Effects of short-term exercise and endurance training on skeletal muscle mitochondria damage induced by particular matter, atmospherically relevant artificial PM2.5.

Introduction: This study aimed to investigate the potential of short-term aerobic exercise to mitigate skeletal muscle mitochondrial damage following ambient PM2.5 exposure, and how 12 weeks of endurance training can enhance aerobic fitness to protect against such damage. Methods: Twenty-four male C57BL/6 J mice were split into sedentary (SED, n = 12) and endurance training (ETR, n = 12) groups. The ETR group underwent 12 weeks of training (10-15 m/min, 60 min/day, 4 times/week), confirmed by an Endurance Exercise Capacity (EEC) test. Post-initial training, the SED group was further divided into SSED (SED and sedentary, n = 6) and SPE (SED and PM2.5 + Exercise, n = 6). Similarly, the ETR group was divided into EEX (ETR and Exercise, n = 6) and EPE (ETR and PM2.5 + Exercise, n = 6). These groups underwent 1 week of atmospherically relevant artificial PM2.5 exposure and treadmill running (3 times/week). Following treatments, an EEC test was conducted, and mice were sacrificed for blood and skeletal muscle extraction. Blood samples were analyzed for oxidative stress indicators, while skeletal muscles were assessed for mitochondrial oxidative metabolism, antioxidant capacity, and mitochondrial damage using western blot and transmission electron microscopy (TEM). Results: After 12 weeks of endurance training, the EEC significantly increased (p < 0.000) in the ETR group compared to the SED group. Following a one-week comparison among the four groups with atmospherically relevant artificial PM2.5 exposure and exercise treatment post-endurance training, the EEX group showed improvements in EEC, oxidative metabolism, mitochondrial dynamics, and antioxidant functions. Conversely, these factors decreased in the EPE group compared to the EEX. Additionally, within the SPE group, exercise effects were evident in HK2, LDH, SOD2, and GPX4, while no impact of short-term exercise was observed in all other factors. TEM images revealed no evidence of mitochondrial damage in both the SED and EEX groups, while the majority of mitochondria were damaged in the SPE group. The EPE group also exhibited damaged mitochondria, although significantly less than the SPE group. Conclusion: Atmospherically relevant artificial PM2.5 exposure can elevate oxidative stress, potentially disrupting the benefits of short-term endurance exercise and leading to mitochondrial damage. Nonetheless, increased aerobic fitness through endurance training can mitigate PM2.5-induced mitochondrial damage.

Osteoblastic Wls Ablation Protects Mice from Total Body Irradiation-Induced Impairments in Hematopoiesis and Bone Marrow Microenvironment.

Ionizing irradiation (IR) causes bone marrow (BM) injury, with senescence and impaired self-renewal of hematopoietic stem cells (HSCs), and inhibiting Wnt signaling could enhance hematopoietic regeneration and survival against IR stress. However, the underlying mechanisms by which a Wnt signaling blockade modulates IR-mediated damage of BM HSCs and mesenchymal stem cells (MSCs) are not yet completely understood. We investigated the effects of osteoblastic Wntless (Wls) depletion on total body irradiation (TBI, 5 Gy)-induced impairments in hematopoietic development, MSC function, and the BM microenvironment using conditional Wls knockout mutant mice (Col-Cre;Wlsfl/fl) and their littermate controls (Wlsfl/fl). Osteoblastic Wls ablation itself did not dysregulate BM frequency or hematopoietic development at a young age. Exposure to TBI at 4 weeks of age induced severe oxidative stress and senescence in the BM HSCs of Wlsfl/fl mice but not in those of the Col-Cre;Wlsfl/fl mice. TBI-exposed Wlsfl/fl mice exhibited greater impairments in hematopoietic development, colony formation, and long-term repopulation than TBI-exposed Col-Cre;Wlsfl/fl mice. Transplantation with BM HSCs or whole BM cells derived from the mutant, but not Wlsfl/fl mice, protected against HSC senescence and hematopoietic skewing toward myeloid cells and enhanced survival in recipients of lethal TBI (10 Gy). Unlike the Wlsfl/fl mice, the Col-Cre;Wlsfl/fl mice also showed radioprotection against TBI-mediated MSC senescence, bone mass loss, and delayed body growth. Our results indicate that osteoblastic Wls ablation renders BM-conserved stem cells resistant to TBI-mediated oxidative injuries. Overall, our findings show that inhibiting osteoblastic Wnt signaling promotes hematopoietic radioprotection and regeneration.

Exposure of newborns to atmospherically relevant artificial particulate matter induces hematopoietic stem cell senescence.

Research on the negative impacts of PM2.5 have been focused on lung, brain, immune, and metabolism-related diseases. However, little is known about the mechanism underlying the effects of PM2.5 on the modulation of hematopoietic stem cell (HSC) fate. Maturation of the hematopoietic system and differentiation of hematopoietic stem progenitor cells (HSPCs) occurs soon after birth when infants are susceptible to external stresses. We investigated how exposure to atmospherically relevant artificial particulate matter of diameter < 2.5 µm (termed, PM2.5) affects HSPCs in newborns. The lungs of newborn mice exposed to PM2.5 exhibited higher levels of oxidative stress and inflammasome activation, which continued during aging. PM2.5 also stimulated oxidative stress and inflammasome activation in bone marrow (BM). PM2.5-exposed infant mice at 12 months but not at 6 months displayed progressive senescence of HSCs accompanied by preferential impairment of the BM microenvironment with age-related phenotypes, as evidenced by colony-forming assay and serial transplantation and animal survival experiments. Further, PM2.5-exposed middle-aged mice did not exhibit radioprotective potential. Collectively, exposure of newborns to PM2.5 causes progressive senescence of HSCs. These findings revealed a novel mechanism by which PM2.5 affects the fate of HSCs, highlighting the crucial role of early life exposure to air pollution in determining human health outcomes.

Periodontal Ligament-Mimetic Fibrous Scaffolds Regulate YAP-Associated Fibroblast Behaviors and Promote Regeneration of Periodontal Defect in Relation to the Scaffold Topography.

Although multiple regenerative strategies are being developed for periodontal reconstruction, guided periodontal ligament (PDL) regeneration is difficult because of its cellular and fibrous complexities. Here, we manufactured four different types of PDL-mimic fibrous scaffolds on a desired single mat. These scaffolds exhibited a structure of PDL matrix and human PDL fibroblasts (PDLFs) cultured on the scaffolds resembling morphological phenotypes present in native PDLF. The scaffold-seeded PDLF exerted proliferative, osteoblastic, and osteoclastogenic potentials depending on the fiber topographical cues. Fiber surface-regulated behaviors of PDLF were correlated with the expression patterns of yes-associated protein (YAP), CD105, periostin, osteopontin, and vinculin. Transfection with si-RNA confirmed that YAP acted as the master mechanosensing regulator. Of the as-spun scaffolds, aligned or grid-patterned microscale scaffold regulated the YAP-associated behavior of PDLF more effectively than nanomicroscale or random-oriented microscale scaffold. Implantation with hydrogel complex conjugated with microscale-patterned or grid-patterned scaffold, but not other types of scaffolds, recovered the defected PDL with native PDL-mimic cellularization and fiber structure in the reformed PDL. Our results demonstrate that PDL-biomimetic scaffolds regulate topography-related and YAP-mediated behaviors of PDLF in relation to their topographies. Overall, this study may support a clinical approach of the fiber-hydrogel complex in guided PDL regenerative engineering.

Local and Systemic Overexpression of COMP-Ang1 Induces Ang1/Tie2-Related Thrombocytopenia and SDF-1/CXCR4-Dependent Anemia.

While supplemental angiopoietin-1 (Ang1) improves hematopoiesis, excessive Ang1 induces bone marrow (BM) impairment, hematopoietic stem cell (HSC) senescence, and erythropoietic defect. Here, we examined how excessive Ang1 disturbs hematopoiesis and explored whether hematopoietic defects were related to its level using K14-Cre;c-Ang1 and Col2.3-Cre;c-Ang1 transgenic mice that systemically and locally overexpress cartilage oligomeric matrix protein-Ang1, respectively. We also investigated the impacts of Tie2 inhibitor and AMD3100 on hematopoietic development. Transgenic mice exhibited excessive angiogenic phenotypes, but K14-Cre;c-Ang1 mice showed more severe defects in growth and life span with higher presence of Ang1 compared with Col2.3-Cre;c-Ang1 mice. Dissimilar to K14-Cre;c-Ang1 mice, Col2.3-Cre;c-Ang1 mice did not show impaired BM retention or senescence of HSCs, erythropoietic defect, or disruption of the stromal cell-derived factor 1 (SDF-1)/CXCR4 axis. However, these mice exhibited a defect in platelet production depending on the expression of Tie2 and globin transcription factor 1 (GATA-1), but not GATA-2, in megakaryocyte progenitor (MP) cells. Treatment with Tie2 inhibitor recovered GATA-1 expression in MP cells and platelet production without changes in circulating RBC in transgenic mice. Consecutive AMD3100 administration not only induced irrecoverable senescence of HSCs but also suppressed formation of RBC, but not platelets, via correlated decreases in number of erythroblasts and their GATA-1 expression in B6 mice. Our results indicate that genetic overexpression of Ang1 impairs hematopoietic development depending on its level, in which megakaryopoiesis is preferentially impaired via activation of Ang1/Tie2 signaling, whereas erythropoietic defect is orchestrated by HSC senescence, inflammation, and disruption of the SDF-1/CXCR4 axis.

Astaxanthin Protects against Hyperglycemia-Induced Oxidative and Inflammatory Damage to Bone Marrow and to Bone Marrow-Retained Stem Cells and Restores Normal Hematopoiesis in Streptozotocin-Induced Diabetic Mice.

Hyperglycemia has various adverse health effects, some of which are due to chronic oxidative and inflammatory impairment of bone marrow (BM), hematopoietic stem cells (HSCs), and mesenchymal stem cells (MSCs). Astaxanthin (ASTX) has been shown to ameliorate hyperglycemia-associated systemic complications and acute mortality, and this effect is partially associated with restoration of normal hematopoiesis. Here, the effects of ASTX on diabetes-induced complications in BM and BM stem cells were investigated, and the underlying molecular mechanisms were elucidated. Ten-week-old C57BL/6 mice received a single intraperitoneal injection of streptozotocin (STZ; 150 mg/kg) in combination with oral gavage of ASTX (12.5 mg/kg) for 30 or 60 consecutive days. Supplemental ASTX ameliorated acute mortality and restored the STZ-impaired bone mass accrual and BM microenvironment in STZ-injected mice. Oral gavage of ASTX suppressed osteoclast formation in the BM of STZ-injected mice. Specifically, supplementation with ASTX inhibited oxidative stress and senescence induction of BM HSCs and MSCs and ameliorated hematopoietic disorders in STZ-injected mice. These effects of ASTX were associated with BM restoration of angiopoietin 1, stromal cell-derived factor 1, ß-catenin, and Nrf2. Long-term ASTX gavage also recovered the STZ-induced dysfunction in migration, colony formation, and mineralization of BM-derived stromal cells. Further, a direct addition of ASTX exhibited direct and dose-dependent inhibition of osteoclastic activation without cytotoxic effects. Collectively, these results indicate that ASTX protects against diabetes-induced damage in the BM microenvironment in BM, HSCs, and MSCs and restores normal hematopoiesis and bone accrual in STZ-injected mice.

Astaxanthin Inhibits Diabetes-Triggered Periodontal Destruction, Ameliorates Oxidative Complications in STZ-Injected Mice, and Recovers Nrf2-Dependent Antioxidant System.

Numerous studies highlight that astaxanthin (ASTX) ameliorates hyperglycemic condition and hyperglycemia-associated chronic complications. While periodontitis and periodontic tissue degradation are also triggered under chronic hyperglycemia, the roles of ASTX on diabetes-associated periodontal destruction and the related mechanisms therein are not yet fully understood. Here, we explored the impacts of supplemental ASTX on periodontal destruction and systemic complications in type I diabetic mice. To induce diabetes, C57BL/6 mice received a single intraperitoneal injection of streptozotocin (STZ; 150 mg/kg), and the hyperglycemic mice were orally administered with ASTX (12.5 mg/kg) (STZ+ASTX group) or vehicle only (STZ group) daily for 60 days. Supplemental ASTX did not improve hyperglycemic condition, but ameliorated excessive water and feed consumptions and lethality in STZ-induced diabetic mice. Compared with the non-diabetic and STZ+ASTX groups, the STZ group exhibited severe periodontal destruction. Oral gavage with ASTX inhibited osteoclastic formation and the expression of receptor activator of nuclear factor (NF)-κB ligand, 8-OHdG, γ-H2AX, cyclooxygenase 2, and interleukin-1ß in the periodontium of STZ-injected mice. Supplemental ASTX not only increased the levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and osteogenic transcription factors in the periodontium, but also recovered circulating lymphocytes and endogenous antioxidant enzyme activity in the blood of STZ-injected mice. Furthermore, the addition of ASTX blocked advanced glycation end products-induced oxidative stress and growth inhibition in human-derived periodontal ligament cells by upregulating the Nrf2 pathway. Together, our results suggest that ASTX does not directly improve hyperglycemia, but ameliorates hyperglycemia-triggered periodontal destruction and oxidative systemic complications in type I diabetes.

Glucose oxidase induces mobilization of long-term repopulating hematopoietic cells in mice.

Hematopoietic stem progenitor cells (HSPCs) mobilized to peripheral blood, rather than those remaining in the bone marrow (BM), are commonly used as stem cell source in the clinic. As reactive oxygen species (ROS) are suggested as mediator of HSPC mobilization, we examined the impacts of glucose oxidase (GO) on peripheral mobilization of BM HSPCs and the associated mechanisms. Intravenous injection of GO induced HSPC mobilization even by single treatment, and the GO-mobilized cells maintained their long-term reconstituting and differentiating potentials in conditioned recipients. GO-injected mice lived a normal life without adverse effects such as stem cell senescence, hematopoietic disorders, and blood parameter alteration. The mobilization effect of GO was even evident in animal models showing poor mobilization, such as old, 5-fluorouracil-treated, or alendronate-treated mice. Importantly, combined injection of GO with granulocyte colony-stimulating factor (G-CSF) and/or AMD3100 enhanced more greatly HSPC mobilization than did G-CSF, AMD3100, or both. The GO-stimulated HSPC mobilization was almost completely attenuated by N-acetyl-L-cysteine treatment. Collectively, our results not only highlight the potential role of GO in HSPC mobilization via ROS signaling, but also provide a GO-based new strategy to improve HSPC mobilization in poorly mobilizing allogeneic or autologous donors via combination with G-CSF and/or AMD3100.

Overexpression of COMP-Angiopoietin-1 in K14-Expressing Cells Impairs Hematopoiesis and Disturbs Erythrocyte Maturation.

Numerous studies highlight the potential benefits potentials of supplemental cartilage oligomeric matrix protein-angiopoietin-1 (COMP-Ang1) through improved angiogenic effects. However, our recent findings show that excessive overexpression of COMP-Ang1 induces an impaired bone marrow (BM) microenvironment and senescence of hematopoietic stem cells (HSCs). Here, we investigated the underlying mechanisms of how excessive COMP-Ang1 affects the function of BM-conserved stem cells and hematopoiesis using K14-Cre;inducible-COMP-Ang1-transgenic mice. Excessive COMP-Ang1 induced peripheral egression and senescence of BM HSCs and mesenchymal stem cells (MSCs). Excessive COMP-Ang1 also caused abnormal hematopoiesis along with skewed differentiation of HSCs toward myeloid lineage rather than lymphoid lineage. Especially, excessive COMP-Ang1 disturbed late-stage erythroblast maturation, followed by decreased expression of stromal cell-derived factor 1 (SDF-1) and globin transcription factor 1 (GATA-1) and increased levels of superoxide anion and p-p38 kinase. However, transplantation with the mutant-derived BM cells or treatment with rhCOMP-Ang1 protein did not alter the frequency or GATA-1 expression of erythroblasts in recipient mice or in cultured BM cells. Together, our findings suggest that excessive COMP-Ang1 impairs the functions of BM HSCs and MSCs and hematopoietic processes, eventually leading to abnormal erythropoiesis via imbalanced SDF-1/CXCR4 axis and GATA-1 expression rather than Ang1/Tie2 signaling axis alterations.

Osteoblastic Wntless deletion differentially regulates the fate and functions of bone marrow-derived stem cells in relation to age.

Although functional association between Wnt signaling and bone homeostasis has been well described through genetic ablation of Wntless (Wls), the mechanisms of how osteoblastic Wls regulates the fate of bone marrow stromal cells (BMSCs) and hematopoietic stem cells (HSCs) in relation to age are not yet understood. Here, we generated Col2.3-Cre;Wlsfl/fl mice that were free from premature lethality and investigated age-related impacts of osteoblastic Wls deficiency on hematopoiesis, BM microenvironment, and maintenance of BMSCs (also known as BM-derived mesenchymal stem/stromal cells) and HSCs. Ablation of osteoblastic Wls deteriorated BM microenvironment and bone mass accrual along with age-independent effects on functions of BMSCs. Osteoblastic Wls deletion impaired HSC repopulation and progeny with skewing toward myeloid lineage cells only at old stage. As proven by hallmarks of stem cell senescence, osteoblastic Wls ablation differentially induced senescence of BMSCs and HSCs in relation to age without alteration in their BM frequency. Our findings support that deletion of Wls in Col2.3-expressing cells induces senescence of BMSCs and impairs BM microenvironment in age-independent manner. Overall, long-term deterioration in BM microenvironment contributes to age-related HSC senescence with impaired progeny and hematopoiesis, which also suggests possible roles of osteoblastic Wls on the maintenance of BM HSCs.