optimization-flow-cytometric-sorting-parameters-for-high-throughput

Optimization of Flow Cytometric Sorting Parameters for High-Throughput Isolation and Purification of Small Extracellular Vesicles

Small extracellular vesicles (sEV) can be released from all cell types and carry protein, DNA, and RNA. Signaling molecules serve as indicators of the ...

Zhejiang University School of Medicine

To construct the expression vector pLCK-CD69-IRES-EGFP that contains mouse cell surface activation protein CD69 and enhanced green fluorescent protein(EGFP),and to generate CD69 transgenic mice based on this vector.

[Construction of expression vector pLCK-CD69-IRES-EGFP and generation of CD69 transgenic mice].

To investigate the differentiation potential of purified CD90 cells sorted from adipose-derived stem cells (ADSCs), CD90 cells were sorted from rabbit ADSCs using flow cytometry. Then, cell expansion of CD90 cells and unsorted ADSCs was observed using an inverted microscope. Furthermore, cell surface markers including CD40, CD105, and CD90 on CD90 cells and unsorted ADSCs were quantified using flow cytometry. Additionally, multi-lineage differentiation ability between CD90 cells and unsorted ADSCs was compared, and expression of adipocyte-related genes PPAR-r and CEBPA as well as stem cell-related gene SOX2 in CD90 cells and unsorted ADSCs was determined using real-time quantitative PCR. We found that CD90 cells had a stronger cell proliferation ability than unsorted ADSCs. CD90 cells showed a stronger ability of osteoblast and chondrocyte differentiation than unsorted ADSCs and CD90 cells, whereas the adipose differentiation ability of CD90 cells was similar to that of ADSCs and CD90 cells. CD14, CD105, and CD90 on CD90 cells were expressed more highly than those on ADSCs. Additionally, the mRNA expression level of SOX2 in CD90 cells was significantly higher than that in ADSCs, whereas the expression of PPAR-r and CEBPA was markedly lower than that in ADSCs. These results suggested that the purified CD90 cells sorted from ADSCs exhibit a stronger differentiation potential than the unsorted ADSCs.

Differentiation potential of rabbit CD90-positive cells sorted from adipose-derived stem cells in vitro.

Replication protein A (RPA) is a multifunctional, single-stranded DNA-binding protein complex and plays a critical role in DNA replication and damage response. Herein, we show that the 70-kDa subunit of RPA (RPA1) is acetylated on lysine 163 by the acetyltransferases GCN5 and PCAF and that such acetylation is reversed principally via the action of the deacetylase HDAC6. UV irradiation promotes cytoplasmic translocation of HDAC6, thereby disrupting the interaction of HDAC6 with RPA1 and increasing RPA1 acetylation. Mutation of the acetylation site of RPA1 specifically impairs the ability of the protein to interact with the key nucleotide excision repair (NER) protein XPA, reduces XPA retention at sites of DNA damage caused by UV, compromises NER, and renders the cell hypersensitive to UV irradiation. Our data suggest that the acetylation status of RPA1 played a crucial role in repair of DNA damage via NER.

UV-Induced RPA1 Acetylation Promotes Nucleotide Excision Repair.

The XPF-ERCC1 heterodimer is a structure-specific endonuclease that is essential for nucleotide excision repair (NER) and interstrand crosslink (ICL) repair in mammalian cells. However, whether and how XPF binding to ERCC1 is regulated has not yet been established. Here, we show that TIP60, also known as KAT5, a haplo-insufficient tumor suppressor, directly acetylates XPF at Lys911 following UV irradiation or treatment with mitomycin C and that this acetylation is required for XPF-ERCC1 complex assembly and subsequent activation. Mechanistically, acetylation of XPF at Lys911 disrupts the Glu907-Lys911 salt bridge, thereby leading to exposure of a previously unidentified second binding site for ERCC1. Accordingly, loss of XPF acetylation impairs the damage-induced XPF-ERCC1 interaction, resulting in defects in both NER and ICL repair. Our results not only reveal a mechanism that regulates XPF-ERCC1 complex assembly and activation, but also provide important insight into the role of TIP60 in the maintenance of genome stability.

Acetylation of XPF by TIP60 facilitates XPF-ERCC1 complex assembly and activation.

Due to the broad-spectrum antibiotic usage and empirical treatments, the pathogenic bacterium, , has shown extremely high detection rates at hospitals with an increasing antibiotic resistance. Therefore, rapid detection of the antibiotic resistance is urgently required and essential for effective treatments. In this study, we evaluated the performance of a newly developed method for ultra-rapid detection of antibiotic resistance in 30-60 min in  by using the SYBR Green I and propidium iodide (PI) staining. A total of 100 clinical isolates were tested for antibiotic resistance using four different antibiotics (ceftriaxone, cefepime, meropenem, and ciprofloxacin). The results showed that the SYBR Green I/PI rapid antibiotic susceptibility test (AST) could reliably detect antibiotic resistance to the four drugs in 60 min, and the results were highly concordant with the conventional AST (i.e., Kirby-Bauer method and broth microdilution method) for detection of ceftriaxone, cefepime, meropenem, and ciprofloxacin resistance with a high accuracy of 99, 96, 96, and 93%, respectively. Therefore, the rapid AST established in our study helps to enable targeted therapy to save lives and reduce the empirical use of antibiotics and ultimately the health and economic burdens of antibiotic resistance.

Rapid Determination of Antibiotic Resistance in  by a Novel Antibiotic Susceptibility Testing Method Using SYBR Green I and Propidium Iodide Double Staining.

Flow cytometric sorting is a vital tool in biological research and clinical diagnostics. Theoretically, a high-speed jet-in-air sorter is a fluorescent-activated cell sorting sorter that ideally processes cells with high purity, yield, and viability. However, high-speed jet-in-air sorting is a complex process due to its inherent requirements for high fluidic stability and electronic and timing precision. Here, we report that an additional manual correction of drop delay leads to improved cell yield. Adding 2% FBS to the loading buffer had no significant effect on the fate of sorted cells in 4 h. However, the addition of a suitable concentration of FBS/BSA in the collecting buffer resulted in a notable increase in cell count and proliferation and a significant decrease in cell apoptosis for cell lines and primary cells. Moreover, the level of gene expression remained steady in the 5% FBS collecting buffer. In summary, here we demonstrate techniques that can be easily followed to refine sorted yields of healthy cells.

Improved strategy for jet-in-air cell sorting with high purity, yield, viability, and genome stability.

Adipose tissue-derived stromal cells are promising candidates investigating the stem cell-related treatment. However, their proportion and utility in the human body decline with time, rendering stem cells incompetent to complete repair processes . The involvement of circRNAs in the aging process is poorly understood. Rat subcutaneous adipose tissue from 10-week-old and 27-month-old rats were used for hematoxylin and eosin (H and E) staining, TUNEL staining, and circRNA sequencing. Rat adipose tissue-derived stromal cells were cultured and overexpressed with circ-ATXN2. Proliferation was examined using xCELLigence real-time cell analysis, EdU staining, and cell cycle assay. Apoptosis was induced by CoCl2 and examined using flow cytometry. RT-PCR assay and Oil Red O staining were used to measure adipogenesis at 48 h and 14 days, respectively. H and E staining showed that the diameter of adipocytes increased; however, the number of cells decreased in old rats. TUNEL staining showed that the proportion of apoptotic cells was increased in old rats. A total of 4,860 and 4,952 circRNAs was detected in young and old rats, respectively. Among them, 67 circRNAs exhibited divergent expression between the two groups (fold change ≥2,  ≤ 0.05), of which 33 were upregulated (49.3%) and 34 were downregulated (50.7%). The proliferation of circ-ATXN2-overexpressing cells decreased significantly , which was further validated by xCELLigence real-time cell analysis, EdU staining, and cell cycle assay. Overexpression of circ-ATXN2 significantly increased the total apoptotic rate from 5.78 ± 0.46% to 11.97 ± 1.61%, early apoptotic rate from 1.76 ± 0.22% to 5.50 ± 0.66%, and late apoptosis rate from 4.02 ± 0.25% to 6.47 ± 1.06% in adipose tissue-derived stromal cells. Furthermore, in circ-ATXN2-overexpressing cells, RT-PCR assay revealed that the expression levels of adipose differentiation-related genes  and  were increased and the Oil Red O staining assay showed more lipid droplets. Our study revealed the expression profile of circRNAs in the adipose tissue of old rats. We found a novel age-related circular RNA-circ-ATXN2-that inhibits proliferation and promotes cell death and adipogenesis in rat adipose tissue-derived stromal cells.

A Novel Age-Related Circular RNA Circ-ATXN2 Inhibits Proliferation, Promotes Cell Death and Adipogenesis in Rat Adipose Tissue-Derived Stromal Cells.

CCR7, collaborated with its ligands CCL19 and CCL21, controls extensive migratory events in the immune system. CCR7-bearing dendritic cells can swarm into T-cell zones in lymph nodes, initiating the antigen presentation and T-cell response. Abnormal expression of CCR7 in dendritic cells will cause a series of inflammatory diseases due to the chaotic dendritic cell trafficking. In this review, we take an in-depth look at the structural-functional domains of CCR7 and CCR7-bearing dendritic cell trajectory to lymph nodes. Then, we summarize the regulatory network of CCR7, including transcriptional regulation, translational and posttranslational regulation, internalization, desensitization, and recycling. Furthermore, the potential strategies of targeting the CCR7 network to regulate dendritic cell migration and to deal with inflammatory diseases are integrated, which not only emphasizes the possibility of CCR7 to be a potential target of immunotherapy but also has an implication on the homing of dendritic cells to benefit inflammatory diseases.

New Insights of CCR7 Signaling in Dendritic Cell Migration and Inflammatory Diseases.

Acetaminophen (APAP) hepatotoxicity is an important cause of acute liver failure, resulting in massive deaths in many developed countries. Currently, the metabolic process of APAP in the body has been well studied. However, the underlying mechanism of APAP-induced liver injury remains elusive. Increasing clinical and experimental evidences indicate that the innate immune responses are involved in the pathogenesis of APAP-induced acute liver injury (AILI), in which immune cells have dual roles of inducing inflammation to exacerbate hepatotoxicity and removing dead cells and debris to help liver regeneration. In this review, we summarize the latest findings of innate immune cells involved in AILI, particularly emphasizing the activation of innate immune cells and their different roles during the injury and repair phases. Moreover, current available treatments are discussed according to the different roles of innate immune cells in the development of AILI. This review aims to update the knowledge about innate immune responses in the pathogenesis of AILI, and provide potential therapeutic interventions for AILI.

Targeting innate immune responses to attenuate acetaminophen-induced hepatotoxicity.

The M2 polarized macrophages modulation has been described as a beneficial approach to facilitate the myelin repairing and inflammation microenvironment remodeling of multiple sclerosis (MS). Whereas, the M2 polarization involves complex mechanisms, and the modulators are still limited. As a protein kinase B (Akt) inhibitor, compound 2 was found promoting M2 polarization activity in our previous research, here we report the identification of a new modulator B9 with high M2-marker Arg1 upregulation activity, M1 polarization inhibition and ablated Akt1 inhibition activities. B9 has promising pharmacokinetic profiles, and significantly ameliorates the symptom and reduces demyelination in EAE mice. Moreover, the inflammation microenvironment is remodeled after B9 administration, with promoted M2-type macrophages and inhibited M1 polarization in the CNS and periphery, and suppressed the proinflammatory Th1 and Th17 cells responses. Therefore, the new macrophage M2 polarization modulator B9 could present a candidate for fulfilling the therapeutic strategies of MS.

Discovery of new macrophage M2 polarization modulators as multiple sclerosis treatment agents that enable the inflammation microenvironment remodeling.

Chronic liver disease (CLD) is an extremely common clinical condition accompanied by sustained inflammatory response leading to tissue damage. Transforming growth factor-β1 (TGF-β1) is known as a master immune regulator in CLDs, but the association between TGF-β1 polymorphisms and CLD risk is controversial and inconclusive, and the genetic dominance of CLDs remains unknown. In this study, the relationship between  polymorphisms and CLD susceptibility is systematically analyzed based on 35 eligible studies. Individuals with the -509 allele (TT or CT) or codon 10 allele (Pro/Pro) show an increased risk of CLDs. Subgroup analyses indicate -509C/T has a significant correlation with cirrhosis and chronic hepatitis C, codon 10 is associated with chronic hepatitis B occurrence, and codon 25 exhibits a relationship with autoimmune hepatitis risk. Missense mutations in G29E, A105S, D191N, and F321L of  are the genetic factors of HCC susceptibility. Furthermore, the  gene expression is significantly elevated in CLD patients, and the  codon 263 is located close to the region where the TGF-β1 dimerization interacts, indicating the  codon 263 variant may affect the secretion of TGF-β1 by altering its dimerization. Together, our findings provide new insights into the immune regulator gene  polymorphisms as susceptibility factors for CLD occurrence and regulators for TGF-β1 expression, which have implications for the regulation of immune factors during CLD development.

Jiajia Wang

Core Facilities

Zhejiang University School of Medicine

Optimization of Flow Cytometric Sorting Parameters for High-Throughput Isolation and Purification of Small Extracellular Vesicles

Jiajia Wang

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Zhejiang University School of Medicine

Optimization of Flow Cytometric Sorting Parameters for High-Throughput Isolation and Purification of Small Extracellular Vesicles

Core Facilities