BACKGROUND:Exosomes are nanoscale extracellular vesicles secreted by various types of cells,with advantages such as high bioavailability,low toxicity,low immunogenicity,and good biocompatibility.However,natural exosomes have certain limitations in clinical therapy.By using bioengineering techniques to modify and engineer exosomes,the engineered exosomes not only improve their original therapeutic effects but also exhibit excellent biostability and targeting specificity,showing great potential for application in the field of tissue repair.OBJECTIVE:To summarize the various strategies for engineering exosomes,including functional loading and surface modification,outline the research progress of engineered exosomes in different tissue repairs,and explore the therapeutic potential of engineered exosomes in tissue repair.METHODS:PubMed database was searched for relevant literature published between 2010 and 2024 using the search terms"engineered exosomes,tissue repair,biomaterials,tissue engineering,wound healing,parenchyma,bone regeneration,cartilage,neural,myocardial,hepatic."Studies that were not closely related to the article's theme,of poor quality,repetitive,or outdated were excluded.A total of 115 articles met the inclusion criteria.RESULTS AND CONCLUSION:(1)Functional loading is used to combine therapeutic molecules with exosomes to obtain additional properties or to enhance the original physiological function of the exosome,among which ultrasonication and extrusion are simple to operate and can obtain higher drug loading capacity at the same time.(2)Surface modification can make exosomes express desired proteins or enhance their targeting,including genetic engineering and chemical modification.Genetic engineering is complicated,poorly reproducible,and the end product is poorly controllable.Chemical modification,on the other hand,is relatively simple and versatile,and is more suitable for designing highly targeted and functionally specific engineered exosomes.(3)Among the techniques for pre-treating cells to obtain engineered exosomes,hypoxic pre-treatment is more widely used because of its simplicity and clearer mechanism,which can activate glycolysis to promote cell proliferation,and regulate the vascular endothelial growth factor receptor signaling pathway through the generation of hypoxia-inducible factors to promote angiogenesis.(4)The function of exosomes is affected by various factors such as cell source,cell state,synthesis process,and extracellular environment.If the engineering strategy is complicated,it is more difficult to ensure the functional consistency of the final engineered exosomes,so the relatively simple and reliable engineering strategy is more suitable for its clinical application.(5)Engineered exosomes combined with biomaterials or scaffolds can be used to treat complex wounds of skin soft tissue,such as infected wounds and diabetic ulcers.This approach enhances exosome delivery and controls their release,promotes tissue repair,controls infection,and regulates the local microenvironment of the wound.(6)A single mechanism of engineered exosomes is often ineffective due to the specificity of the bone tissue fracture,so dual or even multi-functional engineered exosomes are needed to promote fracture repair while anti-inflammatory or remodeling the vascular system.(7)The source of exosomes has a significant impact on neural tissue repair.Exosomes derived from different neural cells promote neural repair through different effects.In addition,the combination of stents and engineered exosomes for traumatic brain injury has obvious advantages,the stent itself provides hemostasis and support,combined with the engineered exosomes itself to promote the repair effect,can obtain better therapeutic effect.(8)In cardiac and hepatic tissue repair,it is needed to develop anti-fibrotic engineered exosomes to resist the abnormal repair of cardiac and hepatic tissues themselves,which will require further research in the future.

BACKGROUND:Dental pulp stem cells,which derived from the dental pulp tissue,are one type of dental-derived mesenchymal stem cells,possess significant properties of self-renewal and multi-lineage differentiation.In recent years,series of researches focus on dental pulp stem cells and their derivatives such as extracellular vesicles,conditioned medium,and decellularized extracellular matrix,those have positive effects on the repair and regeneration of pulp tissue injury,showing an attractive clinical application.OBJECTIVE:To systematically review the researches and applications of dental pulp stem cells and their derivatives in dental pulp tissue engineering.METHODS:Literature searches were conducted in PubMed,China Biology Medicine(CBM),and China National Knowledge Infrastructure(CNKI)databases for articles published from January 2005 to June 2023.The search terms included"dental pulp stem cells,extracellular vesicles,exosomes,apoptotic bodies,conditioned medium,decellularized matrix,regeneration"in Chinese and English.After screening the titles and abstracts,duplicate and irrelevant studies were excluded.Finally,103 studies closely related to dental pulp regeneration were included for review and analysis.RESULTS AND CONCLUSION:Dental pulp stem cells and their derivatives are rich in lots of bioactive factors that can effectively promote odontogenic,angiogenic,and neurogenic differentiation,exhibiting significant potential in the formation of the pulp-dentin complex.However,the clinical translation of dental pulp stem cells and their derivatives still faces several challenges.Future researches should focus on optimizing preparation protocols,elucidating the underlying mechanisms of action,and refining safety assessments to provide novel therapeutic strategies for the repair of dental pulp injury.

BACKGROUND:Currently,treatment method for knee osteoarthritis includes oral medicine,joint cavity drug injection,and physiotherapy,but the curative effect is limited.Existing studies have confirmed that silicon-based bioceramics can promote cartilage and subchondral bone repair and vascular regeneration.OBJECTIVE:To explore the effect of different concentrations of silicon-based bioceramics injected into the knee joint cavity in the treatment of knee osteoarthritis in rats.METHODS:Silicon-based bioceramics-calcium silicate was prepared.Twenty-five SD rats were randomly divided into five groups,with five rats in each group.The healthy group did not receive any intervention,and the modeling group,low-dose calcium silicate group,high-dose calcium silicate group,and saline group used anterior cruciate ligament transection to establish bilateral knee osteoarthritis models.Four weeks after modeling,0.05 mL of 50 and 100 mg/mL calcium silicate solution were injected into the knee joint cavity in the low-dose calcium silicate group and high-dose calcium silicate group,respectively,and 0.05 mL of saline was injected into the knee joint cavity in the saline group,once a week for 4 consecutive weeks.In the fifth week of administration,bilateral knee joint Micro-CT detection,knee joint cartilage hematoxylin-eosin staining,and modified Mankin score were performed.RESULTS AND CONCLUSION:(1)Micro-CT quantitative analysis showed that compared with the healthy group,the volume fraction and number of trabeculae of the medial tibial plateau in the modeling group decreased(P＜0.05),and the separation of trabeculae increased(P＜0.05).Compared with the modeling group,the volume fraction and number of trabeculae of the medial tibial plateau in the low-dose calcium silicate group and the saline group increased(P＜0.05),and the separation of trabeculae decreased(P＜0.05).(2)Hematoxylin-eosin staining showed that the cartilage surface of the healthy group and the low-dose calcium silicate group was relatively smooth and flat,the chondrocytes were evenly distributed,without clustered chondrocytes,the tide line was complete,and the staining was uniform;the cartilage surface of the high-dose calcium silicate group was slightly uneven,the middle and deep cells were disordered,with a small number of clustered chondrocytes,the tide line was discontinuous,and the staining was uneven;the cartilage surface of the saline group and the modeling group was obviously rough,the cells were disordered,with a large number of clustered chondrocytes,the tide line disappeared,and the staining was uneven.The modified Mankin score of the healthy group was lower than that of the high-dose calcium silicate group,the saline group,and the modeling group(P＜0.05).The modified Mankin score of the high-dose calcium silicate group and the low-dose calcium silicate group was lower than that of the saline group and the modeling group(P＜0.05).(3)The results show that calcium silicate knee joint injection has a certain effect in the treatment of knee osteoarthritis.Compared with 100 mg/mL calcium silicate solution,50 mg/mL calcium silicate solution can promote the recovery of subchondral bone and cartilage.

BACKGROUND:Bone remodeling is the biological basis of orthodontic tooth movement.Type 2 diabetes mellitus leads to metabolic changes in the jaw and alveolar bone,so it is hypothesized that tooth mobility characteristics may be altered in a high-sugar environment.OBJECTIVE:To explore the impact of type 2 diabetes mellitus on orthodontic tooth movement in rats within one tooth movement cycle.METHODS:Seventy-two Sprague-Dawley rats were selected.Forty rats were randomly chosen and fed with a high-fat diet to construct a type 2 diabetes mellitus model.Thirty-two rats that were successfully modeled were randomly divided into a type 2 diabetes mellitus group(n=16)and a diabetic orthodontic group(n=16).The remaining 32 rats were randomly divided into a control group(n=16)and an orthodontic group(n=16).The rats in the orthodontic group and the diabetic orthodontic group were equipped with nickel-titanium coil spring orthodontic force application devices to move the unilateral maxillary first molars mesially with a force of 50 g.The rats were anesthetized and sacrificed on the 3rd,7th,14th,and 21st days after orthodontic treatment,and Micro-CT was used to measure the mesial displacement of the first molars and detect the changes in the bone microstructure parameters on the tension side.RESULTS AND CONCLUSION:There were significant differences in the tooth movement distances among the four groups of rats on the 3rd,7th,14th,and 21st days of orthodontic treatment(P＜0.05).There were significant differences in bone mineral density,bone volume fraction and trabecular bone separation on the tension side among the four groups on the 7th,14th,and 21st days of orthodontic treatment(P＜0.05).There were differences in the trabecular thickness among the four groups on the 3rd and 14th days of orthodontic treatment(P＜0.05).The diabetic orthodontic group had the smallest tension-side alveolar bone mineral density,bone volume fraction,and trabecular thickness,and the largest tooth movement distance and trabecular separation on the 21st day of orthodontic treatment.The above results indicate that type 2 diabetes mellitus adversely affects bone microstructural parameters on the tension side in orthodontic tooth movement in rats,suggesting the occurrence of an osteoporotic state.

BACKGROUND:Exosomes are nanoscale extracellular vesicles secreted by various types of cells,with advantages such as high bioavailability,low toxicity,low immunogenicity,and good biocompatibility.However,natural exosomes have certain limitations in clinical therapy.By using bioengineering techniques to modify and engineer exosomes,the engineered exosomes not only improve their original therapeutic effects but also exhibit excellent biostability and targeting specificity,showing great potential for application in the field of tissue repair.OBJECTIVE:To summarize the various strategies for engineering exosomes,including functional loading and surface modification,outline the research progress of engineered exosomes in different tissue repairs,and explore the therapeutic potential of engineered exosomes in tissue repair.METHODS:PubMed database was searched for relevant literature published between 2010 and 2024 using the search terms"engineered exosomes,tissue repair,biomaterials,tissue engineering,wound healing,parenchyma,bone regeneration,cartilage,neural,myocardial,hepatic."Studies that were not closely related to the article's theme,of poor quality,repetitive,or outdated were excluded.A total of 115 articles met the inclusion criteria.RESULTS AND CONCLUSION:(1)Functional loading is used to combine therapeutic molecules with exosomes to obtain additional properties or to enhance the original physiological function of the exosome,among which ultrasonication and extrusion are simple to operate and can obtain higher drug loading capacity at the same time.(2)Surface modification can make exosomes express desired proteins or enhance their targeting,including genetic engineering and chemical modification.Genetic engineering is complicated,poorly reproducible,and the end product is poorly controllable.Chemical modification,on the other hand,is relatively simple and versatile,and is more suitable for designing highly targeted and functionally specific engineered exosomes.(3)Among the techniques for pre-treating cells to obtain engineered exosomes,hypoxic pre-treatment is more widely used because of its simplicity and clearer mechanism,which can activate glycolysis to promote cell proliferation,and regulate the vascular endothelial growth factor receptor signaling pathway through the generation of hypoxia-inducible factors to promote angiogenesis.(4)The function of exosomes is affected by various factors such as cell source,cell state,synthesis process,and extracellular environment.If the engineering strategy is complicated,it is more difficult to ensure the functional consistency of the final engineered exosomes,so the relatively simple and reliable engineering strategy is more suitable for its clinical application.(5)Engineered exosomes combined with biomaterials or scaffolds can be used to treat complex wounds of skin soft tissue,such as infected wounds and diabetic ulcers.This approach enhances exosome delivery and controls their release,promotes tissue repair,controls infection,and regulates the local microenvironment of the wound.(6)A single mechanism of engineered exosomes is often ineffective due to the specificity of the bone tissue fracture,so dual or even multi-functional engineered exosomes are needed to promote fracture repair while anti-inflammatory or remodeling the vascular system.(7)The source of exosomes has a significant impact on neural tissue repair.Exosomes derived from different neural cells promote neural repair through different effects.In addition,the combination of stents and engineered exosomes for traumatic brain injury has obvious advantages,the stent itself provides hemostasis and support,combined with the engineered exosomes itself to promote the repair effect,can obtain better therapeutic effect.(8)In cardiac and hepatic tissue repair,it is needed to develop anti-fibrotic engineered exosomes to resist the abnormal repair of cardiac and hepatic tissues themselves,which will require further research in the future.

BACKGROUND:Dental pulp stem cells,which derived from the dental pulp tissue,are one type of dental-derived mesenchymal stem cells,possess significant properties of self-renewal and multi-lineage differentiation.In recent years,series of researches focus on dental pulp stem cells and their derivatives such as extracellular vesicles,conditioned medium,and decellularized extracellular matrix,those have positive effects on the repair and regeneration of pulp tissue injury,showing an attractive clinical application.OBJECTIVE:To systematically review the researches and applications of dental pulp stem cells and their derivatives in dental pulp tissue engineering.METHODS:Literature searches were conducted in PubMed,China Biology Medicine(CBM),and China National Knowledge Infrastructure(CNKI)databases for articles published from January 2005 to June 2023.The search terms included"dental pulp stem cells,extracellular vesicles,exosomes,apoptotic bodies,conditioned medium,decellularized matrix,regeneration"in Chinese and English.After screening the titles and abstracts,duplicate and irrelevant studies were excluded.Finally,103 studies closely related to dental pulp regeneration were included for review and analysis.RESULTS AND CONCLUSION:Dental pulp stem cells and their derivatives are rich in lots of bioactive factors that can effectively promote odontogenic,angiogenic,and neurogenic differentiation,exhibiting significant potential in the formation of the pulp-dentin complex.However,the clinical translation of dental pulp stem cells and their derivatives still faces several challenges.Future researches should focus on optimizing preparation protocols,elucidating the underlying mechanisms of action,and refining safety assessments to provide novel therapeutic strategies for the repair of dental pulp injury.

BACKGROUND:Currently,treatment method for knee osteoarthritis includes oral medicine,joint cavity drug injection,and physiotherapy,but the curative effect is limited.Existing studies have confirmed that silicon-based bioceramics can promote cartilage and subchondral bone repair and vascular regeneration.OBJECTIVE:To explore the effect of different concentrations of silicon-based bioceramics injected into the knee joint cavity in the treatment of knee osteoarthritis in rats.METHODS:Silicon-based bioceramics-calcium silicate was prepared.Twenty-five SD rats were randomly divided into five groups,with five rats in each group.The healthy group did not receive any intervention,and the modeling group,low-dose calcium silicate group,high-dose calcium silicate group,and saline group used anterior cruciate ligament transection to establish bilateral knee osteoarthritis models.Four weeks after modeling,0.05 mL of 50 and 100 mg/mL calcium silicate solution were injected into the knee joint cavity in the low-dose calcium silicate group and high-dose calcium silicate group,respectively,and 0.05 mL of saline was injected into the knee joint cavity in the saline group,once a week for 4 consecutive weeks.In the fifth week of administration,bilateral knee joint Micro-CT detection,knee joint cartilage hematoxylin-eosin staining,and modified Mankin score were performed.RESULTS AND CONCLUSION:(1)Micro-CT quantitative analysis showed that compared with the healthy group,the volume fraction and number of trabeculae of the medial tibial plateau in the modeling group decreased(P＜0.05),and the separation of trabeculae increased(P＜0.05).Compared with the modeling group,the volume fraction and number of trabeculae of the medial tibial plateau in the low-dose calcium silicate group and the saline group increased(P＜0.05),and the separation of trabeculae decreased(P＜0.05).(2)Hematoxylin-eosin staining showed that the cartilage surface of the healthy group and the low-dose calcium silicate group was relatively smooth and flat,the chondrocytes were evenly distributed,without clustered chondrocytes,the tide line was complete,and the staining was uniform;the cartilage surface of the high-dose calcium silicate group was slightly uneven,the middle and deep cells were disordered,with a small number of clustered chondrocytes,the tide line was discontinuous,and the staining was uneven;the cartilage surface of the saline group and the modeling group was obviously rough,the cells were disordered,with a large number of clustered chondrocytes,the tide line disappeared,and the staining was uneven.The modified Mankin score of the healthy group was lower than that of the high-dose calcium silicate group,the saline group,and the modeling group(P＜0.05).The modified Mankin score of the high-dose calcium silicate group and the low-dose calcium silicate group was lower than that of the saline group and the modeling group(P＜0.05).(3)The results show that calcium silicate knee joint injection has a certain effect in the treatment of knee osteoarthritis.Compared with 100 mg/mL calcium silicate solution,50 mg/mL calcium silicate solution can promote the recovery of subchondral bone and cartilage.

BACKGROUND:Bone remodeling is the biological basis of orthodontic tooth movement.Type 2 diabetes mellitus leads to metabolic changes in the jaw and alveolar bone,so it is hypothesized that tooth mobility characteristics may be altered in a high-sugar environment.OBJECTIVE:To explore the impact of type 2 diabetes mellitus on orthodontic tooth movement in rats within one tooth movement cycle.METHODS:Seventy-two Sprague-Dawley rats were selected.Forty rats were randomly chosen and fed with a high-fat diet to construct a type 2 diabetes mellitus model.Thirty-two rats that were successfully modeled were randomly divided into a type 2 diabetes mellitus group(n=16)and a diabetic orthodontic group(n=16).The remaining 32 rats were randomly divided into a control group(n=16)and an orthodontic group(n=16).The rats in the orthodontic group and the diabetic orthodontic group were equipped with nickel-titanium coil spring orthodontic force application devices to move the unilateral maxillary first molars mesially with a force of 50 g.The rats were anesthetized and sacrificed on the 3rd,7th,14th,and 21st days after orthodontic treatment,and Micro-CT was used to measure the mesial displacement of the first molars and detect the changes in the bone microstructure parameters on the tension side.RESULTS AND CONCLUSION:There were significant differences in the tooth movement distances among the four groups of rats on the 3rd,7th,14th,and 21st days of orthodontic treatment(P＜0.05).There were significant differences in bone mineral density,bone volume fraction and trabecular bone separation on the tension side among the four groups on the 7th,14th,and 21st days of orthodontic treatment(P＜0.05).There were differences in the trabecular thickness among the four groups on the 3rd and 14th days of orthodontic treatment(P＜0.05).The diabetic orthodontic group had the smallest tension-side alveolar bone mineral density,bone volume fraction,and trabecular thickness,and the largest tooth movement distance and trabecular separation on the 21st day of orthodontic treatment.The above results indicate that type 2 diabetes mellitus adversely affects bone microstructural parameters on the tension side in orthodontic tooth movement in rats,suggesting the occurrence of an osteoporotic state.

Objective To explore the predictive value of peripheral blood cells in the efficacy of neoadjuvant immunotherapy combined with chemotherapy for esophageal squamous cell carcinoma. Methods A retrospective study was conducted on patients with esophageal squamous cell carcinoma (clinical stages Ⅱ-Ⅳa) who underwent neoadjuvant immunotherapy combined with chemotherapy at the Department of Thoracic Surgery, Affiliated Hospital of North Sichuan Medical College from April 2020 to November 2023. According to whether the pathology was completely relieved after treatment, patients were divided into a pathological complete remission group and a pathological incomplete remission group. The College of American Pathologists criteria were used to evaluate the tumor pathological regression grade (TRG) after neoadjuvant therapy (TRG=0, 1 defined as a good efficacy group, TRG=2, 3 defined as a poor efficacy group). Results A total of 92 patients with esophageal squamous cell carcinoma were collected, including 72 males and 20 females. The average age was (65.86±7.66) years. The complete remission of pathology was closely related to the number of lymphocytes in the blood before treatment (P=0.019). The area under the curve (AUC) for predicting complete remission of esophageal squamous cell carcinoma after neoadjuvant immunotherapy combined with chemotherapy was 0.678, the maximum Youden index was 0.328, and the optimal cutoff value was 1.845. The incidence of postoperative pulmonary infection in the pathological incomplete remission group was higher than that in the pathological complete remission group (25.0% vs. 5.6%, P=0.030). Using the optimal cutoff value, there were statistically significant differences in pathological N stage and pathological TNM stage between patients with lymphocyte counts <1.845×109/L and ≥1.845×109/L (P<0.05). Treatment response (by TRG) was significantly associated with the pretreatment red blood cell count (P=0.009). The AUC for predicting a good TRG response was 0.669, with a maximum Youden index of 0.385 and an optimal cutoff value of 4.235. Between the good and poor response groups, there were statistically significant differences in postoperative pathological T stage (P<0.001), N stage (P=0.041), and TNM stage (P＜0.001). When stratified by the optimal cutoff value, there were statistically significant differences in age (P＜0.001) and the prevalence of hypertension (P=0.022) between patients with red blood cell counts <4.235×1012/L and ≥4.235×1012/L. Conclusion A pretreatment absolute lymphocyte count ≥1.845×109/L and a red blood cell count <4.235×1012/L are good predictors for pathological complete response and a good pathological response, respectively, following neoadjuvant immunotherapy combined with chemotherapy in patients with esophageal squamous cell carcinoma.

Objective To explore the construction of heart preservation model of empty beating donor based on extracorporeal membrane oxygenation (ECMO). Methods From January 2022 to August 2023, 20 Guangxi Bama miniature pigs weighing 25-30 kg were selected, half male and half female. Under general anesthesia and heparinization, a midline thoracotomy was performed. The pericardium was cut after freeing the anterior and posterior vena cavae, and a perfusion needle was inserted near the brachiocephalic artery in the ascending aorta, connected to a blood collection bag to collect 500-600 mL of blood. The anterior and posterior vena cavae were ligated, the aorta was blocked and perfused with HTK solution to stop the heart beating. The superior and inferior vena cavae were cut off, the right pulmonary vein was decompressed, the aorta and left and right pulmonary arteries and veins were cut off, and the whole heart was removed. An ECMO device was used to continuously perfuse a cardioprotective solution mainly composed of oxygenated warm blood, maintaining the isolated pig heart beating for 8 hours, monitoring (once/hour) ECMO perfusion parameters, blood gas indicators, perfusate electrolytes, inflammatory factors, myocardial enzymes, myoglobin, and troponin levels. Myocardial tissue was taken for hematoxylin-eosin (HE) staining to observe myocardial cell damage and evaluate the quality of heart preservation. Results Among the 20 isolated beating pig hearts, 17 successfully resumed beating, 3 experienced ventricular fibrillation, resuscitated after intracardiac electrical defibrillation, and all 20 pig hearts successfully beat for 8 hours. There was no statistical difference in ECMO perfusion parameters, blood gas indicators, perfusate electrolytes, and inflammatory factors at each time point (P>0.05). There were statistical increases in myocardial enzymes, myoglobin, and troponin levels (P<0.05). HE staining results suggested that there was no severe myocardial damage. Conclusion ECMO technology can be used for pig heart preservation with good results, and this study provides experimental evidence for improving heart preservation research in clinical heart transplantation.