated the effects of bone marrow on compression tests with different settings, i.e., in vitro experiments under unconfined and confined conditions, and computer model simulations. Relatively few controlled studies reported the influence of bone marrow on the shear properties of trabecular bone. CONCLUSION: Bone marrow plays a non-neglectable role in the mechanical properties of trabecular bone, its contribution varies depending on the different loading types and test settings. To obtain the mechanical properties of trabecular bone comprehensively and accurately, the solid matrix (trabeculae) and fluid-like component (bone marrow) should be considered in parallel rather than tested separately.

A Study to Compare the Efficacy of a Biodegradable Dynamic Fixation System With Titanium Devices in Posterior Spinal Fusion Between Articular Processes in a Canine Model.

The objective of this study was to apply a biodegradable dynamic fixation system (BDFS) for lumbar fusion between articular processes and compare the fusion results and biomechanical changes with those of conventional rigid fixation. Twenty-four mongrel dogs were randomly assigned to 2 groups and subjected to either posterior lumbar fusion surgery with a BDFS or titanium rods (TRs) at the L5-L6 segments. Six animals in each group were sacrificed at 8 or 16 weeks. Fusion conditions were evaluated by computed tomography (CT), manual palpation, biomechanical tests, and histological analysis. Biomechanical tests were performed at the L4-7 (for range of motion (ROM)) and L5-6 (for fusion stiffness) segments. Histological examination was performed on organs, surrounding tissues, and the fused area. The magnesium alloy components maintained their initial shape 8 weeks after the operation, but the meshing teeth were almost completely degraded at 16 weeks. The biomechanical analysis revealed an increased lateral bending ROM at 8 weeks and axial torsion ROM at 16 weeks. The L4-5 extension-flexion ROMs in the BDFS group were 2.29 ± 0.86 deg and 3.17 ± 1.08 deg at 16 weeks, respectively, compared with 3.22 ± 0.56 deg and 5.55 ± 1.84 deg in TR group. However, both groups showed similar fusion results. The BDFS design is suitable, and its degradation in vivo is safe. The BDFS can be applied for posterior lumbar fusion between articular processes to complete the fusion well. Additionally, the BDFS can reduce the decline in lateral motion and hypermotion of the cranial adjacent segment in flexion-extension motion.

Calcium-sensing receptor activating ERK1/2 and PI3K-Akt pathways to induce the proliferation of osteosarcoma cells.

Our results showed that the expression of calcium-sensing receptor (CaSR) and the concentration of intracellular calcium were enhanced in the osteosarcoma cells MG-63 compared with in the normal osteoblasts hFOB1.19. GdCl3 (CaSR agonist) significantly increased the proliferation rate of MG-63 cells, the expression of PCNA and Cyclin D1 and decreased the expression of p21Cip/WAF-1 . The effect of NPS2390 (CaSR antagonist) on the above indicators was opposite to GdCl3 . In addition, GdCl3 up-regulated the phosphorylation of ERK1/2, PI3K and Akt and the proliferation rate of MG-63 cells. However, these effects of GdCl3 were cancelled by LY294002 (a PI3K inhibitor) or PD98059 (an ERK1/2 inhibitor). Our results demonstrate that activation of CaSR promotes osteosarcoma cell multiplication by up-regulating ERK1/2 and PI3K-Akt pathways.

The Posttraumatic Increase in the Adhesion of GPCR EMR2/ADGRE2 to Circulating Neutrophils Is Not Related to Injury Severity.

Trauma triggers a rapid innate immune response to aid the clearance of damaged/necrotic cells and their released damage-associated molecular pattern (DAMP). Here, we monitored the expression of EMR2/ADGRE2, involved in the functional regulation of innate immune cells, on circulating neutrophils in very severely and moderately/severely injured patients up to 240 h after trauma. Notably, neutrophilic EMR2 showed a uniform, injury severity- and type of injury-independent posttraumatic course in all patients. The percentage of EMR2+ neutrophils and their EMR2 level increased and peaked 48 h after trauma. Afterwards, they declined and normalized in some, but not all, patients. Circulating EMR2+ compared to EMR2- neutrophils express less CD62L and more CD11c, a sign of activation. Neutrophilic EMR2 regulation was verified in vitro. Remarkably, it increased, depending on extracellular calcium, in controls as well. Cytokines, enhanced in patients immediately after trauma, and sera of patients did not further affect this neutrophilic EMR2 increase, whereas apoptosis induction disrupted it. Likely the damaged/necrotic cells/DAMPs, unavoidable during neutrophil culture, stimulate the neutrophilic EMR2 increase. In summary, the rapidly increased absolute number of neutrophils, especially present in very severely injured patients, together with upregulated neutrophilic EMR2, may expand our in vivo capacity to react to and finally clear damaged/necrotic cells/DAMPs after trauma.

To Detach, Migrate, Adhere, and Metastasize: CD97/ADGRE5 in Cancer.

Tumorigenesis is a multistep process, during which cells acquire a series of mutations that lead to unrestrained cell growth and proliferation, inhibition of cell differentiation, and evasion of cell death. Growing tumors stimulate angiogenesis, providing them with nutrients and oxygen. Ultimately, tumor cells invade the surrounding tissue and metastasize; a process responsible for about 90% of cancer-related deaths. Adhesion G protein-coupled receptors (aGPCRs) modulate the cellular processes closely related to tumor cell biology, such as adhesion and detachment, migration, polarity, and guidance. Soon after first being described, individual human aGPCRs were found to be involved in tumorigenesis. Twenty-five years ago, CD97/ADGRE5 was discovered to be induced in one of the most severe tumors, dedifferentiated anaplastic thyroid carcinoma. After decades of research, the time has come to review our knowledge of the presence and function of CD97 in cancer. In summary, CD97 is obviously induced or altered in many tumor entities; this has been shown consistently in nearly one hundred published studies. However, its high expression at circulating and tumor-infiltrating immune cells renders the systemic targeting of CD97 in tumors difficult.

Selected mechanical properties of human cancellous bone subjected to different treatments: short-term immersion in physiological saline and acetone treatment with subsequent immersion in physiological saline.

BACKGROUND: Physiological saline (0.9% NaCl) and acetone are extensively used for storage (as well as hydration) and removal of bone marrow, respectively, of cancellous bone during preparation and mechanical testing. Our study aimed to investigate the mechanical properties of cancellous bone subjected to short-term immersion in saline and acetone treatment with subsequent immersion in saline. METHODS: Cylindrical samples (Ø6 × 12 mm) were harvested from three positions (left, middle, and right) of 1 thoracic vertebral body, 19 lumbar vertebral bodies, and 5 sacral bones, as well as from 9 femoral heads. All samples were divided into two groups according to the different treatments, (i) samples from the left and middle sides were immersed in saline at 4℃ for 43 h (saline-immersed group, n = 48); (ii) samples from the respective right side were treated with a combination of acetone and ultrasonic bath (4 h), air-dried at room temperature (21℃, 15 h), and then immersed in saline at room temperature (21℃, 24 h) (acetone and saline-treated group, n = 38). All samples were subjected, both before and after treatment, to a non-destructive compression test with a strain of 0.45%, and finally destructive tests with a strain of 50%. Actual density (ρact), initial modulus (E0), maximum stress (σmax), energy absorption (W), and plateau stress (σp) were calculated as evaluation indicators. RESULTS: Based on visual observation, a combination of acetone and ultrasonic bath for 4 h failed to completely remove bone marrow from cancellous bone samples. The mean values of ρact, σmax, W, and σp were significantly higher in the femoral head than in the spine. There was no significant difference in E0 between non-treated and saline-immersed samples (non-treated 63.98 ± 20.23 vs. saline-immersed 66.29 ± 20.61, p = 0.132). The average E0 of acetone and saline-treated samples was significantly higher than that of non-treated ones (non-treated 62.17 ± 21.08 vs. acetone and saline-treated 74.97 ± 23.98, p = 0.043). CONCLUSION: Short-term storage in physiological saline is an appropriate choice and has no effect on the E0 of cancellous bone. Treatment of cancellous bone with acetone resulted in changes in mechanical properties that could not be reversed by subsequent immersion in physiological saline.

Methods for bone quality assessment in human bone tissue: a systematic review.

BACKGROUND: For biomechanical investigations on bone or bone implants, bone quality represents an important potential bias. Several techniques for assessing bone quality have been described in the literature. This study aims to systematically summarize the methods currently available for assessing bone quality in human bone tissue, and to discuss the advantages and limitations of these techniques. METHODS: A systematic review of the literature was carried out by searching the PubMed and Web of Science databases from January 2000 to April 2021. References will be screened and evaluated for eligibility by two independent reviewers as per PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Studies must apply to bone quality assessment with imaging techniques, mechanical testing modalities, and compositional characterization. The terms used for the systematic search were: "(bone quality". Ti,ab.) AND "(human bone specimens)". RESULTS: The systematic review identified 502 relevant articles in total. Sixty-eight articles met the inclusion criteria. Among them, forty-seven articles investigated several imaging modalities, including radiography, dual-energy X-ray absorptiometry (DEXA), CT-based techniques, and MRI-based methods. Nineteen articles dealt with mechanical testing approaches, including traditional testing modalities and novel indentation techniques. Nine articles reported the correlation between bone quality and compositional characterization, such as degree of bone mineralization (DBM) and organic composition. A total of 2898 human cadaveric bone specimens were included. CONCLUSIONS: Advanced techniques are playing an increasingly important role due to their multiple advantages, focusing on the assessment of bone morphology and microarchitecture. Non-invasive imaging modalities and mechanical testing techniques, as well as the assessment of bone composition, need to complement each other to provide comprehensive and ideal information on the bone quality of human bone specimens.

A novel dynamic fixation system with biodegradable components on lumbar fusion between articular processes in a canine model.

The objective of this study was to design a novel dynamic fixation system with biodegradable components, apply it for lumbar fusion between articular processes and compare the fusion results and biomechanical changes to those of conventional rigid fixation. The novel dynamic fixation system was designed using a finite element model, stress distributions were compared and 24 mongrel dogs were randomly assigned to two groups and subjected to either posterior lumbar fusion surgery with a novel dynamic fixation system or titanium rods at the L5-L6 segments. Lumbar spines were assessed in both groups to detect radiographic, manual palpation and biomechanical changes. Histological examination was performed on organs and surrounding tissues. In the novel dynamic fixation system, stress was mainly distributed on the meshing teeth of the magnesium alloy spacer. The magnesium alloy components maintained their initial shape 8 weeks after the operation, but the meshing teeth were almost completely degraded at 16 weeks. The novel dynamic fixation system revealed an increased lateral bending range of motion at 8 weeks; however, both groups showed similar radiographic grades, fusion stiffness, manual palpation and histological results. The novel dynamic fixation system design is suitable, and its degradation in vivo is safe. The novel dynamic fixation system can be applied for posterior lumbar fusion between articular processes and complete the fusion like titanium rods.

The Prevalence of HBV Infection: A Retrospective Study of 13 Years in a Public Hospital of Northeast China.

The prevalence of hepatitis B virus (HBV) infection was an imbalance in different provinces of China. This study aimed to investigate the prevalence of HBV infection and evaluate the prophylactic measures in a public hospital of northeast China over the preceding 13 years. A total of 13,948 patients in 2004 and 15,256 patients in 2017 of Shengjing Hospital of China Medical University were tested of serum HBsAg, HBeAg, HBsAb, HBeAb, and HBcAb levels with Abbott MEIA Kits. In people born before 1992, HBsAg-positive rate was 5.45% and 6.47%; isolated HBsAb positive rate was 14.62% and 21.24%; HBV marker negative rate was 54.27% and 42.77% in 2004 and 2017 survey, respectively. The males had a significant higher HBsAg-positive rate than the females. In people born during 1992-2004, HBsAg positive rate was 0.58% and 0.57%, isolated HBsAb positive rate was 41.47% and 46.57%; and HBV marker negative rate was 51.97% and 46.86% in 2004 and 2017 survey, respectively. Males and females had no difference of HBsAg-positive rate. In children born after 2005, HBsAg positive rate was 0.11%, isolated HBsAb positive rate was 76.68%, and HBV marker negative rate was 18.51% in 2017 survey. No difference of HBsAg-positive rate was found between the genders. A dramatic decrease of HBsAg positive rate and a progressive increase of HBsAb-positive rate were found among people born after 1992 and progressed further in those born after 2005. Immunization of infants and timely birth dose was the key method for prevention of HBV infection. Expanded HB vaccination would be needed for people born before 2005, especially those born between 1992 and 2004.

Chitosan-Gelatin Scaffolds Incorporating Decellularized Platelet-Rich Fibrin Promote Bone Regeneration.

Platelet-rich fibrin (PRF), which functions as a growth factor carrier, has been extensively used to promote soft and hard tissue repair. However, whether decellularized PRF (DPRF) maintains its bioactive effects is unknown. Chitosan/gelatin(C/G) base scaffolds display appropriate biocompatibility and mechanical properties, but they lack biological activity. Thus, the incorporation of DPRF into the C/G scaffold can theoretically improve both the bioactivity of the C/G scaffold and the strength of PRF. In this study, DPRF was prepared using a method combining repeated freeze-thawing and enzymatic digestion. Also, DPRF-loaded chitosan-gelatin scaffolds (C/G/DPRF) were fabricated, using C/G scaffolds as controls. The osteogenic potential of scaffolds was investigated in vitro and in vivo. Compared with the C/G scaffold, C/G/DPRF had a larger pore size (280.8 ± 11.7 µm vs 235.0 ± 11.6 µm; P < 0.05), increased water uptake ratio (13.90 ± 0.09 vs 11.05 ± 0.10; P < 0.05), and similar porosity (90.50 ± 0.87 vs 90.65 ± 0.67; P > 0.05) but reduced compressive modulus (0.81 ± 0.02 MPa vs 1.17 ± 0.05 MPa; P < 0.05). In vitro, C/G/DPRF scaffolds accelerated attachment, proliferation, and osteogenesis-related marker expression of bone marrow stem cells. In vivo, C/G/DPRF scaffolds led to enhanced bone healing and defect closure in a rat calvarial defect model. Thus, we concluded that DPRF remains bioactive and the prepared C/G/DPRF scaffold is a promising material for bone regeneration.