ObjectiveTo investigate the molecular mechanisms by which salvianolic acid B （SalB） inhibits epithelial-mesenchymal transition （EMT） in non-small cell lung cancer （NSCLC） by downregulating phosphoribosylaminoimidazole carboxylase and phosphoribosylaminoimidazole succinocarboxamide synthetase （PAICS） expression. MethodsNSCLC A549 cells and normal bronchial epithelial cells （bronchial epithelium transformed with Ad12-SV40 2B， BEAS-2B） were used as models. Cell viability was assessed using the cell counting kit-8 （CCK-8） assay after treatment with SalB （0， 50， 100， 200， 300， 400， 500 μmol·L^-1 for 24 or 48 h to determine effective and safe intervention concentrations. Cell proliferation， cell cycle distribution， and apoptosis were evaluated by 5-ethynyl-2′-deoxyuridine （EdU） staining and flow cytometry， respectively. Wound healing and Transwell invasion assays were performed to assess cell migration and invasion. RNA sequencing combined with bioinformatic analysis was conducted to identify differentially expressed genes and functional enrichment. Molecular docking was used to predict the binding ability between SalB and PAICS， and the cellular thermal shift assay （CETSA） was performed to evaluate the effect of SalB on the thermal stability of the PAICS protein. Western blot （WB） was used to detect the effects of SalB on PAICS and EMT-related proteins （E-cadherin， N-cadherin， Vimentin， Snail， and Slug）. A functional rescue assay was conducted by PAICS overexpression via plasmid transfection. ResultsCompared with the control group， SalB inhibited A549 cell viability in a dose-dependent manner （P<0.05）， and the effective concentrations （≤300 μmol·L^-1） showed no significant cytotoxicity in BEAS-2B cells. Within this concentration range， SalB significantly inhibited A549 cell proliferation， migration， and invasion， and induced G₀/G₁ phase arrest and apoptosis （P<0.05）. Transcriptomic analysis showed that SalB significantly downregulated PAICS expression， and its functions were enriched in cell proliferation and EMT. Bioinformatic analysis indicated that PAICS is highly expressed in lung adenocarcinoma and is associated with poor prognosis （P<0.01）. Molecular docking showed that SalB has strong binding ability to PAICS （binding energy -9.1 kcal·mol^-1. CETSA results showed that SalB significantly increased the thermal stability of the PAICS protein （P<0.05）. WB results showed that， compared with the control group， SalB dose-dependently downregulated PAICS expression， upregulated E-cadherin， and downregulated N-cadherin， Vimentin， Snail， and Slug （P<0.05）. Functional rescue experiments showed that， compared with the empty vector group， PAICS overexpression significantly enhanced A549 cell proliferation， migration， and invasion， promoted cell cycle progression， and inhibited apoptosis （P<0.05）. Meanwhile， compared with the empty vector + SalB-H group， PAICS overexpression partially reversed the inhibitory effects of SalB on malignant phenotypes and EMT-related proteins （N-cadherin， Vimentin， Snail， and Slug）， and downregulated E-cadherin expression （P<0.05，P<0.01）， indicating that PAICS is a key functional target mediating the antitumor effects of SalB. ConclusionSalB effectively inhibits EMT progression and cell cycle progression in A549 cells by downregulating PAICS expression， thereby exerting anti-NSCLC effects. This study not only reveals that PAICS is a key functional target through which SalB regulates EMT， but also provides experimental evidence supporting SalB as a potential candidate drug for inhibiting NSCLC metastasis.

ObjectiveTo investigate the mechanisms by which eupatilin （Eup） inhibits proliferation， invasion， and metastasis of non-small cell lung cancer （NSCLC） through the enhancer of zeste homolog 2/histone H3 lysine 27 trimethylation （EZH2/H3K27me3） signaling pathway. MethodsIn vivo， a subcutaneous xenograft tumor model was established in nude mice using H1299 cells to evaluate the anti-NSCLC effects of Eup. Immunohistochemistry （IHC-P） was used to detect the expression of proliferation- and invasion/metastasis-related proteins， including proliferating cell nuclear antigen （PCNA）， matrix metalloproteinase-2 （MMP-2）， matrix metalloproteinase-9 （MMP-9）， and vascular endothelial growth factor A （VEGFA）. In vitro， cell counting kit-8 （CCK-8） assays were performed to determine the viability of H1299 cells treated with different concentrations of Eup （0-200 μmol·L^-1） and to select appropriate concentrations. Colony formation and 5-ethynyl-2′-deoxyuridine （EdU） assays were used to evaluate cell proliferation. Wound healing and invasion assays were conducted to assess cell migration and invasion. Human umbilical vein endothelial cell （HUVEC） angiogenesis assays were used to evaluate the effects of Eup on angiogenesis. Transcriptomic analysis was performed to identify the targets of Eup in H1299 cells and to explore its major functions. Molecular docking and molecular dynamics simulations were conducted to predict the binding affinity and interaction stability between Eup and its target proteins. Western blot was used to detect the effects of Eup on the expression levels of EZH2/H3K27me3 pathway-related proteins and proliferation- and invasion/metastasis-related proteins， including PCNA， MMP-2， MMP-9， and VEGFA. ResultsIn the subcutaneous xenograft model， compared with the model group， Eup treatment dose-dependently inhibited the growth of H1299 xenograft tumors， and the tumor inhibition rate was significantly increased （P<0.05）. IHC-P results showed that， compared with the model group， high-dose Eup significantly reduced the expression levels of PCNA， MMP-2， MMP-9， and VEGFA in vivo （P<0.05）. In vitro， compared with the control group， Eup inhibited the proliferation， invasion， and metastasis of NSCLC cells in a concentration-dependent manner. Transcriptomic analysis further showed that， compared with the control group， Eup significantly downregulated EZH2 expression， and its functional effects were associated with inhibition of tumor metastasis. Molecular docking and molecular dynamics simulations indicated that Eup exhibited strong binding affinity with EZH2 and stable interactions. Western blot results demonstrated that， compared with the model group， Eup significantly inhibited， in a dose-dependent manner， the expression levels of EZH2， H3K27me3， and proliferation- and invasion/metastasis-related proteins （PCNA， MMP-2， MMP-9， and VEGFA） in both in vivo and in vitro experiments （P<0.05）. In vitro， compared with the control group， overexpression of EZH2 via plasmid transfection partially reversed the inhibitory effects of Eup on the expression of key proteins involved in proliferation and invasion/metastasis in H1299 cells. ConclusionEup effectively inhibits the proliferation， migration， and invasion of H1299 cells both in vivo and in vitro. The underlying mechanism may be related to inhibition of the EZH2/H3K27me3 signaling pathway and downregulation of proliferation- and invasion/metastasis-related proteins， including PCNA， MMP-2， MMP-9， and VEGFA. Eup may serve as a potential therapeutic agent for suppressing proliferation and invasion/metastasis in NSCLC.

ObjectiveTo investigate the molecular mechanisms by which salvianolic acid B （SalB） inhibits epithelial-mesenchymal transition （EMT） in non-small cell lung cancer （NSCLC） by downregulating phosphoribosylaminoimidazole carboxylase and phosphoribosylaminoimidazole succinocarboxamide synthetase （PAICS） expression. MethodsNSCLC A549 cells and normal bronchial epithelial cells （bronchial epithelium transformed with Ad12-SV40 2B， BEAS-2B） were used as models. Cell viability was assessed using the cell counting kit-8 （CCK-8） assay after treatment with SalB （0， 50， 100， 200， 300， 400， 500 μmol·L^-1 for 24 or 48 h to determine effective and safe intervention concentrations. Cell proliferation， cell cycle distribution， and apoptosis were evaluated by 5-ethynyl-2′-deoxyuridine （EdU） staining and flow cytometry， respectively. Wound healing and Transwell invasion assays were performed to assess cell migration and invasion. RNA sequencing combined with bioinformatic analysis was conducted to identify differentially expressed genes and functional enrichment. Molecular docking was used to predict the binding ability between SalB and PAICS， and the cellular thermal shift assay （CETSA） was performed to evaluate the effect of SalB on the thermal stability of the PAICS protein. Western blot （WB） was used to detect the effects of SalB on PAICS and EMT-related proteins （E-cadherin， N-cadherin， Vimentin， Snail， and Slug）. A functional rescue assay was conducted by PAICS overexpression via plasmid transfection. ResultsCompared with the control group， SalB inhibited A549 cell viability in a dose-dependent manner （P<0.05）， and the effective concentrations （≤300 μmol·L^-1） showed no significant cytotoxicity in BEAS-2B cells. Within this concentration range， SalB significantly inhibited A549 cell proliferation， migration， and invasion， and induced G₀/G₁ phase arrest and apoptosis （P<0.05）. Transcriptomic analysis showed that SalB significantly downregulated PAICS expression， and its functions were enriched in cell proliferation and EMT. Bioinformatic analysis indicated that PAICS is highly expressed in lung adenocarcinoma and is associated with poor prognosis （P<0.01）. Molecular docking showed that SalB has strong binding ability to PAICS （binding energy -9.1 kcal·mol^-1. CETSA results showed that SalB significantly increased the thermal stability of the PAICS protein （P<0.05）. WB results showed that， compared with the control group， SalB dose-dependently downregulated PAICS expression， upregulated E-cadherin， and downregulated N-cadherin， Vimentin， Snail， and Slug （P<0.05）. Functional rescue experiments showed that， compared with the empty vector group， PAICS overexpression significantly enhanced A549 cell proliferation， migration， and invasion， promoted cell cycle progression， and inhibited apoptosis （P<0.05）. Meanwhile， compared with the empty vector + SalB-H group， PAICS overexpression partially reversed the inhibitory effects of SalB on malignant phenotypes and EMT-related proteins （N-cadherin， Vimentin， Snail， and Slug）， and downregulated E-cadherin expression （P<0.05，P<0.01）， indicating that PAICS is a key functional target mediating the antitumor effects of SalB. ConclusionSalB effectively inhibits EMT progression and cell cycle progression in A549 cells by downregulating PAICS expression， thereby exerting anti-NSCLC effects. This study not only reveals that PAICS is a key functional target through which SalB regulates EMT， but also provides experimental evidence supporting SalB as a potential candidate drug for inhibiting NSCLC metastasis.

ObjectiveTo investigate the mechanisms by which eupatilin （Eup） inhibits proliferation， invasion， and metastasis of non-small cell lung cancer （NSCLC） through the enhancer of zeste homolog 2/histone H3 lysine 27 trimethylation （EZH2/H3K27me3） signaling pathway. MethodsIn vivo， a subcutaneous xenograft tumor model was established in nude mice using H1299 cells to evaluate the anti-NSCLC effects of Eup. Immunohistochemistry （IHC-P） was used to detect the expression of proliferation- and invasion/metastasis-related proteins， including proliferating cell nuclear antigen （PCNA）， matrix metalloproteinase-2 （MMP-2）， matrix metalloproteinase-9 （MMP-9）， and vascular endothelial growth factor A （VEGFA）. In vitro， cell counting kit-8 （CCK-8） assays were performed to determine the viability of H1299 cells treated with different concentrations of Eup （0-200 μmol·L^-1） and to select appropriate concentrations. Colony formation and 5-ethynyl-2′-deoxyuridine （EdU） assays were used to evaluate cell proliferation. Wound healing and invasion assays were conducted to assess cell migration and invasion. Human umbilical vein endothelial cell （HUVEC） angiogenesis assays were used to evaluate the effects of Eup on angiogenesis. Transcriptomic analysis was performed to identify the targets of Eup in H1299 cells and to explore its major functions. Molecular docking and molecular dynamics simulations were conducted to predict the binding affinity and interaction stability between Eup and its target proteins. Western blot was used to detect the effects of Eup on the expression levels of EZH2/H3K27me3 pathway-related proteins and proliferation- and invasion/metastasis-related proteins， including PCNA， MMP-2， MMP-9， and VEGFA. ResultsIn the subcutaneous xenograft model， compared with the model group， Eup treatment dose-dependently inhibited the growth of H1299 xenograft tumors， and the tumor inhibition rate was significantly increased （P<0.05）. IHC-P results showed that， compared with the model group， high-dose Eup significantly reduced the expression levels of PCNA， MMP-2， MMP-9， and VEGFA in vivo （P<0.05）. In vitro， compared with the control group， Eup inhibited the proliferation， invasion， and metastasis of NSCLC cells in a concentration-dependent manner. Transcriptomic analysis further showed that， compared with the control group， Eup significantly downregulated EZH2 expression， and its functional effects were associated with inhibition of tumor metastasis. Molecular docking and molecular dynamics simulations indicated that Eup exhibited strong binding affinity with EZH2 and stable interactions. Western blot results demonstrated that， compared with the model group， Eup significantly inhibited， in a dose-dependent manner， the expression levels of EZH2， H3K27me3， and proliferation- and invasion/metastasis-related proteins （PCNA， MMP-2， MMP-9， and VEGFA） in both in vivo and in vitro experiments （P<0.05）. In vitro， compared with the control group， overexpression of EZH2 via plasmid transfection partially reversed the inhibitory effects of Eup on the expression of key proteins involved in proliferation and invasion/metastasis in H1299 cells. ConclusionEup effectively inhibits the proliferation， migration， and invasion of H1299 cells both in vivo and in vitro. The underlying mechanism may be related to inhibition of the EZH2/H3K27me3 signaling pathway and downregulation of proliferation- and invasion/metastasis-related proteins， including PCNA， MMP-2， MMP-9， and VEGFA. Eup may serve as a potential therapeutic agent for suppressing proliferation and invasion/metastasis in NSCLC.

Distinct from the complementary inhibition mechanism through binding to the target with three-dimensional conformation of small molecule inhibitors, targeted protein degradation technology takes tremendous advantage of endogenous protein degradation pathway inside cells to degrade plenty of “undruggable” target proteins, which provides a novel route for the treatment of many serious diseases, mainly including proteolysis-targeting chimeras, lysosome-targeting chimeras, autophagy-targeting chimeras, antibody-based proteolysis-targeting chimeras, etc. Unlike proteolysis-targeting chimeras first found in 2001, which rely on ubiquitin-proteasome system to mainly degrade intracellular proteins of interest, lysosome-targeting chimeras identified in 2020, which was act as the fastly developing technology, utilize cellular lysosomal pathway through endocytosis mediated by lysosome-targeting receptor to degrade both extracellular and membrane proteins. As an emerging biomedical technology, nucleic acid-driven lysosome-targeting chimeras utilize nucleic acids as certain components of chimera molecule to replace with ligand to lysosome-targeting receptor or protein of interest, exhibiting broad application prospects and potential clinical value in disease treatment and drug development. This review mainly introduced present progress of nucleic acid-driven lysosome-targeting chimeras technology, including its basic composition, its advantages compared with antibody or glycopeptide-based lysosome-targeting chimeras, and focused on its chief application, in terms of the type of lysosome-targeting receptors. Most research about the development of nucleic acid-driven lysosome-targeting chimeras focused on those which utilized cation-independent mannose-6-phosphonate receptor as the lysosome-targeting receptor. Both mannose-6-phosphonate-modified glycopeptide and nucleic aptamer targeting cation-independent mannose-6-phosphonate receptor, even double-stranded DNA molecule moiety can be taken advantage as the ligand to lysosome-targeting receptor. The same as classical lysosome-targeting chimeras, asialoglycoprotein receptor can also be used for advance of nucleic acid-driven lysosome-targeting chimeras. Another new-found lysosome-targeting receptor, scavenger receptor, can bind dendritic DNA molecules to mediate cellular internalization of complex and lysosomal degradation of target protein, suggesting the successful application of scavenger receptor-mediated nucleic acid-driven lysosome-targeting chimeras. In addition, this review briefly overviewed the history of lysosome-targeting chimeras, including first-generation and second-generation lysosome-targeting chimeras through cation-independent mannose-6-phosphonate receptor-mediated and asialoglycoprotein receptor-mediated endocytosis respectively, so that a clear timeline can be presented for the advance of chimera technique. Meantime, current deficiency and challenge of lysosome-targeting chimeras was also mentioned to give some direction for deep progress of lysosome-targeting chimeras. Finally, according to faulty lysosomal degradation efficiency, more cellular mechanism where lysosome-targeting chimeras perform degradation of protein of interest need to be deeply explored. In view of current progress and direction of nucleic acid-driven lysosome-targeting chimeras, we discussed its current challenges and development direction in the future. Stability of natural nucleic acid molecule and optimized chimera construction have a great influence on the biological function of lysosome-targeting chimeras. Discovery of novel lysosome-targeting receptors and nucleic aptamer with higher affinity to the target will greatly facilitate profound advance of chimera technique. In summary, nucleic acid-driven lysosome-targeting chimeras have many superiorities, such as lower immunogenicity, expedient synthesis of chimera molecules and so on, in contrast to classical lysosome-targeting chimeras, making it more valuable. Also, the chimera technology provides new ideas and methods for biomedical research, drug development and clinical treatment, and can be used more widely through further research and optimization.

Objective:To investigate the effect and mechanism of injectable photopolymerizable porous gelatin methacrylate anhydride (Porous GelMA)/methacrylated silk fibroin (SilMA) composite hydrogel (PSE) loaded with human umbilical cord mesenchymal stem cell-derived exosomes (hUCMSC-Exos) in promoting knee joint cartilage regeneration.Methods:The porous GelMA solution (60 g/L) was mixed with SilMA solution (200 g/L) at a volume ratio of 6∶1 . The mixture was ultraviolet-irradiated for 30 seconds to form a cured Porous GelMA/SilMA hydrogel (P/S6). The hUCMSC-Exos was isolated via differential centrifugation coupled with ultrafiltration and then was incorporated into the Porous GelMA/SilMA composite solution at 200 μg/ml, followed by ultraviolet irradiation for 30 seconds to generate Exos-loaded PSE. Primary rat chondrocytes (P1) were divided into control group, P/S6 group, and PSE group to characterize the porosity, compressive strength, and sustained exosome release kinetics of PSE hydrogel. Chondrocytes were allocated to control group, interleukin-1β (IL-1β) group, P/S6 group, and PSE group, among which the last three groups were preconditioned with 10 ng/ml IL-1β for 24 hours, and then cultured in complete medium, P/S6 extract and PSE extract for 3 days, respectively, to establish in vitro cartilage defect models, while the control group remained untreated. Western blot and qRT-PCR analysis were conducted to quantify the expression levels of antibody to aggrecan core protein (ACAN), sex-determining region Y-box transcription factor 9 (SOX9), matrix metalloproteinase-13 (MMP13) and collagen type II (COL II). Murine monocyte-macrophage leukemia cells (RAW264.7) were divided into control group, P/S6 group, and PSE group, which were then cultured in complete medium, PSE extract, and PSE extract medium for 3 days, respectively. qRT-PCR was employed to detect the expression levels of recombinant arginase-1 protein (ARG1), mannose receptor (CD206), and inducible nitric oxide synthase (iNOS). Transcriptomic sequencing was used to identify differentially expressed genes during PSE-mediated chondrocyte regeneration, followed by functional enrichment analysis of key signaling pathways. Twenty-four SD rats were selected to establish cartilage defect models and assigned to injury control group, P/S6 group, and PSE group according to the random number table (8 rats per group). The right knee joints of the rats were surgically exposed, and cylindrical osteochondral defects (a diameter of 2.0 mm× a depth of 1.0 mm) were surgically created in the center of the femoral trochlear groove using a drill bit. The injury control group received phosphate-buffered saline, while the P/S6 group and PSE group were injected with corresponding hydrogels followed by photo-crosslinking. Incisions then were closed in layers. At 6 and 10 weeks after injury, specimens were harvested for HE staining and safranin O-fast green staining to evaluate cartilage regeneration and immunohistochemistry staining to quantify the positive area fractions for COL II, MMP13, ARG1, and CD206 in the defect areas. Results:PSE hydrogel exhibited compressive strength matching native cartilage (0.41 MPa), high porosity (85%), and sustained exosome release capacity (cumulative release rate of approximately 85% over 14 days). In chondrocyte repair experiments, compared to the IL-1β group, the PSE group demonstrated significantly upregulated expression of anabolic markers of cartilage (COL II expression increased by 2.1-fold, ACAN by 1.8-fold, and SOX9 by 1.5-fold) ( P<0.01) as well as significantly suppressed expression of catabolic markers (MMP13 expression decreased by 52%) ( P<0.01). In macrophage polarization assays, the PSE group exhibited ARG1 expression increased by 68% when compared to the control group ( P<0.01), thus promoting M2 polarization of macrophages. Transcriptomic analysis revealed that PSE enhanced extracellular matrix (ECM) synthesis by activating the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) pathway and ECM-receptor interaction pathway, as well as by suppressing inflammation-related gene expression. Histological evaluation in animal experiments revealed regeneration of hyaline cartilage with smooth, continuous surfaces in the defect areas in the PSE group. At 10 weeks after surgery, the neocartilage-positive area in the PSE group was (9.94±0.26)%, significantly larger than (1.67±0.11)% in the injury control group ( P<0.01). Besides, the CD206? M2 macrophage-positive area reached (14.44±0.23)% in the PSE group, significantly larger than (3.41±0.36)% in the injury control group ( P<0.01). Conclusions:The PSE hydrogel successfully engineered in the study can significantly promote regenerative repair of knee cartilage defects through a dual mechanism of enhanced ECM anabolism and remodeled inflammatory microenvironment. The core mechanisms involve specific activation of the PI3K/Akt pathway (boosting chondrocyte proliferation and survival) and ECM-receptor interaction pathway (driving ECM synthesis and assembly) by exosome-loaded PSE, while effectively polarizing macrophages toward an anti-inflammatory M2 phenotype so as to coordinately regulate cartilage ECM metabolism and suppress inflammatory responses.

Aim To investigate the effect of Rtv(a P-gp inhibitor and inducer)on the pharmacokinetics of Y101(P-gp substrate)via P-gp.Methods In short-term studies,rats received a single dose of Rtv,where-as in long-term studies they received continuous dosing for seven days.Following this treatment,Y101 was o-rally administered to analyze its blood concentration in rats.Subsequently,the mechanism by which Rtv af-fected Y101 pharmacokinetics was investigated through the everted gut sac model(in vitro),cellular uptake studies,and so on.Results Short-term administra-tion of Rtv significantly increased Y101's AUC,liver-to-plasma partition coefficient,the everted gut sac model(in vitro),and cellular accumulation.Although long-term Rtv treatment had no effect on Y101 pharma-cokinetics or hepatic distribution,it markedly reduced Y101 cellular accumulation in Caco-2 cells,concomi-tant with an upregulation of P-gp expression.Conclu-sions Short-term Rtv administration acts as a compet-itive P-gp inhibitor,enhancing Y101 intestinal absorp-tion and hepatic distribution.In contrast,the plasma pharmacokinetics and hepatic distribution of Y101 are not altered after long-term administration of Rtv,po-tentially attributable to Rtv's dual modulatory effects on P-gp involving both induction and inhibition.Hence,the potential Rtv and Y101 interaction should be close-ly monitored in the clinic.

Hepatocellular carcinoma(HCC)expresses abundant glycolytic enzymes and displays comprehensive glucose metabolism reprogramming.Aldolase A(ALDOA)plays a prominent role in glycolysis;however,little is known about its role in HCC development.In the present study,we aim to explore how ALDOA is involved in HCC proliferation.HCC proliferation was markedly suppressed both in vitro and in vivo following ALDOA knockout,which is consistent with ALDOA overexpression encouraging HCC prolifera-tion.Mechanistically,ALDOA knockout partially limits the glycolytic flux in HCC cells.Meanwhile,ALDOA translocated to nuclei and directly interacted with c-Jun to facilitate its Thr93 phosphorylation by P21-activated protein kinase;ALDOA knockout markedly diminished c-Jun Thr93 phosphorylation and then dampened c-Jun transcription function.A crucial site Y364 mutation in ALDOA disrupted its interaction with c-Jun,and Y364S ALDOA expression failed to rescue cell proliferation in ALDOA deletion cells.In HCC patients,the expression level of ALDOA was correlated with the phosphorylation level of c-Jun(Thr93)and poor prognosis.Remarkably,hepatic ALDOA was significantly upregulated in the promotion and progression stages of diethylnitrosamine-induced HCC models,and the knockdown of Aldoa strikingly decreased HCC development in vivo.Our study demonstrated that ALDOA is a vital driver for HCC development by activating c-Jun-mediated oncogene transcription,opening additional avenues for anti-cancer therapies.

Objective:To investigate the effect and mechanism of injectable photopolymerizable porous gelatin methacrylate anhydride (Porous GelMA)/methacrylated silk fibroin (SilMA) composite hydrogel (PSE) loaded with human umbilical cord mesenchymal stem cell-derived exosomes (hUCMSC-Exos) in promoting knee joint cartilage regeneration.Methods:The porous GelMA solution (60 g/L) was mixed with SilMA solution (200 g/L) at a volume ratio of 6∶1 . The mixture was ultraviolet-irradiated for 30 seconds to form a cured Porous GelMA/SilMA hydrogel (P/S6). The hUCMSC-Exos was isolated via differential centrifugation coupled with ultrafiltration and then was incorporated into the Porous GelMA/SilMA composite solution at 200 μg/ml, followed by ultraviolet irradiation for 30 seconds to generate Exos-loaded PSE. Primary rat chondrocytes (P1) were divided into control group, P/S6 group, and PSE group to characterize the porosity, compressive strength, and sustained exosome release kinetics of PSE hydrogel. Chondrocytes were allocated to control group, interleukin-1β (IL-1β) group, P/S6 group, and PSE group, among which the last three groups were preconditioned with 10 ng/ml IL-1β for 24 hours, and then cultured in complete medium, P/S6 extract and PSE extract for 3 days, respectively, to establish in vitro cartilage defect models, while the control group remained untreated. Western blot and qRT-PCR analysis were conducted to quantify the expression levels of antibody to aggrecan core protein (ACAN), sex-determining region Y-box transcription factor 9 (SOX9), matrix metalloproteinase-13 (MMP13) and collagen type II (COL II). Murine monocyte-macrophage leukemia cells (RAW264.7) were divided into control group, P/S6 group, and PSE group, which were then cultured in complete medium, PSE extract, and PSE extract medium for 3 days, respectively. qRT-PCR was employed to detect the expression levels of recombinant arginase-1 protein (ARG1), mannose receptor (CD206), and inducible nitric oxide synthase (iNOS). Transcriptomic sequencing was used to identify differentially expressed genes during PSE-mediated chondrocyte regeneration, followed by functional enrichment analysis of key signaling pathways. Twenty-four SD rats were selected to establish cartilage defect models and assigned to injury control group, P/S6 group, and PSE group according to the random number table (8 rats per group). The right knee joints of the rats were surgically exposed, and cylindrical osteochondral defects (a diameter of 2.0 mm× a depth of 1.0 mm) were surgically created in the center of the femoral trochlear groove using a drill bit. The injury control group received phosphate-buffered saline, while the P/S6 group and PSE group were injected with corresponding hydrogels followed by photo-crosslinking. Incisions then were closed in layers. At 6 and 10 weeks after injury, specimens were harvested for HE staining and safranin O-fast green staining to evaluate cartilage regeneration and immunohistochemistry staining to quantify the positive area fractions for COL II, MMP13, ARG1, and CD206 in the defect areas. Results:PSE hydrogel exhibited compressive strength matching native cartilage (0.41 MPa), high porosity (85%), and sustained exosome release capacity (cumulative release rate of approximately 85% over 14 days). In chondrocyte repair experiments, compared to the IL-1β group, the PSE group demonstrated significantly upregulated expression of anabolic markers of cartilage (COL II expression increased by 2.1-fold, ACAN by 1.8-fold, and SOX9 by 1.5-fold) ( P<0.01) as well as significantly suppressed expression of catabolic markers (MMP13 expression decreased by 52%) ( P<0.01). In macrophage polarization assays, the PSE group exhibited ARG1 expression increased by 68% when compared to the control group ( P<0.01), thus promoting M2 polarization of macrophages. Transcriptomic analysis revealed that PSE enhanced extracellular matrix (ECM) synthesis by activating the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) pathway and ECM-receptor interaction pathway, as well as by suppressing inflammation-related gene expression. Histological evaluation in animal experiments revealed regeneration of hyaline cartilage with smooth, continuous surfaces in the defect areas in the PSE group. At 10 weeks after surgery, the neocartilage-positive area in the PSE group was (9.94±0.26)%, significantly larger than (1.67±0.11)% in the injury control group ( P<0.01). Besides, the CD206? M2 macrophage-positive area reached (14.44±0.23)% in the PSE group, significantly larger than (3.41±0.36)% in the injury control group ( P<0.01). Conclusions:The PSE hydrogel successfully engineered in the study can significantly promote regenerative repair of knee cartilage defects through a dual mechanism of enhanced ECM anabolism and remodeled inflammatory microenvironment. The core mechanisms involve specific activation of the PI3K/Akt pathway (boosting chondrocyte proliferation and survival) and ECM-receptor interaction pathway (driving ECM synthesis and assembly) by exosome-loaded PSE, while effectively polarizing macrophages toward an anti-inflammatory M2 phenotype so as to coordinately regulate cartilage ECM metabolism and suppress inflammatory responses.

Aim To investigate the effect of Rtv(a P-gp inhibitor and inducer)on the pharmacokinetics of Y101(P-gp substrate)via P-gp.Methods In short-term studies,rats received a single dose of Rtv,where-as in long-term studies they received continuous dosing for seven days.Following this treatment,Y101 was o-rally administered to analyze its blood concentration in rats.Subsequently,the mechanism by which Rtv af-fected Y101 pharmacokinetics was investigated through the everted gut sac model(in vitro),cellular uptake studies,and so on.Results Short-term administra-tion of Rtv significantly increased Y101's AUC,liver-to-plasma partition coefficient,the everted gut sac model(in vitro),and cellular accumulation.Although long-term Rtv treatment had no effect on Y101 pharma-cokinetics or hepatic distribution,it markedly reduced Y101 cellular accumulation in Caco-2 cells,concomi-tant with an upregulation of P-gp expression.Conclu-sions Short-term Rtv administration acts as a compet-itive P-gp inhibitor,enhancing Y101 intestinal absorp-tion and hepatic distribution.In contrast,the plasma pharmacokinetics and hepatic distribution of Y101 are not altered after long-term administration of Rtv,po-tentially attributable to Rtv's dual modulatory effects on P-gp involving both induction and inhibition.Hence,the potential Rtv and Y101 interaction should be close-ly monitored in the clinic.