41 RAPID PRODUCTION OF α-1,3-GALACTOSYLTRANSFERASE-DEFICIENT MINIATURE PIGS BY NUCLEAR TRANSFER FOLLOWING NEONATAL SKIN BIOPSY AND LOSS OF HETEROZYGOSITY

Production of α-1,3-galactosyltransferase (αGT)-deficient pigs is a fundamental task to overcome hyperacute rejection in pig-to-human xenotransplantation. However, the procedure to produce such pigs requires a great deal of cost, time, and labor. Heterozygote αGT knockout (KO) pigs should be bred at least for 2 generations to ultimately produce homozygote progenies. Here, we show that αGT-deficient miniature pigs could be produced in much reduced time using mitotic recombination in neonatal ear skin fibroblasts. Miniature pig fetal fibroblasts were transfected with αGT-targeting vector and treated with neomycin. Eighty-seven colonies were screened by PCR, and 2 among them were identified as homologous recombinants with monoallelic disruption of αGT (targeting efficiency = 2.3%). One of the two colonies was chosen and used for subsequent NT. In total, 559 nuclear transfer embryos reconstructed with αGT gene-targeted fetal fibroblasts were transferred to 5 surrogate gilts. Three gilts became pregnant and developed to term with 3 live piglets delivered. Being analyzed by PCR, all piglets born were found to be αGT gene targeted. Fibroblasts were isolated from ear skin biopsies of a 10-day-old αGT gene-targeted miniature pig. To increase the number of mitotic recombination that occurs spontaneously during cell proliferation, fibroblasts were cultured for 6 to 8 passages. Then, these cells were treated with IB4-conjugated Dynabeads; IB4 lectin binds to galactose-α-1,3-galactose (αGal), the antigen formed by αGT, and is responsible for hyperacute rejection (HAR). Using a magnetic column, fibroblasts bound to IB4 lectin were removed. Remaining cells lacking αGal were cultured further until colony formation. A total of 22 fibroblast colonies were screened by PCR, and 15 among them were confirmed as loss of heterozygosity (LOH) with biallelic disruption of αGT by mitotic recombination (LOH efficiency = 68%). One of these clonal cultures of αGT-deficient fibroblasts was chosen and used for subsequent NT. In total, 729 nuclear transfer embryos reconstructed with αGT-deficient neonatal ear skin fibroblasts were transferred to 4 surrogate gilts. Two gilts became pregnant, and 3 live piglets were produced. Based on PCR, both αGT alleles were targeted in all piglets born. Only 8 months were required from the production of heterozygote to homozygote KO in contrast to approximately 2 years consumed for conventional breeding of heterozygotes. The present study demonstrates that the time required for the production of αGT-deficient miniature pigs could be reduced significantly by neonatal skin biopsies and subsequent selection of mitotic recombinants. Such a procedure may be beneficial for the production of other homozygote KO animals, especially in species that require substantial periods of gestation such as pigs.

290 EFFECT OF EXOGENOUS Oct4 PROTEIN ON DIRECT CONVERSION OF HUMAN FIBROBLASTS INTO NEURAL STEM CELLS

The generation of neural stem cells (NSC) from somatic cells may provide unlimited source of neuronal cells for autologous transplantation to patients of neurological disorders. Recently, direct conversion of fibroblasts into NSC by epigenetic reprogramming has been reported (Han et al. 2012 Cell Stem Cell 10, 465–472; Thier et al. 2012 Cell Stem Cell 10, 473–479; Ring et al. 2012 Cell Stem Cell 11, 100–109). These reprogrammed cells are referred to as induced neural stem cells (iNSC) and they share the characteristics of NSC in their morphology, molecular marker expressions, and capacity to differentiate into neurons, astrocytes, and oligodendrocytes. One of the procedures to convert fibroblasts into iNSC is restriction of Oct4 activity to the initial phase of reprogramming, while Sox2, Klf4, and c-Myc are constitutively expressed. In the present study, we examined the effect of Oct4 in reprogramming of human fibroblasts into iNSC. Oct4 protein was modified by the addition of poly-arginine protein transduction domain to easily penetrate into the cell membrane. We transduced Oct4 protein, in contrast to the previous reports where the Oct4 gene was virally introduced. First, human fibroblasts were transfected by retroviral vectors carrying the genes encoding Sox2, Klf4, and c-Myc. Then, transfected cells were cultured in ReNcell NSC maintenance medium containing Oct4 protein. After 4 days, Oct4 protein was removed from the medium. With Oct4 protein transduction, 21 flat colonies were formed from 4 × 105 fibroblasts. These colonies were picked and passaged for subculture and later became iNSC. However, in the absence of Oct4 protein, no colonies were obtained from the same number of fibroblasts that were initially plated. Approximately 40 days after transduction of reprogramming factors, cluster of iNSC were obtained. These cells expressed molecular markers of human NSC, including Nestin, Sox2, Pax6, and Blbp. Moreover, these iNSC could differentiate into neurons, astrocytes, and oligodendrocytes in vitro. Results of the present study demonstrate that transduction of exogenous Oct4 protein may be essential to the direct conversion of human fibroblasts into iNSC using a combination of reprogramming factors Sox2, Klf4, and c-Myc.

Evaluation of VCAM-1 antibodies as therapeutic agent for atherosclerosis in apolipoprotein E-deficient mice

OBJECTIVE

Blocking agents targeting cell adhesion molecules have been developed to prevent cardiovascular diseases such as atherosclerosis, whereas relatively little attention has been paid to the therapeutic potential of vascular cell adhesion molecule (VCAM)-1 as an inflammatory disease target. Two novel, fully human antibodies, H6 and 7H, against human VCAM-1 (hVCAM-1) were developed and tested to validate the hypothesis that blocking VCAM-1 ameliorates atherosclerosis in apolipoprotein E-deficient (ApoE(-/-)) mice.

METHODS AND RESULTS

Treatment with H6 or 7H effectively inhibited VCAM-1 adhesion to inflammatory cells, and reduced RhoA activation and the production of reactive oxygen species in human umbilical cord vascular endothelial cells. As 7H showed binding affinity to both murine VCAM-1 (mVCAM-1) and hVCAM-1, the therapeutic effects of 7H in ApoE(-/-) mice were tested. After confirming specific in vivo binding activity of 7H to mVCAM-1, we showed that administering 7H resulted in significantly ameliorated plaque formation compared to administering a control antibody in ApoE(-/-) mice fed a Western diet for 12 weeks. Also, 7H treatment significantly reduced infiltration of CD45(+) cells into plaques and reduced inflammation and improved plaque stability.

CONCLUSION

These results indicate that the anti-VCAM-1 antibody attenuates atherosclerosis in ApoE(-/-) mice, improves plaque inflammation and stability as well as inhibiting the adhesion of inflammatory cell, and suggest that blocking VCAM-1 with a monoclonal antibody may be an effective means of anti-atherosclerotic therapy.

One target, different effects: a comparison of distinct therapeutic antibodies against the same targets

To date, more than 30 antibodies have been approved worldwide for therapeutic use. While the monoclonal antibody market is rapidly growing, the clinical use of therapeutic antibodies is mostly limited to treatment of cancers and immunological disorders. Moreover, antibodies against only five targets (TNF-α, HER2, CD20, EGFR, and VEGF) account for more than 80 percent of the worldwide market of therapeutic antibodies. The shortage of novel, clinically proven targets has resulted in the development of many distinct therapeutic antibodies against a small number of proven targets, based on the premise that different antibody molecules against the same target antigen have distinct biological and clinical effects from one another. For example, four antibodies against TNF-α have been approved by the FDA -- infliximab, adalimumab, golimumab, and certolizumab pegol -- with many more in clinical and preclinical development. The situation is similar for HER2, CD20, EGFR, and VEGF, each having one or more approved antibodies and many more under development. This review discusses the different binding characteristics, mechanisms of action, and biological and clinical activities of multiple monoclonal antibodies against TNF-α, HER-2, CD20, and EGFR and provides insights into the development of therapeutic antibodies.

24 TARGETED DISRUPTION OF ATAXIA-TELANGIECTASIA MUTATED GENE IN MINIATURE PIGS BY SOMATIC CELL NUCLEAR TRANSFER

Ataxia-telangiectasia (A-T) is a genetic disease caused by germline biallelic mutation in the ataxia-telangiectasia mutated gene (ATM) that results in partial or complete loss of ATM expression or activity. A diverse phenotype of the disease includes progressive cerebellar ataxia, oculocutaneous telangiectasias, radiation hypersensitivity, increased cancer incidence, immunodeficiency and chromosomal instability. The frequency of A-T in the United States and United Kingdom has been estimated to be 1:40 000. Heterozygous carriers may also have predisposition to diverse cancers. Although ATM-deficient mice have been produced, none reflects the extent of neurological abnormalities involving the loss of Purkinje cells of the cerebellum seen in patients. Hence, miniature pigs, which are anatomically and physiologically closer to humans, might serve as an alternative model for human A-T. In the present study, we attempted a targeted disruption of ATM in miniature pigs by somatic cell nuclear transfer. Most A-T patients possess mutated ATM with truncation, resulting in prematurely terminated ATM proteins that are highly unstable. To induce the truncation of ATM, we disrupted exon 59 region of ATM that has been known to be critical for ATM kinase activity. Miniature pig fetal fibroblasts were transfected with ATM-targeting vector and treated by neomycin for 2 weeks. A total of 139 colonies were screened by PCR and 3 among them were identified as homologous recombinants with monoallelic disruption of ATM (targeting efficiency = 2.1%). One of the 3 colonies was chosen and used for subsequent nuclear transfer. In total, 611 nuclear transfer embryos reconstructed with ATM-targeted fetal fibroblasts were transferred into 5 surrogate gilts. Two gilts became pregnant and developed to term with a total of 5 live piglets delivered. Being analysed by PCR, all piglets born were found to be ATM gene-targeted. Because conventional murine models of human A-T have provided only limited insights into therapies and pharmacological treatments, the generation of miniature pigs with disrupted ATM will allow new opportunities to more precisely understand A-T and to accelerate discovery of strategies for prevention and treatment of the disease. In addition, such animals may be utilised in studying cancer with respect to the involvement of ATM in cell cycle arrest, DNA repair and apoptosis.

Antibodies against non-immunizing antigens derived from a large immune scFv library

Target-specific antibodies can be rapidly enriched and identified from an antibody library using phage display. Large, naïve antibody libraries derived from synthetic or unimmunized sources can yield antibodies against virtually any antigen, whereas libraries from immunized sources tend to be smaller and are used exclusively against the antigen of immunization. In this study, 25 scFv libraries made from the spleens of immunized rabbits, each with a size ranging from 10(8) to higher than 10(9), were combined into a single large library with > 10(10) individual clones. Panning of this combined library yielded target-specific rabbit scFv clones against many non-immunizing antigens, including proteins, peptides, and a small molecule. Notably, specific scFv clones against a rabbit self-antigen (rabbit serum albumin) and a phosphorylated protein (epidermal growth factor receptor pTyr1173) could be isolated from the library. These results suggest that the immune library contained a significant number of unimmunized clones and that a sufficiently large immune library can be utilized similarly to a naïve library, i.e., against various non-immunizing antigens to yield specific antibodies.

Pharmacophore-based strategy for the development of general and specific scFv biosensors for abused antibiotics

We developed fluorescent biosensor systems that are either general or selective to fluoroquinolone antibiotics by using a single-chain variable-fragment (scFv) as a recognition element. The selectivity of these biosensors to fluoroquinolone antibiotics was rationally tuned through the structural modification on the pharmacophore of fluoroquinolone antibiotics and the subsequent selection of scFv receptor modules against these antibiotics-based antigens using phage display. The resulting A2 and F9 scFv's bound to their representative antigen with a moderate affinity (K(D) in micromolar range as determined by surface plasmon resonance). A2 is a specific binder for enrofloxacin and did not cross-react with other fluoroquinolone antibiotics including structurally similar ciprofloxacin, while F9 is a general fluoroquinolone binder that likely bound to the antigen at the common pyridone-carboxylic acid pharmacophore. These scFv-based receptors were successfully applied to the development of one-step fluorescent biosensor which can detect fluoroquinolone antibiotics at concentrations below the level suggested in animal drug application guidelines. The strategy described in this report can be applied to developing convenient field biosensors that can qualitatively detect overused/misused antibiotics in the livestock drinking water.

A control theoretic approach to venom immunotherapy with state jumps

We investigate a model-based control method to boost the immune response. We apply this control method to select the appropriate immune response between the Th1 and Th2 responses. The idea of state jump is discussed using hybrid models notation. To implement the control idea we propose physically available methods.

Replacing the rod with the cone transducin subunit decreases sensitivity and accelerates response decay

Cone vision is less sensitive than rod vision. Much of this difference can be attributed to the photoreceptors themselves, but the reason why the cones are less sensitive is still unknown. Recent recordings indicate that one important factor may be a difference in the rate of activation of cone transduction; that is, the rising phase of the cone response per bleached rhodopsin molecule (Rh*) has a smaller slope than the rising phase of the rod response per Rh*, perhaps because some step between Rh* and activation of the phosphodiesterase 6 (PDE6) effector molecule occurs with less gain. Since rods and cones have different G-protein alpha subunits, and since this subunit (Talpha) plays a key role both in the interaction of G-protein with Rh* and the activation of PDE6, we investigated the mechanism of the amplification difference by expressing cone Talpha in rod Talpha-knockout rods to produce so-called GNAT2C mice. We show that rods in GNAT2C mice have decreased sensitivity and a rate of activation half that of wild-type (WT) mouse rods. Furthermore, GNAT2C responses recover more rapidly than WT responses with kinetic parameters resembling those of native mouse cones. Our results show for the first time that part of the difference in sensitivity and response kinetics between rods and cones may be the result of a difference in the G-protein alpha subunit. They also indicate more generally that the molecular nature of G-protein alpha may play an important role in the kinetics of G-protein cascades for metabotropic receptors throughout the body.