BACKGROUND:The most common complication of traumatic femoral neck fractures after internal fixation is femoral head necrosis.Currently,many studies have reported on the risk factors that affect the occurrence and development of postoperative femoral head necrosis,but there is still a lack of tools to predict the risk of femoral head necrosis after internal fixation of femoral neck fractures.OBJECTIVE:To develop a predictive model that estimates the risk of femoral head necrosis shortly after patients with femoral neck fractures receive cannulated screw internal fixation.METHODS:A retrospective analysis reviewed clinical records of 172 patients who underwent cannulated screw internal fixation for femoral neck fractures at Department of Orthopedics of Mianyang Central Hospital from January 2013 to June 2023.Patients were categorized into two groups based on the presence or absence of femoral head necrosis within one year post-operation:the necrosis group and the non-necrosis group.Univariate analysis,Lasso regression,and multivariate Logistic regression techniques were employed to identify the determinants of femoral head necrosis.A nomogram prediction model was constructed using R language's"rms"package,version 4.0.The receiver operating characteristic curve was used to evaluate the discriminatory ability of the model.The Hosmer-Lemeshow test was used to evaluate the goodness of fit of the model,and the decision curve analysis was used to determine its clinical application benefits.Internal validation of the study was conducted using the Bootstrap method,involving 1 000 repeated samplings.To delve deeper into the primary factors influencing femoral head necrosis post-internal fixation of the femoral neck,this paper employed the SHAP method for data set analysis.RESULTS AND CONCLUSION:(1)The risk factors leading to femoral head necrosis in the short term after cannulated screw fixation of femoral neck fractures include:smoking,diabetes,Garden classification,fracture line location,reduction quality,age,and operation time.(2)The prediction model demonstrated robust performance,evidenced by an area under the curve of 0.940(95％Confidence Interval:0.903 to 0.977),indicating a high level of prediction accuracy.The model achieved a sensitivity of 90.2％and a specificity of 87.6％,indicating that its diagnostic performance was stable.The Hosmer-Lemeshow goodness-of-fit test yielded a chi-square value of 6.593 with a P-value of 0.581,confirming that the model's predictions closely align with the observed outcomes.(3)The calibration curve of the model also performed well,and its overall trend was very close to the ideal curve,further proving the high accuracy of the model.(4)The internal validation was carried out by the Bootstrap method with 1 000 repeated samplings,and the area under the curve of the model internal validation was still as high as 0.939,proving that the model had good stability.(5)Through the decision curve,it is found that within the probability threshold range of 1％to 92％,the model can obtain the maximum net benefit value.(6)The SHAP analysis results show that among the risk factors analyzed in this study,the location of the fracture line serves as the most significant predictor of femoral head necrosis following internal fixation with cannulated screws in femoral neck fractures,and subcapital fractures are extremely prone to femoral head necrosis after surgery.(7)It is concluded that the validated prediction model demonstrates strong discriminative power and reliability,offering practical clinical utility.It serves as a useful reference tool for short-term risk assessment of femoral head necrosis following internal fixation of femoral neck fractures.

OBJECTIVE:Based on different algorithms of machine learning,the prediction model of lumbar disc herniation has become a trend and hot spot in the development of precision medicine.However,there is limited evidence on the reporting quality and methodological quality of prediction models of lumbar disc herniation outcomes using machine learning.This article is aimed to explore the performance of machine learning algorithms in predicting the prognosis of lumbar disc herniation by comprehensively analyzing the report quality and risk of bias of previous studies that developed and validated prognosis prediction models based on machine learning through a comprehensive literature search,in order to explore the performance of machine learning algorithms in predicting the prognosis of lumbar disc herniation.METHODS:The databases of CNKI,WanFang,VIP,SinOMED,PubMed,Web of Science,Embase,and The Cochrane Library were searched by computer.Studies on the use of machine learning to develop(and/or validate)prognostic prediction models for lumbar disc herniation were collected from the inception of the database to December 31,2023.Two researchers independently screened the literature,extracted data,and assessed the risk of bias of the included studies.The reporting quality and risk of bias of the included studies were assessed by the Multivariable Transparent Reporting of Predictive Models(TRIPOD)statement and the Predictive Model Risk of Bias Assessment Tool(PROBAST).The results of the evaluation were analyzed using descriptive statistics and visual charts.RESULTS:(1)A total of 23 articles were included,and the TRIPOD compliance of each study ranged from 11％to 87％,with a median compliance of 54％.The quality of reporting of titles,detailed descriptions of treatment measures,blinding of predictors,handling of missing data,details of risk stratification,specific procedures for enrollment,model interpretation,and model performance was mostly poor,with TRIPOD adherence rates ranging from 4％to 35％.(2)Of all included studies,61％had a high risk of bias and 39％had an unclear overall risk of bias.The area under the curve,accuracy,sensitivity and specificity were used to evaluate the performance of the model.The areas under the curve of 20 models were reported,ranging from 0.561 to 0.999.Three models reported the accuracy of the model,ranging from 82.07％to 89.65％.(3)Among all included studies,the statistical analysis domain was most often assessed as having a high risk of bias,mainly due to the small number of valid samples,the selection of predictors based on univariate analysis and the lack of calibration and discrimination assessment of the model in the study.CONCLUSION:These results indicate that machine learning can achieve good predictive ability in the development and validation of prognostic models for lumbar disc herniation.The commonly used algorithms include regression algorithm,support vector machine,decision tree,random forest,artificial neural network,naive Bayes and other algorithms.Reasonable algorithms combined with clinical practice can improve the accuracy of prognosis prediction of lumbar disc herniation.However,the reporting and methodological quality of prognosis prediction models based on machine learning are poor,the prediction performance of different models varies greatly,and the generalization and extrapolation of research models are unclear.There is an urgent need to improve the design,implementation and reporting of such studies.To promote the application of machine learning in the clinical practice of lumbar disc herniation prediction models,it is necessary to comprehensively consider various predictors related to the prognosis of the disease before modeling,and strictly follow the relevant standards of PROBAST tool during modeling.

BACKGROUND:The prevalence of osteoporosis is high in postmenopausal women,but muscle mass,grip strength,and how these factors affect osteoporosis are understudied,and the exact link between them has not been clarified.OBJECTIVE:To investigate the correlation between muscle mass,grip strength,appendicular skeletal muscle index and bone mineral density in postmenopausal women with osteoporosis and to assess the potential values of these indices in predicting and diagnosing postmenopausal osteoporosis.METHODS:Eighty-three postmenopausal women were collected from the outpatient clinic of the Third Affiliated Hospital of Guangzhou University of Chinese Medicine from February 2023 to January 2024.General data were collected.Bone mineral density was detected.T-value,muscle mass of each part,grip strength were recorded.The body mass index and appendicular skeletal muscle index were calculated.The patients were categorized into non-osteoporosis group(n=17)and postmenopausal osteoporosis group(n=66)according to T value and fracture history,and were statistically analyzed accordingly.RESULTS AND CONCLUSION:(1)The body mass,body mass index,bone mineral density of the overall lumbar spine,muscle mass and appendicular skeletal muscle index were higher in the non-osteoporosis group than the osteoporosis group(P＜0.05).(2)Muscle mass was positively correlated with bone mineral density of the overall lumbar spine and individual vertebrae(P＜0.05).(3)Multiple stepwise linear regression analysis showed that body mass and grip strength were linearly and positively correlated with muscle mass;body height and muscle mass were linearly and positively correlated with grip strength,and body mass was linearly and negatively correlated with grip strength.Body mass index was linearly and positively correlated with bone mineral density,and age was linearly and negatively correlated with bone mineral density.(4)Analysis by receiver operating characteristic curve showed that:muscle mass(the area under the curve,sensitivity,specificity and critical value of muscle mass were 0.744,76.50％,74.20％and 36.50 kg,respectively,with P=0.002)and appendicular skeletal muscle index(the area under the curve,sensitivity,specificity and critical value of appendicular skeletal muscle index were 0.739,82.40％,62.10％and 5.81 kg/m2,respectively,and P=0.002)had good predictive value for postmenopausal osteoporosis.To conclude,a reduction in muscle mass and appendicular skeletal muscle index can help to predict the risk of postmenopausal osteoporosis,and the possibility of osteoporosis should be taken into account in postmenopausal women when muscle mass is＜36.50 kg or appendicular skeletal muscle index is＜5.81 kg/m2,in order to prevent the occurrence of postmenopausal osteoporosis.

BACKGROUND:The quadriceps strength of patients with osteoporosis and sarcopenia is significantly reduced,which can further reduce the function of the knee joint,affect the function of the lower limbs and even lead to a decrease in whole-body coordination.It is speculated that a reasonable quadriceps training program and personalized guidance are beneficial to the recovery of knee joint function in patients with osteoporosis and sarcopenia.OBJECTIVE:To observe the effect of short-term moderate-intensity resistance rehabilitation training on the mass and function of the quadriceps and knee joint function in patients with osteoporosis and sarcopenia.METHODS:Using the integrated physical examination and rehabilitation model,375 patients with osteoporosis and sarcopenia were screened at the Health Management Center of Shanghai Public Health Clinical Center.They underwent 12 weeks of combined/comprehensive exercise rehabilitation based on resistance exercise,including quadriceps resistance isotonic and isometric contraction training twice a week(3-5 sets each time,10-15 minutes per set)and aerobic exercise/balance exercise two or three times a week(30 minutes each time).Assessments and data collection were performed before rehabilitation training,12 weeks after rehabilitation training,and at follow-up 12 weeks after stopping rehabilitation training,mainly including knee joint range of motion and proprioception,quadriceps muscle strength,and cross-sectional area(magnetic resonance imaging results),pain,knee joint function(Hospital for Special Surgery score)and walking function("up-and-go"time and 6 m pace test results)as well as the patient's psychological status assessment.RESULTS AND CONCLUSION:All 375 patients completed 12 weeks of rehabilitation training and 12 weeks of follow-up without any adverse events.(1)Compared with before training,the patients' gait speed and knee range of motion increased significantly after 12 weeks of rehabilitation training(P＜0.01),the time of"stand-to-walk"decreased(P＜0.01),and the proprioception of the knee joint and the strength of the quadriceps femoris were significantly improved(P＜0.01);and at the follow-up visit 12 weeks after stopping training,the above indicators and functions of the patients were well maintained(P＞0.05).(2)Magnetic resonance imaging results showed that the effective cross-sectional area of the quadriceps femoris did not improve significantly after 12 weeks of rehabilitation training(P＞0.05);but the Hospital for Special Surgery score of knee joint function increased significantly(P＜0.01),and the visual analog pain scale score decreased significantly(P＜0.01),suggesting that this may be related to the improvement of quadriceps femoris quality by resistance rehabilitation training.(3)The results of the Hospital Anxiety and Depression Scale score showed that the anxiety and depression scores of the patients continued to decrease,both at 12 weeks of rehabilitation training and at 12 weeks after stopping training(P＜0.01).It is suggested that resistance rehabilitation training of the quadriceps can help patients with osteoporosis and sarcopenia to restore quadriceps muscle strength,increase range of motion,improve proprioception and joint stability,thereby enhancing knee joint function,reducing pain,improving depression and anxiety,and to a certain extent promoting the coordinated recovery of the musculoskeletal system.

BACKGROUND:The inflammatory response of microglia is closely related to neuronal survival,regeneration,and functional recovery after spinal cord injury.Peroxiredoxin 1 is not only involved in the regulation of oxidative stress,but also has an important effect on cell proliferation,apoptosis,and inflammatory response.OBJECTIVE:To investigate the role and mechanism of peroxiredoxin 1 in the inflammatory response of microglia following spinal cord injury.METHODS:(1)Twelve female C57BL/6 mice were randomly divided into sham-operated(n=6)and spinal cord injury(n=6)groups.The sham-operated group was not modeled and acute spinal cord injury models were constructed in the spinal cord injury group using the modified Allen's method.Spinal cord tissue at the injured site was taken at 7 days after modeling and transcriptome sequencing was performed to identify differentially expressed genes.The expression of peroxiredoxin 1 in spinal cord tissues was verified using western blot and RT-qPCR.(2)Mouse microglia BV2 were divided into two groups:the control group was stimulated with lipopolysaccharide for 6 hours,and in the knockout group,lipopolysaccharide stimulation was applied for 6 hours at 24 hours after peroxiredoxin 1 was knocked down in the cells.RT-qPCR was performed to detect mRNA expression of peroxiredoxin 1,inflammatory factors(interleukin 1β,interleukin 6,inducible nitric oxide synthase,tumor necrosis factor α,C-C motif chemokine ligand 2,and C-X-C motif chemokine ligand 2),and western blot was performed to detect the expression of peroxiredoxin 1,inducible nitric oxide synthase,and reactive oxygen/mitogen-activated protein kinase signaling pathway proteins.Mouse microglia BV2 were treated in two groups:the control group was stimulated by hydrogen peroxide for 4 hours,and the knockout group was stimulated by hydrogen peroxide for 4 hours at 24 hours after knockdown of peroxiredoxin 1.The level of reactive oxygen species was detected by 2,7-dichlorodihydrofluorescein diacetate probe.RESULTS AND CONCLUSION:(1)Results from transcriptome sequencing,western blot and RT-qPCR confirmed that peroxiredoxin 1 expression levels in mouse spinal cord tissues were significantly higher in the spinal cord injury group than the sham-operated group(P＜0.05).(2)Peroxiredoxin 1 knockdown in microglial cells led to decreased expression of peroxiredoxin 1 mRNA and protein(P＜0.05),increased mRNA expression of interleukin 1β,interleukin 6,inducible nitric oxide synthase,tumor necrosis factor α,C-C motif chemokine ligand 2,and C-X-C motif chemokine ligand 2(P＜0.05),increased protein expression of inducible nitric oxide synthase,P-P38,P-JNK and P-ERK proteins(P＜0.05),and increased level of reactive oxygen species(P＜0.05).To conclude,peroxiredoxin 1 regulates microglial inflammation by targeting the reactive oxygen species/mitogen-activated protein kinase signaling pathway.

BACKGROUND:BCR/ABL gene is a specific gene of Ph chromosome-positive acute lymphoblastic leukemia,and its expression level has become a sensitive indicator for monitoring minimal residual disease before and after allogeneic hematopoietic stem cell transplantation.However,whether the expression level of BCR/ABL gene before transplantation affects the efficacy of transplantation and how to guide the early intervention of relapse with tyrosine kinase inhibitors after transplantation is still inconclusive.OBJECTIVE:To explore the relationship between BCR/ABL gene expression and recurrence in patients with Ph chromosome positive acute lymphoblastic leukemia before and after related and allogeneic hematopoietic stem cell transplantation.METHODS:Twenty-four patients with Ph chromosome positive acute lymphoblastic leukemia who achieved complete hematological remission and underwent allogeneic hematopoietic stem cell transplantation were selected at the Affiliated Hospital of North China University of Science and Technology between January 2015 and December 2022.Real time fluorescence quantitative polymerase chain reaction was used to dynamically detect the expression levels of BCR/ABL genes during treatment,representing minimal residual disease.Based on BCR/ABL gene expression,tyrosine kinase inhibitors combined with chemotherapy was administered before transplantation to select the timing of allogeneic hematopoietic stem cell transplantation.After transplantation,the disease status was evaluated to guide the use of tyrosine kinase inhibitors,and an early intervention plan for recurrence was developed.RESULTS AND CONCLUSION:Follow-up was until December 2023,with a median follow-up time of 49(12-82)months.There were 8 cases of hematological recurrence,with a median recurrence time of 14(8-39)months and a cumulative recurrence rate of 33％(8/24).Univariate analysis showed that recurrence after allogeneic hematopoietic stem cell transplantation was not significantly correlated with gender,age,extramedullary complications,time from diagnosis to transplantation,HLA typing,acute graft-versus-host disease,and chronic graft-versus-host disease(P＞0.05).There was a significant correlation between the relief treatment course and minimal residual disease levels before transplantation.The second hematology completely resolution and positive minimal residual disease before transplantation had a higher hematological recurrence rate(P＜0.05).The 3-year cumulative recurrence rate,disease-free survival rate,and overall survival rate were 27％,63％,and 74％;the 5-year cumulative recurrence rate,disease-free survival rate,and overall survival rate were 38％,57％,and 74％,respectively.It is concluded that Ph chromosome positive acute lymphoblastic leukemia patients with BCR/ABL gene positive before transplantation have a higher recurrence rate.BCR/ABL gene expression after transplantation can guide the application of tyrosine kinase inhibitors and serve as a basis for early intervention in recurrence.

BACKGROUND:Choline kinase alpha is a key enzyme in phospholipid metabolism,involved in the synthesis of phosphatidylcholine,and plays an important role in maintaining cell membrane integrity and signal transduction.Research has shown that choline kinase alpha is highly expressed in various tumors and is closely related to cell proliferation,metabolic reprogramming,and tumor progression.As a potential therapeutic target,the role of choline kinase alpha in tumor metabolism and mitochondrial function still needs further exploration.OBJECTIVE:To evaluate the effects and the underlying mechanisms of choline kinase alpha on the proliferation and apoptosis of glioma U87MG and U251 cells.METHODS:Short hairpin RNA of choline kinase alpha and its empty vector control were transfected into U87MG and U251 glioma cells.Mitochondrial morphology was observed by transmission electron microscopy.Mitochondrial structure and functional protein levels were assessed by western blot assay.Reactive oxygen species levels in cells were measured using a reactive oxygen species fluorescent probe.Mitochondrial membrane potential was assessed with a JC-1 assay.Intracellular adenosine triphosphate levels were measured by chemiluminescence.Cell proliferation was evaluated using a CCK-8 assay.Apoptosis levels were analyzed by flow cytometry.The mitochondrial fission inhibitor Mdivi-1 was used to protect the mitochondrial function of the choline kinase α-silenced lentiviral cells.Finally,U87MG cells were subcutaneously injected to construct a subcutaneous tumor model in nude mice.The tumor growth in nude mice was observed before and after choline kinase alpha silencing and after the use of the mitochondrial fission inhibitor Mdivi-1.RESULTS AND CONCLUSION:(1)Compared with the empty control group,the mitochondria of U87MG and U251 cells in the choline kinase alpha silencing lentivirus group exhibited significant structural abnormalities in mitochondria,such as vacuolization and cristae disruption.The expressions of mitochondrial structure and function-related proteins TOM20,ACO2,and ATP5A were significantly decreased(P＜0.01,P＜0.001),the expression of SOD2 was significantly increased(P＜0.01,P＜0.000 1),the fluorescence intensity of reactive oxygen species was significantly increased(P＜0.01),the mitochondrial membrane potential and adenosine triphosphate level were significantly decreased(P＜0.01,P＜0.001),the cell proliferation ability was reduced(P＜0.01),and the apoptosis level was increased(P＜0.001).(2)Following Mdivi-1 treatment,the fluorescence intensity of reactive oxygen species in U87MG and U251 cells decreased(P＜0.05,P＜0.01),mitochondrial membrane potential and adenosine triphosphate levels were significantly restored(P＜0.05,P＜0.01,P＜0.001),cell proliferation ability was improved(P＜0.05,P＜0.01),and apoptosis level was decreased(P＜0.05).(3)In addition,the in vitro subcutaneous tumor formation experiment of nude mice showed that compared with the empty control group,the mass and growth rate of subcutaneous tumors formed by U87MG cells in the choline kinase alpha silencing lentivirus group were significantly reduced(P＜0.000 1).After Mdivi-1 treatment,the mass and growth rate of tumors were significantly increased(P＜0.000 1).(4)The results show that choline kinase alpha silencing affects the proliferation and apoptosis of glioma cells by inducing mitochondrial dysfunction.

BACKGROUND:The preparation of curved root canals is a difficult point in root canal treatment,and the main way used in clinical preparation for curved root canals is to gradually deepen the technique,but this technique is prone to lateral penetration when preparing curved root canals,resulting in treatment failure.In view of this situation,some scholars have proposed the use of touch activation technology to prepare,but there are few studies on the influence of this technology combined with different mechanical nickel-titanium instruments on the forming effect of curved root canals at home and abroad.OBJECTIVE:To observe the shaping effect of WaveOneGold,Trunatomy and M3-Pro mechanized nitinol device preparation root canal by using resin simulated root canal step-down technology and tactile controlled activation.METHODS:60 single-bending resin simulated root canals were divided into 6 groups(r=10)according to the random number table method according to the nitinol instrument used.The A1 group was prepared with step-down+WaveOneGold;the A2 group was prepared with step-down+Trunatomy,and the A3 group was prepared with step-down+M3-Pro.Tactile controlled activation+WaveOneGold was used for preparation in group B1;tactile controlled activation+Trunatomy was used for group B2,and tactile controlled activation+M3-Pro was used for preparation in group B3.After the preparation was completed,the pre-preparation and posterior root canal images are obtained using a dental surgical microscope.The root canal offset was analyzed before and after preparation.RESULTS AND CONCLUSION:(1)When WaveOneGold was used,the root canal deviation at 1,4,and 7 mm from the apex was smaller with the tactile controlled activation technique than with the step-down technique(P＜0.05);when Trunatomy was used,the root canal deviation at 6,8,and 10 mm from the apex was smaller with the tactile controlled activation technique than with the step-down technique(P＜0.05);when M3-Pro was used,the root canal deviation at 1,2,and 3 mm from the apex was smaller with the tactile controlled activation technique than with the step-down technique(P＜0.05).(2)When the step-down technique was used,the root canal deviation at 1,4,5,and 7 mm from the apex was smaller with the Trunatomy than with the other two files(P＜0.05),and the root canal deviation at 1,2,3,and 6 mm from the apex was larger with the M3-Pro machine-made nickel-titanium instrument than with the other two files(P＜0.05);when the tactile controlled activation technique was used,the root canal deviation at 2,5,6,8,and 9 mm from the apex after preparation with the Trunatomy file was smaller than that of the other two groups(P＜0.05),and the root canal deviation at 1,4,5,6,and 7 mm from the apex after preparation with the M3-Pro file was larger than that of the other two groups(P＜0.05).(3)The results showed that the three files could cause root canal deviation when preparing root canals.The three files combined with the tactile controlled activation technique could reduce the root canal deviation at some sites of the root canal.The root canal deviation at some sites of the Trunatomy file was less than that of the other two files.

BACKGROUND:Pure titanium and titanium alloy implants are widely used in the field of implant restoration due to their excellent biocompatibility and elastic modulus.However,the biological inertness of the surface of titanium-based implants leads to poor integration with surrounding bone tissues,and surface modification is required to improve the bone integration ability of titanium-based implants.OBJECTIVE:To fabricate hydroxyapatite/graphene oxide/interleukin-4 composite coatings on pure titanium substrates,and to investigate their physicochemical properties and biocompatibility of the coating materials.METHODS:Hydroxyapatite/graphene oxide/interleukin-4 composite coatings were prepared on pure titanium substrates by electrochemical deposition and freeze-drying.Titanium sheets loaded with interleukin-4 and titanium sheets loaded with hydroxyapatite/graphene oxide coatings were prepared at the same time,and the physicochemical properties of pure titanium sheets and the above three titanium sheets were characterized.MC3T3-E1 cells were inoculated on the surfaces of pure titanium sheets and the above three titanium sheets,respectively.Cell proliferation was detected by CCK-8 assay and DAPI staining.Cell activity was detected by Calcein-AM/PI staining.Cell morphology and adhesion were observed by scanning electron microscopy.RESULTS AND CONCLUSION:(1)Scanning electron microscopy,energy-dispersive X-ray spectroscopy,X-ray photoelectron spectroscopy,X-ray diffraction,and Raman spectroscopy confirmed the successful fabrication of the hydroxyapatite/graphene oxide/interleukin-4 composite coating on the titanium surface.The water contact angle of hydroxyapatite/graphene oxide/interleukin-4 group was larger than that of pure titanium group and hydroxyapatite/graphene oxide group,and smaller than that of interleukin-4 group.(2)CCK-8 assay and DAPI staining results showed that hydroxyapatite/graphene oxide/interleukin-4 coating could promote the proliferation of MC3T3-E1 cells.Calcein-AM/PI staining results showed that MC3T3-E1 cells in hydroxyapatite/graphene oxide/interleukin-4 coating group had higher activity and fewer dead cells.Scanning electron microscopy showed that MC3T3-E1 cells adhered to the surfaces of the four groups of materials with good cell morphology.Compared with the pure titanium group,the MC3T3-E1 cells in the interleukin-4 group extended more pseudopodia,the cell-cell connections were closer,and the adhesion area was larger;compared with the hydroxyapatite/graphene oxide group,the MC3T3-E1 cells in the hydroxyapatite/graphene oxide/interleukin-4 group extended more pseudopodia,the cell-cell connections were closer,and the adhesion area was larger.(3)These findings indicate that the hydroxyapatite/graphene oxide/interleukin-4 composite coating possesses favorable physicochemical and biological properties.

BACKGROUND:Promoting skin wound healing is a huge challenge facing global public health.To promote faster and higher-quality wound healing,it is necessary to explore more advantageous dressings to address this problem.OBJECTIVE:To investigate the hemostatic properties of acellular dermal matrix hydrogel and its effect on skin wound healing.METHODS:(1)Acellular dermal matrix hydrogel was prepared,and the differences in microscopic morphology and main components between it and acellular dermal matrix were analyzed.(2)Acellular dermal matrix hydrogel and chitosan hydrogel were used to cover the femoral artery puncture site of rats,and the bleeding quality and coagulation time were recorded.Acellular dermal matrix hydrogel and chitosan hydrogel were mixed with rat anticoagulated blood,and the coagulation index within 30 minutes was detected.(3)A full-thickness skin defect model with a diameter of 12 mm was made on the back of 18 SD rats,and they were randomly divided into 3 groups,with 6 rats in each group:the model group used PBS to clean the wound,and the control group and the experimental group used chitosan hydrogel and acellular dermal matrix hydrogel to cover the wound,respectively.The hydrogel dressing was changed every day,and the treatment was continued for 14 days,and the wound healing was observed.On day 3 after modeling,immunofluorescence staining of inducible nitric oxide synthase(M1 macrophages)and CD206(M2 macrophages)was performed on the wound surface.On day 14 after modeling,hematoxylin-eosin staining,Masson staining,and CD31 immunohistochemical staining were performed on the wound surface.RESULTS AND CONCLUSION:(1)Scanning electron microscopy revealed that the acellular dermal matrix hydrogel had a porous structure,and the Fourier transform infrared spectrum showed that it had the same main components as the acellular dermal matrix.(2)Both acellular dermal matrix hydrogel and chitosan hydrogel had obvious hemostatic ability in vivo.In the in vitro coagulation experiments,the coagulation index of acellular dermal matrix hydrogel was significantly higher than that of chitosan hydrogel.(3)In the rat skin full-thickness defect model,both acellular dermal matrix hydrogel and chitosan hydrogel could improve the wound healing rate.Hematoxylin-eosin and Masson staining results showed that acellular dermal matrix hydrogel could reduce the infiltration of inflammatory cells in the center of the wound.Both acellular dermal matrix hydrogel and chitosan hydrogel could decrease scar width and increase collagen deposition rate.CD31 immunohistochemical staining results showed that both hydrogels could promote angiogenesis in the wound site.Immunofluorescence staining results showed that both hydrogels could reduce the proportion of M1 macrophages and increase the proportion of M2 macrophages,and the effect of acellular dermal matrix hydrogel was stronger than that of chitosan hydrogel.(4)The results show that the acellular dermal matrix hydrogel has good hemostatic properties and the ability to promote wound healing.