Mounting evidence highlights preeclampsia (PE) pathogenesis involves gut microbiota dysregulation and trophoblast ferroptosis. However, the mechanistic nexus bridging intestinal homeostasis and placental ferroptosis remains elusive. Here, we found that Faecalibacterium prausnitzii (F. prausnitzii) reduced blood pressure (SBP/DBP), proteinuria, and levels of anti-angiogenic (sFlt-1) and pro-inflammatory (IL-6, TNF-α) mediators in PE rats established using reduced uterine perfusion pressure (RUPP) surgery. Critically, F. prausnitzii elevated fetal survival rate, increased fetal length and weight, and restored placental length and weight. Moreover, F. prausnitzii restored intestinal barrier function (upregulated claudin-1, occludin, ZO-1/2). In both PE rats' placentas and hypoxia-induced HTR-8/SVneo cells, F. prausnitzii reduced ferroptosis markers (MDA, Fe2+, 8-OHdG, lipid ROS), while increasing GSH, GPX4, and SLC7A11 levels. Mechanistically, F. prausnitzii facilitated the transfer of intestinal-epithelial cell-derived extracellular vesicles (EVs) to the placenta and alleviated PE symptoms, by delivering NRP1 to inhibit trophoblast cell ferroptosis. Molecularly, NRP1 activates SLC7A11 both by directly binding to it and by stabilizing its mRNA via NSUN2-mediated m5C methylation. These findings demonstrate that F. prausnitzii alleviates PE by transporting EVs-encapsulated NRP1 through the gut-placenta axis, which in turn modulates the NSUN2/SLC7A11 pathway to suppress trophoblast ferroptosis. Our findings identify NRP1 as a core mediator of EV-dependent ferroptosis inhibition and highlight the therapeutic potential of targeting the gut microbiota or the NRP1/NSUN2/SLC7A11 axis for PE treatment.

Preeclampsia (PE) is a major pregnancy complication characterized by an aberrant immune response. Methyl CpG binding protein 2 (MeCP2) is a potential regulator of secreted frizzled-related protein 4 (SFRP4), and both MeCP2 and SFRP4 are implicated in immune homeostasis. This study investigated the regulatory role of MeCP2/SFRP4 in immune cells in PE. A rat model of PE induced by reduced uterine perfusion pressure (RUPP) and an in vitro model using lipopolysaccharide (LPS)-stimulated HTR-8/SVneo cells were established. A co-culture system of LPS-challenged HTR-8/SVneo cells and T cells was also employed. MeCP2 expression was reduced and inversely correlated with SFRP4 levels in PE. MeCP2 overexpression suppressed Th1/Th17 differentiation while promoting Th2/Treg phenotypes, along with modulation of associated immune cytokines. It also enhanced colony formation, proliferation, migration, and invasion, while reducing apoptosis following co-culture. SFRP4 supplementation reversed the effects of MeCP2 overexpression on T cell proliferation and cytokine release. Collectively, these findings suggest that MeCP2 regulates T cell phenotype and inflammatory responses by inhibiting SFRP4, providing potential avenues for immunotherapeutic intervention in PE.

PROBLEM:Preeclampsia (PE) is a leading cause of perinatal maternal and fetal mortality. Clinical and pathological studies suggest that placental and decidual cell dysfunction may contribute to this condition. However, the pathogenesis of PE remains poorly understood. Therefore, this study aims to investigate the heterogeneous changes in cell types within placental and decidual tissue isolated from cesarean sections using single-cell sequencing. METHOD OF STUDY:Patients included those diagnosed with PE (n = 3) and normal pregnancy (NP) (n = 3). Overall, 32 279 cells (PE: 16.575; NP: 15 704) were identified across nine cell types, including villous cytotrophoblast (VCT), syncytiotrophoblast (SCT), extravillous trophoblasts (EVT), endothelial cells, neutrophil, Hofbauer cells, T cells, dendritic cells (DC), macrophages, fibroblasts, and B cells. VCT and T cells subclusters and pseudotime were analyzed. The in vivo and in vitro experiments are focused on the invasion ability of EVT. RESULTS:Using gene set variation analysis (GSVA) for differential expression genes, cell-reclustering, and pseudotime analysis, the VCT in patients with PE showed a tendency to differentiate toward SCT instead of EVT. And the invasive ability of PE EVT cells was declined by decreased expression of the invasion-related gene TMEM200A. Additionally, the impaired immune environment of T-cell differentiation into CD8+T cells instead of Treg cells is the main change related to PE. CONCLUSIONS:These findings suggest that understanding how T cell differentiation occurs in the early stage of pregnancy and how the predominantly CD8+T cell-driven immune environment influences VCT differentiation are crucial for elucidating the pathogenesis of PE.

A 34-year-old woman was referred to our hospital at 24+4 weeks of gestation for further evaluation of two cystic masses in the fetal abdomen. The patient had a history of antiphospholipid syndrome and was receiving aspirin for anticoagulation. No other medications were taken during organogenesis. Noninvasive DNA screening for Down syndrome yielded negative results. Whole exome sequencing and chromosome analysis revealed no abnormalities, and there was no family history of congenital anomalies. The upper pulsatile mass measured 41×35×30 mm and was located below the diaphragm and above the renal artery in the descending aorta. It exhibited characteristics consistent with a true aneurysm, such as a smooth wall, a wide communication with the descending aorta, and swirling blood flow within the cystic mass without a biphasic flow spectrum ([Fig. 1]A–C). The distal mass measured approximately 22×10×11 mm and was located below the renal artery. It exhibited a laceration approximately 5.3 mm wide between the mass and the abdominal aorta. Based on its irregular wall structure, uneven echogenicity, narrow laceration with the descending aorta, and the presence of a biphasic flow spectrum, we identified the lower mass as a pseudoaneurysm. A small normal arterial course was observed between these 2 masses.

The pathogenesis of preeclampsia (PE) involves endoplasmic reticulum stress (ERS) and the subsequent induction of mitophagy. Ariadne RBR E3 ubiquitin protein ligase 1 (ARIH1) is a key factor regulating mitophagy, but its role in PE has not been reported. In this study, we aimed to analyze the role of ARIH1 in the pathogenesis of PE. The role of ARIH1 in the pathogenesis of PE was investigated in a PE rat model and in an in vitro hypoxia/reoxygenation (H/R) model using HTR8 trophoblast cells. The study revealed that ARIH1 was upregulated while Mitochondrial fusion protein 2 (MFN2) was downregulated in PE rats and H/R-treated HTR8 cells. Inhibition of ARIH1 reversed the suppressed proliferation and invasion capacities of HTR8 cells under H/R conditions, reduced intracellular reactive oxygen species (ROS) and calcium ions (Ca2+), and modulated the protein expression of LC3II/LC3I, p62, glucose-regulatory protein 78 (GRP78), and C/EBP homologous protein (CHOP). Additionally, mitochondrial membrane potential was improved. Interestingly, treatment with Tunicamycin or Thapsigargin could reverse the inhibitory effects of ARIH1 downregulation on trophoblastic cells by activating endoplasmic reticulum stress (ERS) and mitophagy. Notably, the study identified for the first time that ARIH1 mediates the ubiquitination degradation of MFN2. Inhibition of MFN2 abolished the regulatory effects of ARIH1 downegulation on ERS and mitophagy in trophoblast cells, as well as the associated damage in PE rats. Overall, the findings underscore the crucial role of ARIH1 in regulating mitophagy and ERS through MFN2, highlighting its significance in the pathogenesis of PE.

BACKGROUND:Preeclampsia (PE) is a severe pregnancy-related disorder characterized by hypertension and end-organ manifestation, and remains a leading cause of perinatal maternal and fetal mortality and morbidity in developing countries. The pathogenesis of PE involves reduced uteroplacental blood flow and impaired trophoblast invasion; however, the role of exosomes in these processes is not fully understood. METHODS:This study employed Transwell assay, wound healing assay, and CCK-8 assays to evaluate the effects of umbilical cord exosomes derived from women with PE (PE-exosomes) on trophoblast function. Additionally, miRNA sequencing, in vitro transfection, western blotting, RT-PCR amd FISH assays were used to investigate the involvement of the microRNA-548 (miR-548)/Ras homolog family member A (RhoA) axis. Statistical analysis was performed using t-tests, with a significance threshold of P  <  0.01. RESULTS:Expression levels of miR-548 were significantly elevated in PE-exosomes. Both treatment with PE-exosomes and the overexpression of miR-548 inhibited trophoblast invasion and proliferation. These effects were reversed by RhoA overexpression. Together, these findings suggest that PE-exosomes suppress trophoblast invasion via the miR-548/RhoA axis. In pregnant women with PE, high miR-548 expression levels were observed, and were positively correlated with blood pressure and proteinuria. CONCLUSIONS:Elevated miR-548 levels may contribute to the development of PE, suggesting that miR-548 could serve as a novel diagnostic or therapeutic target for this condition.

Preeclampsia (PE) is a common obstetric syndrome with an unclear etiology and pathogenesis. The study here aimed to investigate the role of Yin Yang 1 (YY1) in PE, and to reveal any YY1-regulated mechanisms in PE. Peripheral blood, placenta, and endometrial tissues of PE patients, healthy volunteers, and patients who had undergone an elective Cesarean section and had a scarred uterus (control group) were collected for analyses. Rat PE models were established by lipopolysaccharide induction. Subsets of these rats were then made to over-express YY1. At 18 d after the PE was established, urine, blood, and placental tissues from all rats were collected. Levels of regulatory-T (T-reg) and helper T-type 17 (T(H)17) cells in both human and rat blood were measured by flow cytometry. ELISA kits were used to evaluate blood levels of inflammatory factors (i.e. IL-6, IL-10, and IL-17) as well. RT-qPCR and Western blot assays were performed to quantify levels of forkhead box P3 (Foxp3), retinoic acid-related orphan receptor C (RORc), and YY1 in the human and rat placenta and endometrial tissues. Expressions of PI3K/AKT pathway-related proteins were also evaluated by Western blots. The results indicated that the PE patients, relative to levels in control group and the healthy control subjects, had decreased circulating levels of T-reg cells/increased T(H)17 cells; tissues from these patients also had relatively-decreased FoxP3 mRNA and protein expressions and elevated RORc mRNA and protein expressions. YY1 was expressed only at low levels in the PE patient placenta and endometrial tissues. In rats, PE rats treated with over-expressed YY1 had (relative to in PE rats without over-induced YY1) increased circulating levels of T-reg cells/decreased T(H)17 cells; tissues from these rats had elevated FoxP3 mRNA and protein expressions and reduced mRNA and protein RORc expressions, as well as indications of alleviated inflammation. In the rat placenta samples, YY1 was also determined to activate the PI3K/AKT pathway. In summary, YY1 regulates the balance among T-reg/T(H)17 cells and so affect the PE process in part through activation of the PI3K/AKT pathway.

Background: This study explored the guiding value of monitoring pregnancy-induced hypertension syndrome (MP) for blood hypercoagulability in combination with ultrasound monitoring of uterine artery blood flow in early pregnancy and fetal growth and development in the second and third trimesters, with the goal of preventing chronic hypertension with preeclampsia (PE) and its clinical effects. Methods: The medical records of 189 pregnant patients with chronic hypertension between June 2016 and June 2021 were retrospectively analyzed; among them, 98 constituted the intervention group. The intervention group received MP screening for blood hypercoagulability in combination with ultrasound monitoring of uterine artery blood flow in early pregnancy and fetal growth and development in the second and third trimesters of pregnancy. Those with abnormalities were given timely symptomatic (low-molecular-weight heparin with or without aspirin) and supportive treatment. The remaining 91 patients who did not receive timely monitoring and intervention constituted the control group. Fetal outcomes and PE rates were compared between groups. Results: The PE incidence in the intervention group was significantly lower than that in the control group (p < 0.01), and the premature delivery of low-birth-weight neonates, fetal loss and neonatal asphyxia incidences were also significantly lower in the intervention group than the control group (p < 0.05). Conclusions: MP screening for blood hypercoagulability combined with ultrasound monitoring of uterine artery blood flow can effectively prevent PE occurrence in pregnant patients with chronic hypertension and significantly improve fetal outcomes. Additionally, MP screening is noninvasive and easy to use at a low cost.

Pre‐eclampsia is a major cause of maternal and fetal mortality. Low molecular weight heparin sodium (LMWH) reduced the incidence of pre‐eclampsia, may be an effective treatment of pre‐eclampsia. But the underlying mechanism of LMWH is unknown. To improve the molecular utilization rate, chitosan‐LMWH nanoparticles (CHsN) are purchased for the study. The prague of pregnancy Sprague‐Dawley rats are injected with nitroso l ‐arginine methyl ester to construct a pre‐eclampsia model. Trichotrophoblast cells HTR‐8/SVneo are cultured under Hypoxia/reoxygenation injury (H/R) simulation conditions to construct the cell model. CHsN ameliorates the integrity of fetal membrane tissue. Administration of CHsN results in decreased urine protein and HB‐EGF levels, accompanied by increased numbers of pups and placenta. Treatment with CHsN increases the proportion of Treg cells and decreases the proportion of Th17 cells. After treatment with CHsN, the levels of LPS, TNF‐α, rank1, slp1, Foxo, NF‐κB, and HIF‐1α are down‐regulated, while the levels of IL‐2, Foxp3, and TGFβ1 are up‐regulated. CRM197 reverses the effect of CHsN. The CHsN improves H/R‐induced HTR‐8/SVneo cells apoptosis through HB‐EGF and affected CD4+T cell differentiation. CHsN ameliorates pre‐eclampsia by regulating Treg/Th17 immune balance and inflammation at the maternal‐fetal interface through HB‐EGF. This provides a theoretical reference for relieving pre‐eclampsia by CHsN.

[This corrects the article DOI: 10.3389/fmolb.2021.763958.].

AIMS:Clinical evidence indicated the activation of endoplasmic reticulum stress (ERS) in pregnant women with preeclampsia (PE), and the regulatory role of melatonin (MT) in ERS. This study aims to explore the possible effect and mechanism of MT on ERS and on the infiltration of trophoblasts in PE.METHODS:The serum expression levels of MT and GRP78 in pregnant women with PE were measured. The cell proliferation, invasion, migration and apoptosis of trophoblasts were also determined. The trophoblast cell infiltration in placenta tissues was detected in EVOS image system. The expressions of ERS related proteins were measured by RT-qPCR and western blot.KEY RESULTS:The PE-serum treatment on HTR-8/SVneo cells led to activated ERS and suppressed cell biological functions. PE mouse models after MT treatment or 4-PBA treatment had reduced blood pressure, proteinuria, apoptosis and increased foetus and placenta weight, in addition to enhanced cell infiltration.CONCLUSIONS:In vivo and in vitro evidence demonstrated MT can simultaneously suppress ERS and ASK1/JNK signal pathway in PE to promote the infiltration of trophoblasts.

This study investigated the implication of monitoring hypertensive disorders in pregnancy (HDP) to prevent preeclampsia (PE) in pregnant women of advanced maternal age. Between January 2016 and April 2021, 262 consecutive pregnant women aged ≥40 years were recruited. Extensive monitoring of hypertensive disorders in pregnancy, including blood hypercoagulability screening and subsequent interventions, was performed in 129 pregnant women in our university hospital. The remaining 133 patients from other centres, who did not receive antenatal maternal pregnancy screening and preventive intervention during the same period, constituted the non-intervention group enabling comparison to mimic a trial. The incidences of hypertensive disorders, mild and severe PE, eclampsia, and chronic hypertension complicated by PE in the intervention group were significantly lower than in the non-intervention group (10.08 versus 20.30%, 8.52 versus 18.80%, 7.75 versus 21.05%, 0 versus 3.01%, and 3.86 versus 15.04%, respectively; P < 0.05). Premature birth, low birth weight, and foetal loss were significantly rarer in the intervention group than in the non-intervention group (6.98 versus 24.81%, 7.75 versus 21.80%, and 0.78 versus 14.29% respectively; P < 0.001). The comparison of MP with routine blood coagulation biochemical examination found that the MP detection system of Beijing Yes Medical Devices Co., Ltd., had similar sensitivity as thromboelastogram. Still, it was significantly better than the routine biochemical indicators (P < 0.01). Based on MP parameters, early anticoagulant treatment with low-molecular-weight heparin or low-dose aspirin in pregnant women with hypercoagulability can effectively prevent the occurrence of PE and significantly improve the prognosis of both mothers and infants.

In this study, a treatment method was assessed for the prevention and treatment of postpartum bleeding after combined surgery in patients having late pregnancy with the complication of acute Stanford type A aortic dissection. The clinical records of ten patients receiving treatment at the Second Xiangya Hospital of Central South University between March 2012 and March 2021 were retrospectively analysed. All patients were diagnosed with acute Stanford type A aortic dissection according to computed tomography angiography of the thoracic and abdominal aorta. Aortic valve function was assessed using two-dimensional echocardiography. All patients experi-enced uterine-incision delivery under systemic anaesthesia. During the operation, intrauterine Bakri balloon tamponade and cervical cerclage were performed. Postpartum bleeding was effectively controlled for all patients. The extracor-poreal circulation time was 230-295 min, the postpartum 24 h bleeding volume was 500-870 mL, the volume of phys-iological saline injected into the balloon was 290-515 mL, and the intrauterine balloon compression time was 28-51 h. No postpartum bleeding occurred. A 42-days follow-up showed no late postpartum bleeding, poor uterine incision healing, or puerperal infection, and no uterine removal was performed. Intrauterine Bakri balloon tamponade plus cervical cerclage can effectively prevent intra-and post-operative postpartum bleeding in pregnant patients with aortic dissection.

Transporter associated with antigen processing 1 (TAP1) is a protein related immune regulation and plays a role in several malignant tumors. However, the effect of TAP1 on immune infiltration, immunotherapy, and metastasis in different cancers has not been reported till date. The cancer genome atlas database, the tumor immune estimation resource database, and the estimation of stromal and immune cells in malignant tumors using expression (ESTIMATE) algorithm were used to determine the correlation between TAP1 expression and the prognosis of a variety of cancers, immune infiltration, immune checkpoint genes, DNA methylation, and neoantigens. Various enrichment analyses were used to study the correlation between TAP1 and key transcription factors using the Kyoto encyclopedia of genes and genomes (KEGG) pathway in ovarian cancer. Immunological methods were used to evaluate the expression of TAP1 protein in ovarian and cervical cancer, and Kaplan–Meier analysis was used to analyze the prognostic value of TAP1. RNA interference (RNAi) was used to verify the effect of TAP1 on ovarian cancer. Compared with normal tissues, cancer tissues showed a significant increase in the expression of TAP1, and TAP1 expression was related to the poor prognosis of cancers such as ovarian cancer. The expression level of TAP1 was correlated with immune checkpoint genes, DNA methylation, tumor mutation burden, microsatellite instability, and neoantigens in various cancers. Our results showed that TAP1 was upregulated in ovarian cancer cell lines and was associated with poor prognosis. Further, we verified the expression of TAP1-related transcription factors (MEF2A and LEF1) and found that TAP1 was closely related to ovarian cancer metastasis in vitro and in vivo. These results indicated that TAP1 could be used as a biomarker for the diagnosis and prognosis of cancer and as a new therapeutic target.

Objective: To explore the early preventive treatment of hypertriglyceridemia-induced acute pancreatitis (HTGP) in pregnancy. Methods: A retrospective cohort analysis was performed to examine the drug intervention on recurrent HTGP and related pregnancy outcomes among women who had HTGP in their past pregnancy and developed hyperlipidemia during the second pregnancy. Participants were identified through inpatient case records under a single physician at the clinic and divided into two groups. The intervention group was given metformin lipid-lowering combined with low-molecular-weight heparin to prevent thrombosis when hypertriglyceridemia was developed during the pregnancy. In contrast, the non-intervention group includes those who did not receive active drug treatment until they developed recurrent HTGP. Metabolic markers were also examined by comparing them with their respective past pregnancies. Results: All participants experienced elevated triglycerides during their two consecutive pregnancies. No pregnant women developed HTGP in the intervention group (n=12), while 10 of 13 (76.9%) women developed HTGP in the non-intervention group. Thus, the outcome seemed to be markedly different. In the intervention group, 11 women were gestated to term, and one was premature; one of 12 (8.3%) births was neonatal asphyxia; there was no low-weight birth, and the prognosis of mother and baby was favorable. Of 10 women who developed recurrent HTGP in the non-intervention group, four suffered from fetal loss, four had premature, and two had full-term delivery; among the three pregnant women without HTGP, one had a premature and two had full-term births; five of thirteen (38.5%) births were neonatal asphyxia. Conclusion: Pregnant women with HTGP history, if not treated, are likely to develop the condition recurrently during pregnancy, but timely intervention on hypertriglyceridemia with lipid-lowering and thrombosis-preventing seemed complete to reduce the recurrent HTGP and improve the pregnancy outcomes.

Background: GRHL2 has been shown to function in ovarian carcinogenesis. However, the relationship between GRHL2 and cisplatin (DDP) resistance in serous ovarian cancer (SOC) is not clear. The purpose of this study was to elucidate the function and mechanism of GRHL2 in DDP resistance of SOC. Materials and Methods: Immunohistochemistry (IHC) was utilized to identify GRHL2 protein expression in DDP resistant and sensitive SOC tissues. GRHL2 mRNA and protein levels were identified using quantitative real-time PCR (qRT-PCR) and Western blotting in SKOV3/DDP and SKOV3 cell lines. We conducted loss- and gain-of-function experiments to uncover the consequence of GRHL2 knockdown or overexpression on the sensitivity of ovarian cancer cells to DDP in vitro and in vivo and the underlying mechanism. Results: It was observed that expression of GRHL2 was higher in DDP resistant SOC tissues relative to DDP sensitive SOC tissues. In addition, the increased expression of GRHL2 led to shorter progression-free survival (PFS) and overall survival (OS). Meanwhile, the GRHL2 transcript and protein levels in SKOV3/DDP were also higher than SKOV3. Small hairpin RNA (shRNA)-facilitated GRHL2 gene knockdown considerably heightened the sensitivity of SKOV3/DDP cells to DDP by inhibiting proliferation and promoting apoptosis, while up-regulation of GRHL2 significantly reduced the sensitivity of SKOV3 cells to DDP by promoting proliferation and decreasing apoptosis. In addition, GRHL2 promotes DDP resistance of SOC through activation of ERK/MAPK signaling pathways. Conclusion: Our results suggest that GRHL2 up-regulation predicts a poor prognosis and promotes the resistance of SOC to DDP. Therefore, GRHL2 may be a possible treatment target for cisplatin-resistant serous ovarian cancer.

Introduction: Epithelial membrane protein 1 (EMP1), a member of the EMP family, is overexpressed in a large number of tumors and is thought to be a cellular connexin on the cell membrane and is involved in proliferation, invasion, metastasis of tumor cells, and epithelial-mesenchymal transition (EMT). Nevertheless, its biomedical function in ovarian cancer is still unclear. Methods: EMP1 was detected in ovarian cancer cell lines by whole transcriptome resequencing. The mRNA of EMP1 was examined by qRT-PCR. The relationship between expression of EMP1 and clinical classification, metastasis, and shortened survival time in ovarian cancer specimens was analysed by immunohistochemical (IHC). The mechanism of EMP1 enhanced proliferation and invasion of ovarian cancer cells was determined by siRNA interference, colony formation, migration and invasion experiments, and Western blot. Results: EMP1 was up-regulated in ovarian cancer cell lines and ovarian cancer tissues in comparison with non-cancerous ovarian specimens. High expression of EMP1 in ovarian cancer specimens was obviously related to high clinical classification, metastasis, and shortened survival time. High expressed EMP1 facilitates cell proliferation, invasion and EMT in ovarian cancer cells. Over-expressed EMP1 increased the protein levels of RAS/RAF/MAPK/c-JUN. Conclusion: Over-expressed EMP1 in ovarian cancer promotes tumor cell proliferation, invasion, and EMT by the MAPK signaling pathway.

The authors describe a method for enhancing the hybridization chain reaction (HCR) by using gold nanoparticles (AuNPs). This can considerably improve the sensitivity of electrochemical immunoassays as demonstrated for the carbohydrate antigen 125 (CA125), a biomarker for ovarian cancer. Compared to previous HCR based assays, the DNA acting as fuel strands were immobilized onto AuNPs, so that dendrimeric like chains were formed on the electrode after HCR. The improved signal is due to the reaction of DNA on the electrode. Specifically, the reaction of the phosphate groups of DNA with molybdate forms redox-active molybdophosphate, and this generates a strong electrochemical current. The immunosensor was prepared by sequential capturing, on the electrode, (a) antibody against CA125, (b) analyte (CA125), and (c) an aptamer against CA125 to form a sandwich structure. The primer on the aptamer sequence initiates HCR by annealing to one strand of DNA on the AuNPs and to another DNA in solution. The increased loading of DNA molecules onto the electrode increases the amount of phosphate groups and subsequently increases the electrical signal. The sensitivity of the assay is found to be significantly improved compared to assays without HCR and when using conventional HCR. The immunosensor was successfully applied to the determination of CA125 in human serum samples. The detection limit (based on an S/N ratio of 3) is 50 μU.mL−1. This indicates that this signal amplification strategy has a large potential in terms of clinical applications. It may be modified such that it also can be applied to the determination of other analytes for which proper aptamers are available.