Advances in immunotherapy of M2 macrophages and gastrointestinal stromal tumor.

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal-derived tumors of the GI tract. They can occur throughout the GI tract, and the survival time of some patients can be improved by first-line targeted therapy with imatinib. However, there are some limitations with imatinib treatment. Immunotherapy for GIST has attracted much attention in recent years, and as one of the most abundant cells in the GIST microenvironment, M2 macrophages play an important role in disease progression. They have unique anti-inflammatory and pro-tumorigenic effects and are one target for immunotherapy. This review summarizes the connection between different factors and the programmed death receptor-1/programmed death ligand-1 pathway and M2 macrophages to reactivate or enhance anti-tumor immunity and improve imatinib efficacy, and to provide new ideas for GIST immunotherapy.

Comprehensive analysis of the effects of the cuprotosis-associated gene SLC31A1 on patient prognosis and tumor microenvironment in human cancer.

Background: Solute carrier family 31 (copper transporter), member 1 (SLC31A1) is a key factor in maintaining intracellular copper concentration and an important factor affecting cancer energy metabolism. Therefore, exploring the potential biological function and value of SLC31A1 could provide a new direction for the targeted therapy of tumors. Methods: This study assessed gene expression levels, survival, clinicopathology, gene mutations, methylation levels, the tumor mutational burden (TMB), microsatellite instability (MSI), and the immune cell infiltration of SLC31A1 in pan-cancer using the Tumor Immune Estimation Resource 2.0 (TIMER2.0), Gene Expression Profiling Interactive Analysis (GEPIA), University of Alabama at Birmingham CANcer (UALCAN) data analysis portal, and cBioPortal databases. To further understand the potential biological mechanisms of SLC31A1 in different cancers, single-cell level sequencing and a Gene Ontology/Kyoto Encyclopedia of Genes and Genomes (GO/KEGG) enrichment analysis of SLC31A1 were also performed. Finally, real-time quantitative polymerase chain reaction (RT-qPCR) and western blotting (WB) were used to validate the expression of SLC31A1 in cancers, such as gastric cancer. Results: SLC31A1 was expressed in most cancer tissues. In kidney renal clear cell carcinoma (KIRC), the high expression of SLC31A1 was associated with good overall survival (OS), while in adrenocortical carcinoma (ACC), breast invasive carcinoma (BRCA), lower grade glioma (LGG), mesothelioma (MESO), and skin cutaneous melanoma (SKCM), the low expression of SLC31A1 was associated with good OS. The highest frequency of SLC31A1 amplification was observed in ACC. In addition, missense mutations accounted for a major portion of the mutation types. The truncation mutation S105Y may be a putative cancer driver. SLC31A1 affected methylation levels in cancer and was associated with the TMB, MSI, and the level of infiltration of various immune cells. Additionally, the single-cell sequencing results showed that SLC31A1 was associated with multiple biological functions in cancer. Finally, the SLC31A1 enrichment analysis revealed that the SLC31A1-related genes were mainly enriched in the mitochondrial matrix and envelope vesicles. The RT-qPCR and WB results were consistent with the predicted results. Conclusions: SLC31A1 may be a potential target related to cancer energy metabolism and may have prognostic value.

Pan­cancer analysis identified ARHGAP23 as a potential biomarker for pancreatic adenocarcinoma.

Rho GTPASE-activating protein 23 (ARHGAP23) is known to activate RHO-GTPase and has an important role in the infiltration and metastasis of tumors. Although previous studies suggested its involvement in certain human cancers, its role in pan-cancer remains unclear. In the present study, the expression, prognosis and potential functions of ARHGAP23 in pan-cancer were evaluated through various public databases such as Human Protein Atlas, Tumor IMmune Estimation Resource, Gene Set Co-Expression Analysis, Gene Expression Profiling Interactive Analysis, cBio Cancer Genomics Portal, Tumor-Immune System Interactions Database (TISIDB) and others. Through these data combined with a variety of biological information analysis methods, the potential role of ARHGAP23 as a carcinogenic gene was explored in the present study. The present analysis revealed that ARHGAP23 expressed abnormalities in >10 tumors, which was associated with differences in prognosis. Furthermore, the findings of the present study indicated that ARHGAP23 is associated with DNA methylation and multiple immune cell infiltrations in these tumors. ARHGAP23 expression was related to clinical prognosis, DNA methylation and immune infiltration. These findings support the potential of ARHGAP23 as a prognostic biomarker and a molecular target for cancer treatment.

Comparison of the safety and effectiveness of different surgical timing for acute cholecystitis after percutaneous transhepatic gallbladder drainage: a systematic review and meta-analysis.

BACKGROUND: To compare the efficacy and safety of laparoscopic cholecystectomy (LC) in the treatment of acute cholecystitis (AC) at different time points after percutaneous transhepatic gallbladder drainage (PTGBD). METHODS: PubMed, EMBASE, Cochrane Library, and Web of Science were searched from database inception to 1 May 2022. The last date of search was the May 30, 2022. The Newcastle-Ottawa scale (NOS) was used to conduct quality assessments, and RevMan (Version 5.4) was used to perform the meta-analysis. RESULTS: A total of 12 studies and 4379 patients were analyzed. Compared with the < 2-week group, the ≥ 2-week group had shorter operation time, less intraoperative blood loss, shorter postoperative hospital stay, lower rate of conversion to laparotomy, and fewer complications. There was no statistical difference between the two groups regarding bile duct injury, bile leakage, and total cost. CONCLUSIONS: The evidence indicates that the ≥ 2-week group has the advantage in less intraoperative blood loss, minor tissue damage, quick recovery, and sound healing in treating AC. It can be seen that LC after 2 weeks is safe and effective for AC patients who have already undergone PTGBD and is recommended, but further confirmation is needed in a larger sample of randomized controlled studies.

The crosstalking of lactate-Histone lactylation and tumor.

Lactate was once considered to be a by-product of energy metabolism, but its unique biological value was only gradually explored with the advent of the Warburg effect. As an end product of glycolysis, lactate can act as a substrate for energy metabolism, a signal transduction molecule, a regulator of the tumor microenvironment and immune cells, and a regulator of the deubiquitination of specific enzymes, and is involved in various biological aspects of tumor regulation, including energy shuttling, growth and invasion, angiogenesis and immune escape. Furthermore, we describe a novel lactate-dependent epigenetic modification, namely histone lactylation modification, and review the progress of its study in tumors, mainly involving the reprogramming of tumor phenotypes, regulation of related gene expression, mediation of the glycolytic process in tumor stem cells (CSCs) and influence on the tumor immune microenvironment. The study of epigenetic regulation of tumor genes by histone modification is still in its infancy, and we expect that by summarizing the effects of lactate and histone modification on tumor and related gene regulation, we will clarify the scientific significance of future histone modification studies and the problems to be solved, and open up new fields for targeted tumor therapy.

Unexpected reaction of "wild-type" gastrointestinal stromal tumor to imatinib: case report and literature review.

Background: Most of gastrointestinal stromal tumors (GISTs) are driven by mutations in the KIT/PDGFRA genes and can benefit from TKIs treatment. However, a small subset of GIST (10%-15%) are called "wild-type" GISTs due to the lack of these mutations. Theoretically, they would not benefit from TKIs treatment and may even develop resistance. Therefore, this unexpected response may challenge inherent perceptions. Herein, we present a case of giant wild-type GIST exhibiting an unexpected response to imatinib(IM), followed by laparoscopic surgical resection. Subsequently, potential underlying mechanisms are discussed. Case description: This case describes a 57-year-old man who presented with abdominal pain for two weeks. CT revealed a massive lesion near the splenic hilum along the greater curvature of the stomach, concurrently involving the splenic hilar vessels and surrounding lymph nodes. Ultrasound-guided fine needle aspiration biopsy confirmed it is a mesenchymal spindle cell tumor,GIST. Due to the enormous volume and local invasion, neoadjuvant chemotherapy was initially considered. After 6 months of IM 400 mg/d, CT imaging revealed marked changes in tumor heterogeneity and a significant reduction in volume. Subsequently, laparoscopic surgical resection was performed. Postoperative pathological examination, immunohistochemistry, and genetic testing collectively confirmed it is a wild-type GIST.The patient recovered well and was discharged on the 6th day after surgery, with continued oral IM(400 mg/d) after discharge. No recurrence was observed during follow-up until the publication of this report. Conclusion: This unexpected response suggests that wild-type GISTs may benefit from TKIs treatment, and the potential mechanisms warrant further investigation. Additionally, true wild-type GIST may not be discerned due to current limitations of Next-Generation Sequencing(NGS). Therefore, for advanced/high-risk GIST, additional genetic analysis can be performed after negative NGS results.

A Forgotten Corner in Cancer Immunotherapy: The Role of Lipids.

In the past decade, cancer immunotherapy has achieved great success owing to the unravelling of unknown molecular forces in cancer immunity. However, it is critical that we address the limitations of current immunotherapy, including immune-related adverse events and drug resistance, and further enhance current immunotherapy. Lipids are reported to play important roles in modulating immune responses in cancer. Cancer cells use lipids to support their aggressive behaviour and allow immune evasion. Metabolic reprogramming of cancer cells destroys the equilibrium between lipid anabolism and catabolism, resulting in lipid accumulation within the tumour microenvironment (TME). Consequently, ubiquitous lipids, mainly fatty acids, within the TME can impact the function and phenotype of infiltrating immune cells. Determining the complex roles of lipids and their interactions with the TME will provide new insight for improving anti-tumour immune responses by targeting lipids. Herein, we present a review of recent literature that has demonstrated how lipid metabolism reprogramming occurs in cancer cells and influences cancer immunity. We also summarise the potential for lipid-based clinical translation to modify immune treatment.

Intestinal congestion and reperfusion injury: damage caused to the intestinal tract and distal organs.

In clinical practice, intestinal autologous diseases, ailments and organ transplants can cause severe congestive damage to the intestinal tract. However, after the etiological factor is gotten rid of and blood flow is free without any hinderance, further damage to the intestinal wall often occurs, causing other related organ dysfunctions. This ultimately results in intestinal congestion reperfusion injury (ICRI). When the structure and function of the intestine are destroyed, bacteria, metabolites and endotoxins in the intestinal tract perfuse and enter the portal vein through the already compromised intestinal mucosa, to the other organs via the liver. Nevertheless, this gives rise to further aggravation of the injury, and reperfusion injury syndrome occurs. ICRI is a very common complication encountered by clinicians, and its harm is more severe and serious as compared with that caused by ischemia-reperfusion. Quite a few number of studies on ICRI have been reported to date. The exact mechanism of the injury is still idiopathic, and effective treatment strategies are still limited. Based on recent studies, this article is aimed at reviewing the destruction, damage mechanisms resulting from ICRI to the intestinal anatomical sites and distant organs. It is geared towards providing new ideas for the prevention and therapeutic approaches of ICRI.

Auditory and Visual Stimulation for Abdominal Postoperative Patients Experiencing Enhanced Recovery After Surgery (ERAS).

The Enhanced Recovery After Surgery program can reduce postoperative complications, hospital stay, and overall costs in patients, although the evidence for physical intervention with patients is still lacking. This study provides visual and auditory physical interventions to patients in order to explore the effects of Enhanced Recovery After Surgery following abdominal surgery. The study group consisted of patients who had undergone laparoscopic cholecystectomy, radical resection of gastric cancer, or radical resection of colon cancer; we randomly divided them into a control group and a visual and auditory intervention group. We then monitored the bowel sound frequency and time of the first anal self-exsufflation for both groups after surgery. We found that compared with the control group, patients who had undergone laparoscopic cholecystectomy and radical gastrectomy who received auditory intervention had increased bowel sound frequency and a shorter time until first anal self-exsufflation. In addition, patients with colon cancer who received both auditory and visual stimulation had increased bowel sounds and shorter time until the first anal self-exsufflation. These results suggest that visual and auditory interventions significantly improve patients' gastrointestinal function, shorten the hospitalization period, and reduce complications after operation.

Advances and challenges of neoadjuvant therapy in pancreatic cancer.

Pancreatic cancer has been becoming the second cause of cancer death in the western world, and its disease burden has increased. Neoadjuvant therapy is one of the current research hotspots in the field of pancreatic cancer, aiming to improve the surgical rate and prognosis of pancreatic cancer. Based on the latest evidence, this review discussed neoadjuvant therapy in pancreatic cancer from the following three aspects: patient selection, protocols selection of neoadjuvant therapy, and treatment response evaluation and resectability prediction. A big controversy existed on the indications of neoadjuvant treatment, but it was agreed that any patient who is likely to achieve R0 resection due to neoadjuvant therapy should be the targeted population. A variety of chemotherapy regimens were tried for neoadjuvant therapy in pancreatic cancer, and FOLFIRINOX and Nab-Paclitaxel plus Gemcitabine are two preferred regimens at present. It was challenging to evaluate treatment response and predict resectability after neoadjuvant therapy, although imaging by CT is widely used. Based on new findings of the remarkable performance of several chemotherapy regimens with or without radiotherapy, the neoadjuvant indications of pancreatic cancer have extended in recent years. However, it is still a challenge to assess the neoadjuvant treatment response and determine the timing of surgery.

Effects of Antibiotic Use on Outcomes in Cancer Patients Treated Using Immune Checkpoint Inhibitors: A Systematic Review and Meta-Analysis.

Antibiotic (ATB) use seems to negatively affect the outcomes of immune checkpoint inhibitors (ICIs). The aim of this review is to clarify whether ATB use influences the efficacy of ICI treatment in cancer patients. Databases of MEDLINE, Embase, and Cochrane Library were searched for reports published in English between January 2007 and December 2019. We included studies that compared the outcomes of ATB use and no-ATB use in cancer patients using ICIs. Two reviewers independently selected eligible studies and extracted the data. Meta-analysis was performed with pooling of unadjusted hazard ratios (HRs) for overall survival (OS) and progression-free survival (PFS), and with pooling of odds ratios (ORs) for objective response rate (ORR). Thirty-eight studies involving 8409 patients were finally included for qualitative or quantitative analyses. Cancer types included renal cell carcinoma, non-small cell lung cancer, urothelial carcinoma, melanoma, gastrointestinal cancer, and others. Meta-analyses revealed that ATB use was associated with poor OS [HR: 1.80, 95% confidence interval (CI): 1.44-2.26, P<0.001], PFS (HR: 1.55, 95% CI: 1.26-1.91, P<0.001) and ORR (OR: 0.63, 95% CI: 0.42-0.95, P=0.03). Subgroup analysis found that these relationships were not influenced by cancer type or ICI regimens, but were dependent on the timing of ATB use. Narrative results of multivariable analyses further confirmed the negative effects of ATB use on OS and PFS. In cancer patients using ICIs, pre-ATB use close to the start of ICI treatment (within 60 d) was detrimental to outcomes in terms of OS, PFS, and ORR.

Prognostic role of urokinase plasminogen activator in hepatocellular carcinoma: A protocol for systematic review and meta analysis.

BACKGROUND: Previous studies have showed that the high expression of urokinase plasminogen activator (uPA) in pathology and serology is closely related to the progression of hepatocellular carcinoma (HCC). However, there are no systematic reviews for these evidence, and the association between uPA and HCC is still not completely understood. Therefore, we will undertake a systematic review of the literature to summarize previous evidence regarding this topic, in order to clarify the prognostic significance of uPA in HCC. METHODS AND ANALYSIS: Studies comparing the HCC patients with high and low expression of uPA on the clinicopathological features and the prognosis are eligible for this review. Outcomes include all endpoints about survival and clinicopathological features. Prospective or retrospective primary studies which published in English will be included. Four databases of Medline, EMBASE, Web of Science, and the Cochrane Library will be systematically searched from their inception to Mar 2021 to retrieve relevant studies. Reference lists of included studies will be manually reviewed and grey literatures will be identified by Google Scholar. Two reviewers will independently screen the records and extract the information and data of the included studies. The Newcastle-Ottawa Scale will be used to assess the quality of included studies. Hazard ratio and 95% confidence interval will be pooled to assess the association between uPA expression and the prognosis. Pooled odds ratio and 95% confidence interval will be used for other outcomes. Heterogeneity will be assessed using the Cochrane Q test and I2 statistic, and a subgroup analysis will be performed if necessary. Grades of Recommendation, Assessment, Development and Evaluation method will be applied to assess the certainty of evidence. ETHICS AND DISSEMINATION: This protocol required information extracted from previously published articles. So, there is no ethical problem in this study. We plan to publish our findings in peer-reviewed journals and relevant conference proceedings. SYSTEMATIC REVIEW REGISTRATION: This study has been registered with the International Prospective Register of Systematic Reviews database (no.CRD42020150340).

Prognostic significance of tissue factor in patients with pancreatic cancer: a systematic review protocol.

INTRODUCTION: Pancreatic cancer is a highly aggressive digestive system tumour with poor prognosis. Venous thromboembolism (VTE) is a well-known complication of pancreatic cancer, and tissue factor (TF) contributes to the generation of a hypercoagulable state and thrombotic disease in pancreatic cancer. Several studies showed that an elevated TF level was related to the development of VTE and influenced the survival of patients with pancreatic cancer. Thus, we wish to conduct a systematic review of literature to clarify the prognostic significance of TF in pancreatic cancer. METHODS AND ANALYSIS: Studies comparing the circulating microparticle-associated TF (MP TF) level between patients who had pancreatic cancer with and without VTE will be included to evaluate the roles of TF in VTE development. Studies comparing the survival data between patients with high TF expression and low TF expression will also be included to explore the association of TF expression with patient survival. The outcomes are plasma MP TF level and survival endpoints (overall and progression-free survival), respectively. Primary studies of any type published in English will be included. Two reviewers will search Medline, EMBASE and Cochrane databases from inception to June 2020, retrieve relevant studies, and independently select the literatures and extract data from the included studies. The quality of each included study will be assessed by the Newcastle-Ottawa Scale score. The HR and 95% CI of each study will be pooled for survival outcome, and the standardised mean difference (SMD) with 95% CIs will be used for continuous outcomes. If meta-analysis is inappropriate, the result will only be reported qualitatively. Subgroup and sensitivity analyses will be considered to identify sources of heterogeneity. The Grades of Recommendation, Assessment, Development and Evaluation method will be applied to assess the level of evidence of this systematic review. ETHICS AND DISSEMINATION: There are no concerning ethical issues. The results will be published. PROSPERO REGISTRATION NUMBER: CRD42019133665.

Key Genes Associated with Prognosis and Tumor Infiltrating Immune Cells in Gastric Cancer Patients Identified by Cross-Database Analysis.

Background: The molecular mechanisms underlying gastric cancer (GC) progression are unclear. The authors examined key genes associated with the prognosis and tumor-infiltrating immune cells in patients with GC. Materials and Methods: Gene expression omnibus (GEO) was used to filter and obtain GC-related differentially expressed genes (DEGs). The molecular functions, biological processes, and cellular components of the DEGs were subjected to enrichment analysis. Protein-protein interaction networks of proteins encoded by the DEGs were analyzed using STRING. The authors also identified hub genes of GC, as well as their expression levels in GC and their relationship with patient prognosis. The relationship between hub genes and tumor-infiltrating immune cells was analyzed by Tumor IMmune Estimation Resource. Results: Six GEO datasets were included in this study, and 265 DEGs were identified. These DEGs were enriched in different signaling pathways and had different biological functions. Six hub genes were potentially significantly related to the molecular mechanisms of GC (TOP2A, FN1, SPARC, COL3A1, COL1A1, and TIMP1). These genes are potential markers of prognosis. Five hub genes were significantly positively correlated with the number of macrophages, neutrophils, and dendritic cells. Conclusions: The authors provide a theoretical basis for exploring the molecular regulation mechanism underlying GC and identifying therapeutic targets.

Assessment of the quality of systematic reviews on COVID-19: A comparative study of previous coronavirus outbreaks.

Several systematic reviews (SRs) have been conducted on the COVID-19 outbreak, which together with the SRs on previous coronavirus outbreaks, form important sources of evidence for clinical decision and policy making. Here, we investigated the methodological quality of SRs on COVID-19, severe acute respiratory syndrome (SARS), and Middle East respiratory syndrome (MERS). Online searches were performed to obtain SRs on COVID-19, SARS, and MERS. The methodological quality of the included SRs was assessed using the AMSTAR-2 tool. Descriptive statistics were used to present the data. In total, of 49 SRs that were finally included in our study, 17, 16, and 16 SRs were specifically on COVID-19, MERS, and SARS, respectively. The growth rate of SRs on COVID-19 was the highest (4.54/month) presently. Of the included SRs, 6, 12, and 31 SRs were of moderate, low, and critically low quality, respectively. SRs on SARS showed the optimum quality among the SRs on the three diseases. Subgroup analyses showed that the SR topic (P < .001), the involvement of a methodologist (P < .001), and funding support (P = .046) were significantly associated with the methodological quality of the SR. According to the adherence scores, adherence to AMSTAR-2 items sequentially decreased in SRs on SARS, MERS, and COVID-19. The methodological quality of most SRs on coronavirus outbreaks is unsatisfactory, and those on COVID-19 have higher risks of poor quality, despite the rapid actions taken to conduct SRs. The quality of SRs should be improved in the future. Readers must exercise caution in accepting and using the results of these SRs.

Risk of venous thromboembolism in patients undergoing gastric cancer surgery: protocol for a systematic review and meta-analysis.

INTRODUCTION: Venous thromboembolism (VTE) is a serious life-threatening complication in patients with gastric cancer. Abnormal coagulation function and tumour-related treatment may contribute to the occurrence of VTE. Many guidelines considered that surgical treatment would put patients with cancer at high risk of VTE, so positive prevention is needed. However, there are no studies that have systematically reviewed the postoperative risk and distribution of VTE in patients with gastric cancer. We thus conduct this systematic review to determine the risk of VTE in patients with gastric cancer undergoing surgery and provide some evidence for clinical decision-making. METHODS AND ANALYSIS: Studies reporting the incidence of VTE after gastric cancer surgery will be included. Primary studies of randomised controlled trials, cohort studies, population-based surveys and cross-sectional studies are eligible for this review and only studies published in Chinese and English will be included. We will search the Medline, Embase, Web of Science, CBM, CNKI and Wanfang data from their inception to November 2019. Two reviewers will independently select studies and extract data. The quality of each included study will be assessed with tools corresponding to their study design. Meta-analysis will be used to pool the incidence data from included studies. Heterogeneity of the estimates across studies will be assessed, if necessary, a subgroup analysis will be performed to explore the source of heterogeneity. The Grades of Recommendation, Assessment, Development and Evaluation method is applied to assess the level of evidence obtained from this systematic review. ETHICS AND DISSEMINATION: This proposed systematic review and meta-analysis is based on published data, and thus ethical approval is not required. The results of this review will be sought for publication. PROSPERO REGISTRATION NUMBER: CRD42019144562.

Systematic assessment of complications after robotic-assisted total versus distal gastrectomy for advanced gastric cancer: A retrospective propensity score-matched study using Clavien-Dindo classification.

BACKGROUND: Despite increasing evidence demonstrated robot-assisted distal gastrectomy (RADG) is safe and feasible for the treatment of advanced gastric cancer (AGC), robot-assisted total gastrectomy (RATG) remains a challenging procedure due to its technical difficulties and possible postoperative complications (POCs). This study aimed to systematically evaluate POCs following RATG. METHODS: Between January 2017 and January 2019, 319 AGC patients with pathological stage T2-4aN0-3M0 who underwent RADG or RATG were enrolled. POCs were stratified using the Clavien-Dindo classification. One-to-one propensity score matching was performed to reduce confounding differences. RESULTS: After matching, 266 patients met the criteria for further analysis. Ultimately, 64 patients (24.1%) who developed POCs had 126 clinical manifestation events. Overall the POCs rate was significantly greater after RATG in comparison with RADG (29.3% vs. 18.8%; P = 0.045), and more major POCs (Clavien-Dindo grade ≥ IIIa) were observed in the RATG group (14.3% vs. 5.3%; P = 0.013). The POCs were then classified into local and systemic POCs. The rates of local POCs (35.3% vs. 19.5%; P = 0.004) and systemic POCs (24.8% vs. 15.0%; P = 0.046) were significantly higher in the RATG group than the RADG group. Subgroup analysis showed that the anastomotic leakage rate was higher after RATG (5.3% vs. 0.8%; P = 0.031), whereas the remaining POCs were similar between the two groups. Patients with higher POCs significantly had longer postoperative length of stay (R = 0.895, P = 0.003). Multivariate analysis confirmed age, extent of resection, and TNM stage were risk factors for all POCs. CONCLUSIONS: These findings demonstrated that RATG is technically feasible and safe for treatment of AGC with acceptable morbidity and mortality rates. The POCs rate of RATG was higher than RADG, especially for anastomotic leakage. More effective anastomotic techniques are needed in RATG to prevent leakage.

In Vitro Study on the Dynamics of Blood Flow Impelled by an Alternating Current Magnetohydrodynamic Blood Pump.

Artificial hearts are effective devices to treat heart failure in clinical practice and can be divided into two categories: artificial hearts and ventricular assist devices. The goal of this work was to investigate the fluidity and biological changes of in vitro sheep blood using a novel alternating current (AC) magnetohydrodynamic blood pump (central magnetic intensity: 0.9 T, alternating current frequency of the electric motor: 0-80 Hz). Blood samples were collected from five sheep and were divided into two groups: the control group (no exposure to an external magnetic field) and the exposed group (3 h of exposure to an alternating magnetic field). The blood cell counts, changes in blood viscosity, and ultrastructural changes of the blood cells under transmission electron microscopy were investigated. This study demonstrated several findings: (i) Continuous sheep blood flow can be achieved; (ii) The blood cell counts remained unchanged after 3 h of exposure to an alternating magnetic field; (iii) Compared with the control group, the high- and low-shear viscosities of the whole blood from the sheep significantly decreased after 3 h of exposure to an alternating magnetic field (P < 0.05 and P < 0.01, respectively). Plasma viscosity was significantly reduced after exposure to high-intensity alternating magnetic fields (P < 0.001); (iv) The cytoplasm of blood cells (especially erythrocytes) became lighter in color in the exposure group compared to the control group, and "beads-on-string" aggregations of black particles appeared. This work provides detailed and reliable scientific research data for the development of this type of blood pump, which may serve as a transition to the clinical artificial heart.

[Effect of high-intensity alternating magnetic field on viscosity of sheep blood].

OBJECTIVE: To explore the changes of blood viscosity in high-intensity alternating magnetic field and the mechanisms.
 Methods: Five adult sheep were randomly selected and the blood samples were placed in high-intensity alternating magnetic field. Before and after exposure, the blood samples were taken and divided into 2 groups: a control group and a magnetic field group. The blood rheology and transmission electron microscopy (TEM) were performed.
 Results: Compared to the control group, the high shear viscosity of whole blood was decreased in the magnetic field group (P<0.05); the whole blood low shear viscosity and plasma viscosity were also decreased (both P<0.01). TEM showed the changes in red blood cell morphology and the double concave disc curvature. The radian of double concave disc and cell volume in the magnetic field group was larger than those in the control group.
 Conclusion: The high intensity alternating magnetic field may affect the distribution of surface charge and molecular current in blood cells, which in turn decrease the aggregation of cells and the blood viscosity.