Evaluation of supporting role of a foldable capsular vitreous body with magnetic resonance imaging in the treatment of severe retinal detachment in human eyes

PURPOSE

To determine the supporting role of a novel foldable capsular vitreous body (FCVB) with magnetic resonance imaging (MRI) in the treatment of severe retinal detachment in human eyes.

METHODS

The study examined nine eyes of nine patients. Among the nine eyes, five had suffered penetrating injuries while four had suffered contusions of the eyeball involving large defects of the retina or choroids. A standard three-port pars plana vitrectomy was performed, FCVB was triple-folded and sent into the vitreous cavity; balanced salt solution (BSS) was injected into the capsule to support the retina. Three cardinal axes of nine eyes were examined using MRI at baseline and at the 3-month follow up.

RESULTS

MRI revealed that the signal intensity of the FCVB was similar to the normal vitreous body, with low-signal intensity on T1-weighted image and high-signal intensity on T2-weighted image. In three pre-operative silicone oil- or heavy silicone oil-filled eyes, FCVBs were not fully inflated, and eyeball deformation was observed in one eye. Shifts of three cardinal axes of three eyes (horizontal, anteroposterior, and vertical) according to MRI, were -4.33, -4.67, and -2.67 mm. In the remaining six eyes, FCVBs were well distributed in the vitreous cavity and evenly supported the retina; the cardinal axes of the eyes were similar to pre-operation. Shifts of three cardinal axes of six eyes were -0.34, -0.34, and -0.34 mm. In a total of nine eyes, shifts of three cardinal axes were -1.67, -1.77, and -1.11 mm. Statistically significant difference showed only between the horizontal axis of nine eyes pre-operatively and post-operatively (P1=0.041, P2=0.058, P3=0.123).

CONCLUSION

This study demonstrated the effectiveness of MRI to monitor the supporting role of an FCVB in the treatment of severe retinal detachment in human eyes.

Atorvastatin or transgenic expression of TFPI inhibits coagulation initiated by anti-nonGal IgG binding to porcine aortic endothelial cells

BACKGROUND

Intravascular thrombosis remains a barrier to successful xenotransplantation. Tissue factor (TF) expression on porcine aortic endothelial cells (PAECs), which results from their activation by xenoreactive antibodies (Abs) to Galα1,3Gal (Gal) and subsequent complement activation, plays an important role.

OBJECTIVES

The present study aimed to clarify the role of Abs directed against nonGal antigens in the activation of PAECs to express functional TF and to investigate selected methods of inhibiting TF activity.

METHODS

PAECs from wild-type (WT), α1,3-galactosyltransferase gene-knockout (GT-KO) pigs, or pigs transgenic for CD46 or tissue factor pathway inhibitor (TFPI), were incubated with naïve baboon serum (BS) or sensitized BS (with high anti-nonGal Ab levels). TF activity of PAECs was assessed.

RESULTS

Only fresh, but not heat-inactivated (HI), naïve BS activated WT PAECs to express functional TF. Similarly, PAECs from CD46 pigs were resistant to activation by naïve BS, but not to activation by fresh or HI sensitized BS. HI sensitized BS also activated GT-KO PAECs to induce TF activity. TF expression on PAECs induced by anti-nonGal Abs was inhibited if serum was pretreated with (i) an anti-IgG Fab Ab or (ii) atorvastatin, or (iii) when PAECs were transgenic for TFPI.

CONCLUSIONS

Anti-nonGal IgG Abs activated PAECs to induce TF activity through a complement-independent pathway. This implies that GT-KO pigs expressing a complement-regulatory protein may be insufficient to prevent the activation of PAECs. Genetic modification with an 'anticoagulant' gene (e.g. TFPI) or a therapeutic approach (e.g. atorvastatin) will be required to prevent coagulation dysregulation after pig-to-primate organ transplantation.

5 PRODUCTION OF TRANSGENIC LIVESTOCK USING A LENTIVIRUS EXPRESSING MULTIPLE SHORT INTERFERING RNAs TARGETING FOOT AND MOUTH DISEASE VIRUS

One goal of transgenic livestock production is developing animals with enhanced production characteristics. Transgenic animals with resistance to viral disease could greatly reduce economic losses. The use of short interfering RNA (siRNA) or short hairpin RNA (shRNA) targeting viral genomes have shown great promise in vitro for both human and animal applications. However, because of the rapid mutation rate, viruses are able to escape single siRNA inhibition. One method to reduce the chances of a functional escape virus is to target its genome with multiple shRNAs simultaneously. The goal of this research project was to produce a recombinant lentiviral vector that expresses three unique shRNAs targeting different regions of the foot and mouth disease virus (FMDV) and use it to produce transgenic livestock. In these initial experiments we used the goat as our model system. Previously, we confirmed that three distinct siRNAs individually could reduce the ability of the FMDV virion to replicate in vitro. Based upon these results we produced a recombinant lentiviral vector that utilised three bovine Pol III promoters (7sk, H1, U6-2), each transcribing a different effective shRNA targeting FMDV. In addition, the vector also contained the fluorescent marker zsGreen and an antibiotic resistance gene. The lentiviral vector was co-transfected with pCMV and pMDG into 293T cells to produce replication incompetent retroviral particles. The supernatant was collected and ultra-centrifuged (50 000 × g for 1.5 h) to concentrate the viral particles resulting in a high-titer viral preparation (>109 mL–1 infective viral particles). To produce the transgenic caprine offspring, three embryo donors were superovulated and naturally bred. Nineteen zygotes were surgically collected from the oviduct 24 h after mating. Recombinant lentivirus was microinjected into the zygote perivitelline space. Immediately following the injections, four goat embryos were surgically transferred into the oviduct of each synchronized recipient. Pregnancy was determined by ultrasound at Day 30 in 2 of 5 recipients that received embryos. One pregnancy was carried to term resulting in triplets; 1 live birth, and 2 stillborn. The placenta and tissue sample of the live goat both contained a subpopulation of zsGreen positive cells when analysed with fluorescent microscopy. A fibroblast cell line was derived from the tissue sample and placed under antibiotic selection. Results indicate that only the fluorescent cells also expressed a resistance to antibiotic selection. RNA was collected from the fibroblast cells and mature shRNA production was confirmed using the QuantiMir kit (System Biosystems). Expression of all 3 mature shRNAs was verified in these cells. This data further supports that the entire transgene was integrated into the genome. This is the first report of transgenic livestock produced that expresses multiple shRNAs targeting a viral genome.

337 PRODUCTION OF TRANSGENIC SHEEP USING RECOMBINANT LENTIVIRUS MICROINJECTION OF IN VIVO PRODUCED EMBRYOS

The development of transgenic technology has enormous potential for livestock improvement. Several methods have been employed for generating transgenic livestock to date, the most popular being pronuclear injection or somatic cell nuclear transfer using genetically modified cells. However, the high cost and relatively low efficiencies seen with these methods have prompted development of alternative methods for producing transgenic livestock. Recently, the introduction of transgenes using viral vectors, in particular lentiviral vectors, has provided an avenue for increasing the efficiency of transgenic livestock production. Microinjection of concentrated lentivirus into the perivitelline space of oocytes and zygotes has been demonstrated as an effective means of creating transgenic livestock (cattle, sheep, and swine). In this study, we investigated the efficiency of producing transgenic sheep through microinjection of recombinant lentivirus into in vivo produced zygotes. Recombinant lentivirus was produced through co-transfection of HEK293T cells with various lentiviral transfer plasmids (each coding for a short hairpin RNA and a fluorescent marker protein) as well as a packaging plasmid and a plasmid encoding the vesicular stomatitis virus glycoprotein (VSV-G), which was used to pseudotype viral particles. For lentivirus concentration, a total of 36 mL of viral supernatant was produced per viral construct. Viral supernatant was ultracentrifuged on a 15% sucrose cushion at 4°C for 1.5 h at a speed of 50 000 × g. The resulting viral pellet was resuspended in 30 μL of PBS and virus was frozen at –80°C until needed. Zygotes were surgically flushed from oviducts of superovulated donor ewes 24 h post-mating. Concentrated recombinant lentivirus (titer ≥ IU mL–1) was then microinjected into the perivitelline space. Injected embryos were surgically transferred into the oviduct of synchronized recipient ewes immediately after injection (3–4 embryos per ewe). Pregnancies were confirmed by ultrasound at 35 days of gestation. The pregnancy rate was 39% (45/114 ewes exhibiting at least one viable fetus). A subset of pregnant ewes was killed at 60 to 70 days gestation to harvest a total of 36 fetuses. Analysis of transgene incorporation was performed by PCR using genomic DNA isolated from skin and liver tissue samples. Two independent PCR reactions were performed per sample, and PCR analysis revealed 14 of the collected fetuses to be transgenic (39%). The remaining pregnancies were allowed to progress to term, and 32 lambs were born. Genomic DNA was isolated from blood samples collected on each lamb, and PCR analysis was performed as above. Of the lambs born, 13 of 32 (40%) were confirmed to be transgenic by PCR analysis. Southern blot analysis is currently underway to confirm PCR data. These results demonstrate that microinjection of recombinant lentivirus into in vivo produced sheep zygotes is an effective and efficient method for generating transgenic sheep.

248 PRODUCTION OF FLAGGED RECOMBINANT BOVINE BMP15 TO IMPROVE BOVINE IN VITRO EMBRYO PRODUCTION SYSTEMS

Current in vitro systems for bovine embryo production are inefficient and produce embryos with lower viability than their in vivo-derived counterparts. Recent reports demonstrate that in vitro bovine oocyte maturation systems could benefit from the addition of oocyte-secreted factors, specifically GDF9 and BMP15 (Gilchrist et al. 2007 Theriogenology 67, 6–15). The long-term goal of this work is to produce species-specific recombinant oocyte-secreted factors capable of improving bovine embryo production in vitro. In the current project, the objective was to produce a cell line that expresses recombinant bovine BMP15. This protein is first translated as a large precursor peptide consisting of propeptide and mature regions, which are enzymatically cleaved to form the active mature protein. The wild-type BMP15 gene was cloned using reverse transcriptase PCR with RNA obtained from bovine ovarian tissue. For improved detection and purification of the active form of the recombinant protein, a detectable FLAG tag sequence (DYKDDDDK) was incorporated into the wild-type BMP15 gene by PCR and cloned into pCDNA expression vector. The FLAG tag was introduced immediately 3′ of the cleavage site at the N-terminal portion of the mature protein to produce recombinant FLAG-tagged BMP15 (rbFL-BMP15). To ensure efficient production of the mature protein, a Kozak sequence was inserted 5′ of the start ATG and the cleavage site altered to be recognised by PACE/furin enzymes, which are endogenously expressed in most mammalian cells including HEK-293 cells (Li et al. 2009 Mol. Hum. Reprod. 15, 779–788). Following sequencing to verify transcript fidelity, pCDNA-rbFL-BMP15 was transfected into HEK-293 cells, and mature protein production was detected by Western blot analysis. Cells plated at 85% confluency were transfected with Lipofectamine 2000, and lysates were harvested 48 h post-transfection. The presence of bovine rbFL-BMP-15 in cell lysates was confirmed by Western blot using the anti-FLAG antibody. Ongoing experiments will test the bioactivity of the purified rbFL-BMP15 by evaluating activation of the SMAD 1/5 pathway via Western blot for phosphorylated SMAD 1/5. After a biologically active protein is confirmed, purified protein will be collected for testing during in vitro maturation of bovine oocytes. We anticipate the species-specific form of oocyte-secreted factors will further enhance in vitro embryo production systems beyond that reported using heterologous factors.

Atorvastatin or transgenic expression of TFPI inhibits coagulation initiated by anti-nonGal IgG binding to porcine aortic endothelial cells

BACKGROUND

Intravascular thrombosis remains a barrier to successful xenotransplantation. Tissue factor (TF) expression on porcine aortic endothelial cells (PAECs), which results from their activation by xenoreactive antibodies (Abs) to Galα1,3Gal (Gal) and subsequent complement activation, plays an important role.

OBJECTIVES

The present study aimed to clarify the role of Abs directed against nonGal antigens in the activation of PAECs to express functional TF and to investigate selected methods of inhibiting TF activity.

METHODS

PAECs from wild-type (WT), α1,3-galactosyltransferase gene-knockout (GT-KO) pigs, or pigs transgenic for CD46 or tissue factor pathway inhibitor (TFPI), were incubated with naïve baboon serum (BS) or sensitized BS (with high anti-nonGal Ab levels). TF activity of PAECs was assessed.

RESULTS

Only fresh, but not heat-inactivated (HI), naïve BS activated WT PAECs to express functional TF. Similarly, PAECs from CD46 pigs were resistant to activation by naïve BS, but not to activation by fresh or HI sensitized BS. HI sensitized BS also activated GT-KO PAECs to induce TF activity. TF expression on PAECs induced by anti-nonGal Abs was inhibited if serum was pretreated with (i) an anti-IgG Fab Ab or (ii) atorvastatin, or (iii) when PAECs were transgenic for TFPI.

CONCLUSIONS

Anti-nonGal IgG Abs activated PAECs to induce TF activity through a complement-independent pathway. This implies that GT-KO pigs expressing a complement-regulatory protein may be insufficient to prevent the activation of PAECs. Genetic modification with an 'anticoagulant' gene (e.g. TFPI) or a therapeutic approach (e.g. atorvastatin) will be required to prevent coagulation dysregulation after pig-to-primate organ transplantation.

Structures and antimicrobial activities of pyridoacridine alkaloids isolated from different chromotypes of the ascidian Cystodytes dellechiajei

Three new pentacyclic alkaloids were isolated from different chromotypes of the western Mediterranean ascidian Cystodytes dellechiajei. The purple color morph collected in Catalonia contained the known compounds kuanoniamine D (1), shermilamine B (2), N-deacetylkuanoniamine D (3), and styelsamine C (4) and a new alkaloid named N-deacetylshermilamine B (5). The green color morph collected in the Balearic Islands contained the known compounds 11-hydroxyascididemin (6) and 8,9-dihydro-11-hydroxyascididemin (7) and two new alkaloids named cystodimine A (8) and cystodimine B (9). The blue color morph collected in Catalonia yielded the known compound ascididemin (10). The structures of all compounds were elucidated on the basis of spectroscopic data, mainly 1D and 2D NMR data. The antimicrobial potential of the pyridoacridine alkaloids isolated from each color morph was evaluated and compared.

Impact of thrombocytopenia on survival of baboons with genetically modified pig liver transplants: clinical relevance

A lack of deceased human donor livers leads to a significant mortality in patients with acute-on-chronic or acute (fulminant) liver failure or with primary nonfunction of an allograft. Genetically engineered pigs could provide livers that might bridge the patient to allotransplantation. Orthotopic liver transplantation in baboons using livers from alpha1,3-galactosyltransferase gene-knockout (GTKO) pigs (n = 2) or from GTKO pigs transgenic for CD46 (n = 8) were carried out with a clinically acceptable immunosuppressive regimen. Six of 10 baboons survived for 4-7 days. In all cases, liver function was adequate, as evidenced by tests of detoxification, protein synthesis, complement activity and coagulation parameters. The major problem that prevented more prolonged survival beyond 7 days was a profound thrombocytopenia that developed within 1 h after reperfusion, ultimately resulting in spontaneous hemorrhage at various sites. We postulate that this is associated with the expression of tissue factor on platelets after contact with pig endothelium, resulting in platelet and platelet-peripheral blood mononuclear cell(s) aggregation and deposition of aggregates in the liver graft, though we were unable to confirm this conclusively. If this problem can be resolved, we would anticipate that a pig liver could provide a period during which a patient in liver failure could be successfully bridged to allotransplantation.

4 CHARACTERIZATION OF LENTIVIRAL SHORT-HAIRPIN RNA EXPRESSION VECTORS CONTAINING SINGLE OR MULTIPLE BOVINE POLYMERASE III PROMOTERS

Lentiviral vectors have become an important and efficient molecular biology tool to integrate foreign DNA into target genomes. These vectors have been previously used in our laboratory to make cloned transgenic fetuses expressing short-hairpin RNAs (shRNAs) targeting the caprine prion mRNA (Golding et al. 2006 Proc. Natl. Acad. Sci. USA 103, 5285-5290) and bovine myostatin mRNA. Specially designed shRNAs have a robust ability to decrease protein expression by initiating a mRNA destruction pathway or by translational inhibition. However, initial experiments targeting foot and mouth (FMDV) viral RNA have indicated that polymerase (Pol) II promoters may be unable to produce enough mature shRNA particles to significantly knock down viral replication in vitro. The goal of this research project was to identify and utilize bovine Pol III promoters to express shRNAs in lentiviral vectors and to express multiple unique shRNAs from a single lentiviral vector using different Pol III promoters. This goal is particularly important to the successful reduction of FMDV replication in a cell, as it limits random mutations from escaping the shRNA-mediated viral genome destruction. The 3 bovine Pol III promoters we selected were 7sk, U6-2, and H1. They were individually amplified from the same genomic DNA preparation. The promoters were inserted immediately upstream of our shRNA expression sequence, resulting in lentiviral vectors designated GT-b7sk, GT-bU6-2, and GT-bH1.To confirm that the promoters were functional, a luciferase reporter assay was performed in HEK 293T cells, where each vector expressed either a shRNA targeting luciferase (luc) or a non-specific shRNA.All promoters expressing luc shRNA resulted in significant reduction of luciferase activity between 68 and 80% compared with non-targeting controls. In addition, there was no significant difference between Pol III promoters when analyzing reduced luciferase activity. In the second phase of the study, we developed 7 unique combinations of 2 or 3 Pol III shRNA expression cassettes to test individual shRNA function with one shRNA designed to target luciferase and the others non-targeting. In multiple Pol III expression constructs, the U6-2 and 7sk promoters resulted in the greatest reduction of luciferase activity at 89 and 95%, respectively. In addition, luciferase activity was reduced to the greatest extent when the luc shRNA was expressed from the second (82%) or third (87%) Pol III cassette. Overall, bovine Pol III-based promoters are effective at expressing shRNAs from a lentiviral vector. In addition, multiple Pol III shRNA expression cassettes can be inserted into a single lentiviral vector and still achieve significant reduction of target protein. These vectors will be used to create transgenic cattle and pigs that express multiple shRNAs targeting the FMDV genome with hopes of creating animals that are resistant to FMDV.

434 REPLICATION COMPETENT LENTIVIRUS (RCL) ANALYSIS IN RECIPIENT ANIMALS OF TRANSGENIC EMBRYOS PRODUCED BY LENTIVIRAL TRANSFER

Lentiviral vectors have become a useful tool for gene therapies and the expression of small hairpin (sh)RNAs to target genes both in vitro and in vivo. This is due primarily to their ability to integrate transgenes into both dividing and nondividing cells, as well as the lack of silencing in the germ cell line. However, the retroviral basis for these recombinant, replication-incompetent viruses has prompted investigation into their safety for use in therapeutics and transgenic animal production. Concerns are that recombination with wild-type viruses or endogenous retroviral elements may allow the integrated provirus genome to become replication competent. In order to investigate this, transgenic embryos produced by lentiviral-mediated gene transfer were transferred into recipient animals. The lentiviral plasmids used in this experiment contained a self-inactivating 3′ untranslated region as well as a green fluorescent protein (GFP) reporter gene (Miyoshi et al. 1998 J.Virol. 72, 8150-8157). Recombinant lentivirus was produced through cotransfection of HEK293T cells with the lentiviral transfer plasmid as well as a packaging plasmid and a plasmid encoding the vesicular stomatitis virus glycoprotein (VSV-G), which was used to pseudotype viral particles. Two methods were used for production of transgenic embryos. The first was lentiviral transduction of bovine fetal fibroblasts followed by somatic cell nuclear transfer. The second was incubation of IVP hatched ovine blastocysts in culture medium containing infectious recombinant lentiviral particles. Recipients were then sacrificed and analyzed for the presence of replication competent lentivirus (RCL). Tissues collected from each recipient included blood, lung, lymph node, kidney, liver, mammary gland, ovary, skeletal muscle, spleen, and uterus. In addition, when available, fetal and placental samples were collected. Analyses for RCL included a serum ELISA test for presence of the p24 HIV antigen as well as real-time quantitative PCR (qRT-PCR) on genomic DNA for the presence of VSV-G. To date, a total of 13 recipients including both sheep and cattle have been analyzed. All animals had p24 titers below the level of detection for the assay (<12.5 pg mL-1). Additionally, the tissues mentioned above have been analyzed by qRT-PCR for 6 of the 13 recipients so far, and all have been negative for VSV-G as determined by comparison with positive and negative control samples. Additional collections and analysis are ongoing. A lack of detection of RCL in these animals will build confidence in the use of lentiviral vectors in transgenic animal production and will lend support for their safety in both animal and human therapies.

5 INHIBITION OF FOOT AND MOUTH DISEASE VIRUS IN VITRO USING RNA INTERFERENCE

The use of short-hairpin RNA (shRNA) targeting viral genomes has shown great promise in human medicine and in vitro research in animal agriculture. However, this research has not been extrapolated into livestock applications. Foot and mouth disease virus (FMDV) is a world-wide disease resulting in decreased production and export limitations in countries with endemic FMDV, as well as severe economical impacts if an outbreak occurs in an FMDV-free country. The long-term goal for this project is to produce transgenic cattle that express shRNA targeting the FMDV genome resulting in resistance to infection. As a starting point, five siRNA and one non-targeting control siRNA (Null) were developed targeting different highly conserved regions of a FMDV type-A based replicon. The siRNA were transfected into BHK cells 48 h before viral RNA challenge. Eighteen hours post challenge the cells were lysed and analyzed. Three siRNA targeting the non-structural polymerase protein exhibited severe knockdown of 87, 90, and 92% when compared with the Null siRNA transfected control. The siRNA targeting the VPG3 cap protein reduced activity by 59%, and the siRNA targeting the internal ribosomal entry site had a minimal effect of 15% reduction. Based upon these results, we produced recombinant lentiviral particles designed to deliver the shRNA sequence targeting the FMDV genome and the fluorescent marker, dsRed, into a bovine fetal fibroblast cell line. This transgenic cell line expressing the most effective shRNA (based on initial siRNA screening) was used for somatic cell nuclear transfer to create bovine embryos. One hundred and sixty oocytes were enucleated, of which 149 had successful fusion resulting in 35 blastocysts after in vitro culture. Two embryos per recipient were transferred into five recipients. At Day 40 of pregnancy three of the five recipients had a fetus, but no heart beat could be detected. We are currently in the process of creating another cell line and repeating this experiment. If successful, transgenic calves will be visually and genetically analyzed for expression of dsRed and shRNA targeting FMDV. Transgenic and control animals/tissues will then be analyzed for resistance to infection with FMDV.

44 ATTEMPTS TO USE SOMATIC CELLS ISOLATED FROM FROZEN BOVINE SEMEN FOR NUCLEAR TRANSFER

Somatic cells in semen are a potential source of nuclei for nuclear transfer to produce genetically identical animals. This is especially important when an animal has died and the only viable genetic material available is frozen semen. In our previous studies, epithelial cells were cultured from fresh ovine and bovine ejaculates and blastocyst stage embryos were produced using these cells (Liu J et al. 2007 Biol. Reprod. special issue, 177; Liu J et al. 2008 Reprod. Fertil. Dev. 20, 102). However, growing cells from frozen semen can be difficult. We hypothesized that nuclei of the somatic cells in frozen semen can be used for nuclear transfer even though the cell membrane and cytoplasm are damaged during the semen freezing process. Electrical fusion or piezo assisted direct injection was applied to introduce nuclei of somatic cells isolated from frozen bovine semen (not cultured) into enucleated bovine oocytes. With electrical fusion, only 5 of the 64 (7.8%) recombined couplets fused, which is lower than our normal fusion rate of approximately 70%. Of the 5 fused embryos, one cleaved and developed to a 4-cell stage embryo. Staining with propidium iodide indicated that less than 10% of somatic cells isolated from frozen bovine semen were viable. These results suggest that it might not be practical to introduce nuclei of the cells in frozen semen into oocytes by fusion due to the high proportions of dead cells. Membranes of the cells in frozen semen were hard and difficult to break by piezo pulses or drawing in and out of the injection pipette. Therefore, whole cell intracytoplasmic injection was applied. After couplet recombination, activation was induced by applying two 0.3 kV cm–1, 55 μs direct-current pulses delivered by an Eppendorf Multiporator (Eppendorf, North America) in activation medium that was composed of 0.28 m Mannitol (Sigma-Aldrich, St. Louis, MO, USA), 0.1 mm CaCl2 (Sigma-Aldrich), and 0.1 mm MgSO4 (Sigma-Aldrich), followed by incubation in 10 μg mL–1 cycloheximide (Sigma-Aldrich) and 5 μg mL–1 cytochalasin B (Sigma-Aldrich) for 5 h in a humidified 5% CO2, 5% O2, and 90% N2 gas mixture at 38.5°C. Of the 299 recombined embryos, 82 (27.4%) either cleaved or were fragmented. Of the 82 embryos, 48 were examined and 42 (87.5%) were determined to be fragmented (contained intact donor cells). Low cleavage rates were observed in embryos produced by direct injection (4.5%), but no further embryonic development occurred. Cells cultured from fresh bovine semen were used as positive controls for whole cell intracytoplasmic injection. Of the 74 recombined embryos, 73 (98.6%) cleaved and 4 developed into blastocysts. These results highlight the difficulty of obtaining viable embryos by employing nuclear transfer and somatic cells obtained from frozen semen samples. Additional research is warranted given the potential value of this approach for recovering lost genetics.

308 DEVELOPMENT OF TRANSGENIC LIVESTOCK WITH REDUCED MYOSTATIN EXPRESSION USING RNA INTERFERENCE

RNA interference (RNAi) is a means of regulating gene expression by targeting mRNA in a sequence-specific manner for degradation or translational inhibition. Short hairpin RNAs (shRNAs) and siRNAs have been extensively employed for manipulating gene expression in a wide range of species. However, the great majority of this work has involved in vitro studies with cells grown in culture. Our goal for this project is to produce transgenic livestock in which myostatin, a negative regulator of muscle growth, has been targeted for silencing by RNAi. In theory, livestock in which myostatin has been silenced should exhibit increased muscle growth and development. To that end, we designed shRNAs to target the bovine myostatin mRNA sequence. The shRNAs were cloned into a lentiviral vector that contains a cytomegalovirus promoter controlling green fluorescent protein and shRNA expression as well as neomycin resistance. Infective lentivirus was made in HEK293T cells through co-transfection of the lentiviral vector, a packaging plasmid, and a plasmid expressing the VSVG pseudotype. Bovine fetal fibroblasts were transduced, selected using Geneticin®, and nuclear transfer was utilized to produce cloned transgenic embryos. There were 186 fusion attempts resulting in 160 fused embryos (fusion rate = 86%). Of these, 54 reached the blastocyst stage (34%) and 10 embryos were transferred into 5 recipient females (2 embryos per recipient). At 40 days, ultrasound revealed 1 confirmed pregnancy. Current plans are to harvest this fetus at 90 days and analyze it for evidence of myostatin knockdown. The production of transgenic animals exhibiting myostatin knockdown through lentiviral-mediated RNAi will demonstrate the utility of RNAi in the study of gene function in large animal models without the need for homologous recombination techniques, which are currently inefficient in species other than mice.

Neuroprotective effect of deep hypothermic circulatory arrest with low priming volume: study in a rabbit model

OBJECTIVE

The aim of the study was to investigate the possible neuroprotective effects of a low priming volume following deep hypothermic circulatory arrest (DHCA) in a rabbit model.

METHODS

Rabbits were randomized into three groups: DHCA with low priming volume (Group L), DHCA with high priming volume (Group H), and sham-operated group (Group S). The priming volume of Groups L and H were 75 ml and 210 ml, respectively. The rabbits were simultaneously placed on CPB and brain microdialysis, cooled to 16 to 18 degrees C with DHCA for 60 minutes. Physiological parameters were regularly recorded. The extracellular levels of glutamate, glucose, lactate, and pyruvate in the hippocampus were collected by microdialysis and measured by HPLC and a microdialysis analyzer. Brain damage was evaluated with light microscopy and electron microscopy and TUNEL staining.

RESULTS

In order to keep the mean arterial pressure and acid-base balance within defined physiological ranges, more doses of dopamine and sodium bicarbonate were administered in Group H than in Group L (P < 0.05). The ratios of lactate/glucose and lactate/pyruvate in Group H increased significantly compared with those in Group L from the beginning of weaning from CPB (P < 0.05). The levels of extracellular glutamate in the two DHCA groups increased significantly (P < 0.05). After weaning from CPB, the glutamate values in Group H remained at higher levels compared with those in Group L (P < 0.05). The percentage of injured neurons, TUNEL positive staining, and the mitochondria score of the hippocampus CA1 in Group H were significantly higher than in Group L (P < 0.05).

CONCLUSIONS

A low priming volume during DHCA could have a neuroprotective effect compared with a high priming volume.

145 REESTABLISHMENT OF AN EXTINCT STRAIN OF SHEEP UTILIZING ASSISTED REPRODUCTIVE TECHNOLOGIES

The objective of this study was to reestablish an extinct strain of sheep that exhibits spontaneous X-linked factor VIII deficiency closely mimicking human hemophilia A. Twenty female carriers of the trait, produced in a previous study (Bormann et al. 2006 Reprod. Fertil. Dev. 18, 201–202), were backcrossed using 3 straws of semen from their affected sire using either IVF or multiple ovulation embryo transfer (MOET). Eleven oocyte donors were synchronized with CIDRs (15 days) and superovulated with a declining dose of FSH (204 mg) twice daily for 3.5 days. Nine MOET donors were synchronized using CIDRs (14 days), superovulated with a declining dose of FSH (184 mg) BID for 3 days with pregnant mare serum gonadotropin (PMSG; 200 IU) given with the final dose of FSH, and given 1000 IU of hCG 12 h post-CIDR removal. Recipient ewes were synchronized using sponges (Ovakron, HeriotAgvet, Rowville, Victoria, Australia) containing 30 mg of flugestone acetate (14 days) and given PMSG (400 IU) at sponge removal, followed by 1000 IU of hCG 12 h post-sponge removal. Oocytes were collected via follicular aspiration during midventral laparotomy and matured as previously reported. Semen for IVF was prepared by centrifugation on a Percoll gradient. Oocytes and sperm were incubated in mTALP with 20% estrus sheep serum (modified from Bavister et al. 1977 Bio. Reprod. 16, 228–237) for 20 h, then vortexed to remove cumulus cells, and cultured in G1.3 medium (Vitrolife, Englewood, CO) with BSA until transfer. Embryos were surgically transferred into oviducts of recipients 24 to 48 h following IVF. The 9 MOET donors were surgically inseminated at the uterotubal junction with approximately 1–2.0 � 106 spermatazoa. Oviducts of eight of these ewes were flushed 48 h post-insemination with warm M199 containing Hanks salts, 25 mm HEPES, 10% FBS, and 0.5 µg mL–1 gentamicin. MOET embryos were surgically transferred to synchronized recipients within 5 h. One MOET donor was not flushed due to poor response and did not produce an offspring. Utilizing 140 ova, IVF produced 54 embryos for an embryo/oocyte rate of 38.6%. All IVF embryos were transferred into 15 recipients resulting in 3 lambs for a lamb/embryo rate of 5.5%. The MOET donors produced 38 embryos and 13 apparently unfertilized ova, generating an embryo/oocyte rate of 74.5%. MOET embryos were transferred into 21 synchronized recipients. MOET produced 16 lambs for a lamb/embryo rate of 42.1%. Co-transfer of 1 IVF and 1 MOET embryo into a single recipient produced one offspring. Utilizing multiple reproductive technologies over a two-year period, 8 hemophilic offspring (7 females and 1 male), 6 carrier females, and 6 unaffected males were produced. This strain of sheep will be used to produce affected offspring for stem cell-based therapies.

140 UTILIZATION OF LASER-ASSISTED HATCHING TO IMPROVE THE PREGNANCY RATE OF IN VITRO-FERTILIZED BOVINE EMBRYOS

In vitro-produced (IVP) bovine embryos are known to produce a lower pregnancy rate when compared to conventional in vivo-produced embryos. The inability of the IVP embryo to hatch from the zona pellucida (ZP) after embryo transfer is thought to be one contributing factor. This study was designed to evaluate the utilization of a microscope objective-mounted laser to cut the ZP to assist hatching prior to transfer into the recipient. Preliminary data were acquired to evaluate the effect of laser treatment on in vitro development and blastomere survival following treatment. In six replicates, bovine oocytes were in vitro-matured, fertilized, and cultured as per standard laboratory procedures (TransOva Genetics, Sioux Center, IA, USA). On Days 5, 6, and 7 of in vitro culture, embryos were randomly divided into 3 treatment groups: no treatment (Control; n = 63), sham ZP cut (Sham; n = 68), or ZP cut (Cut; n = 70). Control embryos were immediately returned to the incubator following selection. Sham embryos were exposed to all conditions as Cut except laser-assisted hatching. The XYClone� system is a 300-mW, class 1 laser that emits a 3.5-µm beam at a wavelength of 1480 nm (Hamilton Thorne Biosciences, Beverly, MA, USA). This laser was used to produce the Cut group, using a pulse strength of 90% and pulse length of 600 µs. Embryos were returned to culture until Day 8 when rates of embryonic development and the percentage of live cells were determined. Chi-square was used to analyze all data. No significant effect of treatment or day of exposure was noted in either the total number of developing embryos or the ratio of live cells in each embryo. Mean live cells ranged from 89 to 96% across all treatments regardless of day of treatment. To investigate IVP embryo viability after laser-assisted hatching, commercially produced embryos (TransOva Genetics, Sioux Center, IA, USA) were randomly divided into two groups on the day of transfer, Control or Cut. The ZP of treated embryos were cut with slightly reduced laser exposure of 80% pulse strength and pulse length of 500 µs on Day 7, immediately prior to transfer into estrus-synchronized recipients. Pregnancy rates were determined via ultrasonagraphy at Day 30 (n = 337) and, due to the commercial nature of this project, only a subset of the Day 30 pregnant cows was checked at Day 60 (n = 289). The 30-day pregnancy rates were 49.2% and 54.1% for Control (n = 189) and Cut (n = 148) embryos, respectively, and were not statistically different (P > 0.05). However, at Day 60, the pregnancy rates for the Control (45.7%; n = 166) and Cut groups (57.7%; n = 123) were statistically different (P < 0.05). These results demonstrate that laser-assisted hatching using the XYClone system can improve 60-day pregnancy rates for in vitro-produced embryos.

Inhibition of the Na+/H+ exchanger protects the immature rabbit myocardium from ischemia and reperfusion injury

BACKGROUND

This study investigated the cardioprotective effects of pharmacologic pretreatment with HOE642, a selective Na(+)/H(+ )exchanger (NHE) isoform-1 inhibitor, in immature rabbit hearts, as compared with ischemic preconditioning (IPC).

METHODS

For this study, 36 isolated immature New Zealand white rabbit hearts were equilibrated on the Langendorff apparatus. They were randomly divided into three groups: control group, IPC group, and HOE642 group. The hearts in each group were subjected to 60 min of ischemia plus 60 min of reperfusion (I/R). In the IPC group, the hearts were preconditioned by 5 min of ischemia followed by 10 min of reperfusion before I/R. In the HOE642 group, the hearts were pretreated with HOE642 (5 mumol/l) for 15 min before I/R. Left ventricular performance (LVDP, +dp/dt(max), -dp/dt(max)), coronory artery flow (CF), myocardial water content, adenosine triphosphate (ATP), cardiac-specific enzymes (creatine kinase [CK], CK fraction MB [CK-MB], and lacate dehydrogenase [LDH]), and intracellular calcium content were measured. Myocardial ultrastructure was observed under transmission electron microscopy.

RESULTS

The recovery rates for left ventricular performance and CF in both the HOE642 and the IPC groups increased compared with those for the control subjects (p < 0.05). Moreover, the recovery rates for LVDP, +dp/dt(max), -dp/dt(max), and CF in the HOE642 group were markedly higher than in the IPC group at most time points of reperfusion (p < 0.05). Compared with the control group, CK, CK-MB, and LDH in the HOE642 group were decreased significantly (p < 0.05), whereas only LDH was reduced in the IPC group (p < 0.05). Water content was significantly reduced and ATP reserve was significantly increased in both the IPC and HOE642 groups (p < 0.05). However, compared with the IPC group, water content in the HOE642 group was significantly lower (81.26% +/- 1.26% vs 83.58% +/- 1.27%; p < 0.05) and ATP was significantly higher (21.46 +/- 2.40 vs 17.66 +/- 1.50 mug/g; p < 0.05). The HOE642 pretreatment exerted a better effect of reducing calcium overload than IPC (265.8 +/- 41.1 vs 408.5 +/- 56.8 mg/kg dry weight; p < 0.05). The blinded ultrastructural assessment under transmission electron microscopy showed that HOE642 brought about more myocyte salvage than IPC.

CONCLUSION

This study demonstrated that HOE642 pretreatment is superior to IPC against ischemia and reperfusion injury in isolated immature rabbit myocardium.

Systemic AAV-9 transduction in mice is influenced by animal age but not by the route of administration

Adeno-associated virus (AAV) serotype-9 (AAV-9) has attracted great attention as an optimal vehicle for body-wide gene delivery. Here we examined the effect of animal age (newborn vs adult) and the route of administration (intravenous vs intra-arterial) on systemic AAV-9 transduction. We delivered an alkaline phosphatase (AP) reporter gene AAV vector (AV.RSV.AP) to either newborn (via either the facial vein or the left ventricular cavity) or adult (via tail vein) C57Bl/10 mice. At 12 weeks' postinfection, we examined the AP expression. We observed efficient transduction in multiple skeletal muscles and the heart, irrespective of the age or delivery route. However, the soleus muscle, which consists mainly of slow-twitch myofibers, was poorly transduced. Besides striated muscle, we also found consistent high-level transduction in the lung. Abundant AP-positive cells were seen in alveolar cells and vasculature, but not in bronchioles. Interestingly, several organs demonstrated an age-dependent profile. In particular, the aorta, liver and kidney were preferentially transduced in adult mice while the inner layer of retina was strongly transduced only following the neonatal administration. Taken together, our results demonstrate the robustness of intravascular AAV-9 delivery for muscle and lung gene therapy applications. The unique expression patterns in the aorta, liver, kidney and retina call for special attention when designing AAV-9 gene therapy applications for these organs.

Increased asynchronous release and aberrant calcium channel activation in amyloid precursor protein deficient neuromuscular synapses

Despite the critical roles of the amyloid precursor protein (APP) in Alzheimer's disease pathogenesis, its physiological function remains poorly established. Our previous studies implicated a structural and functional activity of the APP family of proteins in the developing neuromuscular junction (NMJ). Here we performed comprehensive analyses of neurotransmission in mature neuromuscular synapse of APP deficient mice. We found that APP deletion led to reduced paired-pulse facilitation and increased depression of synaptic transmission with repetitive stimulation. Readily releasable pool size and total releasable vesicles were not affected, but probability of release was significantly increased. Strikingly, the amount of asynchronous release, a measure sensitive to presynaptic calcium concentration, was dramatically increased, and pharmacological studies revealed that it was attributed to aberrant activation of N- and L-type Ca(2+) channels. We propose that APP modulates synaptic transmission at the NMJ by ensuring proper Ca(2+) channel function.