Low-frequency somatic copy number alterations in normal human lymphocytes revealed by large-scale single-cell whole-genome profiling.

Genomic-scale somatic copy number alterations in healthy humans are difficult to investigate because of low occurrence rates and the structural variations' stochastic natures. Using a Tn5-transposase-assisted single-cell whole-genome sequencing method, we sequenced over 20,000 single lymphocytes from 16 individuals. Then, with the scale increased to a few thousand single cells per individual, we found that about 7.5% of the cells had large-size copy number alterations. Trisomy 21 was the most prevalent aneuploid event among all autosomal copy number alterations, whereas monosomy X occurred most frequently in over-30-yr-old females. In the monosomy X single cells from individuals with phased genomes and identified X-inactivation ratios in bulk, the inactive X Chromosomes were lost more often than the active ones.

Associations of BRAFV600E mutation with the American College of Radiology Thyroid Imaging Reporting and Data System and clinicopathological characteristics in pediatric patients with papillary thyroid carcinoma.

BACKGROUND: Identifying the associations between BRAFV600E mutation, the American College of Radiology Thyroid Imaging Reporting and Data System (TI-RADS) and clinicopathological characteristics could assist in making appropriate treatment strategies for pediatric patients with papillary thyroid carcinoma. OBJECTIVE: To retrospectively assess the associations between BRAFV600E mutation, TI-RADS, and clinicopathological characteristics in pediatric patients with papillary thyroid carcinoma. MATERIALS AND METHODS: Between May 2013 and May 2023, pediatric patients with papillary thyroid carcinoma who underwent thyroidectomy were retrospectively evaluated. Univariate and multivariate logistic regression analyses were performed to determine the associations between BRAFV600E mutation, TI-RADS, and clinicopathological characteristics. The diagnostic performance of TI-RADS to predict BRAFV600E mutation was assessed. RESULTS: The BRAFV600E mutation was found in 59.1% (39/66) of pediatric patients with papillary thyroid carcinoma. Multivariate analyses showed that hypoechoic/very hypoechoic [odds ratio (OR) = 8.48; 95% confidence interval (CI) = 1.48-48.74); P-value = 0.02] and punctate echogenic foci (OR = 24.3; 95% CI = 3.80-155.84; P-value = 0.001) were independent factors associated with BRAFV600E mutation. In addition, BRAFV600E mutation was significantly associated with TI-RADS 5 (OR = 12.61; 95% CI = 1.28-124.49; P-value = 0.03). There were no associations between BRAFV600E mutation and nodule size, composition, shape, margin, cervical lymph node metastasis, or Hashimoto's thyroiditis (P-value > 0.05). Combined with hypoechoic/very hypoechoic and punctate echogenic foci, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 89.7%, 85.2%, 89.7%, 85.2%, and 87.9%, respectively. CONCLUSIONS: Hypoechoic/very hypoechoic, punctate echogenic foci, and TI-RADS 5 are independently associated with BRAFV600E mutation in pediatric patients with papillary thyroid carcinoma.

RNA sequencing by direct tagmentation of RNA/DNA hybrids.

Transcriptome profiling by RNA sequencing (RNA-seq) has been widely used to characterize cellular status, but it relies on second-strand complementary DNA (cDNA) synthesis to generate initial material for library preparation. Here we use bacterial transposase Tn5, which has been increasingly used in various high-throughput DNA analyses, to construct RNA-seq libraries without second-strand synthesis. We show that Tn5 transposome can randomly bind RNA/DNA heteroduplexes and add sequencing adapters onto RNA directly after reverse transcription. This method, Sequencing HEteRo RNA-DNA-hYbrid (SHERRY), is versatile and scalable. SHERRY accepts a wide range of starting materials, from bulk RNA to single cells. SHERRY offers a greatly simplified protocol and produces results with higher reproducibility and GC uniformity compared with prevailing RNA-seq methods.

Interfacial Nanoinjection-Based Nanoliter Single-Cell Analysis.

Single-cell analysis offers unprecedented resolution for the investigation of cellular heterogeneity and the capture of rare cells from large populations. Here, described is a simple method named interfacial nanoinjection (INJ), which can miniaturize various single-cell assays to be performed in nanoliter water-in-oil droplets on standard microwell plates. The INJ droplet handler can adjust droplet volumes for multistep reactions on demand with high precision and excellent monodispersity, and consequently enables a wide range of single-cell assays. Importantly, INJ can be coupled with fluorescence-activated cell sorting (FACS), which is currently the most effective and accurate single-cell sorting and isolation method. FACS-INJ pipelines for high-throughput plate well-based single-cell analyses, including single-cell proliferation, drug-resistance testing, polymerase chain reaction (PCR), reverse-transcription PCR, and whole-genome sequencing are introduced. This FACS-INJ pipeline is compatible with a wide range of samples and can be extended to various single-cell analysis applications in microbiology, cell biology, and biomedical diagnostics.

Uniform and accurate single-cell sequencing based on emulsion whole-genome amplification.

Whole-genome amplification (WGA) for next-generation sequencing has seen wide applications in biology and medicine when characterization of the genome of a single cell is required. High uniformity and fidelity of WGA is needed to accurately determine genomic variations, such as copy number variations (CNVs) and single-nucleotide variations (SNVs). Prevailing WGA methods have been limited by fluctuation of the amplification yield along the genome, as well as false-positive and -negative errors for SNV identification. Here, we report emulsion WGA (eWGA) to overcome these problems. We divide single-cell genomic DNA into a large number (10(5)) of picoliter aqueous droplets in oil. Containing only a few DNA fragments, each droplet is led to reach saturation of DNA amplification before demulsification such that the differences in amplification gain among the fragments are minimized. We demonstrate the proof-of-principle of eWGA with multiple displacement amplification (MDA), a popular WGA method. This easy-to-operate approach enables simultaneous detection of CNVs and SNVs in an individual human cell, exhibiting significantly improved amplification evenness and accuracy.

Microfluidic single-cell whole-transcriptome sequencing.

Single-cell whole-transcriptome analysis is a powerful tool for quantifying gene expression heterogeneity in populations of cells. Many techniques have, thus, been recently developed to perform transcriptome sequencing (RNA-Seq) on individual cells. To probe subtle biological variation between samples with limiting amounts of RNA, more precise and sensitive methods are still required. We adapted a previously developed strategy for single-cell RNA-Seq that has shown promise for superior sensitivity and implemented the chemistry in a microfluidic platform for single-cell whole-transcriptome analysis. In this approach, single cells are captured and lysed in a microfluidic device, where mRNAs with poly(A) tails are reverse-transcribed into cDNA. Double-stranded cDNA is then collected and sequenced using a next generation sequencing platform. We prepared 94 libraries consisting of single mouse embryonic cells and technical replicates of extracted RNA and thoroughly characterized the performance of this technology. Microfluidic implementation increased mRNA detection sensitivity as well as improved measurement precision compared with tube-based protocols. With 0.2 M reads per cell, we were able to reconstruct a majority of the bulk transcriptome with 10 single cells. We also quantified variation between and within different types of mouse embryonic cells and found that enhanced measurement precision, detection sensitivity, and experimental throughput aided the distinction between biological variability and technical noise. With this work, we validated the advantages of an early approach to single-cell RNA-Seq and showed that the benefits of combining microfluidic technology with high-throughput sequencing will be valuable for large-scale efforts in single-cell transcriptome analysis.

Single Cell Total RNA Sequencing through Isothermal Amplification in Picoliter-Droplet Emulsion.

Prevalent single cell RNA amplification and sequencing chemistries mainly focus on polyadenylated RNAs in eukaryotic cells by using oligo(dT) primers for reverse transcription. We develop a new RNA amplification method, "easier-seq", to reverse transcribe and amplify the total RNAs, both with and without polyadenylate tails, from a single cell for transcriptome sequencing with high efficiency, reproducibility, and accuracy. By distributing the reverse transcribed cDNA molecules into 1.5 × 105 aqueous droplets in oil, the cDNAs are isothermally amplified using random primers in each of these 65-pL reactors separately. This new method greatly improves the ease of single-cell RNA sequencing by reducing the experimental steps. Meanwhile, with less chance to induce errors, this method can easily maintain the quality of single-cell sequencing. In addition, this polyadenylate-tail-independent method can be seamlessly applied to prokaryotic cell RNA sequencing.

Safety and efficacy of tirofiban treatment in the endovascular treatment of patients with acute ischaemic stroke - A meta-analysis.

OBJECT: The use of endovascular therapy (EVT) has become a widespread strategy for the clinical management of acute ischemic stroke (AIS). However, the combination of arterial injection of tirofiban with EVT for AIS continues to be a subject of controversy. This meta-analysis was conducted to assess the safety and efficacy of this treatment approach. METHODS: Relevant studies were identified through a systematic literature search in Pubmed, EMBASE, Web of Science, and Cochrane Library databases, covering articles published from January 2010 to January 2023. The efficacy outcomes included favorable functional outcomes, recanalization rates, and safety outcomes including mortality and symptomatic intracranial hemorrhage (sICH). RESULTS: The meta-analysis consisted of data from 13 studies, which included 1 randomized controlled trial (RCT), 7 prospective cohort studies, and 5 retrospective cohort studies, encompassing a total of 3477 patients. The study results indicate that the intra-arterial (IA) tirofiban+EVT for AIS is associated with significant improvements in favorable functional outcomes (OR, 1.21; 95%CI, 1.05-1.40; P = 0.009) and recanalization rate (OR, 1.33; 95%CI, 1.06-1.65; P = 0.01), as well as significant reductions in mortality rates (OR, 0.65; 95%CI, 0.53-0.79; P = 0.0001). Subgroup analysis revealed that administering a maintenance dose of intravenous (IV) tirofiban post-EVT was significantly associated with improved functional outcomes and reduced mortality in patients. In addition, there was no increase in the incidence of sICH (OR, 0.92; 95%CI, 0.71-1.20; P = 0.54). CONCLUSION: The administration of Intra-arterial tirofiban combined with EVT is an effective and safe treatment strategy for AIS, and postoperative maintenance doses of intravenous tirofiban may be more effective than IA only.

Contrast-enhanced ultrasound for differentiating benign from malignant focal solid renal lesions in pediatric patients.

The contrast-enhanced ultrasound (CEUS) has been mainly applied to adults to differentiate benign and malignant renal lesions, however, the characteristics of CEUS in pediatric has not been as well studied as in adults. In the present work, the eligible pediatric patients who underwent renal CEUS between March 2016 and February 2023 were retrospectively analyzed. It included 20 lesions (median diameter, 8.4 cm; range, 1.8-18.0 cm) from 20 patients (median age, 28.0 months; range, 3.0-212.0 months; 9 boys) in malignant group and 5 lesions (median diameter, 3.8 cm; range, 1.3-7.5 cm) from 5 patients (median age, 25.0 months; range, 0.7-216.0 months; 2 boys) in benign group. The diagnostic performance was assessed. Nonparametric and Chi-square tests were performed. With hyperenhancement plus wash-out, CEUS showed a sensitivity of 95.0% [95% confidence interval (CI): 75.1%, 99.9%], a specificity of 80.0% (CI: 28.4%, 99.5%), a positive predictive value of 95.0% (CI: 75.1%, 99.9%) and a negative predictive value of 80.0% (CI: 28.4%, 99.5%). It suggested that CEUS is a valuable technique for identifying between malignant and benign renal lesions in children.

Targeted sequencing for hereditary breast and ovarian cancer in BRCA1/2-negative families reveals complex genetic architecture and phenocopies.

Approximately 20% of breast cancer cases are attributed to increased family risk, yet variation in BRCA1/2 can only explain 20%-25% of cases. Historically, only single gene or single variant testing were common in at-risk family members, and further sequencing studies were rarely offered after negative results. In this study, we applied an efficient and inexpensive targeted sequencing approach to provide molecular diagnoses in 245 human samples representing 134 BRCA mutation-negative (BRCAX) hereditary breast and ovarian cancer (HBOC) families recruited from 1973 to 2019 by Dr. Henry Lynch. Sequencing identified 391 variants, which were functionally annotated and ranked based on their predicted clinical impact. Known pathogenic CHEK2 breast cancer variants were identified in five BRCAX families in this study. While BRCAX was an inclusion criterion for this study, we still identified a pathogenic BRCA2 variant (p.Met192ValfsTer13) in one family. A portion of BRCAX families could be explained by other hereditary cancer syndromes that increase HBOC risk: Li-Fraumeni syndrome (gene: TP53) and Lynch syndrome (gene: MSH6). Interestingly, many families carried additional variants of undetermined significance (VOUSs) that may further modify phenotypes of syndromic family members. Ten families carried more than one potential VOUS, suggesting the presence of complex multi-variant families. Overall, nine BRCAX HBOC families in our study may be explained by known likely pathogenic/pathogenic variants, and six families carried potential VOUSs, which require further functional testing. To address this, we developed a functional assay where we successfully re-classified one family's PMS2 VOUS as benign.

Aging atlas reveals cell-type-specific effects of pro-longevity strategies.

Organismal aging involves functional declines in both somatic and reproductive tissues. Multiple strategies have been discovered to extend lifespan across species. However, how age-related molecular changes differ among various tissues and how those lifespan-extending strategies slow tissue aging in distinct manners remain unclear. Here we generated the transcriptomic Cell Atlas of Worm Aging (CAWA, http://mengwanglab.org/atlas ) of wild-type and long-lived strains. We discovered cell-specific, age-related molecular and functional signatures across all somatic and germ cell types. We developed transcriptomic aging clocks for different tissues and quantitatively determined how three different pro-longevity strategies slow tissue aging distinctively. Furthermore, through genome-wide profiling of alternative polyadenylation (APA) events in different tissues, we discovered cell-type-specific APA changes during aging and revealed how these changes are differentially affected by the pro-longevity strategies. Together, this study offers fundamental molecular insights into both somatic and reproductive aging and provides a valuable resource for in-depth understanding of the diversity of pro-longevity mechanisms.

Aging Atlas Reveals Cell-Type-Specific Regulation of Pro-longevity Strategies.

Organism aging occurs at the multicellular level; however, how pro-longevity mechanisms slow down aging in different cell types remains unclear. We generated single-cell transcriptomic atlases across the lifespan of Caenorhabditis elegans under different pro-longevity conditions (http://mengwanglab.org/atlas). We found cell-specific, age-related changes across somatic and germ cell types and developed transcriptomic aging clocks for different tissues. These clocks enabled us to determine tissue-specific aging-slowing effects of different pro-longevity mechanisms, and identify major cell types sensitive to these regulations. Additionally, we provided a systemic view of alternative polyadenylation events in different cell types, as well as their cell-type-specific changes during aging and under different pro-longevity conditions. Together, this study provides molecular insights into how aging occurs in different cell types and how they respond to pro-longevity strategies.

Digital polymerase chain reaction in an array of femtoliter polydimethylsiloxane microreactors.

We developed a simple, compact microfluidic device to perform high dynamic-range digital polymerase chain reaction (dPCR) in an array of isolated 36-femtoliter microreactors. The density of the microreactors exceeded 20000/mm(2). This device, made from polydimethylsiloxane (PDMS), allows the samples to be loaded into all microreactors simultaneously. The microreactors are completely sealed through the deformation of a PDMS membrane. The small volume of the microreactors ensures a compact device with high reaction efficiency and low reagent and sample consumption. Future potential applications of this platform include multicolor dPCR and massively parallel dPCR for next generation sequencing library preparation.

High dynamic range optical projection tomography (HDR-OPT).

Traditional optical projection tomography (OPT) acquires a single image at each rotation angle, thereby suffering from limitations in CCD dynamic range; this conventional usage cannot resolve features in samples with highly heterogeneous absorption, such as in small animals with organs of varying size. We present a novel technique, applying multiple-exposure high dynamic range (HDR) imaging to OPT, and demonstrate its ability to resolve fine details in zebrafish embryos, without complicated chemical clearing. We implement the tomographic reconstruction algorithm on the GPU, yielding a performance increase of two orders of magnitude. These features give our method potential application in high-throughput, high-resolution in vivo 3D imaging.

Profiling mouse cochlear cell maturation using 10× Genomics single-cell transcriptomics.

Juvenile and mature mouse cochleae contain various low-abundant, vulnerable sensory epithelial cells embedded in the calcified temporal bone, making it challenging to profile the dynamic transcriptome changes of these cells during maturation at the single-cell level. Here we performed the 10x Genomics single-cell RNA sequencing (scRNA-seq) of mouse cochleae at postnatal days 14 (P14) and 28. We attained the transcriptomes of multiple cell types, including hair cells, supporting cells, spiral ganglia, stria fibrocytes, and immune cells. Our hair cell scRNA-seq datasets are consistent with published transcripts from bulk RNA-seq. We also mapped known deafness genes to corresponding cochlear cell types. Importantly, pseudotime trajectory analysis revealed that inner hair cell maturation peaks at P14 while outer hair cells continue development until P28. We further identified and confirmed a long non-coding RNA gene Miat to be expressed during maturation in cochlear hair cells and spiral ganglia neurons, and Pcp4 to be expressed during maturation in cochlear hair cells. Our transcriptomes of juvenile and mature mouse cochlear cells provide the sequel to those previously published at late embryonic and early postnatal ages and will be valuable resources to investigate cochlear maturation at the single-cell resolution.

High-throughput single-cell whole-genome amplification through centrifugal emulsification and eMDA.

Single-cell whole-genome sequencing (scWGS) is mainly used to probe intercellular genomic variations, focusing on the copy number variations or alterations and the single-nucleotide variations (SNVs) occurring within single cells. Single-cell whole-genome amplification (scWGA) needs to be applied before scWGS but is challenging due to the low copy number of DNA. Besides, many genomic variations are rare within a population of cells, so the throughput of currently available scWGA methods is far from satisfactory. Here, we integrate a one-step micro-capillary array (MiCA)-based centrifugal droplet generation technique with emulsion multiple displacement amplification (eMDA) and demonstrate a high-throughput scWGA method, MiCA-eMDA. MiCA-eMDA increases the single-run throughput of scWGA to a few dozen, and enables the assessment of copy number variations and alterations at 50-kb resolution. Downstream target enrichment further enables the detection of SNVs with 20% allele drop-out.

Tagmentation on Microbeads: Restore Long-Range DNA Sequence Information Using Next Generation Sequencing with Library Prepared by Surface-Immobilized Transposomes.

The next generation sequencing (NGS) technologies have been rapidly evolved and applied to various research fields, but they often suffer from losing long-range information due to short library size and read length. Here, we develop a simple, cost-efficient, and versatile NGS library preparation method, called tagmentation on microbeads (TOM). This method is capable of recovering long-range information through tagmentation mediated by microbead-immobilized transposomes. Using transposomes with DNA barcodes to identically label adjacent sequences during tagmentation, we can restore inter-read connection of each fragment from original DNA molecule by fragment-barcode linkage after sequencing. In our proof-of-principle experiment, more than 4.5% of the reads are linked with their adjacent reads, and the longest linkage is over 1112 bp. We demonstrate TOM with eight barcodes, but the number of barcodes can be scaled up by an ultrahigh complexity construction. We also show this method has low amplification bias and effectively fits the applications to identify copy number variations.

Single-Cell-Based Platform for Copy Number Variation Profiling through Digital Counting of Amplified Genomic DNA Fragments.

We develop a novel single-cell-based platform through digital counting of amplified genomic DNA fragments, named multifraction amplification (mfA), to detect the copy number variations (CNVs) in a single cell. Amplification is required to acquire genomic information from a single cell, while introducing unavoidable bias. Unlike prevalent methods that directly infer CNV profiles from the pattern of sequencing depth, our mfA platform denatures and separates the DNA molecules from a single cell into multiple fractions of a reaction mix before amplification. By examining the sequencing result of each fraction for a specific fragment and applying a segment-merge maximum likelihood algorithm to the calculation of copy number, we digitize the sequencing-depth-based CNV identification and thus provide a method that is less sensitive to the amplification bias. In this paper, we demonstrate a mfA platform through multiple displacement amplification (MDA) chemistry. When performing the mfA platform, the noise of MDA is reduced; therefore, the resolution of single-cell CNV identification can be improved to 100 kb. We can also determine the genomic region free of allelic drop-out with mfA platform, which is impossible for conventional single-cell amplification methods.

Spinning micropipette liquid emulsion generator for single cell whole genome amplification.

Many on-chip approaches that use flow-focusing to pinch the continuous aqueous phase into droplets have become the most popular methods that provide monodisperse emulsion droplets. However, not every lab can easily adapt a microfluidic workflow into their familiar protocols. We develop an off-chip approach, spinning micro-pipette liquid emulsion (SiMPLE) generator, to produce highly stable monodisperse water-in-oil emulsions using a moving micropipette to disperse the aqueous phase in an oil-filled microcentrifuge tube. This method provides a simple way to produce picoliter-size droplets in situ with no dead volume during emulsification. With SiMPLE, single-cell emulsion whole genome amplification was performed to demonstrate that this novel method can seamlessly be integrated with experimental operations and supplies that most researchers are familiar with. The SiMPLE generator has effectively lowered the technical difficulties in applications relying on emulsion droplets.