An easy-to-implement, non-invasive head restraint method for monkey fMRI.

Functional magnetic resonance imaging (fMRI) in behaving monkeys has a strong potential to bridge the gap between human neuroimaging and primate neurophysiology. In monkey fMRI, to restrain head movements, researchers usually surgically implant a plastic head-post on the skull. Although time-proven to be effective, this technique could create burdens for animals, including a risk of infection and discomfort. Furthermore, the presence of extraneous objects on the skull, such as bone screws and dental cement, adversely affects signals near the cortical surface. These side effects are undesirable in terms of both the practical aspect of efficient data collection and the spirit of "refinement" from the 3R's. Here, we demonstrate that a completely non-invasive fMRI scan in awake monkeys is possible by using a plastic head mask made to fit the skull of individual animals. In all of the three monkeys tested, longitudinal, quantitative assessment of head movements showed that the plastic mask has effectively suppressed head movements, and we were able to obtain reliable retinotopic BOLD signals in a standard retinotopic mapping task. The present, easy-to-make plastic mask has a strong potential to simplify fMRI experiments in awake monkeys, while giving data that is as good as or even better quality than that obtained with the conventional head-post method.

Valley Index as a Predictor of Prenatal Diagnosis of Total Anomalous Pulmonary Venous Connection.

INTRODUCTION: Total anomalous pulmonary venous connection (TAPVC) has a low prenatal diagnostic rate. Therefore, we investigated whether Doppler waveforms with a low pulsatility in the pulmonary veins can indicate fetal TAPVC. METHODS: This retrospective study included 16 fetuses with TAPVC, including 10 with complex congenital heart disease and 104 healthy fetuses that underwent fetal echocardiography. Pulmonary venous S and D wave flow velocities and the valley (representing the lowest velocity between the S and D waves) were measured. Valley indices I and II were then calculated as (velocity of valley/greater of the S and D wave velocities) and (velocity of valley/lesser of the S and D wave velocities), respectively. RESULTS: Supra/infracardiac TAPVC cases exhibited significantly greater valley indices than that of the healthy group. After adjusting for gestational age at fetal echocardiography, valley indices I (odds ratio [OR] 7.26, p < 0.01) and II (OR: 9.23, p < 0.01) were significant predictors of supra/infracardiac TAPVC. Furthermore, valley indices I and II exhibited a high area under the curve for detecting supra/infracardiac TAPVC, regardless of the presence of pulmonary venous obstruction. CONCLUSION: The valley index may be a useful tool for the detection of fetal TAPVC.

Small Extracellular Vesicles from adipose-derived stem cells suppress cell proliferation by delivering the let-7 family of microRNAs in ovarian cancer.

INTRODUCTION: Ovarian cancer is the leading cause of death among women with gynecological cancer, and novel treatment options are urgently needed. Extracellular vesicles (EVs), including exosomes, may be one of the most promising therapeutic tools for various diseases. In this study, we aimed to investigate the therapeutic effects of adipose-derived stem cell-derived EVs (ADSC-EVs) on ovarian cancer cell lines. MATERIALS AND METHODS: ADSCs and the ovarian cancer cell lines SKOV3 and OV90 were used for analysis. ADSC-EVs were isolated through ultracentrifugation and validated using a cryotransmission electron microscope, nanoparticle tracking analysis, and western blotting. Then, the effect of ADSC-EVs on ovarian cancer cells was investigated using IncuCyte and microRNA sequencing. Moreover, the potential functions of miRNAs were evaluated by gain-of function analysis and in silico analysis. RESULTS: ADSC-EVs suppressed SKOV3 and OV90 cell proliferation. In particular, small EVs (sEVs) from ADSCs exhibited a stronger antitumor effect than ADSC-medium/large EVs (m/lEVs). Comparison of the miRNA profiles between ADSC-sEVs and ADSC-m/lEVs, along with downstream pathway analysis, suggested the involvement of the let-7 family. Overexpression of hsa-let-7b-5p and hsa-let-7e-5p significantly suppressed the proliferation of SKOV3 cells. In silico analysis revealed that four potential target genes of hsa-let-7b-5p and hsa-let-7e-5p were significantly associated with the prognoses of the patients. CONCLUSION: ADSC-sEVs had a stronger antitumor effect than ADSC-m/lEVs. Hsa-let-7b-5p and hsa-let-7e-5p, which are highly abundant in ADSC-sEVs, suppressed cell proliferation. These findings may open up new possibilities for therapeutic approaches using ADSC-sEVs.

Novel therapeutic strategies targeting UCP2 in uterine leiomyosarcoma.

Uterine leiomyosarcoma (ULMS) is a malignant stromal tumor arising from the myometrium with a poor prognosis and very limited response to current chemotherapy. This study aimed to identify novel targets for ULMS through a three-step screening process using a chemical library consisting of 1271 Food and Drug Administration-approved drugs. First, we evaluated their inhibitory effects on ULMS cells and identified four candidates: proscillaridin A, lanatoside C, floxuridine, and digoxin. Then, we subcutaneously or orthotopically transplanted SK-UT-1 cells into mice to establish mouse models. In vivo analyses showed that proscillaridin A and lanatoside C exerted a superior antitumor effect. The results of mRNA sequencing showed that uncoupling protein 2 (UCP2) was suppressed in the sirtuin signaling pathway, increasing reactive oxygen species (ROS) and inducing cell death. Moreover, the downregulation of UCP2 induced ROS and suppressed ULMS cell growth. Furthermore, analyses using clinical samples showed that UCP2 expression was significantly upregulated in ULMS tissues than in myoma tissues both at the RNA and protein levels. These findings suggested that UCP2 is a potential therapeutic target and can contribute to the development of novel therapeutic strategies in patients with ULMS.

Ferroptosis induced by plasma-activated Ringer's lactate solution prevents oral cancer progression.

OBJECTIVE: This study aimed to investigate the effect of plasma-activated Ringer's lactate solution (PAL) on oral squamous cell carcinoma (OSCC) cells and carcinogenic processes with a particular focus on iron and collagenous matrix formation. MATERIALS AND METHODS: We used three OSCC cell lines, one keratinocyte cell line, and two fibroblast lines, and cell viability assays, immunoblotting, flow cytometry, and transmission electron microscopy were performed to evaluate the effect and type of cell death. The effect of PAL treatment on lysyl oxidase (LOX) expression was investigated in vitro and in vivo. Tamoxifen-inducible Mob1a/b double-knockout mice were used for the in vivo experiment. RESULTS: PAL killed OSCC cells more effectively than the control nontumorous cells and suppressed cell migration and invasion. Ferroptosis occurred and the protein level of LOX was downregulated in cancer cells in vitro and in vivo. Additionally, PAL improved the survival rate of mice and suppressed collagenous matrix formation. CONCLUSIONS: We demonstrated that PAL specifically kills OSCC cells and that ferroptosis occurs in vitro and in vivo. Furthermore, PAL can prevent carcinogenesis and improve the survival rate of oral cancer, especially tongue cancer, by changing collagenous matrix formation via LOX suppression.

Absent pulmonary valve with tricuspid atresia/stenosis: literature review with new three long-term cases.

Absent pulmonary valve (APV) syndrome with tricuspid atresia or tricuspid stenosis (TA/TS) is an extremely rare malformation recently reported as a variant of APV with intact ventricular septum (VS). The condition, however, has univentricular physiology and unique structural and clinical features. The purpose of this study was to update the current knowledge about this condition by describing long-term outcomes of three new cases and reviewing the available literatures. A systematic literature search was performed to collect clinical and anatomical data of APV with TA/TS. Institutional medical records were retrospectively reviewed to identify APV with TA/TS patients. In a total of 62 (59 reported and 3 new) cases, patent ductus arteriosus was present in 98% of APV patients with TA/TS. A large ventricular septal defect, dilatation of the pulmonary arteries, which is typically found in APV with tetralogy of Fallot, and respiratory distress at birth were rarely reported. Most of the recent cases were successfully managed by the Glenn or Fontan procedure. Coronary artery anomaly and ventricular arrhythmia were more frequently reported as the cause of death or severe neurological sequelae (9/16 and 3/8, respectively). Additional surgical intervention was required in the mid/long-term period in three cases due to left-ventricular outflow obstruction and in two due to aortic dilatation. The Fontan and Glenn procedures improved the survival in the last two decades. In addition to coronary artery anomaly and ventricular arrhythmia, left-ventricular outflow tract obstruction and aortic dilatation should be carefully monitored.

Fetal case of rare association of hypoplastic left heart syndrome and absent atrial septum accompanied by mixed form of supracardiac total anomalous pulmonary venous connection.

Abnormal pulmonary venous flow patterns on fetal echocardiography and a nutmeg lung pattern on fetal magnetic resonance imaging are seen in patients with pulmonary venous stenosis. The association between these findings and the degree of pulmonary venous stenosis remains unknown. We report an extremely rare case of a fetus diagnosed with hypoplastic left heart syndrome complicated by an absent atrial septum and supracardiac total anomalous pulmonary venous connection with left pulmonary venous congestion. This case suggests that compared to non-pulsatile continuous pulmonary venous flow, the nutmeg lung pattern can only be observed with severe pulmonary congestion and advanced pulmonary lymphangiectasia.

Agenesis of the venous duct with abnormal return of the umbilical vein into the superior vena cava: A case report.

INTRODUCTION: Agenesis of the venous duct is rare, with an incidence rate of .04%-.6%. Abnormal drainage of the umbilical vein (UV) to superior vena cava (SVC) is seen in .5% of agenesis of the venous duct cases. We present a case of agenesis of the venous duct with drainage of the UV into the SVC accompanied by tetralogy of Fallot. CASE PRESENTATION: The fetus was diagnosed with agenesis of the venous duct and tetralogy of Fallot at 29 gestational weeks. The UV directly returned to the SVC. Cardiomegaly and pericardial effusion were observed but did not deteriorate. The female infant was born at 40 gestational weeks. Contrast-enhanced computed tomography showed that the UV was occluded at its proximal aspect. No abnormality of the portal system was noted. The infant underwent intracardiac repair and was doing well at 16 months of age. DISCUSSION/CONCLUSION: Although the extrahepatic drainage type of agenesis of the venous duct is occasionally associated with heart failure and hydrops, severe hydrops was absent in this case. It was speculated that vascular resistance in the long pathway to the SVC restricted direct inflow from the UV. Portosystemic shunts and agenesis of the portal system are reported complications of agenesis of the venous duct. Prenatal agenesis of the venous duct diagnosis may be crucial for early postnatal diagnosis of these conditions.

Multiple neuronal circuits for variable object-action choices based on short- and long-term memories.

At each time in our life, we choose one or few behaviors, while suppressing many other behaviors. This is the basic mechanism in the basal ganglia, which is done by tonic inhibition and selective disinhibition. Dysfunctions of the basal ganglia then cause 2 types of disorders (difficulty in initiating necessary actions and difficulty in suppressing unnecessary actions) that occur in Parkinson's disease. The basal ganglia generate such opposite outcomes through parallel circuits: The direct pathway for initiation and indirect pathway for suppression. Importantly, the direct pathway processes good information and the indirect pathway processes bad information, which enables the choice of good behavior and the rejection of bad behavior. This is mainly enabled by dopaminergic inputs to these circuits. However, the value judgment is complex because the world is complex. Sometimes, the value must be based on recent events, thus is based on short-term memories. Or, the value must be based on historical events, thus is based on long-term memories. Such memory-based value judgment is generated by another parallel circuit originating from the caudate head and caudate tail. These circuit-information mechanisms allow other brain areas (e.g., prefrontal cortex) to contribute to decisions by sending information to these basal ganglia circuits. Moreover, the basal ganglia mechanisms (i.e., what to choose) are associated with cerebellum mechanisms (i.e., when to choose). Overall, multiple levels of parallel circuits in and around the basal ganglia are essential for coordinated behaviors. Understanding these circuits is useful for creating clinical treatments of disorders resulting from the failure of these circuits.

Pro-tumoral behavior of omental adipocyte-derived fibroblasts in tumor microenvironment at the metastatic site of ovarian cancer.

Adipocyte-rich omentum offers "good soil" for disseminating ovarian cancer (OvCa), contributing to therapeutic difficulty. However, little is understood about the association between adipocytes and tumor growth at peritoneal dissemination site. Herein, we report the induction of adipocyte dedifferentiation by OvCa cells and pro-tumorigenic effects of resulted adipocyte-derived fibroblasts. We confirmed that malignant ascites promoted the dedifferentiation of the primary human adipocytes obtained from surgical omental specimen into omental adipocyte-derived fibroblast (O-ADF) that possess both mesenchymal stem cell and myofibroblast-like features. This promotion of dedifferentiation by malignant ascites was blocked by addition of Wnt signaling inhibitor. The effects of dedifferentiated adipocytes in proliferation and migration of OvCa cells were analyzed with in vitro coculturing experimental models and in vivo mice model, and we demonstrated that OvCa cell lines showed enhanced proliferative characteristics, as well as increased migratory abilities upon coculturing with O-ADF. Additionally, exogenous transforming growth factor-ß1 augmented desmoplastic morphological change of O-ADF, leading to higher proliferative ability. Our results suggest that OvCa cells promote dedifferentiation of peritoneal adipocytes by activating Wnt/ß-catenin signaling, and generated O-ADFs exhibit pro-tumoral hallmarks.

Prenatally diagnosed left atrial appendage aneurysm with various postnatal imaging investigations: A case report.

A congenital left atrial appendage aneurysm (LAAA) is a rare cardiac malformation, that is, usually diagnosed in adulthood. It is rarely diagnosed prenatally. In most cases, surgical resection is recommended soon after the diagnosis has been made due to the risk of arrhythmia and thrombotic events. The present report describes a case of LAAA that was prenatally diagnosed and was asymptomatic postnatally. Imaging revealed the relation of the cardiac and airway structures around the LAAA in detail. The patient underwent surgical resection of the LAAA successfully at 7 months of age and is currently healthy at 5 years of age.

Ovarian cancer-associated mesothelial cells induce acquired platinum-resistance in peritoneal metastasis via the FN1/Akt signaling pathway.

Peritoneal dissemination of ovarian cancer (OvCa) arises from the surface of the peritoneum, covered by monolayer of mesothelial cells (MCs). Given that both OvCa cells and MCs are present in the same peritoneal metastatic microenvironment, they may establish cell-to-cell crosstalk or phenotypic alterations including the acquisition of platinum-resistance in OvCa cells. Herein, we report how OvCa-associated mesothelial cells (OCAMs) induce platinum-resistance in OvCa cells through direct cell-to-cell crosstalk. We evaluated mutual associations between OvCa cells and human primary MCs with in vitro coculturing experimental models and in silico omics data analysis. The role of OCAMs was also investigated using clinical samples and in vivo mice models. Results of in vitro experiments show that mesenchymal transition is induced in OCAMs primarily by TGF-ß1 stimulation. Furthermore, OCAMs influence the behavior of OvCa cells as a component of the tumor microenvironment of peritoneal metastasis. Mechanistically, OCAMs can induce decreased platinum-sensitivity in OvCa cells via induction of the FN1/Akt signaling pathway via cell-to-cell interactions. Histological analysis of OvCa peritoneal metastasis also illustrated FN1 expression in stromal cells that are supposed to originate from MCs. Further, we also confirmed the activation of Akt signaling in OvCa cells in contact with TGF-ß1 stimulated peritoneum, using an in vivo mice model. Our results suggest that the tumor microenvironment, enhanced by direct cell-to-cell crosstalk between OvCa cells and OCAMs, induces acquisition of platinum-resistance in OvCa cells, which may serve as a novel therapeutic target for prevention of OvCa peritoneal dissemination.

Protein kinase A accelerates the rate of early stage differentiation of pluripotent stem cells.

In normal development, the rate of cell differentiation is tightly controlled and critical for normal development and stem cell differentiation. However, the underlying mechanisms regulating the rate of the differentiation are unknown, and manipulation of the rate of the stem cell differentiation is currently difficult. Here we show that activation of protein kinase A (PKA) accelerates the rate of mouse embryonic stem cell (ESC) differentiation through an early loss of ESC pluripotency markers and early appearance of mesodermal and other germ layer cells. The activation of PKA hastened differentiation by increasing the expression of a histone H3 lysine 9 (H3K9) dimethyltransferase, G9a protein, and the level of a negative epigenetic histone mark, H3K9 dimethylation (H3K9me2), in the promoter regions of the pluripotency markers Nanog and Oct4. These results elucidate a novel role of PKA on ESC differentiation and offer an experimental model for controlling the rate of ESC differentiation.

Non-thermal plasma-activated lactate solution kills U251SP glioblastoma cells in an innate reductive manner with altered metabolism.

Ringer's lactate solution irradiated by non-thermal plasma, comprised of radicals, electrons, and ions, is defined as plasma-activated lactate (PAL). PAL exhibited antitumor effects in glioblastoma U251SP cells, which we termed PAL-specific regulated cell death. In contrast to the oxidative stress condition typical of cells incubated in plasma-activated medium (PAM), U251SP cells treated with Ringer's lactate solution or PAL exhibited changes in intracellular metabolites that were reductive in the redox state, as measured by the ratio of oxidative/reductive glutathione concentrations. In the metabolomic profiles of PAL-treated cells, the generation of acetyl-CoA increased for lipid metabolism from alanine and asparagine. PAL thus induces regulated death of U251SP glioblastoma cells in more innate microenvironments than PAM.

Encoding prediction signals during appetitive and aversive Pavlovian conditioning in the primate lateral hypothalamus.

The lateral hypothalamus (LH), which plays a role in homeostatic functions such as appetite regulation, is also linked to arousal and motivational behavior. However, little is known about how these components are encoded in the LH. Thus cynomolgus monkeys were conditioned with two distinct contexts, i.e., an appetitive context with available rewards and an aversive context with predicted air puffs. Different LH neuron groups encoded different degrees of expectation, predictability, and risks of rewards in a specific manner. A nearly equal number of one-third of the recorded LH neurons showed a positive or negative correlation between their response to visual conditioned stimuli (CS) that predicted the probabilistic delivery of rewards (0%, 50%, and 100%) and the associative values. For another one-third of recorded neurons, a nearly equal number showed a positive or negative correlation between their responses to rewards [appetitive unconditioned stimulus (US)] and reward predictability. Some neurons exhibited their highest or lowest trace-period responses in the 50% reward trials. These response modulations were represented independently and overlaid on a consistent excitatory or inhibitory response across the conditioning events. LH neurons also showed consistent responses in the aversive context. However, the responses to aversive conditioning events depending on the air puff value and predictability were less common. The multifaceted modulation of consistent activity related to outcome predictions may reflect motivational and arousal signals. Furthermore, it may underlie the role the LH plays in the integration and relay of signals to cortices for adaptive and goal-directed physiological and behavioral responses to environmental changes. NEW & NOTEWORTHY The lateral hypothalamus (LH) is implicated in motivational and arousal behavior; however, the detailed information carried by single LH neurons remains unclear. We demonstrate that primate LH neurons encode multiple combinations of signals concerning different degrees of expectation, appreciation, and uncertainty of rewards in consistent responses across conditioning events and between different contexts. This multifaceted modulation of activity may underlie the role of the LH as a critical node integrating motivational signals with arousal signals.

Identification of neuron-type specific promoters in monkey genome and their functional validation in mice.

Viral gene delivery is one of the most versatile techniques for elucidating the mechanisms underlying brain dysfunction, such as neuropsychiatric disorders. Due to the complexity of the brain, expression of genetic tools, such as channelrhodopsin and calcium sensors, often has to be restricted to a specified cell type within a circuit implicated in these disorders. Only a handful of promoters targeting neuronal subtypes are currently used for viral gene delivery. Here, we isolated conserved promoter regions of several subtype-specific genes from the macaque genome and investigated their functionality in the mouse brain when used within lentiviral vectors (LVVs). Immunohistochemical analysis revealed that transgene expression induced by the promoter sequences for somatostatin (SST), cholecystokinin (CCK), parvalbumin (PV), serotonin transporter (SERT), vesicular acetylcholine transporter (vAChT), substance P (SP) and proenkephalin (PENK) was largely colocalized with specific markers for the targeted neuronal populations. Moreover, by combining these results with in silico predictions of transcription factor binding to the isolated sequences, we identified transcription factors possibly underlying cell-type specificity. These findings lay a foundation for the expansion of the current toolbox of promoters suitable for elucidating these neuronal phenotypes.

Non-thermal plasma-activated medium modified metabolomic profiles in the glycolysis of U251SP glioblastoma.

Non-equilibrium atmospheric pressure plasma (NEAPP) is a mixture of radicals, electrons, anions, cations and light at near body temperature. Plasma-activated medium (PAM) is realized using NEAPP provided by engineered devices and irradiated to a cell culture medium for a period of 600 s. Glioblastoma cells U251SP cultivated in PAM previously indicated that antitumor effects induced PAM-specific apoptotic cell-death. Metabolomic profiles of a hundred intracellular metabolites were analyzed using capillary electrophoresis mass spectrometry. The metabolomic profiles of the PAM-treated U251SP cells were changed significantly with inhibition of the glycolysis pathway and with enhancement of the pentose phosphate pathway.

Effect of Plasma-Activated Lactated Ringer's Solution on Pancreatic Cancer Cells In Vitro and In Vivo.

BACKGROUND: The medical applications of nonequilibrium atmospheric pressure plasma in cancer therapy have attracted attention. We previously reported on the antitumor effect of plasma-activated medium. However, this approach requires plasma-activated liquids that are administrable to the human body. In this study, we produced plasma-activated lactated Ringer's solution (PAL) and evaluated its antitumor effect and mechanism. Furthermore, we evaluated the effect of the intraperitoneal administration of PAL using a peritoneal dissemination mouse tumor model. METHODS: The antitumor effect of PAL on pancreatic cancer cell lines was evaluated using proliferation and apoptosis assays. In addition, cellular reactive oxygen species (ROS) generation was examined. The role of ROS was assessed using a proliferation assay with N-acetyl cysteine (NAC). An adhesion assay was performed to evaluate the effect of PAL on cell adhesion. Finally, pancreatic cancer cells stably expressing luciferase (AsPC-1/CMV-Luc) were injected intraperitoneally into mice, followed by intraperitoneal injection of PAL. Peritoneal dissemination was monitored using in vivo bioluminescent imaging. RESULTS: The antitumor effect of PAL was shown in all cell lines in vitro. The TUNEL assay showed that PAL induced apoptosis. ROS uptake was observed in PAL-treated cells, and the antitumor effect was inhibited by NAC. Cell adhesion also was suppressed by PAL. The intraperitoneal administration of PAL suppressed the formation of peritoneal nodules in vivo. CONCLUSIONS: Our study demonstrated the antitumor effects of PAL in vitro and in vivo. Intraperitoneal administration of PAL may be a novel therapeutic option for peritoneal metastases.

＜Editors' Choice＞ Effects of exosomes derived from the induced pluripotent stem cells on skin wound healing.

Recently, the effects of stem cell supernatants or exosomes, such as skin wounds, have attracted attention. However, the effects of the induced pluripotent stem (iPS) cell-derived exosomes (iPS-Exos) have not been investigated in detail. Here, we investigated the effects of iPS-Exos on skin wound healing using an animal model. We isolated iPS-Exos from the iPS cell culture media. Control exosomes were isolated from unused iPS cell culture media (M-Exos). We first observed the morphologic characteristics of the isolated exosomes and examined the expression of surface antigens. The effects of these exosomes on the migratory response and proliferation of fibroblasts were analyzed as well. Additionally, using a diabetic ulcer model, the effects of iPS-Exos and M-Exos on skin wound healing were investigated. Transmission electron microscope analysis demonstrated that the size of iPS-Exos (120 ± 25 nm) was significantly larger than that of M-Exos (≤ 100 nm). Flow cytometry analyses showed that iPS-Exos were positive for CD9, CD63, and CD81, whereas they were negative for HLA-ABC and -DR expression. The migratory ability of fibroblasts cocultured with iPS-Exos was shown to be higher than that of the cells cocultured with M-Exos, as demonstrated using scratch assay. Skin wound healing model results showed that the administration of iPS-Exos results in a faster wound closure compared with that observed in the M-Exo group. In conclusion, the results obtained here indicate that iPS-Exos may promote the migration of fibroblasts in vitro and in vivo, suggesting the possibility of using iPS-Exos for the treatment of diabetic ulcer.

Intraperitoneal Administration of Plasma-Activated Medium: Proposal of a Novel Treatment Option for Peritoneal Metastasis From Gastric Cancer.

BACKGROUND: The administration of fluid irradiated with non-equilibrium atmospheric pressure plasma (NEAPP) has attracted much interest as a novel therapeutic method for cancer. The authors previously reported on the efficacy of plasma-activated medium (PAM) for treating cancer cell lines through the induction of apoptosis. In this study, the therapeutic effect of PAM was evaluated in vivo using a peritoneal metastasis mouse model. METHODS: Two gastric cancer cell lines were used in proliferation assays performed to optimize the production of PAM by changing the distance between the plasma source and the medium surface and by altering the volume of irradiated medium. Wound-healing and adhesion assays were conducted to determine the effect of PAM therapy on cell migration and adhesion capacity in vitro. Finally, a mouse model established by the intraperitoneal injection of enhanced green fluorescent protein-tagged gastric cancer cells was used to explore the efficacy of PAM administered intraperitoneally in inhibiting peritoneal metastasis formation. RESULTS: Shorter distances between the plasma source and the medium surface and smaller volumes of treated medium increased the anti-tumor effect of PAM. The PAM treatment attenuated gastric cancer cell migration and adhesion in vitro. The intraperitoneal administration of PAM decreased the formation of peritoneal metastatic nodules by 60% in the mouse model, and no adverse events were observed. CONCLUSIONS: Plasma-activated liquids may represent a novel therapeutic method for the treatment of peritoneal metastases in gastric cancer.