Validation of a preclinical dry eye model in New Zealand white rabbits during and following topical instillation of 1% ophthalmic atropine sulfate

Background : The objective of this study was to validate an animal model for dry eye during and after the administration of 1% ophthalmic atropine sulfate(OAS) in New Zealand white(NZW) rabbits.Methods : OAS(1%) was applied three times per day to 30 eyes of 15 healthy NZW rabbits. Sacrifice, enucleation, and lacrimal gland removal took place on days 15, 21,and 30(OAS group). A second group(n = 5) was used as control. Clinical evaluations took place on days 3, 10, 15, 18, 21, 24 and 30. The primary endpoints were:Schirmer I test, tear break-up time(TBUT), and corneal fluorescein staining. As secondary endpoints, clinical changes including intraocular pressure, and histopathology were evaluated.Results : While OAS was administered, the Schirmer I test showed a statistically significant reduction for OAS group versus control( p < 0.001), and versus basal production( p < 0.001). TBUT showed statistically significant differences between groups(days 3 and 10;p = 0.001) and versus basal values(day 3;p < 0.001). Fluorescein staining showed a statistically significant difference(day 3;p = 0.001). The most frequent clinical finding was conjunctival hyperemia(76.9% OAS vs. 20% control). For histopathology, all OAS subjects presented some degree of inflammation(86.7% minimal;13.3% mild) whereas the control presented only 30% minimal inflammation. Goblet cell density showed no difference.Conclusions : The effectiveness of the OAS dry eye model in NZW rabbits as reported in previous studies was confirmed, provided that the application of the drug is maintained throughout the intervention;it is not a viable model after OAS administration is suspended.

Propofol Target-Controlled Infusion Modeling in Rabbits:Pharmacokinetic and Pharmacodynamic Analysis

This study aimed to establish a new propofol target-controlled infusion（TCI） model in animals so as to study the general anesthetic mechanism at multi-levels in vivo. Twenty Japanese white rabbits were enrolled and propofol（10 mg/kg） was administrated intravenously. Artery blood samples were collected at various time points after injection, and plasma concentrations of propofol were measured. Pharmacokinetic modeling was performed using Win Nonlin software. Propofol TCI within the acquired parameters integrated was conducted to achieve different anesthetic depths in rabbits, monitored by narcotrend. The pharmacodynamics was analyzed using a sigmoidal inhibitory maximal effect model for narcotrend index（NI） versus effect-site concentration. The results showed the pharmacokinetics of propofol in Japanese white rabbits was best described by a two-compartment model. The target plasma concentrations of propofol required at light anesthetic depth was 9.77±0.23 μg/m L, while 12.52±0.69 μg/m L at deep anesthetic depth. NI was 76.17±4.25 at light anesthetic depth, while 27.41±5.77 at deep anesthetic depth. The effect-site elimination rate constant（ke0） was 0.263/min, and the propofol dose required to achieve a 50% decrease in the NI value from baseline was 11.19 μg/m L（95% CI, 10.25–13.67）. Our results established a new propofol TCI animal model and proved the model controlled the anesthetic depth accurately and stably in rabbits. The study provides a powerful method for exploring general anesthetic mechanisms at different anesthetic depths in vivo.

A New Model of Experimental Cerebral Infarction in New Zealand White Rabbits

To develop an easy, reproducible experimental model of cerebral infarction(CI)without craniotomy in New Zealand white rabbits,a silicone rubber cylinder embedded in a nylon suture was delivered to the middle cerebral arteries through the internal carotid artery in anesthetized animals.Rabbits were sacrificed 0.5-5 h after embolization.CI size and location were ascertained by the tripheny1-2H-tetrazoliuni chloride(TTC)staining method;cerebral blood flow(CBF)was measured prior to and after embolization.Pco2,temperature and blood pressure were monitored and kept constant.CI occurred in all rabbits after 4 h of ischemia,in 50% after 3 h and only in 33% after 2.5 h.CI did not occur within less than 2.5 h of ischemia.No correlation was found between size and location of CI and occlusion time.CBF was maximally reduced in the right MCA territory but was also reduced in both anterior cerebral arteries and left MCA territories.This model is technically easy and the retrievable embolus allows the study of reperfusion by pulling on the nylon suture.It is suitable for studying chemical and molecular changes of the ischemic cells and/or for studying neuroimage changes after ischemic stroke.

Awake rabbit model of ischemic spinal cord injury with delayed paraplegia:The role of ambient temperature

Background:Paraplegia after spinal cord ischemia is a devastating condition in the clinic.Here,we develop an awake rabbit model of spinal cord ischemia with delayed paraplegia and explore the influence of ambient temperature on the outcomes after injury.Methods:A total of 47 male rabbits were involved in the present study.Transient spinal cord ischemia was induced by occluding the infrarenal abdominal aorta of awake rabbits at different ambient temperatures.To find the optimal conditions for developing delayed paraplegia,hindlimb motor function after ischemia was evaluated between experiments.Results:The onset and magnitude of ischemic injury varied with the ambient temperature maintained during the peri-i schemia period.More serious spinal cord injury occurred when ischemia was induced at higher temperatures.At 18°C,25-minute ischemia resulted in 74%of rabbits developing delayed paraplegia.At a temperature of 28°C or higher,most of the animals developed acute paraplegia immediately.While at 13°C,rabbits usually regained normal motor function without paraplegia.Conclusion:This awake rabbit model is highly reproducible and will be helpful in future studies of delayed paraplegia after spinal cord ischemia.The ambient temperature must be considered while using this model during investigation of therapeutic interventions.

Evaluation of the Effects of Cypermethrin on Female Reproductive Function by Using Rabbit Model and of the Protective Role of Chinese Propolis

The prophylactic effects of Chinese propolis against cypermethrin toxicity were evaluated by performing ovary and uterus histopathology, as well as by characterizing ovarian function, embryos, and litters. Cypermethrin induced atypia in the ovary and uterus, and decreased the ovulation sites and the number of embryos. Cypermethrin-induced oxidative stress during pregnancy, decreased the parturition rate as well as the number and weight of offspring and increased the incidence of morphological malformations in the offspring. Administration of propolis to cypermethrin-treated animals mitigated cypermethrin-induced reproductive toxicity.

Susceptibility-weighted imaging is suitable for evaluating signal strength in different brain regions of a rabbit model of acute hemorrhagic anemia

Acute hemorrhagic anemia can decrease blood flow and oxygen supply to brain, and affect its physiological function. While detecting changes in brain function in patients with acute hemorrhagic anemia is helpful for preventing neurological complications and evaluating therapeutic effects, clinical changes in the nervous systems of these patients have not received much attention. In part, this is because current techniques can only indirectly detect changes in brain function following onset of anemia, which leads to lags between real changes in brain function and their detection.

Accelerated and enhanced osteointegration of MAO-treated implants:histological and histomorphometric evaluation in a rabbit model

Microarc oxidation（MAO） has become a promising technique for the surface modification of implants. Therefore, the aims of this study were to further quantitatively and qualitatively evaluate the osteointegration abilities of MAO-treated and smooth surface（SF） implants in vivo and to investigate the areas in which the superiority of MAO-treated implants are displayed. In a rabbit model,a comprehensive histomorphological, osteogenic, mineralizational, and integrative assessment was performed using light microscopy, fluorescence microscopy, confocal laser scanning microscopy, and radiographic analyses. Compared with the SF groups, the MAO-treated groups exhibited more active contact osteogenesis, as well as distant osteogenesis, under fluorescence examination, the mineral apposition rate was found to be greater for all of the MAO-treated implants, and the osteointegration index（OI） value was greater in the MAO-treated groups at different times. In conclusion, the calcium-rich amorphous layer created by MAO provided a better environment for osteointegration, with more active contact osteogenesis, a more rapid mineral apposition rate and greater OI values.

Effect of a novel tyrosine kinase inhibitor nintedanib on bFGF and VEGF concentrations in a rabbit retinal vein occlusion model

AIM:To evaluate whether a novel tyrosine kinase inhibitor nintedanib could inhibit basic fibroblast growth factor(bFGF)and vascular endothelial growth factor(VEGF)simultaneously for retinal vascular disease in vivo.METHODS:After a laser induced rabbit retinal vein occlusion(RVO)model was made,0.5 mg of nintedanib was injected intravitreally in the left eye on the third day while the right eye was as a control.Intracameral samples were taken on the day before laser treatment and days 1,3,7,14,21,and 28 after treatment.Enzyme-linked immunosorbent assay(ELISA)was used to test the bFGF and VEGF-A concentrations in the aqueous humor.RESULTS:Both bFGF and VEGF-A rose significantly on the third day after laser treatment in both eyes.In the control eye the bFGF concentration peaked on the 14th day while the VEGF-A concentration dropped rapidly soon after the third day.After nintadanib injection in the study eye,both bFGF and VEGF-A showed a significant reduction on the 4th day(7th day after laser treatment)when compared to the control eye,and kept on low level in the following several weeks.CONCLUSION:Intravitreal injection of nintedanib can inhibit the expression of bFGF and VEGF in the process of RVO model to a certain extent,which is expected to become a new method for the treatment of retinal vascular diseases or fibrotic diseases.

Radiosensitivity of β-elemene on rabbit VX2 renal transplant carcinoma model

Objective To investigate the effects of low dosage of β-elemene on the radiosensitivity of rabbit VX2 renal transplant carcinoma model. Methods We took the rabbit VX2 renal transplant carcinoma as the model. Experimental rabbits were divided into three groups: the control group, the radiation group, and the radiation +β-elemene (radiosensitivity) group. The change of tumor was observed by Spiral CT and B ultrasound to compare its regrowth period. The tumor was measured by light microscopy and electron microscopy. Results The tumor in radiosensitivity group was restrained obviously and the sensitization enhancement ratio (SER) of β-elemene was 1.89. Different apoptosis was observed under transmission electron microscopy. Conclusion Low dosage β-elemene can enhance the radiosensitivity of rabbit VX2 renal transplant carcinoma model and induce the apoptosis of tumor cells, but the mechanism needs further study. It promotes apoptosis in mechanisms in vitro.

Bifunctional staining for ex vivo determination of area at risk in rabbits with reperfused myocardial infarction

AIM: To develop a method for studying myocardial area at risk(AAR) in ischemic heart disease in correlation with cardiac magnetic resonance imaging(c MRI). METHODS: Nine rabbits were anesthetized, intubated and subjected to occlusion and reperfusion of the left circumflex coronary artery(LCx) to induce myocardial infarction(MI). ECG-triggered c MRI with delayed en-hancement was performed at 3.0 T. After euthanasia, the heart was excised with the LCx re-ligated. Bifunctional staining was performed by perfusing the aorta with a homemade red-iodized-oil(RIO) dye. The heart was then agar-embedded for ex vivo magnetic resonance imaging and sliced into 3 mm-sections. The AAR was defined by RIO-staining and digital radiography(DR). The perfusion density rate(PDR) was derived from DR for the AAR and normal myocardium. The MI was measured by in vivo delayed enhancement(i DE) and ex vivo delayed enhancement(e DE) c MRI. The AAR and MI were compared to validate the bifunctional straining for cardiac imaging research. Linear regression with Bland-Altman agreement, one way-ANOVA with Bonferroni's multiple comparison, and paired t tests were applied for statistics.RESULTS: All rabbits tolerated well the surgical procedure and subsequent c MRI sessions. The openchest occlusion and close-chest reperfusion of the LCx, double suture method and bifunctional staining were successfully applied in all animals. The percentage MI volumes globally(n = 6) and by slice(n = 25) were 36.59% ± 13.68% and 32.88% ± 12.38% on i DE, and 35.41% ± 12.25% and 32.40% ± 12.34% on e DE. There were no significant differences for MI determination with excellent linear regression correspondence(r global = 0.89; r slice = 0.9) between i DE and e DE. The percentage AAR volumes globally(n = 6) and by slice(n = 25) were 44.82% ± 15.18% and 40.04% ± 13.64% with RIO-staining, and 44.74% ± 15.98% and 40.48% ± 13.26% by DR showing high correlation in linear regression analysis(r global = 0.99; r slice = 1.0). The mean differences of the two AAR measurements on BlandAltman were almost zero, indicating RIO-staining and DR were essentially equivalent or inter-replaceable. The AAR was significantly larger than MI both globally and slice-by-slice(P < 0.01). After correction with the background and the blank heart without bifunctional staining(n = 3), the PDR for the AAR and normal myocardium was 32% ± 15% and 35.5% ± 35%, respectively,which is significantly different(P < 0.001), suggesting that blood perfusion to the AAR probably by collateral circulation was only less than 10% of that in the normal myocardium.CONCLUSION: The myocardial area at risk in ischemic heart disease could be accurately determined postmortem by this novel bifunctional staining, which may substantially contribute to translational cardiac imaging research.

Selective Posterior Epiphysiodesis of the Triradiate Cartilage of the Acetabulum: Preliminary Results of an Experimental Study in Rabbits

Background: Residual acetabular dysplasia is one of the main complications of developmental dysplasia of the hip (DDH). Without treatment, over time degenerative osteoarthritis of the joint will develop, inexorably leading to the need for joint replacement. Acetabular and/or femoral osteotomies do not avoid the appearance of osteoarthritis in a significant number of patients. The purpose of this study was to assess the possibility of provoking changes in the morphology of the acetabulum through selective epiphysiodesis of the extra-articular portion of the ilioischial arm of the triradiate cartilage, using a percutaneous cannulated screw with the guidance of an imaging intensifier in an experimental model in rabbits. Methods: In a pilot study, 3-week-old New Zealand rabbits (n = 20) were submitted to unilateral surgery of the hip while the contralateral hip of the same group was used as a control. Posterior epiphysiodesis to the triradiate cartilage of the acetabulum was performed by placement of a cannulated screw. The rabbits were followed-up until 18 weeks of life. Radiographic measurements of the hips were performed immediately postoperatively and at 12 weeks of life and before the rabbits were sacrificed at week 18. Three-dimensional computed tomography (3D-CT) scans were performed. Non-parametric tests for paired samples and the Wilcoxon test were used to compare the differences between group 1 and group 2. A p < 0.05 was considered significant. Results: The non-intervened hips showed that, when the rabbit matured, the acetabulum lost concavity and depth. When comparing the median differences of the angles evaluated at 12 weeks between groups, a statistically significant difference was found in all radiographic measurements: an increase in Wiberg’s angle but a decrease in acetabular index, acetabular angle of Sharp, acetabular depth index, and acetabular anteversion. Evaluating the operated hips at 12 and 18 weeks (three months after having removed the screw) using 3D-CT, we observed a rebound effect in the correction confirming that the effect obtained through selective epiphysiodesis did not cause the definitive closure of the cartilage. Conclusions: Selective growth arrest of the ilioischial arm of the triradiate cartilage (posterior epiphysiodesis) can alter growth and change the shape of the acetabulum in rabbits. A rebound effect was observed when the screw was removed, confirming that the technique did not provoke definitive closure of the physis. Level of evidence: Level-2, therapeutic study.

Phasic study of intestinal homeostasis disruption in experimental intestinal obstruction

AIM: To investigate the phasic alteration of intestinal homeostasis in an experimental model of intestinal obstruction.

An Appreciation for the Rabbit Ladderlike Modeling of Radiation-induced Lung Injury with High-energy X-Ray

Background：To evaluate the utility of rabbit ladderlike model of radiation-induced lung injury （RILI） for the future investigation of computed tomography perfusion.Methods：A total of 72 New Zealand rabbits were randomly divided into two groups：36 rabbits in the test group were administered 25 Gy of single fractionated radiation to the whole lung of unilateral lung;36 rabbits in the control group were sham-radiated.All rabbits were subsequently sacrificed at 1,6,12,24,48,72 h,and 1,2,4,8,1 6,24 weeks after radiation,and then six specimens were extracted from the upper,middle and lower fields of the bilateral lungs.The pathological changes in these specimens were observed with light and electron microscopy;the expression of tumor necrosis factor-α （TNF-a） and transforming growth factor-βl （TGF-β1） in local lung tissue was detected by immunohistochemistry.Results：（1） Radiation-induced lung injury occurred in all rabbits in the test group.（2） Expression of TNF-a and TGF-β1 at 1 h and 48 h after radiation,demonstrated a statistically significant difference between the test and control groups （each P 〈 0.05）.（3） Evaluation by light microscopy demonstrated statistically significant differences between the two groups in the following parameters （each P 〈 0.05）：thickness of alveolar wall,density of pulmonary interstitium area （1 h after radiation）,number offibroblasts and fibrocytes in interstitium （24 h after radiation）.The test group metrics also correlated well with the time ofpostradiation.（4） Evaluation by electron microscopy demonstrated statistically significant differences in the relative amounts of collagen fibers at various time points postradiation in the test group （P 〈 0.005）,with no significant differences in the control group （P 〉 0.05）.At greater than 48 h postradiation the relative amount of collagen fibers in the test groups significantly differ from the control groups （each P 〈 0.05）,correlating well with the time postradiation （r =0.99318）.Conclusions：A consistent and reliable rabbit model of RILI can be generated in gradient using 25 Gy of high-energy X-ray,which can simulate the development and evolution of RILI.

Creation of a rabbit model for intrauterine adhesions using electrothermal injury

The pathogenesis and therapeutic treatment of intrauterine adhesions （IUAs） remain unsolved, highlighting the need for stable and effective experimental animal models. In this study, uterine electrocoagulaUon of twenty-one female New Zealand White rabbits was carried out to establish an IUA model. As rabbits have two completely separate uterine horns, each rabbit had its own internal control： one uterine horn was given an electrothermal injury （Group A, n=21）, and the contralateral uterine horn received no treatment and served as the control （Group B, n=21）. The en- dometrial morphology, number of endometrial glands, area of endometrial fibrosis, and number of implanted fetuses were compared between the two groups. In Group A, the numbers of endometrial glands on Days 7 and 14 and the number of implanted fetuses were significantly lower than those in Group B（P〈0.05, P〈0.05, and P〈0.01, respectively）, while the ratio of the area with endometrial stromal fibrosis to the total endometrial area was significantly increased （P〈0.01）. These results suggest that this method of electrothermal injury is effective for the establishment of a rabbit lUA model between 7 and 14 d after surgery.

Mechanism of Chronic Stress-induced Reduced Atherosclerotic Medial Area and Increased Plaque Instability in Rabbit Models of Chronic Stress

Background： Chronic stress contributes to increased risks ofatherosclerotic diseases including heart disease, stroke, and transient ischemic attack. However, its underline mechanisms are poorly understood. This study aimed to elucidate the mechanism via which chronic stress exerts its effect on atherosclerosis （AS）. Methods： Fifty male New Zealand white rabbits were used. Aortic balloon-injury model was applied. Both social stress and physical stress methods were adopted to establish chronic stress models. The lumen stenotic degree, intimal and medial areas, maximum fibrous cap thickness, and plaque contents were measured with histological sections. Proteomic methods were applied to detect protein changes in abdominal aortas to identify the specialized mediators. Real-time reverse transcription-polymerase chain reaction was used for further verification and investigation. Results： The stress rabbits exhibited lower body weight, worse fur state, more inactivity behavior, and higher serum cortisol level. Chronic stress was significantly associated with the decreased medial area and increased plaque instability, which was manifested by thinner fibrous caps, larger lipid cores, more macrophages, and new vessels but fewer smooth muscle cells and elastic fibers. After chronic stress, the apoptosis-related genes UBE2K, BAX, b）~S, Ca.v^ase 3, Caspase 9, and P53 were upregulated, and B^Z-2/BAX was down-regulated; the angiogenesis-related genes ANG and VEGF-A were also highly expressed in atherosclerotic arteries. Conclusions： Rabbit models of chronic stress were successfully established by applying both social stress and physical stress for 8 weeks. Chronic stress can reduce AS tunica media and accelerate plaque instability by promoting apoptosis and neovascularization.

Effects of external stimuli on the pacemaker function of the sinoatrial node in sodium channel gene mutations models

Loss of function and gain of function mutations of the sodium channel were investigated using an intact two-dimensional rabbit sinoatrial node (SAN) and atrial cell model. The effects of three external stimuli (acetylcholine secretion by the vagal nerve, acid-base concentration, and tissue temperature) on cardiac pacemaker function and conduction were studied. Our results show that these two groups of mutations have different effects on pacemaker function and conduction. Furthermore, we found that the negative effects of these mutations could be altered by external stimuli. The bradycardic effects of mutations were magnified by an increase in acetylcholine level. Changes in acid-base concentration and tissue temperature increased the ability of the SAN to recover its pacemaker function. The results of this study increase our understanding of sodium channel disorders, and help to advance research on the treatment of these conditions.

Use of N,O-carboxymethyl chitosan to prevent postsurgical adhesions in a rabbit double uterine horn model： a randomized controlled design

In previous studies, N,O-carboxymethyl chitosan has been shown to decrease the incidence and intensity of abdominal adhesions. In the present study, adhesions were induced in 220 rabbits using a double uterine horn model. Rabbits were randomized to receive an operation only or an operation+medical chitosan intraperitoneally. Twenty-two rabbits from each group were euthanized at one of five different times(Day 3, 7, 14, 28, or 42), and adhesion formation was given gross and histopathological scores. Reductions were observed in adhesion extent(P=0.0337) and tenacity(P=0.0271) as well as inflammation(P<0.0001) on Day 3 when medical chitosan was applied. Prior to Day 14, fibrosis was less obvious in the medical chitosan group(P<0.0005). The tenacity scores were significantly lower in the medical chitosan group following Day 14(P<0.05), while the type scores were lower in the medical chitosan group following Day 28(P<0.03). Thus, medical chitosan decreased both the gross and the histopathological scores of the induced adhesions.

Pharmacokinetic study of repaglinide floating drug delivery system in rabbits by RP-HPLC method

The present work is aimed to study the pharmacokinetic parameters of optimized repaglinide floating drug delivery system(FDDS) by 24 factorial designs,followed by comparison with a commercially available formulation.The main effects and interactions of formulation variables were studied by using normal and pareto charts.The optimized formulation shows a fickian diffusion drug release mechanism.Pharmacokinetic parameters of the designed drug delivery system were evaluated in rabbit models.Mean while a simple,specific high performance liquid chromatographic method was developed and validated as per biopharmaceutical specifications,the linearity was observed at the range of 110-550 ng/mL(r2 = 0.999).By using methanol-phosphate buffer(pH 2.5)(70:30,v/v) as mobile phase at the flow rate of 1.0 mL/min the validation shows a better retention time of 5.2 min for repaglinide.And the same validation method was used for pharmacokinetic profile analysis of repaglinide marketed products and FDDS.The comparative pharmacokinetic results such as tmax,half-life,area under the curve,mean residence times were increased significantly for the repaglinide in FDDS than the marketed product of repaglinide except Cmax and elimination rate constant.

Development of fusiform aneurysms induced by topical application of elastase in a rabbit model

Background: Research on the etiology and pathophysiology of fusiform aneurysm has been impeded due to the inability to collect fusiform aneurysm specimens. We aim to resolve this through the development of a novel fusiform aneurysm model in rabbits.Methods: Sixty New Zealand White rabbits were divided into ten groups (n = 6 per group): groups A, B, C, D, E and groups a, b, c, d, e. Elastase, at a concentration of 0, 0.5, 1, 2.5 and 5 U/μL respectively was administered to each rabbit to incubate their carotid arteries. Three weeks later, angiography, histomorphometry,immunohistochemistry and immunofluorescent were performed.Results: Heparin administration is indispensable. No thrombosis was observed in groups A, B, C, D and E, whereas,increased thromboembolism occurred in groups a, b, c, d and e. Based on the size and wall thickness of aneurysms specimens, 5 U/μL was the optimal concentration of elastase to induce fusiform aneurysms. At 5 U/μL, the intraluminal carotid diameter increased significantly from 2.50 ± 0.32 mm to 3.11 ± 0.55 mm (p < 0.01). The wall thickness significantly reduced from 176.0 ± 39.8 μm to 39.7 ± 14.6 μm (p < 0.01) post aneurysm induction. The histolopathological evaluation revealed the elastic lamina and the smooth muscle cell''''s lamina were markedly attenuated and the intimal endothelial lamina became thin or even absent.Conclusions: Our research demonstrates that intracranial fusiform aneurysm could be modeled in rabbit carotid artery adventitia incubation by porcine pancreatic elastase.

Bimetallic clusterzymes-loaded dendritic mesoporous silica particle regulate arthritis microenvironment via ROS scavenging and YAP1 stabilization

Clusterzymes are synthetic enzymes exhibiting substantial catalytic activity and selectivity,which are uniquely driven by single-atom constructs.A dramatic increase in antioxidant capacity,158 times more than natural trolox,is noted when single-atom copper is incorporated into gold-based clusterzymes to form Au_(24)Cu_(1).Considering the inflammatory and mildly acidic microenvironment characteristic of osteoarthritis(OA),pH-dependent dendritic mesoporous silica nanoparticles(DMSNs)coupled with PEG have been employed as a delivery system for the spatial-temporal release of clusterzymes within active articular regions,thereby enhancing the duration of effectiveness.Nonetheless,achieving high therapeutic efficacy remains a significant challenge.Herein,we describe the construction of a Clusterzymes-DMSNs-PEG complex(CDP)which remarkably diminishes reactive oxygen species(ROS)and stabilizes the chondroprotective protein YAP by inhibiting the Hippo pathway.In the rabbit ACLT(anterior cruciate ligament transection)model,the CDP complex demonstrated inhibition of matrix metalloproteinase activity,preservation of type Ⅱ collagen and aggregation protein secretion,thus prolonging the clusterzymes’protective influence on joint cartilage structure.Our research underscores the efficacy of the CDP complex in ROS-scavenging,enabled by the release of clusterzymes in response to an inflammatory and slightly acidic environment,leading to the obstruction of the Hippo pathway and downstream NF-κB signaling pathway.This study illuminates the design,composition,and use of DMSNs and clusterzymes in biomedicine,thus charting a promising course for the development of novel therapeutic strategies in alleviating OA.