Modification of i-GONAD Suitable for Production of Genome-Edited C57BL/6 Inbred Mouse Strain

Improved genome editing via oviductal nucleic acid delivery (i-GONAD) is a novel method for producing genome-edited mice in the absence of ex vivo handling of zygotes. i-GONAD involves the intraoviductal injection of clustered regularly interspaced short palindromic repeats (CRISPR) ribonucleoproteins via the oviductal wall of pregnant females at 0.7 days post-coitum, followed by in vivo electroporation (EP). Unlike outbred Institute of Cancer Research (ICR) and hybrid mouse strains, genome editing of the most widely used C57BL/6J (B6) strain with i-GONAD has been considered difficult but, recently, setting a constant current of 100 mA upon EP enabled successful i-GONAD in this strain. Unfortunately, the most widely used electroporators employ a constant voltage, and thus we explored conditions allowing the generation of a 100 mA current using two electroporators: NEPA21 (Nepa Gene Co., Ltd.) and GEB15 (BEX Co., Ltd.). When the current and resistance were set to 40 V and 350–400 Ω, respectively, the current was fixed to 100 mA. Another problem in using B6 mice for i-GONAD is the difficulty in obtaining pregnant B6 females consistently because estrous females often fail to be found. A single intraperitoneal injection of low-dose pregnant mare’s serum gonadotrophin (PMSG) led to synchronization of the estrous cycle of these mice. Consequently, approximately 51% of B6 females had plugs upon mating with males 2 days after PMSG administration, which contrasts with the case (≈26%) when B6 females were subjected to natural mating. i-GONAD performed on PMSG-treated pregnant B6 females under conditions of average resistance of 367 Ω and average voltage of 116 mA resulted in the production of pregnant females at a rate of 56% (5/9 mice), from which 23 fetuses were successfully delivered. Nine (39%) of these fetuses exhibited successful genome editing at the target locus.

Recent Advances and Future Perspectives of In Vivo Targeted Delivery of Genome-Editing Reagents to Germ Cells, Embryos, and Fetuses in Mice

The recently discovered clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (Cas9) systems that occur in nature as microbial adaptive immune systems are considered an important tool in assessing the function of genes of interest in various biological systems. Thus, development of efficient and simple methods to produce genome-edited (GE) animals would accelerate research in this field. The CRISPR/Cas9 system was initially employed in early embryos, utilizing classical gene delivery methods such as microinjection or electroporation, which required ex vivo handling of zygotes before transfer to recipients. Recently, novel in vivo methods such as genome editing via oviductal nucleic acid delivery (GONAD), improved GONAD (i-GONAD), or transplacental gene delivery for acquiring genome-edited fetuses (TPGD-GEF), which facilitate easy embryo manipulation, have been established. Studies utilizing these techniques employed pregnant female mice for direct introduction of the genome-editing components into the oviduct or were dependent on delivery via tail-vein injection. In mice, embryogenesis occurs within the oviducts and the uterus, which often hampers the genetic manipulation of embryos, especially those at early postimplantation stages (days 6 to 8), owing to a thick surrounding layer of tissue called decidua. In this review, we have surveyed the recent achievements in the production of GE mice and have outlined the advantages and disadvantages of the process. We have also referred to the past achievements in gene delivery to early postimplantation stage embryos and germ cells such as primordial germ cells and spermatogonial stem cells, which will benefit relevant research.

Choice of Feeders Is Important When First Establishing iPSCs Derived From Primarily Cultured Human Deciduous Tooth Dental Pulp Cells

Feeder cells are generally required to maintain embryonic stem cells (ESCs)/induced pluripotent stem cells (iPSCs). Mouse embryonic fibroblasts (MEFs) isolated from fetuses and STO mouse stromal cell line are the most widely used feeder cells. The aim of this study was to determine which cells are suitable for establishing iPSCs from human deciduous tooth dental pulp cells (HDDPCs). Primary cultures of HDDPCs were cotransfected with three plasmids containing human OCT3/4, SOX2/KLF4, or LMYC/LIN28 and pmaxGFP by using a novel electroporation method, and then cultured in an ESC qualified medium for 15 days. Emerging colonies were reseeded onto mitomycin C-treated MEFs or STO cells. The colonies were serially passaged for up to 26 passages. During this period, colony morphology was assessed to determine whether cells exhibited ESC-like morphology and alkaline phosphatase activity to evaluate the state of cellular reprogramming. HDDPCs maintained on MEFs were successfully reprogrammed into iPSCs, whereas those maintained on STO cells were not. Once established, the iPSCs were maintained on STO cells without loss of pluripotency. Our results indicate that MEFs are better feeder cells than STO cells for establishing iPSCs. Feeder choice is a key factor enabling efficient generation of iPSCs.

A new objective histological scale for studying human photoaged skin

BACKGROUND

A quantitative understanding of the histological alteration of the skin is important for assessing the severity of photoaging.

METHODS

We performed Elastica-van Gieson staining and immunohistochemistry for decorin on 34 facial skin sections. We evaluated the alteration of collagen fibers and decorin (a modulator for collagen fibrillogenesis), according to the 5 grades of morphological change in elastic fibers that was established by Kligman (1969). The objectivity of a stage (Stages I-VI), which was established in this study, was evaluated using weighted kappa statistical analysis based on the degree of agreement in stage determination by 11 observers using a blind procedure. Correlation between the crow's-feet-area wrinkles grades of another 26 women and stages was also analyzed.

RESULTS

The initial alteration of elastic fibers was observed in the deep dermis. Decorin was not detected in very severely altered skin. Based on the combination of changes in the elastic fibers, collagenic fibers, and decorin, skin tissues were categorized into 6 stages according to severity. The statistical analysis showed almost perfect agreement between observers. Significant positive correlation between stages and wrinkle scores was found.

CONCLUSIONS

We propose a new objective histological scale that is useful for assessing the severity of photoaging.

Targeted toxin-based selectable drug-free enrichment of Mammalian cells with high transgene expression

Almost all transfection protocols for mammalian cells use a drug resistance gene for the selection of transfected cells. However, it always requires the characterization of each isolated clone regarding transgene expression, which is time-consuming and labor-intensive. In the current study, we developed a novel method to selectively isolate clones with high transgene expression without drug selection. Porcine embryonic fibroblasts were transfected with pCEIEnd, an expression vector that simultaneously expresses enhanced green fluorescent protein (EGFP) and endo-β-galactosidase C(EndoGalC; an enzyme capable of digesting cell surface α-Gal epitope) upon transfection. After transfection, the surviving cells were briefly treated with IB4SAP (α-Gal epitope-specific BS-I-B₄ lectin conjugated with a toxin saporin). The treated cells were then allowed to grow in normal medium, during which only cells strongly expressing EndoGalC and EGFP would survive because of the absence of α-Gal epitopes on their cell surface. Almost all the surviving colonies after IB4SAP treatment were in fact negative for BS-I-B₄ staining, and also strongly expressed EGFP. This system would be particularly valuable for researchers who wish to perform large-scale production of therapeutically important recombinant proteins.

Generation of Mouse STO Feeder Cell Lines That Confer Resistance to Several Types of Selective Drugs

Feeder cells are generally required for establishment and maintenance of embryonic stem (ES)/induced pluripotent stem (iPS) cells. Increased demands for generation of those cells carrying various types of vectors (i.e., KO vectors and transgenes) also require feeder cells that confer resistance to any types of preexisting selective drugs. Unfortunately, the use of the feeders that are resistant to various drugs appears to be limited to a few laboratories. Here we generated a set of gene-engineered STO feeder cells that confer resistance to several commercially available drugs. The STO cells, which have long been used as a feeder for mouse ES and embryonal carcinoma (EC) cells, were transfected with pcBIH [carrying bleomycin resistance gene (ble) and hygromycin B phosphotransferase gene (Hyg)], pcBIP [carrying ble and puromycin resistance gene (puro)], or pcBSN [carrying ble and neomycin resistance gene (neo)]. The resulting stably transfectants (termed SHB for pcBIH, SPB for pcBIP, and SNB for pcBSN) exhibited bleomycin/hygromycin, bleomycin/puromycin, or bleomycin/neomycin, as expected. The morphology of these cells passaged over 18 generations was indistinguishable from that of parental STO cells. Of isolated clones, the SHB3, SPB3, and SNB2 clones successfully supported the growth of mouse ES cells in an undifferentiated state, when coculture was performed. PCR analysis revealed the presence of the selective markers in these clones, as expected. These SHB3, SPB3, and SNB2 cells will thus be useful for the acquisition and maintenance of genetically manipulated ES/iPS cells.

Whole-genome amplification-based GenomiPhi for multiple genomic analysis of individual early porcine embryos

The multiple displacement amplification (MDA) method, which relies on isothermal DNA amplification using the DNA polymerase of the bacteriophage phi29, was recently developed for high-performance, whole-genome amplification (WGA). The objective of the present study was to determine whether a target sequence could be successfully amplified by conventional PCR when the genomic DNA of a single Day-7 porcine blastocyst (derived from SCNT of a gene-engineered fibroblast) was amplified by the MDA method and used as a template. The yield of double-stranded DNA was 103.5 ± 16.0 ng/embryo (range, 75-125), as assessed by a PocoGreen assay. However, non-specific products (20 ± 5 ng/tube) were also generated, even in the negative control. Thus, ∼81% of the 103.5 ng (84 ng) of amplified DNA was estimated to be porcine sequences (2.2 × 10(3)-fold enrichment). In addition, PCR confirmed the presence of transgenes, as well as endogenous α-1,3-galactosyltransferase and homeobox Nanog genes in all embryos. Sequencing of the amplified products verified the fidelity of this system. In conclusion, the MDA-mediated WGA, which was simple, inexpensive, and did not require a thermal cycler, could be a powerful tool for multiple genomic analyses of individual early porcine embryos.

Efficient transfection of primarily cultured porcine embryonic fibroblasts using the Amaxa Nucleofection system

Porcine embryonic fibroblasts (PEF) are important as donor cells for nuclear transfer for generation of genetically modified pigs. In this study, we determined an optimal protocol for transfection of PEF with the Amaxa Nucleofection system, which directly transfers DNA into the nucleus of cells, and compared its efficiency with conventional lipofection and electroporation. Cell survival and transfection efficiency were assessed using dye-exclusion assay and a green fluorescent protein (GFP) reporter construct, respectively. Our optimized nucleofection parameters yielded survival rates above 60%. Under these conditions, FACS analysis demonstrated that 79% of surviving cells exhibited transgene expression 48 h after nucleofection when program U23 was used. This efficiency was higher than that of transfection of PEFs with electroporation (ca. 3-53%) or lipofection (ca. 3-8%). Transfected cells could be expanded as stably transgene-expressing clones over a month. When porcine nuclear transfer (NT) was performed using stable transformant expressing GFP as a donor cell, 5-6% of reconstituted embryos developed to blastocysts, from which 30-50% of embryos exhibited NT-embryo-derived green fluorescence. Under the conditions evaluated, nucleofection exhibited higher efficiency than conventional electroporation and lipofection, and may be a useful alternative for generation of genetically engineered pigs through nuclear transfer.

Factors affecting long-term compliance of osteoporotic patients with bisphosphonate treatment and QOL assessment in actual practice: alendronate and risedronate

The aim of our study was to examine compliance with a daily dose of 5 mg alendronate (ALN) and 2.5 mg risedronate (RDN) in actual practice, and to determine the causes of noncompliance through a questionnaire. In addition, we studied the quality of life (QOL) of patients through another disease-related questionnaire. The overall compliance rate remained at approximately 40% one year after the initial dose. The rates did not differ significantly between the ALN group (783 patients) and the RDN group (491 patients). The compliances in the female group and the rheumatism group were better than in the male group and the nonrheumatism group. From the questionnaire, 36% of noncompliant patients showed adverse effects (AEs), and the other noncompliant patients stopped the medication in spite of having no AEs. A logistic regression analysis of factors that might have affected long-term compliance included AEs, an understanding of the disease, the method of ingestion, visiting medical facilities, the shape of the tablet, the cost of the drug, and the explanation of the doctor or pharmacist. This analysis showed that noncompliance occurred mainly due to AEs, the inconvenience of visiting a medical facility, unusual methods of ingestion, and a poor understanding of the disease. According to the results of the questionnaire for QOL assessment, the patients who continued the medication for more than 1 year had improved scores for pain in both the ALN and RDN groups. Osteoporotic treatment needs long-term patient compliance. To improve compliance, it is very important that doctors and pharmacists ensure that patients understand the purpose of this therapy.