Objective To investigate the effects of exosomes derived from hypoxia-treated mesenchymal stem cells on chondrocyte injury.Methods After mesenchymal stem cells were subjected to hypoxic treatment,the secreted exosomes were collected and co-cultured with IL-1β-stimulated chondrocytes.Cell viability was assessed using the CCK-8 assay,while apoptosis was evaluated by flow cytometry and the measurement of Caspase-3 and PARP activities.Intracellular levels of ROS,Fe2+,and MDA were quantified using commercial assay kits.The expression of GPX4,SLC7A11,and ACSL4 was analyzed at both mRNA and protein levels via qRT-PCR and Western blot,respectively.Additionally,the secretion of COL2A1,MMP13,ADAMTS5,TNF-α,IL-6,and PGE2 was determined by ELISA.Results Chondrocyte viability was significantly enhanced following the uptake of exosomes derived from hypoxia-treated mesenchymal stem cells(H-Exo)(P<0.05).IL-1β treatment reduced chondrocyte viability,increased Caspase-3 and PARP activities,and promoted apoptosis(P<0.05);however,H-Exo effectively reversed IL-1 β-induced apoptotic effects.Furthermore,IL-1 β markedly down-regulated the expression of GPX4 and SLC7A11,up-regulated ACSL4 expression,and elevated intracellular levels of ROS,Fe2+,and MDA(P<0.05),indicating the induction of ferroptosis.Both the ferroptosis inhibitor and H-Exo significantly attenuated IL-1β-triggered ferroptosis,and H-Exo counteracted the detrimental effects of IL-1β as well as those induced by a ferroptosis inducer.Additionally,IL-1β suppressed the expression of the chondrogenic marker COL2A1,up-regulated the catabolic enzymes MMP13 and ADAMTS5,and enhanced the secretion of pro-inflammatory cyto-kines TNF-α,IL-6,and PGE2(P<0.05).Notably,H-Exo alleviated IL-1β-mediated inflammation and restored the balance between chondrogenic anabolism and catabolism.Conclusions Exosomes secreted by mesenchymal stem cells under hypoxic conditions can effectively inhibit chondrocyte apoptosis and ferroptosis,thereby alleviating cellular injury.These findings suggest that such exosomes exert a protective effect on chondrocytes and hold prom-ise as a novel therapeutic strategy for cartilage repair.

Objective To investigate the effects of exosomes derived from hypoxia-treated mesenchymal stem cells on chondrocyte injury.Methods After mesenchymal stem cells were subjected to hypoxic treatment,the secreted exosomes were collected and co-cultured with IL-1β-stimulated chondrocytes.Cell viability was assessed using the CCK-8 assay,while apoptosis was evaluated by flow cytometry and the measurement of Caspase-3 and PARP activities.Intracellular levels of ROS,Fe2+,and MDA were quantified using commercial assay kits.The expression of GPX4,SLC7A11,and ACSL4 was analyzed at both mRNA and protein levels via qRT-PCR and Western blot,respectively.Additionally,the secretion of COL2A1,MMP13,ADAMTS5,TNF-α,IL-6,and PGE2 was determined by ELISA.Results Chondrocyte viability was significantly enhanced following the uptake of exosomes derived from hypoxia-treated mesenchymal stem cells(H-Exo)(P<0.05).IL-1β treatment reduced chondrocyte viability,increased Caspase-3 and PARP activities,and promoted apoptosis(P<0.05);however,H-Exo effectively reversed IL-1 β-induced apoptotic effects.Furthermore,IL-1 β markedly down-regulated the expression of GPX4 and SLC7A11,up-regulated ACSL4 expression,and elevated intracellular levels of ROS,Fe2+,and MDA(P<0.05),indicating the induction of ferroptosis.Both the ferroptosis inhibitor and H-Exo significantly attenuated IL-1β-triggered ferroptosis,and H-Exo counteracted the detrimental effects of IL-1β as well as those induced by a ferroptosis inducer.Additionally,IL-1β suppressed the expression of the chondrogenic marker COL2A1,up-regulated the catabolic enzymes MMP13 and ADAMTS5,and enhanced the secretion of pro-inflammatory cyto-kines TNF-α,IL-6,and PGE2(P<0.05).Notably,H-Exo alleviated IL-1β-mediated inflammation and restored the balance between chondrogenic anabolism and catabolism.Conclusions Exosomes secreted by mesenchymal stem cells under hypoxic conditions can effectively inhibit chondrocyte apoptosis and ferroptosis,thereby alleviating cellular injury.These findings suggest that such exosomes exert a protective effect on chondrocytes and hold prom-ise as a novel therapeutic strategy for cartilage repair.

BACKGROUND:Myocardial patches are used as an effective way to repair damaged myocardium,and there is controversy over which cells to use to make myocardial patches and how to maximize the therapeutic effect of myocardial patches in vivo. OBJECTIVE:To find out the best way to make myocardial patches by overviewing the cellular sources of myocardial patches and strategies for perfecting them. METHODS:The first author searched PubMed and Web of Science databases by using"cell sheet,cell patch,cardiomyocytes,cardiac progenitor cells,fibroblasts,embryonic stem cell,mesenchymal stem cells"as English search terms,and searched CNKI and Wanfang databases by using"myocardial patch,biological 3D printing,myocardial"as Chinese search terms.After enrollment screening,94 articles were ultimately included in the result analysis. RESULTS AND CONCLUSION:(1)The cellular sources of myocardial patches are mainly divided into three categories:somatic cells,monoenergetic stem cells,and pluripotent stem cells,respectively.There are rich sources of cells for myocardial patches,but not all of them are suitable for making myocardial patches,e.g.,myocardial patches made from fibroblasts and skeletal myoblasts carry a risk of arrhythmogenicity,and mesenchymal stem cells have a short in vivo duration of action and ethical concerns.With the discovery of induced multifunctional stem cells,a reliable source of cells for making myocardial patches is available.(2)There are two methods of making myocardial patches.One is using cell sheet technology.The other is using biological 3D printing technology.Cell sheet technology can preserve the extracellular matrix components intact and can maximally mimic the cell growth ring in vivo.However,it is still difficult to obtain myocardial patches with three-dimensional structure by cell sheet technology.Biologicasl 3D printing technology,however,can be used to obtain myocardial patches with three-dimensional structures through computerized personalized design.(3)The strategies for perfecting myocardial patches mainly include:making myocardial patches after co-cultivation of multiple cells,improving the ink formulation and scaffold composition in biological 3D printing technology,improving the therapeutic effect of myocardial patches,suppressing immune rejection after transplantation,and perfecting the differentiation and cultivation protocols of stem cells.(4)There is no optimal cell source or method for making myocardial patches,and myocardial patches obtained from a particular cell or technique alone often do not achieve the desired therapeutic effect.Therefore,researchers need to choose the appropriate strategy for making myocardial patches based on the desired therapeutic effect before making them.

BACKGROUND:The anterior cruciate ligament has unique nonlinear mechanical properties under a complex physiological loading environment.Elastin is an important contributor to the mechanical properties of the anterior cruciate ligament,but its mechanical response to the anterior cruciate ligament under axial tension is not clear. OBJECTIVE:To quantitatively analyze the effect of elastin on the tensile mechanical response of the anterior cruciate ligament. METHODS:Elastase solution and control buffer were prepared.The porcine anterior cruciate ligament samples were prepared into small-size samples and randomly soaked in 0,0.1,1.0,2.0,5.0,and 10.0 U/mL elastase solution for 6 hours,and other small samples of the same size were soaked in 2 U/mL elastase solution for 0,1,3,6,9,and 12 hours.To determine suitable soaking conditions for elastin-targeted enzymes and verify the digestive effect,histological staining was used to compare the effects of enzyme treatment on tissue structure and composition.The ligament samples were randomly divided into elastase-treated group and PBS group,and immersed in 2 U/mL elastase solution and PBS buffer for 6 hours,respectively.A mechanical tensile test was performed before and after immersion. RESULTS AND CONCLUSION:(1)The biochemical results showed that being treated in 2 U/mL elastase solution for 6 hours could reduce the elastin content by 31.1%,and had no significant effect on other mechanical-related components in the tissue.(2)The histological results showed that elastase was able to penetrate the tissue,and the loose degree of tissue increased after treatment.(3)In the mechanical results before and after treatment,the mechanical properties of the PBS group decreased significantly,only the low-tension elastic modulus increased significantly and the initial length increased significantly in the elastase-treated group.(4)The intergroup comparison results showed that there was no significant difference between the two groups in pre-treatment,but the low-tension elastic modulus,initial slopes,saturated slopes,and initial length of the elastase-treated group after treatment were significantly higher than those in the PBS group.(5)These results suggest that elastin degradation significantly affects the biomechanical properties of the anterior cruciate ligament and further complements our understanding of the structure-function relationship of the anterior cruciate ligament.

Objective:To explore the feasibility and effect of applying spherical fitting technology in CT three-dimensional reconstruction in preoperative planning of the resection range of Cam-type femoral acetabular impingement (FAI).Methods:46 Cam-type FAI patients who underwent arthroscopic femoroplasty in the Department of Sports Medicine in the Third Affiliated Hospital of Southern Medical University from July 2020 to June 2022 were enrolled in the spherical fitting group, including 26 females and 20 males, with an average age of 38.4±15.2 years (range of 24-53 years). The preoperative planning was performed using spherical fitting technology in CT three-dimensional reconstruction. Another 42 Cam-type FAI patients who underwent arthroscopic femoroplasty from July 2018 to June 2020 were enrolled in the observation group, including 25 females and 17 males, with an average age of 43.6±18.4 years (range 24-61 years). The preoperative planning was performed using CT three-dimensional reconstruction observation method. This study evaluated the impact of femoroplasty planned by spherical fitting technique on patients' prognosis though comparing the differences of postoperative α angle, femoral head-neck offset ratio, modified Harris hip score (mHHS), and visual analog score (VAS) at 3, 6, 9, and 12 months between two groups.Results:The average follow-up time was 11.8±0.6 months in spherical fitting group and 11.3±0.8 months in observation group. There was no significant difference regarding α angle, femoral head-neck offset ratio, mHHS, and VAS between two groups preoperatively ( P>0.05). The mHHS in two groups increased gradually, while VAS decreased sequentially at 3, 6, 9, and 12 months postoperatively. The postoperative mHHS and VAS were significantly better than those before surgery ( P<0.05). The mHHS was 83.2±14.8 vs. 70.5±11.2 in spherical fitting group and observation group at the followup of 9 months with significant difference ( t=4.471, P=0.007). It was 85.7±13.3 vs. 73.2±12.5 at the followup of 12 months with significant difference ( t=4.596, P=0.008). No significant difference was found in α angle, femoral head-neck offset ratio or mHHS at 3 and 6 months postoperatively ( P>0.05), and no significant difference was found in VAS at 3, 6, 9, and 12 months postoperatively between two groups. Conclusion:The spherical fitting technology in CT three-dimensional reconstruction could assist surgeons with planning of the resection range of Cam deformity preoperatively, and achieve a smooth progress of arthroscopic femoroplasty intraoperatively; after short term follow-up, we found that patients who underwent femoroplasty using this technology achieved satisfactory outcomes.

Objective:To analyze the surveillance data of Kashin-Beck disease (KBD) in Shandong Province, master the changes of KBD, and provide scientific basis for formulating prevention and control strategies of KBD and adjustment of the prevention and control focus of KBD.Methods:According to the requirements of the "National KBD Monitoring Plan" and the "Shandong KBD Monitoring Plan", from 2016 to 2020, the disease monitoring was carried out in the villages of KBD areas in Shandong Province, including the number of clinical positive cases, the number of X-ray positive cases, and the number of metaphyseal positive cases. The detection rate was calculated, and the dynamic changes of the disease was analyzed macroscopically.Results:From 2016 to 2020, a total of 1 816 children aged 7 - 12 years were clinically examined in Shandong Province, and no child with KBD was found. A total of 1 224 children were examined by X-ray, among which 1 positive patient was found in 2016 and 2017, respectively, both of whom were metaphyseal changes, with a total detection rate of 0.16%. There were 367 adult patients with KBD in Shandong Province, including 304 patients with grade Ⅰ, 47 patients with grade Ⅱ and 16 patients with grade Ⅲ. All villages in the KBD areas in Shandong Province had reached the elimination standard, with the elimination rate of 100%.Conclusion:No clinical case of KBD is detected in children aged 7 - 12 years in Shandong Province from 2016 to 2020, which has reached the elimination standard and is in a continuous elimination state.

Objective     To compare the mid- and long-term efficacy of minimally invasive coronary artery bypass grafting (MICS) versus conventional coronary artery bypass grafting (CABG). Methods     This study analyzed 679 patients with coronary heart disease treated in the Minimally Invasive Heart Center of Beijing Anzhen Hospital from 2015 to 2019, including 532 males and 147 females with an average age of 61.16 years. A total of 281 patients underwent MICS (a MICS group) and 398 patients underwent conventional CABG (a CABG group). The clinical data of the patients in the two groups were analyzed. Results    The average operation time was longer (P<0.001), the total hospital stay was shorter (P<0.001), and the amount of drainage 24 h after the operation was less (P=0.029) in the MICS group. There was no statistical difference in the incidence of perioperative complications between the two groups. The median follow-up time was 2.68 years. The follow-up results showed that the total incidence of cumulative main adverse cardiovascular and cerebrovascular events in the CABG group was higher at 2 years (6.2% vs. 3.8%) and 4 years (9.3% vs. 7.6%), but the difference was not statistically significant (P>0.05). There was no statistical difference in 2- or 4-year all-cause death between the two groups (3.5% vs. 2.8%, 5.6% vs. 2.8%, P>0.05). At the same time, there was no statistical difference in the incidence of myocardial infarction, stroke or revascularization between the two groups (P>0.05). Conclusion    Compared with conventional CABG, MICS can achieve satisfactory mid- and long-term outcomes.

Objective:To dynamically monitor the prevalence and trend of dental fluorosis in children in Shandong Province, and to evaluate the prevention and control measures for drinking water-borne endemic fluorosis (referred to as drinking water-borne fluorosis), and to provide scientific basis for the next step.Methods:Totally 40 counties (cities, districts) were selected as project counties (cities, districts) from drinking water-borne fluorosis areas in Shandong Province in 2018, and all counties (cities, districts) were selected in 2019 and 2020, to investigate the situation of water improvement, detect water fluoride content, and investigate the prevalence of dental fluorosis in children aged 8 - 12 years.Results:From 2018 to 2020, the detection rates of dental fluorosis in children aged 8 - 12 years were 10.30% (503/4 884), 8.94% (25 895/289 539) and 8.66% (24 061/277 689), respectively, with statistically significant differences (χ 2 = 27.10, P < 0.001), and the dental fluorosis indexes were 0.21, 0.18 and 0.17, respectively. The total detection rates of dental fluorosis in children of different age groups in the 3 years were 7.26% (6 590/90 775), 7.97% (9 303/116 680), 9.29% (12 167/130 915), 9.29% (12 238/131 670) and 9.95% (10 161/102 072), the differences were statistically significant (χ 2 = 615.71, P < 0.001). In the 3 years, the total detection rate of dental fluorosis was 8.93% (28 101/314 737) in boys and 8.69% (22 358/257 375) in girls, the difference was statistically significant (χ 2 = 10.27, P = 0.001). In 2018 and 2019, the detection rates of dental fluorosis of children aged 8 - 12 years in water fluoride qualified villages [5.74% (235/4 095) and 7.98% (20 200/253 082)] were significantly lower than those in villages with excessive water fluoride [33.97% (268/789) and 15.62% (5 695/36 457), χ 2 = 570.61, 2 283.76, P < 0.001]. Conclusions:The prevalence of dental fluorosis among children aged 8 - 12 years has been effectively controlled, and remarkable results have been achieved in prevention and treatment of drinking water-borne fluorosis in Shandong Province. However, the detection rate of dental fluorosis among children in a few endemic villages is high, so it is necessary to continue to strengthen the monitoring of fluoride content in drinking water and the condition of dental fluorosis among children.

Objective:To evaluate the effect of health education of a three-year special action for prevention and control of drinking water-borne endemic fluorosis (referred to as drinking water-borne fluorosis) in Shandong Province, and to provide basis for formulating health education measures in the next step.Methods:Nineteen of the disease affected counties (cities and districts) were selected as project counties (cities and districts) in key areas for prevention and control of drinking water-borne fluorosis in Shandong Province in 2018, and 50 disease affected counties (cities and districts) were selected in 2019, and the project counties (cities and districts) were expanded to all of the 105 disease affected counties (cities and districts) in Shandong Province in 2020. Three disease affected townships (towns) were selected in each county (city and district), and health education activities on drinking water-borne fluorosis were carried out in Grade 4 to Grade 6 of the central primary schools and the three villages under its jurisdiction. Students and housewives were selected to conduct questionnaire surveys on prevention and control knowledge of drinking water-borne fluorosis before and after health education. The incidence of dental fluorosis among children aged 8 - 12 years was investigated annually in 6 villages (with children aged 8 - 12 years > 50) , where health education activity was implemented and the incidence of dental fluorosis among children was > 30%, water fluoride content was > 1.5 mg/L and water improvement time was < 5 years.Results:After health education, the awareness rates of drinking water-borne fluorosis in fifth grade pupils [92.46% (4 571/4 944) vs 65.80% (3 334/5 067) in 2018; 94.84% (12 897/13 599) vs 73.55% (9 993/13 587) in 2019; 95.59% (30 407/ 31 809) vs 77.52% (24 463/31 557) in 2020] and housewives [94.12% (2 400/2 550) vs 76.04% (1 939/2 550) in 2018; 94.99% (6 412/6 750) vs 72.00% (4 860/6 750) in 2019; 95.53% (16 183/16 941) vs 78.43% (12 971/16 539) in 2020] were significantly improved (χ 2 = 1 070.47, 2 315.27, 4 456.40, 328.25, 1 294.80, 2 174.63, P < 0.05). After health education in 2020, there were significant differences in the correct answer rates of epidemic causes, hazards and preventive measures of drinking water-borne fluorosis in the questionnaire of fifth grade pupils and housewives (χ 2 = 390.78, 164.94, P < 0.05). The awareness rates of drinking water-borne fluorosis in fifth grade pupils and housewives in the eastern region (Qingdao City, Yantai City and Weifang City) were significantly higher than those in the western region (Dezhou City, Liaocheng City and Heze City) before health education (χ 2 = 547.43, 210.12, P < 0.05), and after health education, the awareness rates increased to more than 90%. The detection rate of dental fluorosis in children decreased year by year (χ 2trend = 27.95, P < 0.05). Conclusions:Through implementation of a three-year special action for prevention and control of drinking water-borne fluorosis in Shandong Province, the awareness rate of fluorosis among target populations has been significantly improved. However, it is still necessary for government departments to further increase investment in health education and carry out health education activities in a deep-going way.

Objective To explore the feasibility,reproducibility and reliability of the T 2* MRI technique in quantifying different concentrations of MnCl2water phantoms at 3.0T.Methods The water phantoms with different concentrations of MnCl2underwent T2* imaging at both 1.5T and 3.0T MRI,and repeated imaging at 3.0T MRI after 1 month.A Spearman correlation was used to determine the relationship of T2* values and Mn concentrations,and established the linear regression equations by using the simple linear regression.W ilcoxon signed-rank sum test and Bland-Altman method were used to evaluate the reproducibility of twice T 2* measurements at 3.0T,and the interclass correlation coefficient(ICC)was calculated.Results T2* values of the phantoms were negatively correlated to Mn concentrations(r= -1.000,P<0.001),and R2* values of the phantoms were positively correlated to Mn concentrations(r=1.000,P<0.001). T2* values of the phantoms measured at 3.0T were positively correlated to that measured at 1.5T(r=1.000,P<0.001).The linear regression equation was T2* 3.0T =0.651T2* 1.5T +0.041.There was no statistical difference of T2* values between the two measurements at 3.0T (Z= -1.732,P=0.083),and ICC was 1.000.Conclusion 3.0T MRI is feasible to quantify cardiac iron deposition.