Mechanism of Action of Mesenchymal Stem Cell-Derived Exosomes in the Intervertebral Disc Degeneration Treatment and Bone Repair and Regeneration

Exosomes are extracellular vesicles formed by various donor cells that regulate gene expression and cellular function in recipient cells. Exosomes derived from mesenchymal stem cells (MSC-Exos) perform the regulatory function of stem cells by transporting proteins, nucleic acids, and lipids. Intervertebral disc degeneration (IDD) is one of the main causes of low back pain, and it is characterized by a decreased number of nucleus pulposus cells, extracellular matrix decomposition, aging of the annulus fibrosus, and cartilage endplate calcification. Besides, nutrient transport and structural repair of intervertebral discs depend on bone and cartilage and are closely related to the state of the bone. Trauma, disease and aging can all cause bone injury. However, there is a lack of effective drugs against IDD and bone injury. Recent MSC-Exos fine tuning has led to significant progress in the IDD treatment and bone repair and regeneration. In this review, we looked at the uniqueness of MSC-Exos, and the potential treatment mechanisms of MSC-Exos with respect to IDD, bone defects and injuries.

Role of Macrophages and Plasminogen Activator Inhibitor-1 in Delayed Bone Repair Induced by Glucocorticoids in Mice

Glucocorticoids delay fracture healing and induce osteoporosis. However, the mechanisms by which glucocorticoids delay bone repair have yet to be clarified. Plasminogen activator inhibitor-1 (PAI-1) is the principal inhibitor of plasminogen activators and an adipocytokine that regulates metabolism. We herein investigated the roles of macrophages in glucocorticoid-induced delays in bone repair after femoral bone injury using PAI-1-deficient female mice intraperitoneally administered with dexamethasone (Dex). Dex significantly decreased the number of F4/80-positive macrophages at the damaged site two days after femoral bone injury. It also attenuated bone injury-induced decreases in the number of hematopoietic stem cells in bone marrow in wild-type and PAI-1-deficient mice. PAI-1 deficiency significantly weakened Dex-induced decreases in macrophage number and macrophage colony-stimulating factor (M-CSF) mRNA levels at the damaged site two days after bone injury. It also significantly ameliorated the Dex-induced inhibition of macrophage phagocytosis at the damaged site. In conclusion, we herein demonstrated that Dex decreased the number of macrophages at the damaged site during early bone repair after femoral bone injury partly through PAI-1 and M-CSF in mice.

Role of yoga prana vidya healing techniques in successful and speedy recovery of orthopaedic cases of bone injuries and fractures: a multiple case study

<p class="abstract">Bones form a vital part of the skeletal system providing mechanical support, strength, structure and protection to the human body. Inability of the bone to resist any kind of stress caused accidently can result in a bone injury or a fracture. This article provides a summary of eleven cases of bone injury and fracture treated successfully by yoga prana vidya (YPV) techniques as a complementary medicine for faster recovery. The study was carried out by two healers who independently healed eleven cases of bone injury and fracture using the bone regeneration techniques of YPV. Further, the data was collected and the results were analysed. By application of YPV healing techniques complementarily, it is observed that full recovery took place within 10 days to 45 days for the 3 hospitalised cases, and within 3 to 8 days for the two patients who had bandage/dressing done at a medical facility. In case of the remaining 6 patients who sought YPV healing help in preference to seeking medical help the recovery took place within 5 to 20 days. helping the patients to lead a normal life thereafter. It is observed that YPV techniques can be used for faster recovery of patients with injured and fractured bones. This paper shows the successful results when the techniques were applied on eleven participants. It is recommended to conduct further studies on a larger scale for the healing of bone related cases such as injury and fractures.</p>

Integrated computational and in vivo models reveal Key Insights into Macrophage Be-havior during bone healing

Myeloid-derived monocyte and macrophages are key cells in the bone that contribute to remod-eling and injury repair. However, their temporal polarization status and control of bone-resorbing osteoclasts and bone-forming osteoblasts responses is largely unknown. In this study, we fo-cused on two aspects of monocyte/macrophage dynamics and polarization states over time: 1) the injury-triggered pro- and anti-inflammatory monocytes/macrophages temporal profiles, 2) the contributions of pro- versus anti-inflammatory monocytes/macrophages in coordinating healing response. Bone healing is a complex multicellular dynamic process. While traditional in vitro and in vivo experimentation may capture the behavior of select populations with high resolution, they cannot simultaneously track the behavior of multiple populations. To address this, we have used an integrated a coupled ordinary differential equations (ODEs)-based framework describing mul-tiple cellular species to in vivo bone injury data in order to identify and test various hypotheses regarding bone cell populations dynamics. Our approach allowed us to infer several biological insights including, but not limited to,: 1) anti-inflammatory macrophages are key for early osteo-clast inhibition and pro-inflammatory macrophage suppression, 2) pro-inflammatory macrophag-es are involved in osteoclast bone resorptive activity, whereas osteoblasts promote osteoclast differentiation, 3) Pro-inflammatory monocytes/macrophages rise during two expansion waves, which can be explained by the anti-inflammatory macrophages-mediated inhibition phase be-tween the two waves. In addition, we further tested the robustness of the mathematical model by comparing simulation results to an independent experimental dataset. Taken together, this novel comprehensive mathematical framework allowed us to identify biological mechanisms that best recapitulate bone injury data and that explain the coupled cellular population dynamics involved in the process. Furthermore, our hypothesis testing methodology could be used in other contexts to decipher mechanisms in complex multicellular processes.

Periostin - A biomarker in adults with asthma

<p>Asthma is a common, heterogeneous condition where current treatment options are limited to a ‘one size fits all’ approach. Biological therapies targeting specific components of the Type 2 inflammatory pathway are emerging as potential alternatives for those who are inadequately controlled on current treatment options. Biomarkers, such as serum periostin, can be used in clinical settings to identify potential responders to these treatments. The aim of this research was to investigate the epidemiology of periostin and its ability to predict important clinical outcomes in asthma. Six studies were conducted: two cohort studies observing the change to periostin after bone and dental injury in non-asthmatic adults; a cohort study investigating reference ranges of periostin in Chinese adults with and without asthma; two longitudinal studies measuring the change in periostin in asthmatic adults with stable and unstable disease; and a longitudinal cohort study investigating the association between periostin and risk of exacerbation. There was a biphasic response of serum periostin after bone injury. This was particularly marked after joint replacement surgery where periostin fell within 48 hours by a ratio of geometric means 0.80 (95% CI 0.75 to 0.86) before rising to a maximum level at eight weeks with a ratio of geometric means 1.89 (95% CI 1.77 to 2.02). There was no significant change to periostin after simple or surgical tooth extractions with a maximal ratio of geometric means of 1.02 (95% CI 0.95 to 1.10). Serum periostin was higher in Chinese non-asthmatic adults versus Caucasian non- asthmatic adults, mean periostin 57 ng/ml and 49.7 ng/ml respectively, difference (95% CI) 8.2 (5.8 to 10.6) ng/ml. Serum periostin remained stable in adults with well- controlled asthma with an intra-class coefficient for variation of 0.93. In unstable asthma, there was a decrease in serum periostin one week after the start of a severe exacerbation and treatment with systemic corticosteroids, with a ratio of geometric means 0.86 (95% CI 0.82 to 0.92) before stabilising four weeks later. Finally, adults with mild to moderate asthma with low baseline levels of periostin were more likely to have a severe asthma exacerbation with a hazard ratio (95% CI) 0.62 (0.35 to 1.09) per 0.693 ng/ml increase of log periostin. In conclusion, serum periostin showed significant biphasic variation in response to bone injury, the magnitude and duration of which was proportional to bone size. Whilst this pattern was not replicated in adults undergoing dental surgery, it suggests that serum periostin can be affected by non-asthma related conditions. Periostin demonstrated higher mean values in Chinese adults than in Caucasian adults, indicating ethnicity-specific reference ranges may be required if it were to become a clinical biomarker. Intra-participant variability of serum periostin was low in a homogenous group of well controlled, moderate to severe asthmatic adults, but there was wide variability between individuals in this group suggesting that factors other than asthma are likely to affect serum periostin levels. Serum periostin was suppressed during and after treatment for a severe exacerbation for up to four weeks. This is likely due to the exacerbation and/or its treatment, suggesting the interpretation of periostin as a biomarker for response to biological therapies should not occur within four weeks of a severe exacerbation. The reported positive association between periostin and risk of severe exacerbation in populations with severe eosinophilic asthma does not extend to a general population of mild to moderate asthmatics, in which an inverse associated was observed. Serum periostin may be useful in predicting treatment responsiveness of patients to monoclonal antibody therapy directed against IL-4Rα, IL-13 and IgE. However, it may be difficult to use as a biomarker clinically, as numerous non-asthma related factors, such as bone injury and ethnicity, have been shown to significantly affect serum levels, making interpretation difficult.</p>

Periostin - A biomarker in adults with asthma

<p>Asthma is a common, heterogeneous condition where current treatment options are limited to a ‘one size fits all’ approach. Biological therapies targeting specific components of the Type 2 inflammatory pathway are emerging as potential alternatives for those who are inadequately controlled on current treatment options. Biomarkers, such as serum periostin, can be used in clinical settings to identify potential responders to these treatments. The aim of this research was to investigate the epidemiology of periostin and its ability to predict important clinical outcomes in asthma. Six studies were conducted: two cohort studies observing the change to periostin after bone and dental injury in non-asthmatic adults; a cohort study investigating reference ranges of periostin in Chinese adults with and without asthma; two longitudinal studies measuring the change in periostin in asthmatic adults with stable and unstable disease; and a longitudinal cohort study investigating the association between periostin and risk of exacerbation. There was a biphasic response of serum periostin after bone injury. This was particularly marked after joint replacement surgery where periostin fell within 48 hours by a ratio of geometric means 0.80 (95% CI 0.75 to 0.86) before rising to a maximum level at eight weeks with a ratio of geometric means 1.89 (95% CI 1.77 to 2.02). There was no significant change to periostin after simple or surgical tooth extractions with a maximal ratio of geometric means of 1.02 (95% CI 0.95 to 1.10). Serum periostin was higher in Chinese non-asthmatic adults versus Caucasian non- asthmatic adults, mean periostin 57 ng/ml and 49.7 ng/ml respectively, difference (95% CI) 8.2 (5.8 to 10.6) ng/ml. Serum periostin remained stable in adults with well- controlled asthma with an intra-class coefficient for variation of 0.93. In unstable asthma, there was a decrease in serum periostin one week after the start of a severe exacerbation and treatment with systemic corticosteroids, with a ratio of geometric means 0.86 (95% CI 0.82 to 0.92) before stabilising four weeks later. Finally, adults with mild to moderate asthma with low baseline levels of periostin were more likely to have a severe asthma exacerbation with a hazard ratio (95% CI) 0.62 (0.35 to 1.09) per 0.693 ng/ml increase of log periostin. In conclusion, serum periostin showed significant biphasic variation in response to bone injury, the magnitude and duration of which was proportional to bone size. Whilst this pattern was not replicated in adults undergoing dental surgery, it suggests that serum periostin can be affected by non-asthma related conditions. Periostin demonstrated higher mean values in Chinese adults than in Caucasian adults, indicating ethnicity-specific reference ranges may be required if it were to become a clinical biomarker. Intra-participant variability of serum periostin was low in a homogenous group of well controlled, moderate to severe asthmatic adults, but there was wide variability between individuals in this group suggesting that factors other than asthma are likely to affect serum periostin levels. Serum periostin was suppressed during and after treatment for a severe exacerbation for up to four weeks. This is likely due to the exacerbation and/or its treatment, suggesting the interpretation of periostin as a biomarker for response to biological therapies should not occur within four weeks of a severe exacerbation. The reported positive association between periostin and risk of severe exacerbation in populations with severe eosinophilic asthma does not extend to a general population of mild to moderate asthmatics, in which an inverse associated was observed. Serum periostin may be useful in predicting treatment responsiveness of patients to monoclonal antibody therapy directed against IL-4Rα, IL-13 and IgE. However, it may be difficult to use as a biomarker clinically, as numerous non-asthma related factors, such as bone injury and ethnicity, have been shown to significantly affect serum levels, making interpretation difficult.</p>

Fracture healing is delayed in the absence of gasdermin signaling

Amino-terminal fragments from proteolytically cleaved gasdermins (GSDMs) form plasma membrane pores that enable the secretion of interleukin-1β (IL-1β) and IL-18. Excessive GSDM-mediated pore formation can compromise the integrity of the plasma membrane thereby causing the lytic inflammatory cell death, pyroptosis. We found that GSDMD and GSDME were the only GSDMs that were readily expressed in bone microenvironment. Therefore, we tested the hypothesis that GSDMD and GSDME are implicated in fracture healing owing to their role in the obligatory inflammatory response following injury. We found that bone callus volume and biomechanical properties of injured bones were significantly reduced in mice lacking either GSDM compared with wild-type (WT) mice, indicating that fracture healing was compromised in mutant mice. However, compound loss of GSDMD and GSDME did not exacerbate the outcomes, suggesting shared actions of both GSDMs in fracture healing. Mechanistically, bone injury induced IL-1β and IL-18 secretion in vivo, a response that was mimicked in vitro by bone debris and ATP, which function as inflammatory danger signals. Importantly, the secretion of these cytokines was attenuated in conditions of GSDMD deficiency. Finally, deletion of IL-1 receptor reproduced the phenotype of Gsdmd or Gsdme deficient mice, implying that inflammatory responses induced by the GSDM-IL-1 axis promote bone healing after fracture.

Treatment of Radiation Bone Injury with Transplanted hUCB-MSCs via Wnt/β-Catenin

Radiation-induced bone injury (RIBI) is one of the complications after radiotherapy for malignant tumors. However, there are no effective measures for the treatment of RIBI in clinical practice, and the mechanism of RIBI is unclear. We use a single high-dose ionizing radiation (6Gy) to analyze the effect of radiotherapy on osteoblast function. Human umbilical cord blood mesenchymal stem cells (hUCB-MSCs) were cocultured with irradiated osteoblasts to examine their therapeutic effects and mechanisms on osteoblast injury. The hUCB-MSC transplantation mouse model is used to confirm the in vivo role of hUCB-MSC treatment in radiation bone injury. Western blot analysis, qRT-PCR, immunohistochemistry, and immunofluorescence staining were used to analyze gene expression and angiogenesis. The apoptosis and migration of osteoblasts were measured by Hoechst staining, scratch test, and transwell. The differentiation of osteoblasts was measured by ALP and Alizarin red staining and transmission electron microscopy. The bone-related parameters of mice were evaluated by micro-CT analysis. We found that radiation can damage the DNA of osteoblasts; induce apoptosis; reduce the differentiation, migration, and adhesion of osteoblasts, leading to lipogenesis of bone marrow mesenchymal stem cells (BMSCs) and reducing the source of osteoblasts; and increase the number of osteoclasts in bone tissue, while MSC treatment prevents these changes. Our results reveal the inhibitory effect of radiation on osteoblast function. hUCB-MSCs can be used as a therapeutic target for the development of new therapeutic strategies for radiotherapy of bone injury diseases.

Mathematical Modelling of Destabilization Stress Factors of Stable-Elastic Fixation of Distal Trans- and Suprasyndesmotic Fibular Fractures

Introduction. Specification of possible stress factors destabilizing the fibula stable osteosynthesis by the intramedullary nail with distal blocking and elastic fixation of distal syndesmosis by the thread with endobuttons by mathematical modelling of distal unstable ankle injuries. Material and Methods. We studied the thread tension during the combined stable-elastic fixation of unstable injuries of the ankle joint in cross-syndesmosis fractures of the fibula (B, C Danis–Weber classification), which includes a one-time stable minimally invasive fixation with the intramedullary nail and elastic fixation by the thread with endobuttons. We used a titanium alloy for the intramedullary nail and polyester for the thread. The deformed state was studied using the methods of mechanics. Results. A model of a fractured fibula blocked with the intramedullary nail and fixed with the elastic thread was developed. A formulation to specify the rational tension forces of the elastic thread depending on the parameters of the fibula and intramedullary blocking nail and on the location of the bone injury was obtained. The effect of foot rotation on the thread tension was investigated. The results of theoretical research should be implemented in medical practice. Conclusions. A mathematical model of the damaged fibula blocked by the intramedullary nail and fixed with the elastic thread was developed. Dependences for calculation of tension of the fixing thread were obtained. A slight increase in thread tension during foot rotation was found.

The effect of cartilage decellularized extracellular matrix-chitosan compound on treating knee osteoarthritis in rats

Knee osteoarthritis (KOA) refers to a common disease in orthopaedics, whereas effective treatments have been rarely developed. As indicated from existing studies, chondrocyte death, extracellular matrix degradation and subchondral bone injury are recognized as the pathological basis of KOA. The present study aimed to determine the therapeutic effect of decellularized extracellular matrix-chitosan (dECM-CS) compound on KOA. In this study, rat knee cartilage was decellularized, and a satisfactory decellularized extracellular matrix was developed. As suggested from the in vitro experiments, the rat chondrocytes co-cultured with allogeneic dECM grew effectively. According to the results of the alamar blue detection, dECM did not adversely affect the viability of rat chondrocytes, and dECM could up-regulate the genes related to the cartilage synthesis and metabolism. As reported from the animal experiments, dECM-CS compound could protect cartilage, alleviate knee joint pain in rats, significantly delay the progress of KOA in rats, and achieve high drug safety. In brief, dECM-CS compound shows a good therapeutic effect on KOA.