Strategies for Optimization of the Clustered Regularly Interspaced Short Palindromic Repeat-Based Genome Editing System for Enhanced Editing Specificity.

The clustered regularly interspaced short palindromic repeats (CRISPR) system is inarguably the most valuable gene editing tool ever discovered. Currently, three classes of CRISPR-based genome editing systems have been developed for gene editing, including CRISPR/CRISPR associate system (Cas) nucleases, base editors, and prime editors. Ever-evolving CRISPR technology plays an important role in medicine; however, the biggest obstacle to its use in clinical practice is the induction of off-target effects (OTEs) during targeted editing. Therefore, continuous improvement and optimization of the CRISPR system for reduction of OTEs is a major focus in the field of CRISPR research. This review aims to provide a comprehensive guide for optimization of the CRISPR-based genome editing system.

Efficient Editing of an Adenoviral Vector Genome with CRISPR/Cas9.

Immunotherapy based on genetic modification of T cells has played an important role in the treatment of tumors and viral infections. Moreover, adenoviral vectors engineered with improved safety due to their inability to integrate into the host genome have been key in the clinical application of T cell therapy. However, the commonly used adenoviral vector Ad5 exhibits low efficiency of infection of human T cells and the details of the intracellular trafficking pathway of adenoviral vectors in human primary T cells remains unclear. Resolution of these issues will depend on successful modification of the adenoviral vector. To this end, here we describe the successful establishment of a simple and efficient method for editing adenoviral vectors in vitro using the CRISPR-Cas9 gene editing system to target the adenoviral fiber gene.

Development of a Self-Restricting CRISPR-Cas9 System to Reduce Off-Target Effects.

Development of the CRISPR-Cas9 gene-editing system has given rise to a new era of gene editing with wide applications in biology, medicine, agriculture, and other fields. However, the overexpression of Cas9 nuclease causes off-target effects and may trigger an immune response in vivo. Therefore, we constructed a self-restricting CRISPR-Cas9 system, where the target gene sequence corresponding to the guide RNA (gRNA) is inserted on either end of the Cas9 promoter. When double-strand breaks (DSBs) are induced in the target gene sequence, the Cas9 promoter is cut off and transcription ceases. With this system, expression of Cas9 protein at 60 h after transfection is only 10% that of the wild-type system, with about 70% promoter deletion efficiency. The target site editing efficiency and homologous recombination efficiency of the self-restricting system remain at about 50% and 30%, respectively, while the frequency of off-target indel formation decreased by 76.7%. Further, the number of indel types was also reduced from 13 to 2. Because this system does not include additional gRNA sequences, the possibility of introducing new off-target mutations is decreased. Importantly, this system is composed of a single plasmid, which could potentially be easily introduced in vivo using a viral vector or nanoparticles.

[Effect of miRNA from Glycyrrhiza uralensis decoction on gene expression of human immune cells].

MicroRNAs(miRNA) are small non-coding RNAs that regulate the expression of protein coding genes by repressing translation of protein coding mRNA or enhancing mRNA degradation. Its functions have attracted more and more attention from the public. In recent years, the cross-border regulation of miRNA has become a new research direction, and provides a new perspective for people to comprehensively understand the functions of miRNA. Plant miRNA is usually methylated and not easy to degrade. According to our previous researches, there were abundant small RNAs in the decoction of dried liquorice, which provides a new way to study the mechanism of action of licorice. In this study, small RNAs extracted from Glycyrrhiza uralensis decoction and synthesized miRNA mimics were used to treat peripheral blood mononuclear cells(PBMC) isolated from healthy volunteers. The gene expression of toll-like receptors(TLRs), some transcription factors, signal molecules and cytokines were analyzed by RT-PCR. The results showed that glycyrrhiza miRNA could significantly regulate PBMC by inhibiting the expression of genes involved in T cell differentiation, inflammation and apoptosis. The study brought new ideas to us in comprehensively studying the mechanism of licorice and developing the traditional Chinese medicine.

Percutaneous transforaminal endoscopic surgery (PTES) for symptomatic lumbar disc herniation: a surgical technique, outcome, and complications in 209 consecutive cases.

BACKGROUND: We designed an easy posterolateral transforaminal endoscopic decompression technique, termed PTES, for radiculopathy secondary to lumbar disc herniation. The purpose of the study is to describe the technique of PTES and evaluate the efficacy and safety for treatment of lumbar disc herniation including primary herniation, reherniation, intracanal herniation, and extracanal herniation and to report outcome and complications. METHODS: PTES was performed to treat 209 cases of intracanal or extracanal herniations with or without extruding or sequestrated fragment, high iliac crest, scoliosis, calcification, or cauda equina syndrome including recurrent herniation after previous surgical intervention at the index level or adjacent disc herniation after decompression and fusion. Preoperative and postoperative leg pain was evaluated using the 10-point visual analog scale (VAS) and the results were determined to be excellent, good, fair, or poor according to the MacNab classification at 2-year follow-up. RESULTS: The patients were followed for an average of 26.3 ± 2.3 months. The VAS score of leg pain significantly dropped from 9 (6-10) before operation to 1 (0-3) (P < 0.001) immediately after the operation and to 0 (0-3) (P < 0.001) 2 years after operation. At 2-year follow-up, 95.7% (200/209) of the patients showed excellent or good outcomes, 2.9% (6/209) fair and 1.4% (3/209) poor. No patients had any form of permanent iatrogenic nerve damage and a major complication, although there were one case of infection and one case of recurrence. CONCLUSIONS: PTES for lumbar disc herniation is an effective and safe method with simple orientation, easy puncture, reduced steps, and little X-ray exposure, which can be applied in almost all kinds of lumbar disc herniation, including L5/S1 level with high iliac crest, herniation with scoliosis or calcification, recurrent herniation, and adjacent disc herniation after decompression and fusion. The learning curve is no longer steep for surgeons.

Influence of cell physiological state on gene delivery to T lymphocytes by chimeric adenovirus Ad5F35.

Adoptive transfer of genetically-modified T cells is a promising approach for treatment of both human malignancies and viral infections. Due to its ability to efficiently infect lymphocytes, the chimeric adenovirus Ad5F35 is potentially useful as an immunotherapeutic for the genetic modification of T cells. In previous studies, it was found that the infection efficiency of Ad5F35 was significantly increased without enhanced expression of the viral receptor after T cell stimulation; however, little is known about the underlying mechanism. Nonetheless, cell physiology has long been thought to affect viral infection. Therefore, we aimed to uncover the physiologic changes responsible for the increased infection efficiency of Ad5F35 following T cell stimulation. Given the complexity of intracellular transport we analyzed viral binding, entry, and escape using a Jurkat T cell model and found that both cell membrane fluidity and endosomal escape of Ad5F35 were altered under different physiological states. This, in turn, resulted in differences in the amount of virus entering cells and reaching the cytoplasm. These results provide additional insight into the molecular mechanisms underlying Ad5F35 infection of T cells and consequently, will help further the clinical application of genetically-modified T cells for immunotherapy.

[Extraction of miRNA from Glycyrrhiza uralensis Decoction and Its Effect on Immune Cells].

OBJECTIVE: To extract microRNA(miRNA) from Glycyrrhiza uralensis(liquorice) decoction and to explore its effect on mmune cells. METHODS: With dried processed liquorice, the water decoction was prepared according to the conventional method and subsequently concentrated by rotary evaporation. The concentrated decoction was further freeze-dried by freeze dryer, and miRNAs were extracted with Plant MicroRNA Extraction Kit. The extracted miRNA was digested by DNase I and then analyzed through the agarose gell electrophoresis. The PBMC was isolated from healthy volunteers and treated respectively by liquorice water extract, glycyrrhizic acid, glycyrrhetic acid and liquorice miRNAs. After 24 hours, the cells numbers were counted, and the changes of cell morphology were observed. The expression of CD3, CD56 and HLA-DR were analyzed by flow cytometry to identify the change of cell subsets in PBMC. RESULTS: miRNAs could be extracted from the decoction of dried liquorice which further confirmed the stability of miRNAs. The in vitro culture experiment showed that,compared with the controls, PBMC treated with liquorice miRNAs appeared apparent cell aggregation and increased cell number and HLA-DR+ cells proportion. CONCLUSION: The miRNAs are successfully extracted from the freeze-dried decoction of dried liquorice. It is indicated that liquorice miRNAs have significant stimulative effects on the growth of PBMC and HLA-DR+ cells subset.

Forced expression of indoleamine-2,3-dioxygenase in human umbilical cord-derived mesenchymal stem cells abolishes their anti-apoptotic effect on leukemia cell lines in vitro.

The ability of mesenchymal stem cells (MSCs) to preserve cancer cells potentially constitutes the adverse effect of MSC-based cell therapy in the context of hematologic malignancy. In an effort to reverse this undesirable feature of MSCs, we manipulated human umbilical cord-derived MSCs (UC-MSCs) to express indoleamine-2,3-dioxygenase (IDO), an enzyme that induces immune suppression by inhibiting T cell proliferation and triggering apoptosis in immune cells. Cultures of human UC-MSCs were generated by plastic adherence method. Full-length cDNA of human IDO was cloned into adenovirus shuttle vector. Then, the recombinant virus harboring IDO gene was produced in 293 cells and used to infect UC-MSCs. Expression of IDO protein was detected within infected UC-MSCs, and accumulation of kynurenine was observed in the supernatant. Two human leukemia cell lines, Jurkat and HL-60, were cultured on the monolayer of native or infected UC-MSCs, respectively. It was observed that forced IDO expression abolished the anti-apoptotic effect of UC-MSCs on these leukemia cells and enhanced their proliferation inhibitory effect on activated human lymphocytes as well as leukemia cells. These results suggested that equipping MSCs with IDO could be one of the reasonable strategies to reverse their cancer-supportive effect unfavorable for clinical applications.

Chimeric adenoviral vector Ad5F35L containing the Ad5 natural long-shaft exhibits efficient gene transfer into human T lymphocytes.

Adoptive therapy using T cells modified with tumour antigen-specific T cell receptor (TCR) genes has become a popular area of research in tumour biotherapy research. However, the efficiency of this treatment is low. To increase the efficiency of this therapy, the antigen specific TCR expression in the T cells needs to be improved. Adenoviral vector-mediated gene expression is an attractive approach to bypass the issue of TCR gene modification. The efficiency of adenovirus vector serotype 5 (Ad5) infection is low due to the absence of coxsackievirus B-adenovirus receptor (CAR) expression in T cells. In the present study, a chimeric adenoviral vector (Ad5F35L) was generated; this construct contained both the natural long-shaft of Ad5 and the Ad35 knob. A transduction study showed that the Ad5F35L vector exhibited a higher transduction efficiency in human primary T lymphocytes than the Ad5 vector and the Ad5F35S vector, which contained the Ad35 natural short-shaft and the Ad35 knob. Similar transduction efficiencies were observed for both CD4(+) T lymphocytes and CD8(+) T lymphocytes and the transfection was independent of the expression of cell surface receptors. The activation of T lymphocytes resulted in an improvement of the Ad5F35L transduction efficiency in CD4(+) T cells and a decrease in Ad5F35L transduction efficiency in CD8(+) T cells. The results demonstrate that Ad5F35L is a promising viral vector and will facilitate the clinical application of tumour antigen-specific TCR gene therapy.

Identification of a novel HLA-A2-restricted mutated Survivin epitope and induction of specific anti-HCC CTLs that could effectively cross-recognize wild-type Survivin antigen.

Peptide vaccine based on tumor-associated antigen (TAA), which usually belongs to self-antigen with poor immunogenicity, has been considered as an attractive option for treatment of malignant tumors. The ideal TAA epitopes should have stable affinity to major histocompatibility complex (MHC) molecules and elicit strong anti-tumor immune response. Although point-mutation technology of TAA peptide may increase the binding capability to MHC molecules, some previous studies have revealed that part of the variant peptides results in lymphocyte not to effectively cross-recognize and kill the target tumor expressed wild-type TAA. Here, we designed a novel HLA-A2-restricted mutated TAA Survivin epitope nonapeptide Sur79L2 (KLSSGCAFL) that showed higher binding ability compared to wild-type peptide Sur79 (KHSSGCAFL) in T2-binding assays. To investigate whether Sur79L2 can induce Survivin-specific anti-hepatocellular carcinoma (HCC) response, we stimulated tumor-associated lymphocytes from a HCC patient with Sur79L2 in vitro. IFN-γ release and cytotoxicity assays showed Sur79L2 could effectively cross-recognize and lysis T2 cell plus peptide Sur79 and HCC cell lines (expression of wild-type Survivin antigen) in an HLA-A2-restricted manner. In contrast, peptide Sur95 (ELTLGEFLKL) that has been reported as a very promising anti-tumor epitope in a variety of tumors except HCC were not able to generate detectable cytotoxic immune responses against HCC in this study. Our results suggest that point-mutated peptide Sur79L2 is a new HLA-A2-restricted CTL epitope and may be useful for the immunotherapy for patients with HCC.

Dynamic infrared imaging for analysis of fingertip temperature after cold water stimulation and neurothermal modeling study.

The human hand is considered to be the terminus of the nervous system. It contains numerous capillary vessels, and it plays an important role in the regulation of the autonomic nervous system. We have used infrared thermography and ultrasound Doppler flowmetry to investigate characteristics of the temperature variation of the hand and the blood flow after cold stimuli. We have also developed an image processing algorithm to measure temperature of various parts of the hand via sequential thermal images. Measured results show that local cold stimuli will induce oscillation of temperature, which may be due to neuroregulation during rewarming. Finally, in order to explain the mechanism of autonomic nervous system (ANS) regulation we have developed an ANS regulation model on the basis of the knowledge of the physiology and bioheat transfer. The results computed using our model are in good agreement with the experimental results.

[Tumor-specific T cell recptor gene transfection promotes memory T cell differentiation in vitro].

OBJECTIVE: To investigate effect of tumor-specific T cell receptor gene transfection on memory T cell differentiation in vitro. METHODS: TCRVbeta7.1 gene was transferred into peripheral blood mononuclear cells (PBMCs) obtained from healthy adults, and the expression of Vbeta7.1 was detected by flow cytometry before and after the transfection. Memory T cell differentiation was induced by stimulation with the hepatocarcinoma cell line BEL-7402 in vitro. The expression of surface molecules CD45RO, CD45RA and CCR7 was analyzed by flow cytometry to identify the phenotype and subsets of the memory T cells. Fluorescence-activated cell sorting was performed to detect the apoptosis of the tumor cells, and enzyme-linked immunoabsorbent assay was used to determine the production of interferon-gamma (IFN-gamma) for assessing the immune function of the memory T cells. RESULTS: Flow cytometry showed that TCRVbeta7.1 gene was efficiently expressed after transfection. After stimulation by the tumor cells in vitro, the expression of CD45RO in TCRVbeta7.1 gene-modified T cells increased gradually, and analysis of the coexpression of CD45RA and CCR7 revealed that the effector memory T cells constituted the majority of the differentiated memory T cells. The apoptotic rate of the tumor cells induced by the T cells increased significantly with also obviously increased INF-gamma secretion in the memory T cells. CONCLUSION: Tumor-specific TCRVbeta7.1 gene transfection can promote the differentiation of the memory T cells, the majority of which belongs to effector memory T cells that perform immune functions by inducing apoptosis and cytokine secretion.

[New advances in Sox gene family].

The Sox family of transcription factors are found throughout the animal kingdom. They are characterized by the presence of a HMG domain, involved in the regulation of such diverse developmental processes of early embryogenesis as sex determination,chondrogenesis,haemopoiesis,neural development and lens development. The deletion or mutation of SOX proteins results in developmental defects and congential disease in human. One Sox gene has different effects on the same promoters in the different cells or the different promoters in a cell. Some Sox gene exhibit a remarkable crosstalk and functional redundancy among each other. This paper reviewed the advances related to the Sox gene family in recent years.