Virus shedding dynamics in asymptomatic and mildly symptomatic patients infected with SARS-CoV-2

Objectives

Asymptomatic patients, together with those with mild symptoms of coronavirus disease 2019 (COVID-19), may play an important role in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission. However, the dynamics of virus shedding during the various phases of the clinical course of COVID-19 remains unclear at this stage.

Methods

A total of 18 patients found to be positive for SARS-CoV-2 infection by real-time reverse transcription PCR (RT-PCR) assay and admitted to Chongqing University Central Hospital between 29 January and 5 February 2020 were enrolled into this study. Medical data, pulmonary computed tomographic (CT) scan images and RT-PCR results were periodically collected during the patients' hospital stay. All participants were actively followed up for 2 weeks after discharge.

Results

A total of nine (50%) asymptomatic patients and nine (50%) patients with mild symptoms of COVID-19 were identified at admission. Six patients (66.7%) who were asymptomatic at admission developed subjective symptoms during hospitalization and were recategorized as being presymptomatic. The median duration of virus shedding was 11.5, 28 and 31 days for presymptomatic, asymptomatic and mildly symptomatic patients, separately. Seven patients (38.9%) continued to shed virus after hospital discharge. During the convalescent phase, detectable antibodies to SARS-CoV-2 and RNA were simultaneously observed in five patients (27.8%).

Conclusions

Long-term virus shedding was documented in patients with mild symptoms and in asymptomatic patients. Specific antibody production to SARS-CoV-2 may not guarantee virus clearance after discharge. These observations should be considered when making decisions regarding clinical and public health, and when considering strategies for the prevention and control of SARS-CoV-2 infection.

Correction to Preparation of Engineered Extracellular Vesicles Derived from Human Umbilical Cord Mesenchymal Stem Cells with Ultrasonication for Skin Rejuvenation

[This corrects the article DOI: 10.1021/acsomega.9b03561.].

Abstract B53: Extracellular vesicle-based liquid biopsy via lipid-based nanoprobes

Extracellular vesicles (EVs) can mediate intercellular communication by transferring cargo proteins and nucleic acids between cells. The pathophysiologic roles and clinical value of EVs are under intense investigation, yet most studies are limited by technical challenges in the isolation of nanoscale EVs (nEVs). Here, we report a lipid-nanoprobe system that enables spontaneous labeling of nEVs for subsequent magnetic enrichment in 15 minutes, with isolation efficiency and cargo composition similar to what can be achieved by the much slower and bulkier method of ultracentrifugation. We also show that this approach allows for downstream analyses of nucleic acids and proteins, enabling the identification of EGFR and KRAS mutations following nEV isolation from the blood plasma of non-small cell lung cancer patients. The efficiency and versatility of the lipid-nanoprobe approach open up opportunities in point-of-care cancer diagnostics.

Citation Format: Siyang Zheng, Hongzhang He, Faming Wang, Yuan Wan. Extracellular vesicle-based liquid biopsy via lipid-based nanoprobes [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr B53.

Chromosomal abnormalities detected by karyotyping and microarray analysis in twins with structural anomalies

OBJECTIVES

To evaluate the incidence and types of chromosomal abnormalities detected in twins with structural anomalies and compare their distribution according to chorionicity and amnionicity and by structural-anomaly type. The added value of chromosomal microarray analysis (CMA) over conventional karyotyping in twins was also estimated.

METHODS

This was a single-center, retrospective analysis of 534 twin pregnancies seen over an 11-year period, in which one or both fetuses were diagnosed with congenital structural anomalies on ultrasound. The ultrasound findings and invasive prenatal diagnostic results were reviewed. Twin pregnancies were categorized as monochorionic monoamniotic (MCMA), monochorionic diamniotic (MCDA) or dichorionic diamniotic (DCDA). Chromosomal abnormalities detected by G-banding karyotyping and/or CMA were analyzed by chorionicity and amnionicity and by structural-anomaly type.

RESULTS

The 534 twin pairs analyzed comprised 25 pairs of MCMA, 112 pairs of MCDA and 397 pairs of DCDA twins. Of the 549 fetuses affected by structural anomalies, 432 (78.7%) underwent invasive prenatal testing and cytogenetic results were obtained. The incidence of overall chromosomal abnormalities in the DCDA fetuses (25.4%) was higher than that in the MCMA (3.7%) and MCDA (15.3%) fetuses. The incidence of aneuploidy was significantly higher in the DCDA group (22.8%) than in the MCMA (0.0%) and MCDA (12.4%) groups. The incidence of chromosomal abnormalities detected in fetuses, with anomalies of the cardiovascular, faciocervical, musculoskeletal, genitourinary and gastrointestinal systems, was higher in the DCDA group than in the MCDA group. In both the DCDA and MCDA groups, hydrops fetalis was associated with the highest incidence of chromosomal abnormality; of these fetuses, 67.6% had Turner syndrome (45,X). Pathogenic copy-number variations (CNVs) undetectable by karyotyping were identified by CMA in five (2.0%; 95% CI, 0.3-3.7%) DCDA fetuses. No pathogenic CNVs were found in MCMA and MCDA twins.

CONCLUSIONS

Dichorionic twins with structural anomalies have a higher risk of chromosomal abnormalities, especially aneuploidies, than do monochorionic twins. The incremental diagnostic yield of CMA over karyotyping seems to be lower (2.0%) in twins than that reported in singleton pregnancy. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Individualized prediction of late-onset dysphagia in head and neck cancer survivors

BACKGROUND

Limited data exist regarding which head and head and neck cancer (HNC) survivors will suffer from long-term dysphagia.

METHODS

From a population-based cohort of 1901 Utah residents with HNC and ≥3 years follow-up, we determined hazard ratio for dysphagia, aspiration pneumonia, or gastrostomy associated with various risk factors. We tested prediction models with combinations of factors and then assessed discrimination of our final model.

RESULTS

Cancer site in the hypopharynx, advanced tumor classification, chemoradiation, preexisting dysphagia, stroke, dementia, esophagitis, esophageal spasm, esophageal stricture, gastroesophageal reflux, thrush, or chronic obstructive pulmonary disease were associated with increased risk of long-term dysphagia. Our final prediction tool gives personalized risk calculation for diagnosis of dysphagia, aspiration pneumonia, or gastrostomy tube placement at 5, 10, and 15 years after HNC based on 18 factors.

CONCLUSION

We developed a clinically useful risk prediction tool to identify HNC survivors most at risk for dysphagia.

Structural maintenance of chromosomes 2 is identified as an oncogene in bladder cancer in vitro and in vivo

Taurine upregulated gene 1 (TUG1) has been found to promote bladder cancer cell growth in our recent research. In this study, TUG1-depleted bladder cancer cells were used to identify potent players in bladder cancer. Human gene expression arrays were used for transcriptome profiling of TUG1-depleted bladder cancer cells. Cell proliferation was analyzed by MTT assay. Cell apoptosis and cell cycle were analyzed by flow cytometry. Colony formation assay was used to observe the changes of colony formation rates. Xenograft formation assay was performed in nude mice. Immunohistochemical staining was used to test the gene expression levels in tissues from bladder cancer patients. We found that deregulated genes were strongly enriched in cell cycle or pathways in cancer in TUG1-depleted bladder cancer cells. Structural maintenance of chromosomes 2 (SMC2) was inhibited after TUG1 knockdown. The depletion of TUG1 or SMC2 led to G2/M phase arrest in bladder cancer cells. SMC2 depletion inhibited bladder cancer cell proliferation, promoted apoptosis, decreased colony formation, and reduced tumor growth in xenograft nude mice. Overexpression of SMC2 restored the growth of TUG1-depleted cells. The expression levels of SMC2 were higher in human bladder cancer tissues than that in paired normal tissues. Our data suggest that SMC2 is an oncogene in bladder cancer and depletion of SMC2 might have potential therapeutical significance in bladder cancer.

Nano-Affi: a solution-phase, label-free, colorimetric aptamer affinity assay based on binding-inhibited aggregation of gold nanoparticles

The ideal way to assess aptamer affinity is when both aptamer and target are in a native state, without the unpredictable interference associated with labelling and surface immobilization.

Quantum Logic Spectroscopy with Ions in Thermal Motion

A mixed-species geometric phase gate has been proposed for implementing quantum logic spectroscopy on trapped ions, which combines probe and information transfer from the spectroscopy to the logic ion in a single pulse. We experimentally realize this method, show how it can be applied as a technique for identifying transitions in currently intractable atoms or molecules, demonstrate its reduced temperature sensitivity, and observe quantum-enhanced frequency sensitivity when it is applied to multi-ion chains. Potential applications include improved readout of trapped-ion clocks and simplified error syndrome measurements for quantum error correction.

Preparation of Engineered Extracellular Vesicles Derived from Human Umbilical Cord Mesenchymal Stem Cells with Ultrasonication for Skin Rejuvenation

Extracellular vesicles (EVs) are lipid-bilayer-enclosed vesicles of submicron size that are secreted by various cells. As mediators of intercellular communication, EVs can alter the physiological state of recipient cells by delivering encapsulated proteins and nucleic acids. Incontestably, growing evidence has shown important biological roles and the clinical relevance of EVs. The use of stem cell-derived EVs as a cell-free therapeutic modality for skin treatment has emerged as a promising application in dermatology. However, the moderate isolation efficiency of prevalent ultracentrifugation and low secretion rate make the massive low-cost production of EVs difficult. Here, we report development of engineered EVs (eEV) derived from human umbilical cord mesenchymal stem cells (hucMSCs) for skin treatment. Ultrasonication was used to shear intact hucMSCs for only 1 min, followed by regular centrifugation and filtration for producing nanoscale eEVs. This approach has ∼20-fold higher yield and ∼100-fold faster production than that of naturally secreted EVs (nsEV), while the production cost decreased to less than 10%. The eEVs have similar morphology, size distribution, and typical protein markers compared to nsEVs. Moreover, in vitro, both nsEVs and eEVs promote the proliferation and migration of dermal fibroblasts and increase in the expression of collagen, elastin, and fibronectin, whereas the matrix metalloproteinases-1 (MMP-1) and MMP-3 production can be significantly reduced. The wound-healing study in mice showed that both nsEVs and eEVs promote wound recovery in comparison with the controls. In sum, our results indicate that hucMSC-derived eEVs prepared by ultrasonication potentially can be used to increase skin extracellular matrix and enhance skin rejuvenation.

LncRNA SNHG8 participates in the development of endometrial carcinoma through regulating c-MET expression by miR-152

OBJECTIVE

To investigate the possible function and mechanism of lncRNA SNHG8 in the pathogenesis of endometrial carcinoma.

PATIENTS AND METHODS

We utilized qRT-PCR to detect the expression of SNHG8 in 60 cases of endometrial carcinoma and 25 cases of normal endometrium; after that, the endometrial carcinoma cell lines were screened. SNHG8 was transfected into endometrial carcinoma cells by Lipofectamine and the proliferative activity of cells was detected by cell counting kit-8 (CCK-8) assay. Bioinformatics methods were used to detect the target microRNA. miR-152 is predicted to bind to SNHG8 and target genes of c-MET. Luciferase reporter assay was performed to detect the relative luciferase activity between miR-152 and c-MET, SNHG8. The interactions between SNHG8, miR-152, and c-MET were further verified by transfection of miR-152 mimics, miR-152 mimics + OE-SNHG8, SNHG8 siRNA, and SNHG8 siRNA + miR-152 inhibitor.

RESULTS

SNHG8 expression in endometrial carcinoma tissue was significantly higher than that in normal endometrium. After transfection with SNHG8 siRNA, the cell viability of AN3CA cells decreased, whereas the activity of Ishikawa was increased after transfection with SNHG8 overexpression plasmid. Bioinformatics predictions and dual luciferase reporter assay illustrated that SNHG8 was bound to miR-152 and miR-152 targeted on c-MET. In addition, miR-152 mimics inhibited the expression of c-MET, and the inhibitory effect was reversed after SNHG8 overexpression. Silencing SNHG8 reduced c-MET expression, and c-MET expression was reversed after addition of miR-152 inhibitor.

CONCLUSIONS

SNHG8 is highly expressed in endometrial carcinoma, and SNHG8 targets c-MET through miR-152 to regulate the proliferation of endometrial cancer cells.

Synchronous multiple lung cancers presenting as multifocal pure ground glass nodules: are whole-body positron emission tomography/computed tomography and brain enhanced magnetic resonance imaging necessary?

Background

Multifocal ground glass nodules (GGNs) represent a special radiological pattern indicative of synchronous multiple lung cancers (SMLCs), especially adenocarcinoma. However, the necessity of performing whole-body positron emission tomography/computed tomography (PET-CT) scanning and brain enhanced magnetic resonance imaging (MRI) as a staging workup for multifocal pure GGN (pGGN) patients remains unclear. The purpose of this study was to determine the utility of these two imaging scans for patients with multifocal pGGNs.

Methods

This retrospective study was reviewed and approved by the ethics committee of the Cancer Hospital of the Chinese Academy of Medical Sciences. The study cohort was retrospectively selected from patients with multifocal pGGNs who underwent whole-body PET-CT examinations and/or brain enhanced MRIs between January 2010 and February 2019 at our institution. The additional value of the two exams for detecting nodal and distant metastases was evaluated.

Results

In total, 73 patients (male-to-female ratio, 20:53; median age, 57 years) with multifocal pGGNs who underwent whole-body PET-CT (55 patients) and/or brain enhanced MRI (25 patients) were enrolled. No clearly metastatic lesions were detected. Among the enrolled patients, 53 (128 pGGNs) underwent complete surgical resection. All pGGNs were adenocarcinomas and/or preneoplasias, and no lymph node metastases were found on final pathology. Whole-body PET-CT and brain enhanced MRI added no definite benefit compared with chest CT alone before surgery.

Conclusions

Whole-body PET-CT scans and brain enhanced MRIs are not necessary for patients with multifocal pGGNs.

Long-term Cardiovascular Outcomes Among Endometrial Cancer Survivors in a Large, Population-Based Cohort Study

Background

Endometrial cancer is the second most common cancer among female cancer survivors in the United States. Cardiovascular disease is the leading cause of death among endometrial cancer survivors. Studies that examine long-term cardiovascular outcomes among endometrial cancer survivors are critical.

Methods

Cohorts of 2648 endometrial cancer survivors diagnosed between 1997 and 2012 and 10 503 age-matched women from the general population were identified. Cardiovascular disease diagnoses were identified from electronic medical records and statewide ambulatory surgery and statewide inpatient data. Cox regression models were used to estimate hazard ratios (HRs) at one to five years, more than five to 10 years, and more than 10 years after cancer diagnosis.

Results

Between one and five years after diagnosis, increased cardiovascular risks among endometrial cancer survivors were observed for phlebitis, thrombophlebitis, and thromboembolism (HR = 2.07, 99% confidence interval [CI] = 1.57 to 2.72), pulmonary heart disease (HR = 1.74, 99% CI = 1.26 to 2.40), and atrial fibrillation (HR = 1.50, 99% CI = 1.07 to 2.11). At more than five to 10 years, some elevated risk persisted for cardiovascular diseases. Compared with patients who had surgery, patients who additionally had radiation therapy and/or chemotherapy were at increased risk for heart and circulatory system disorders between one and five years after cancer diagnosis. Older age and obesity were also risk factors for hypertension and heart disease among endometrial cancer survivors.

Conclusions

Endometrial cancer survivors are at higher risk for various adverse long-term cardiovascular outcomes compared with women from the general population. This study suggests that increased monitoring for cardiovascular diseases may be necessary for endometrial cancer patients for 10 years after cancer diagnosis.

Recyclable coherent random lasers assisted by plasmonic nanoparticles in DCM-PVA thin films

Recyclable coherent random lasers assisted by plasmonic nanoparticles in DCM-PVA thin films are studied. Four DCM-PVA films with different nanoparticles are made, and the radiation characteristics of these random lasers are studied. The results show that the emission spectrum of the DCM-PVA film with Au nanoparticle of 50 nm in diameter is optimal, and its threshold is about 6.53 µJ/pulse. Underlying mechanisms are discussed in detail. Then the DCM-PVA film with Au nanoparticles of 50 nm in diameter is detached from a glass substrate and adhered to different substrates. Coherent random lasers also occur when the sample is based on different substrates. Finally, a method of making samples recyclable is proposed, and the emission spectrum of samples as a function of cycle index is studied. The results show that recyclable coherent random lasers can be realized with this method. This study provides a new way, to the best of our knowledge, to realize recyclable coherent random lasers with low-threshold.

Long-Term Functional Stability of Functional Nucleic Acid-Gold Nanoparticle Conjugates with Different Secondary Structures

Thiolated functional nucleic acid-gold nanoparticle conjugates (FNA-AuNPs) are the core recognition elements in biosensors. The long-term functional stability (LTFS) is critical for their practical applications and, however, has been overlooked. Here we report on the huge effects of multiple experimental factors on LTFS, including spacer- and buffer-composition, secondary structures of FNAs, and surface blocking. We quantitatively determined these effects by measuring the relative hybridization capacity (RHC, the relative amount of complementary DNA hybridized with the same amount of conjugates) for linear DNA-AuNP or the relative signal change generated by their function (RSC-F) for molecular beacon (MB) and G-quadruplex (G4)-AuNPs. There is a positive relationship between the spacer affinity [oligoadenine (A₁₀) > oligothymine (T₁₀) > oligoethlyene glycol (EG₁₈)] of the linear DNA probes and the LTFS. The LTFS of linear DNA-AuNP in phosphate buffer (PB) was much better than that in Good's buffers such as HEPES, Tris, and MES. The secondary structure of FNAs also strongly impacted the LTFS, showing the substantially decreased LTFS from G4- to linear DNA- to MB-AuNPs, where EG₁₈ spacer was used for all these conjugates. The surface blocking of FNA-AuNPs greatly improved the LTFS. We experimentally determined that the LTFS of FNA-AuNPs was directly related to the dissociation of DNAs caused by the in situ generated H₂O₂ due to the oxidase activity of AuNP and thereby oxidation of Au-thiol bonds. The oxidase activity of AuNP was favored at high temperature, low pH, high AuNP concentration, high Good's buffer concentration, and high salt concentration, corresponding well with the positive effects of high affinity spacer, PB, and surface blocking on the LTFS of FNA-AuNPs. Our study has implications on both fundamental surface science and practical applications.

Primary colorectal lymphoma: computed tomography and double-contrast barium enema examination findings with histopathological correlation in 19 patients

Background

Primary colorectal lymphoma (PCL) is a rare disorder, the accurate imaging diagnosis of which remains a clinical challenge. This study aimed to characterize the imaging features of PCL by double-contrast barium enema (DCBE) examination and computed tomography (CT) and correlate them with histopathological findings.

Methods

DCBE (n=6) and CT (n=19) findings for 19 pathologically proven PCLs were evaluated and compared with histopathological findings in this retrospective analysis.

Results

Non-Hodgkin lymphoma was present in all patients, and the most common histological type was diffuse large B-cell lymphoma (63.2%, 12/19). The most common site was the ileocecum (84.2%, 16/19). CT revealed circumferential infiltrative lesions (68.4%, 13/19), polypoid masses (26.3%, 5/19) and ulcerative lesions (5.3%, 1/19). Most (94.7%, 18/19) lesions appeared as moderate enhancements. Fourteen (73.7%, 14/19) patients had serous membrane infiltration presenting as a poorly defined serous membrane and focal opacities in the pericolonic fat. Regional lymph node involvement was observed in twelve (63.2%, 12/19) patients who presented with aggregated nodules or masses. Frequent findings of the DCBE exam included a filling defect and niche with slight mucosal destruction, mild luminal narrowing and preserved peristalsis. The imaging appearance reflected the gross pathological findings well, although the preoperative diagnostic accuracy was low.

Conclusions

The imaging features of PCL have a relatively characteristic appearance but are still, at times, hardly differentiated from carcinoma. Familiarity with the radiological features of PCL on DCBE and CT can help ensure a correct diagnosis.

ZNF424 Induces Apoptosis and Inhibits Proliferation in Lung Carcinoma Cells

Background:

Previously, we showed that the Zinc finger-containing transcription factor ZNF424 inhibits p21 transcription, which has been widely associated with various cancers. However, because the roles of ZNF424 in tumorigenesis have not been characterized, we correlated ZNF424 expression with tumorigenesis in lung cancer.

Results:

The present immunohistochemical analyses show significantly lower ZNF424 expression levels in 43 of 60 lung cancer tissues compared with adjacent tissues. Moreover, flow cytometry assays indicated that overexpression of ZNF424 induces apoptosis in A549 human lung carcinoma cells, and overexpression of ZNF424 significantly increases numbers of G1 phase cells and decreases numbers of S phase cells, suggesting that ZNF424 inhibits proliferation. Western Blot analyses show that overexpression of ZNF424 decreases protein expression levels of the mitogen-activated protein kinase (MAPK) signaling proteins P-P38 and P-ERK in A549 cells.

Conclusion:

These are the first data to associate ZNF424 with tumorigenesis and demonstrate an inhibitory role in lung cancer, indicating the potential of ZNF424 expression as a diagnostic marker of lung tumorigenesis.

[Clinical and molecular characteristics of GATA2 related pediatric primary myelodysplastic syndrome]

Objective: To clarify the prevalence, clinical features and molecular characteristics of germline GATA2 mutations in pediatric primary myelodysplastic syndromes (MDS) . Methods: Next-generation sequencing technology was used to detect mutations in GATA2 and other myeloid malignancy genes in 129 children with primary MDS from Jan. 2007 to Jan. 2018. The relationship between genotypes and phenotypes was analyzed. Results: Germline GATA2 mutations accounted for 8.5% (11/129) of all primary MDS cases, and 14.0% (11/50) of MDS with excess blasts (MDS-EB) and acute myeloid leukaemia with myelodysplasia-related changes (AML-MRC) . Compared with GATA2 wild-type patients, GATA2 mutated patients were older at diagnosis[8 (1-16) years old vs 6 years old (range: 1 month old-18 years old) , P=0.035]and higher risk of monosomy 7 (72.7%vs 5.2%, P<0.001) and classified into MDS-EB and AML-MRC compared with refractory cytopenia of childhood (RCC) (63.6%vs 36.4%, P=0.111) . The multivariate analysis showed SETBP1 mutation (P=0.041, OR=9.003, 95%CI 1.098-73.787) and isolated monosomy 7 (P=0.002, OR=24.835, 95%CI 3.305-186.620) were significantly associated with germline mutated GATA2. Overall survival (OS) and outcomes of hematopoietic stem cell transplantation (HSCT) were not influenced by GATA2 mutational status. Conclusions: Our data identify germline GATA2 mutations have a high prevalence in older pediatric patients with monosomy 7, and high risk of progression into advanced MDS subtypes. GATA2 mutation status does not affect OS in pediatric primary MDS.

Family History Associates With Increased Risk of Colorectal Cancer in Patients With Inflammatory Bowel Diseases

BACKGROUND & AIMS

Individuals with inflammatory bowel diseases (IBDs) have an increased risk of developing colorectal cancer (CRC). Although family history of CRC is a well-established risk factor in healthy individuals, its role in patients with IBD is less clear. We aimed to estimate the risk of CRC in a cohort of patients with IBD from Utah and the significance of family history of CRC in a first-degree relative (FDR).

METHODS

We identified Utah residents with IBD, using the Intermountain Healthcare and University of Utah Health Sciences databases, from January 1, 1996, through December 31, 2011. CRCs were identified using the Utah Cancer Registry and linked to pedigrees from the Utah Population Database. CRC incidence was compared with that of the state population by standardized incidence ratios (SIRs).

RESULTS

A cohort of 9505 individuals with IBD was identified and 101 developed CRC during the study period. The SIR for CRC in patients with Crohn's disease was 3.4 (95% CI, 2.3-4.4), and in patients with ulcerative colitis was 5.2 (95% CI, 3.9-6.6). Patients with IBD and a concurrent diagnosis of primary sclerosing cholangitis had the greatest risk of CRC (SIR, 14.8; 95% CI, 8.3-21.2). A history of CRC in a FDR was associated with a nearly 8-fold increase in risk of CRC in patients with IBD (SIR, 7.9; 95% CI, 1.6-14.3), compared with the state population.

CONCLUSIONS

Patients with IBD have a 3- to 5-fold increase in risk of CRC, and those with CRC in a FDR have an almost 8-fold increase in risk. Family history may act as a simple measure to identify individuals with IBD at highest risk for CRC and indicates the need for enhanced surveillance in this population.

Enrichment of extracellular vesicles with lipid nanoprobe functionalized nanostructured silica

Nanoscale extracellular vesicles (nEVs) have recently demonstrated potential value in cancer diagnostics and treatment monitoring, but translation has been limited by technical challenges in nEV isolation. Thus, we have developed a one-step nEV isolation platform that utilizes nEV size-matched silica nanostructures and a surface-conjugated lipid nanoprobe with an integrated microfluidic mixer. The reported platform has 28.8% capture efficiency from pancreatic cancer plasma and can sufficiently enrich nEVs for simpler positive identification of point mutations, particularly KRAS, in nEV DNA from the plasma of pancreatic cancer patients.

Abstract 2437: Microfluidic device integrated with lipid nanoprobe for extracellular vesicle isolation toward non-invasive cancer diagnosis

Extracellular vesicles (EVs) can mediate intercellular communication by transferring cargo proteins and nucleic acids between cells. Recently, they have been demonstrated for potential value in cancer diagnostics and treatment monitoring. However, relevant clinical translation is mainly limited by technical challenges in EV isolation. We previously reported lipid nanoprobes, which is a nanomaterial system of labeling probe and capture probe. The labeling probe is constructed with a lipid molecule as the active component to label EVs rapidly and spontaneously with high efficiency, while the capture probe can isolate labeled EVs magnetically. Herein, we report on the development of a microfluidic device with integrated lipid nanoprobe for on-chip EV isolation towards instrument development for clinical translation. The nanostructured substrate of the device is integrated with a micromixer for one-step isolation of EVs from 1-ml plasma. We validated the device with plasma collected from pancreatic cancer patients, followed by DNA mutation detection of EV cargo. Size-tunable nanostructures are fabricated by patterning high-resolution iron thin films on fused silica substrates. By judicious thermal annealing, homogeneously dispersed iron nanoparticles are formed by fission and fusion on the substrate, which are served as a mask for silica dry-etching. Subsequently, selected lipid nanoprobes, which can instantaneously insert into lipid bilayers of EVs, are grafted onto the nanostructured substrate in a micromixer. This platform is verified first to isolate cultured cancer cell-derived EVs spiked-in plasma samples that emulated clinical samples. This platform is further applied to isolate EVs from pancreatic cancer patients’ plasma and identified KRASmutations in EV DNA with highly sensitive droplet digital PCR. Together, this platform enables rapid and efficient isolation of EVs from plasma specimens, and thus, holds great potential in clinical translation.

Citation Format: Siyang Zheng, Yuan Wan, Mackenzie Maurer, Yi-Qiu Xia, Si-Jie Hao, Wen-Long Zhang, Nelson S. Yee. Microfluidic device integrated with lipid nanoprobe for extracellular vesicle isolation toward non-invasive cancer diagnosis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2437.