Objective:To investigate the expression and methylation status of the SALL4 gene in placental tissues of fetal growth restriction (FGR) and its effects on trophoblast cell proliferation, migration, and invasion. Methods:Placental tissues were collected from 20 full-term FGR patients and 20 healthy term controls who underwent regular prenatal examination and cesarean section at the Third Affiliated Hospital, Zhengzhou University between July 2023 and February 2024. SALL4 mRNA and protein expression were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot. Methylation specific polymerase china reaction (MSP) assessed promoter methylation levels. HTR8/SVneo cells were transfected with SALL4-targeting small interfering RNA (si-SALL4) or negative control small interfering RNA (si-NC). HTR8/SVneo cells were treated with the demethylating agent 5-aza-2′-deoxycytidine (5-Aza-dC) to inhibit gene methylation (5-Aza-dC group) or with 10% RPMI-1640 medium as a vehicle control. Transfection efficiency (for siRNA) and the efficacy of 5-Aza-dC-induced demethylation were assessed by qRT-PCR and Western blot. The functional effects of SALL4 knockdown and methylation inhibition on trophoblast cells were evaluated using proliferation assays, scratch wound healing assays, and Transwell invasion assays. Statistical analyses included independent t-tests and Chi-square test. Results:(1) Human tissues: FGR placentas showed lower SALL4 mRNA (0.802±0.194 vs. 1.015±0.186, t=3.55) and protein expression (0.445±0.114 vs. 0.701±0.113, t=3.19), alongside higher methylation rates of SALL4 [80% (16/20) vs. 15% (3/20), χ2=14.44] compared to controls (all P<0.05). (2) In vitro: si-SALL4 transfection reduced HTR8/SVneo proliferation (OD450 at 48 h: 0.653±0.021 vs. 0.827±0.040, t=6.60), migration [healing rate at 48 h: (24.317±2.637)% vs. (49.327±1.961)%, t=13.18], and invasion [counted invaded cells: (133.000±6.557) vs. (272.667±18.009) cells, t=12.62] versus si-NC (all P<0.05). Conversely, 5-Aza-dC treatment increased HTR8/SVneo proliferation (0.917±0.042 vs. 0.783±0.031, t=－4.47), migration [(71.097±3.354)% vs. (51.632±2.877)%, t=－7.63], and invasion [(384.000±12.166) vs. (202.833±7.095) cells, t=－13.69] versus vehicle control (all P<0.05). Conclusions:Hypermethylation of the SALL4 promoter in FGR placentas suppresses its expression, impairing trophoblast cell function. Demethylation restores SALL4 expression and enhances cellular proliferation, migration, and invasion, involving in the occurrence and development of FGR disease.

Intervertebral disc degeneration (IDD) is largely attributed to impaired endogenous repair. Nucleus pulposus-derived stem cells (NPSCs) senescence leads to endogenous repair failure. Small extracellular vesicles/exosomes derived from mesenchymal stem cells (mExo) have shown great therapeutic potential in IDD, while whether mExo could alleviate NPSCs senescence and its mechanisms remained unknown. We established a compression-induced NPSCs senescence model and rat IDD models to evaluate the therapeutic efficiency of mExo and investigate the mechanisms. We found that mExo significantly alleviated NPSCs senescence and promoted disc regeneration while knocking down thioredoxin (TXN) impaired the protective effects of mExo. TXN was bound to various endosomal sorting complex required for transport (ESCRT) proteins. Autocrine motility factor receptor (AMFR) mediated TXN K63 ubiquitination to promote the binding of TXN on ESCRT proteins and sorting of TXN into mExo. Knocking down exosomal TXN inhibited the transcriptional activity of nuclear factor erythroid 2-related factor 2 (NRF2) and activator protein 1 (AP-1). NRF2 and AP-1 inhibition reduced endogenous TXN production that was promoted by exosomal TXN. Inhibition of NRF2 in vivo diminished the anti-senescence and regenerative effects of mExo. Conclusively, AMFR-mediated TXN ubiquitination promoted the sorting of TXN into mExo, allowing exosomal TXN to promote endogenous TXN production in NPSCs via TXN/NRF2/AP-1 feed-forward circuit to alleviate NPSCs senescence and disc degeneration.

Objective:To investigate the expression and methylation status of the SALL4 gene in placental tissues of fetal growth restriction (FGR) and its effects on trophoblast cell proliferation, migration, and invasion. Methods:Placental tissues were collected from 20 full-term FGR patients and 20 healthy term controls who underwent regular prenatal examination and cesarean section at the Third Affiliated Hospital, Zhengzhou University between July 2023 and February 2024. SALL4 mRNA and protein expression were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot. Methylation specific polymerase china reaction (MSP) assessed promoter methylation levels. HTR8/SVneo cells were transfected with SALL4-targeting small interfering RNA (si-SALL4) or negative control small interfering RNA (si-NC). HTR8/SVneo cells were treated with the demethylating agent 5-aza-2′-deoxycytidine (5-Aza-dC) to inhibit gene methylation (5-Aza-dC group) or with 10% RPMI-1640 medium as a vehicle control. Transfection efficiency (for siRNA) and the efficacy of 5-Aza-dC-induced demethylation were assessed by qRT-PCR and Western blot. The functional effects of SALL4 knockdown and methylation inhibition on trophoblast cells were evaluated using proliferation assays, scratch wound healing assays, and Transwell invasion assays. Statistical analyses included independent t-tests and Chi-square test. Results:(1) Human tissues: FGR placentas showed lower SALL4 mRNA (0.802±0.194 vs. 1.015±0.186, t=3.55) and protein expression (0.445±0.114 vs. 0.701±0.113, t=3.19), alongside higher methylation rates of SALL4 [80% (16/20) vs. 15% (3/20), χ2=14.44] compared to controls (all P<0.05). (2) In vitro: si-SALL4 transfection reduced HTR8/SVneo proliferation (OD450 at 48 h: 0.653±0.021 vs. 0.827±0.040, t=6.60), migration [healing rate at 48 h: (24.317±2.637)% vs. (49.327±1.961)%, t=13.18], and invasion [counted invaded cells: (133.000±6.557) vs. (272.667±18.009) cells, t=12.62] versus si-NC (all P<0.05). Conversely, 5-Aza-dC treatment increased HTR8/SVneo proliferation (0.917±0.042 vs. 0.783±0.031, t=－4.47), migration [(71.097±3.354)% vs. (51.632±2.877)%, t=－7.63], and invasion [(384.000±12.166) vs. (202.833±7.095) cells, t=－13.69] versus vehicle control (all P<0.05). Conclusions:Hypermethylation of the SALL4 promoter in FGR placentas suppresses its expression, impairing trophoblast cell function. Demethylation restores SALL4 expression and enhances cellular proliferation, migration, and invasion, involving in the occurrence and development of FGR disease.

Objective:To investigate the role and molecular mechanism of sensory neuron-derived exosomes (nExo) in mediating intervertebral disc degeneration (IDD).Methods:A rat IDD model was constructed, with nExo injected into the intervertebral disc. After 4 weeks, the degenerative grades of operated discs were evaluated using histological staining, while the senescent phenotype of nucleus pulposus stem cells (NPSC) in the tissue was evaluated using immunofluorescence staining. For in vitro experiments, 24 hours after the treatment of nExo to NPSC, immunoblotting, flow cytometry, or senescence-associated β-galactosidase staining was applied to evaluate the senescent phenotype of NPSC. Transcriptomics analysis was applied to identify the key molecules that mediate nExo-induced cells senescence. After 4 weeks of injecting nExo and TXN into the rat tail disc degeneration model.Results:nExo increased the degenerative grades of IDD and increased the proportion of TEK +p16 + and TEK +p21 + cells (from 36.32% ±4.04%, 33.69% ±4.56% in IDD group to 56.41% ±5.26%, 50.14% ±8.49% in IDD+nExo group, respectively; t=7.420, P<0.001; t=4.184, P<0.0019, respectively) in the disc tissue. Besides, nExo promoted the expression of p16 and p21 in NPSC and increased the percentage of cells with positive senescence-associated β-galactosidase staining (from 7.32%±1.73% to 58.22%±11.38%, t=7.658, P=0.002), while the percentage of G2/M cells was downregulated (from 18.10%±1.32% to 1.60%±0.67%, t=19.290, P<0.001). Transcriptomic analysis showed that the differential genes of CTRL vs. nExo were closely related to cell senescence, and TXN was screened by intersecting the differential gene set with the cellular senescence gene sets from the published database. Furthermore, we verified that nExo decreased the content of TXN in NPSC, while exogenous TXN downregulated the expression of p16 and p21 in NPSC, reduced the positive cell rate of senescence-associated β-galactosidase staining (from 58.84%±3.99% to 21.68%±8.16%, t=7.048, P=0.021), increased the percentage of G2/M cells (from 1.21%±0.34% to 15.26%±2.60%, t=9.259, P=0.001). TXN significantly reduced the grade of disc tissue degeneration (histological score: 14.33±0.82 in the nExo group; 8.17±1.17 in the nExo+TXN group, t=10.590, P<0.001), significantly increased the content of extracellular matrix (from 10.94±4.35 μg/mg to 50.55±12.16 μg/mg, t=7.512, P<0.001), and reduced the proportion of TEK +p16 + and TEK +p21 + double-positive cells (from 54.92%±4.21% and 60.31%±9.02% to 27.93%±3.26% and 33.75%±8.07%, respectively; t=12.430, P<0.001; t=5.375, P<0.001, respectively). Conclusion:nExo promotes cell senescence and IDD by downregulating TXN in NPSC.