BACKGROUND:Much of the current research on M2 macrophage-derived exosomes focuses on their effects on wound healing and osteoblast proliferation and differentiation,while few studies have focused on their role in regulating microglia phenotype.OBJECTIVE:To discuss the role and molecular mechanisms of M2 macrophage-derived exosomes in the phenotypic regulation of microglia.MERHODS:(1)Bone marrow primary macrophages were extracted and then stimulated with 50 ng/mL interleukin 4 for 24 hours to promote macrophage M2-type polarization.Flow cytometry and cellular immunofluorescence were used to identify the M2-type macrophage marker CD206.(2)M2 macrophage-derived exosomes were extracted and identified.(3)Microglia BV2 were randomly divided into three groups:control group,lipopolysaccharide group,and treatment group.No treatment was done in the control group.500 ng/mL lipopolysaccharide was added to the intervention for 24 hours in the lipopolysaccharide group.500 ng/mL lipopolysaccharide and 25 μg/mL M2 macrophage-derived exosomes were added simultaneously to the treatment group for 24 hours.ELISA was performed to detect the secretion of tumor necrosis factor α and interleukin 10 in the culture supernatant.qRT-PCR was performed to detect the mRNA expression of inducible nitric oxide synthase,arginase 1,interleukin 1β,and interleukin 10 in the cells.Western blot assay was performed to detect the protein expression of inducible nitric oxide synthase,arginase 1,and nuclear factor-κB signaling pathway related protein expression.RESULTS AND CONCLUSION:(1)ELISA results showed that the secretion of tumor necrosis factor α was significantly increased in the lipopolysaccharide group compared with the control group.The secretion of tumor necrosis factor α was reduced and the secretion of interleukin 10 was increased in the treatment group compared with the lipopolysaccharide group.(2)The qRT-PCR results showed that compared with the control group,the mRNA expression of interleukin 1β and inducible nitric oxide synthase increased in the lipopolysaccharide group.Compared with the lipopolysaccharide group,the mRNA expression of interleukin 1β and inducible nitric oxide synthase decreased,and the mRNA expression of interleukin 10 and arginase 1 increased in the treatment group.(3)Western blot assay results showed that the expression of inducible nitric oxide synthase protein was increased in the lipopolysaccharide group compared with the control group.The expression of inducible nitric oxide synthase protein was decreased and the expression of arginase 1 protein was elevated in the treatment group compared with the lipopolysaccharide group.(4)Compared with the control group,the expression of p65 and p-IκB-α proteins in the nuclear factor-κB signaling pathway was reduced in the lipopolysaccharide group,whereas the expression of p65 and p-IκB-α proteins was elevated in the treatment group compared with the lipopolysaccharide group.The results showed that M2-type macrophage-derived exosomes could significantly inhibit lipopolysaccharide-induced inflammatory responses in microglia,enhance the expression of the anti-inflammatory factor interleukin 10,suppress the expression of the pro-inflammatory factors tumor necrosis factor α and interleukin 1β,and promote microglial cell phenotypes polarized from the M1-type to the M2-type.The mechanism may be related to the inhibition of nuclear factor-κB signaling pathway activation by M2-type macrophage-derived exosomes.

AIM:To observe the changes of atrial fibrillation susceptibility,and the remodeling of atrial myo-cyte action potential,ultrarapid activation delayed rectifier potassium current(IKur)and transient outward potassium cur-rent(Ito)in elderly mice,and to explore the mechanism of atrial fibrillation from the single cell electrophysiological level.METHODS:The C57BL/6J mice were divided into old group(20 months old)and young group(4 months old).Atrial fi-brillation was induced by esophageal atrial pacing.The atrial myocytes were isolated,and action potential and ion currents were recorded with patch-clamp technique.The associated proteins were detected by Western blot technique.RE-SULTS:(1)Compared with young mice,the total incidence of atrial fibrillation was significantly increased in old mice(20.0%at 4 months old vs 60.0%at 20 months old,P<0.01).(2)The action potential duration of atrial myocytes in aged mice was shortened,and more significantly after stimulation.(3)The density of Ito and IKur in atrial myocytes of aged mice increased significantly,from(12.6±1.4)pA/pF to(21.7±1.1)pA/pF,and from(7.5±1.5)pA/pF to(13.3±2.1)pA/pF,respectively(P<0.01).After stimulation,the current increased more significantly,especially in older atrial cells.Compared with the young mice,the steady-state activation curve of Ito in the atrial myocytes of the aged mice shifted towards the depolarization,suggesting that activation of Ito channels in the aged mice increased at the same voltage stimula-tion.(4)Compared with young group,the expression of KV4.2(generating Ito)and KV1.5(generating IKur)proteins in the atrial tissue of the mice in old group was significantly increased,and the expression of caveolin-3 and end-binding protein 1(EB1)was up-regulated,suggesting that the increases in KV4.2 and KV1.5 total channel proteins and effective proteins in the cell membrane might contribute to the increase in the remodeling of potassium currents in the elderly atrial myo-cytes.CONCLUSION:The incidence of atrial fibrillation in elderly mice is significantly augmented,which may be related to the increases in Ito and IKur in atrial myocytes.The remodeling of potassium currents in elderly atrial myocytes is one of the electrophysiological bases leading to the shortening of action potential duration and the occurrence of atrial fibrillation.

AIM:To observe the changes of atrial fibrillation susceptibility,and the remodeling of atrial myo-cyte action potential,ultrarapid activation delayed rectifier potassium current(IKur)and transient outward potassium cur-rent(Ito)in elderly mice,and to explore the mechanism of atrial fibrillation from the single cell electrophysiological level.METHODS:The C57BL/6J mice were divided into old group(20 months old)and young group(4 months old).Atrial fi-brillation was induced by esophageal atrial pacing.The atrial myocytes were isolated,and action potential and ion currents were recorded with patch-clamp technique.The associated proteins were detected by Western blot technique.RE-SULTS:(1)Compared with young mice,the total incidence of atrial fibrillation was significantly increased in old mice(20.0%at 4 months old vs 60.0%at 20 months old,P<0.01).(2)The action potential duration of atrial myocytes in aged mice was shortened,and more significantly after stimulation.(3)The density of Ito and IKur in atrial myocytes of aged mice increased significantly,from(12.6±1.4)pA/pF to(21.7±1.1)pA/pF,and from(7.5±1.5)pA/pF to(13.3±2.1)pA/pF,respectively(P<0.01).After stimulation,the current increased more significantly,especially in older atrial cells.Compared with the young mice,the steady-state activation curve of Ito in the atrial myocytes of the aged mice shifted towards the depolarization,suggesting that activation of Ito channels in the aged mice increased at the same voltage stimula-tion.(4)Compared with young group,the expression of KV4.2(generating Ito)and KV1.5(generating IKur)proteins in the atrial tissue of the mice in old group was significantly increased,and the expression of caveolin-3 and end-binding protein 1(EB1)was up-regulated,suggesting that the increases in KV4.2 and KV1.5 total channel proteins and effective proteins in the cell membrane might contribute to the increase in the remodeling of potassium currents in the elderly atrial myo-cytes.CONCLUSION:The incidence of atrial fibrillation in elderly mice is significantly augmented,which may be related to the increases in Ito and IKur in atrial myocytes.The remodeling of potassium currents in elderly atrial myocytes is one of the electrophysiological bases leading to the shortening of action potential duration and the occurrence of atrial fibrillation.

Objective:To investigate the clinical characteristics of limb overgrowth following proximal femoral osteotomy (PFO) for unilateral developmental dysplasia of the hip (DDH) in children.Methods:A retrospective analysis was conducted on 36 children with unilateral DDH who underwent PFO at Xi'an Honghui Hospital from June 2017 to June 2021. The cohort included 4 males and 32 females, with a mean age of 4.23±3.15 years (range: 2-12 years), comprising 28 left-sided and 8 right-sided cases. According to the International Hip Dysplasia Institute (IHDI) classification, there were 2 type I, 9 type II, 16 type III, and 9 type IV cases. Radiographic parameters [femoral length, femoral neck anteversion angle, neck-shaft angle, acetabular index (AI), center-edge angle (CEA), center-head distance discrepancy (CHDD)] and PFO parameters (varus angle, shortening length, derotation angle) were measured on X-ray and 3D CT reconstructions. Comparisons were made between the overgrowth ≥1 cm group ( n=14) and <1 cm group ( n=22) to analyze risk factors and patterns. Results:The overgrowth ≥1 cm group had significantly younger patients (2.49±1.03 years vs. 5.13±3.47 years, t=-2.757, P<0.001). Overgrowth magnitude varied significantly across age subgroups: 11.08±6.17 mm in the 2-4 years group, 5.08±0.19 mm in the >4-<6 years group, and 2.44±4.50 mm in the ≥6 years group ( F=5.436, P=0.031). The highest incidence of overgrowth occurred in the 2-4 years subgroup (56%, 20/36). Limb overgrowth initiated at 3 months postoperatively, exhibited a linear correlation with follow-up duration during 6-18 months [ r=0.78, 95% CI(0.62, 0.88), P<0.001)], and plateaued after 18 months [ r=-0.15, 95% CI(-0.75, 0.57), P=0.710]. Postoperative CEA and CHDD showed significant improvements ( P<0.05), while AI remained unchanged ( P>0.05). Conclusions:Children aged 2-4 years exhibit higher incidence and severity of post-PFO limb overgrowth. The rapid progression phase occurs within 6-18 months postoperatively, stabilizing thereafter. CEA and CHDD serve as critical indicators for evaluating intervention efficacy in DDH-related overgrowth.

Background: Diabetic pain patients have increased pain at night. Exosomes can relieve neuropathic pain. This study aimed to investigate the efficacy of exosome administration at different time points in relieving diabetic neuropathic pain (DNP) in rats. Methods: M2 macrophages from bone marrow were induced in mice and exosomes were extracted. A diabetic rat model was induced using streptozotocin, with the mechanical withdrawal threshold (MWT) of the rats beingmeasured at ≤ 80% of the basal value after 14 days, indicating successful construction of the DNP rat model.Exosomes were administered on three consecutive days at ZT0 (zeitgeber time) and ZT12. Parameters including blood glucose levels, body weight, MWT, and thermal withdrawal latency (TWL) were assessed in the rats. The lumbar spinal cord of rats was examined on days 21 and 28 to measure inflammatory factors and observe the expression of M1 and M2 microglia. Furthermore, microglia were exposed to lipopolysaccharide (LPS) and LPS + exosomes in a controlled in vitro setting to assess alterations in microglia phenotype involving the NF-kB p65 andIKBα inflammatory signaling pathways. Results: The findings revealed that administration of exosomes during the rat resting period at ZT12 resulted in increased MWT and TWL, as well as a shift in microglia polarization towards the M2 phenotype. In vitro analysis indicated that exosomes influenced microglia polarization and suppressed the phosphorylation of NF-kB p65 andIKBα.  Conclusions Temporal therapy with exosomes effectively reduces pain in DNP rats by polarizing microglia andaffecting NF-kB p65 and IKBα signaling pathways.

Background: Diabetic pain patients have increased pain at night. Exosomes can relieve neuropathic pain. This study aimed to investigate the efficacy of exosome administration at different time points in relieving diabetic neuropathic pain (DNP) in rats. Methods: M2 macrophages from bone marrow were induced in mice and exosomes were extracted. A diabetic rat model was induced using streptozotocin, with the mechanical withdrawal threshold (MWT) of the rats beingmeasured at ≤ 80% of the basal value after 14 days, indicating successful construction of the DNP rat model.Exosomes were administered on three consecutive days at ZT0 (zeitgeber time) and ZT12. Parameters including blood glucose levels, body weight, MWT, and thermal withdrawal latency (TWL) were assessed in the rats. The lumbar spinal cord of rats was examined on days 21 and 28 to measure inflammatory factors and observe the expression of M1 and M2 microglia. Furthermore, microglia were exposed to lipopolysaccharide (LPS) and LPS + exosomes in a controlled in vitro setting to assess alterations in microglia phenotype involving the NF-kB p65 andIKBα inflammatory signaling pathways. Results: The findings revealed that administration of exosomes during the rat resting period at ZT12 resulted in increased MWT and TWL, as well as a shift in microglia polarization towards the M2 phenotype. In vitro analysis indicated that exosomes influenced microglia polarization and suppressed the phosphorylation of NF-kB p65 andIKBα.  Conclusions Temporal therapy with exosomes effectively reduces pain in DNP rats by polarizing microglia andaffecting NF-kB p65 and IKBα signaling pathways.

Background: Diabetic pain patients have increased pain at night. Exosomes can relieve neuropathic pain. This study aimed to investigate the efficacy of exosome administration at different time points in relieving diabetic neuropathic pain (DNP) in rats. Methods: M2 macrophages from bone marrow were induced in mice and exosomes were extracted. A diabetic rat model was induced using streptozotocin, with the mechanical withdrawal threshold (MWT) of the rats beingmeasured at ≤ 80% of the basal value after 14 days, indicating successful construction of the DNP rat model.Exosomes were administered on three consecutive days at ZT0 (zeitgeber time) and ZT12. Parameters including blood glucose levels, body weight, MWT, and thermal withdrawal latency (TWL) were assessed in the rats. The lumbar spinal cord of rats was examined on days 21 and 28 to measure inflammatory factors and observe the expression of M1 and M2 microglia. Furthermore, microglia were exposed to lipopolysaccharide (LPS) and LPS + exosomes in a controlled in vitro setting to assess alterations in microglia phenotype involving the NF-kB p65 andIKBα inflammatory signaling pathways. Results: The findings revealed that administration of exosomes during the rat resting period at ZT12 resulted in increased MWT and TWL, as well as a shift in microglia polarization towards the M2 phenotype. In vitro analysis indicated that exosomes influenced microglia polarization and suppressed the phosphorylation of NF-kB p65 andIKBα.  Conclusions Temporal therapy with exosomes effectively reduces pain in DNP rats by polarizing microglia andaffecting NF-kB p65 and IKBα signaling pathways.

Background: Diabetic pain patients have increased pain at night. Exosomes can relieve neuropathic pain. This study aimed to investigate the efficacy of exosome administration at different time points in relieving diabetic neuropathic pain (DNP) in rats. Methods: M2 macrophages from bone marrow were induced in mice and exosomes were extracted. A diabetic rat model was induced using streptozotocin, with the mechanical withdrawal threshold (MWT) of the rats beingmeasured at ≤ 80% of the basal value after 14 days, indicating successful construction of the DNP rat model.Exosomes were administered on three consecutive days at ZT0 (zeitgeber time) and ZT12. Parameters including blood glucose levels, body weight, MWT, and thermal withdrawal latency (TWL) were assessed in the rats. The lumbar spinal cord of rats was examined on days 21 and 28 to measure inflammatory factors and observe the expression of M1 and M2 microglia. Furthermore, microglia were exposed to lipopolysaccharide (LPS) and LPS + exosomes in a controlled in vitro setting to assess alterations in microglia phenotype involving the NF-kB p65 andIKBα inflammatory signaling pathways. Results: The findings revealed that administration of exosomes during the rat resting period at ZT12 resulted in increased MWT and TWL, as well as a shift in microglia polarization towards the M2 phenotype. In vitro analysis indicated that exosomes influenced microglia polarization and suppressed the phosphorylation of NF-kB p65 andIKBα.  Conclusions Temporal therapy with exosomes effectively reduces pain in DNP rats by polarizing microglia andaffecting NF-kB p65 and IKBα signaling pathways.

Background: Diabetic pain patients have increased pain at night. Exosomes can relieve neuropathic pain. This study aimed to investigate the efficacy of exosome administration at different time points in relieving diabetic neuropathic pain (DNP) in rats. Methods: M2 macrophages from bone marrow were induced in mice and exosomes were extracted. A diabetic rat model was induced using streptozotocin, with the mechanical withdrawal threshold (MWT) of the rats beingmeasured at ≤ 80% of the basal value after 14 days, indicating successful construction of the DNP rat model.Exosomes were administered on three consecutive days at ZT0 (zeitgeber time) and ZT12. Parameters including blood glucose levels, body weight, MWT, and thermal withdrawal latency (TWL) were assessed in the rats. The lumbar spinal cord of rats was examined on days 21 and 28 to measure inflammatory factors and observe the expression of M1 and M2 microglia. Furthermore, microglia were exposed to lipopolysaccharide (LPS) and LPS + exosomes in a controlled in vitro setting to assess alterations in microglia phenotype involving the NF-kB p65 andIKBα inflammatory signaling pathways. Results: The findings revealed that administration of exosomes during the rat resting period at ZT12 resulted in increased MWT and TWL, as well as a shift in microglia polarization towards the M2 phenotype. In vitro analysis indicated that exosomes influenced microglia polarization and suppressed the phosphorylation of NF-kB p65 andIKBα.  Conclusions Temporal therapy with exosomes effectively reduces pain in DNP rats by polarizing microglia andaffecting NF-kB p65 and IKBα signaling pathways.

Objective:To investigate the clinical characteristics of limb overgrowth following proximal femoral osteotomy (PFO) for unilateral developmental dysplasia of the hip (DDH) in children.Methods:A retrospective analysis was conducted on 36 children with unilateral DDH who underwent PFO at Xi'an Honghui Hospital from June 2017 to June 2021. The cohort included 4 males and 32 females, with a mean age of 4.23±3.15 years (range: 2-12 years), comprising 28 left-sided and 8 right-sided cases. According to the International Hip Dysplasia Institute (IHDI) classification, there were 2 type I, 9 type II, 16 type III, and 9 type IV cases. Radiographic parameters [femoral length, femoral neck anteversion angle, neck-shaft angle, acetabular index (AI), center-edge angle (CEA), center-head distance discrepancy (CHDD)] and PFO parameters (varus angle, shortening length, derotation angle) were measured on X-ray and 3D CT reconstructions. Comparisons were made between the overgrowth ≥1 cm group ( n=14) and <1 cm group ( n=22) to analyze risk factors and patterns. Results:The overgrowth ≥1 cm group had significantly younger patients (2.49±1.03 years vs. 5.13±3.47 years, t=-2.757, P<0.001). Overgrowth magnitude varied significantly across age subgroups: 11.08±6.17 mm in the 2-4 years group, 5.08±0.19 mm in the >4-<6 years group, and 2.44±4.50 mm in the ≥6 years group ( F=5.436, P=0.031). The highest incidence of overgrowth occurred in the 2-4 years subgroup (56%, 20/36). Limb overgrowth initiated at 3 months postoperatively, exhibited a linear correlation with follow-up duration during 6-18 months [ r=0.78, 95% CI(0.62, 0.88), P<0.001)], and plateaued after 18 months [ r=-0.15, 95% CI(-0.75, 0.57), P=0.710]. Postoperative CEA and CHDD showed significant improvements ( P<0.05), while AI remained unchanged ( P>0.05). Conclusions:Children aged 2-4 years exhibit higher incidence and severity of post-PFO limb overgrowth. The rapid progression phase occurs within 6-18 months postoperatively, stabilizing thereafter. CEA and CHDD serve as critical indicators for evaluating intervention efficacy in DDH-related overgrowth.