Speed of in vitro embryo development affects the likelihood of foaling and the foal sex ratio

The success of invitro embryo production (IVEP) in horses has increased considerably during recent years, but little is known about the effect of the speed of invitro embryo development. Blastocysts (n=390) were produced by intracytoplasmic sperm injection of IVM oocytes from warmblood mares, cryopreserved, thawed and transferred into recipient mares on Days 3, 4, 5 or 6 after ovulation. The time required for invitro-produced (IVP) embryos to reach the blastocyst stage was recorded (Day 7 vs Day 8). The likelihood of foaling was affected by the speed of invitro embryo development and recipient day after ovulation at transfer. The odds ratio for foaling was ~0.63 for transfer of Day 8 (46%) compared with Day 7 (56%) IVP blastocysts. The highest likelihood of pregnancy (72%) and foaling (60%) was observed when IVP blastocysts were transferred to recipient mares on Day 4 after ovulation. Finally, the sex (colt:filly) ratio was higher after transfer of Day 7 (71%:29%) than Day 8 (54%:46%) IVP blastocysts, suggesting that the speed of embryo development is sex dependent. In conclusion, the speed of invitro embryo development in our IVEP system affects the likelihood of foaling and the sex of the foal.

126 EXPRESSION OF THE RECEPTOR FOR ADVANCED GLYCATION END PRODUCTS IN BOVINE OOCYTES AND EMBRYOS CULTURED IN LOW AND HIGH OXYGEN

The receptor for advanced glycation end products (RAGE) is a member of the immunoglobulin superfamily that binds a broad repertoire of advanced glycation end products ligands. It is constitutively expressed at a high level during embryonic development, but its levels decrease in adult tissues. The RAGE-ligand interaction induces a series of signal transduction cascades and leads to the activation of several inflammatory signalling pathways. This is why RAGE is frequently associated with pro-inflammatory responses and it is implicated as an underlying condition in immune disorders, cardiovascular diseases, diabetes, Alzheimer’s disease, and cancer. However, the physiological function of RAGE during embryogenesis and in aging is largely undefined. The aim of this work was to determine the basal levels on RAGE expression in bovine oocytes (germinal vesicle, GV, and in vitro-matured metaphase II) and in vitro-derived embryos developed in SOF medium, by qPCR (3 replicates each containing pooled RNA from 20 oocytes or embryos, t-test P < 0.05) and immunostaining. The expression of RAGE was similar in bovine oocytes, in cleaving embryos up to morula, and afterward declined at the blastocyst stage. However, a more detailed investigation, by the separation of the inner cell mass (ICM) from the trophoblast, indicated that expression decreased only in the trophoblast (over 5-fold) while it was maintained high in the isolated ICM. In the trophoblast, compared to the ICM, this finding coincided with an elevated expression of PSMA6 gene, which encodes for the 20S proteasome subunit, and ubiquitin (UBB) gene, suggesting a link between proteasome activity and RAGE expression. Then we investigated the expression of RAGE and the proteasome-ubiquitin system in embryos cultured under different oxygen concentrations [i.e. physiological (5%) or high (20%) O2 levels]. Preliminary results showed that RAGE expression was lower in embryos cultured in 20% O2 and conversely the expression of PSMA6 and UBB genes was higher. Thus, these results indicate that the activity of RAGE-mediated stress response pathway in pre-implantation bovine embryos is affected by O2 tension during in vitro culture. This work was funded by projects Epihealth FP7 n. 278418, EpiHealthNet FP7-PEOPLE-2012-ITN n. 317146, and Fecund FP7 n. 312097.

203 SINGLE-STEP GENE EDITING OF 3 XENOANTIGENS IN PORCINE FIBROBLASTS USING PROGRAMMABLE NUCLEASES

Programmable nucleases (ZFN, Tal Effector Nucleases, and CRISPR) opened a new era for mammal genome editing, in particular for the pigs used for xenotransplantation. Multiple gene editing events are required both for knockout (KO) of xenoantigens and for targeted integration of human protective genes (Perota et al. 2016 J. Genet. Genomics 43, 233–23). The objective of the present work was to edit selected pig lines to KO the enzymes coding for the most relevant xenoantigens (i.e. GGTA1, CMAH, and B4GalNT2), combining Talens and CRISPR/Cas9 technologies to magnetic beads selection (Li et al. 2013 Xenotransplantation 22, 20–31). Primary porcine adult fibroblasts were transfected using Nucleofector (V-024 program). In a single reaction 2 × 106 fibroblasts were co-transfected using 2 different sets of TALENS (4 μg/set) specific for CMAH (Conchon et al., 2013) and GGTA1 (Perota et al., 2015) genes together with B4GalNT2-specific CRISPR/Cas9 expression vector (2 μg; pX330-B4GalNT2; Estrada et al., 2015). Eight days post-transfection (DPT), Gal–/– cells were selected initially using biotin-conjugated IB4 lectin (Sigma, St. Louis, MO, USA) and magnetic beads (Dynabeads M-280, Thermo Fisher Scientific, Waltham, MA, USA). The selected cells were then plated on 150-mm Petri dishes (200 cells/dish) and cultured for 10 days. Selected colonies were expanded for PCR analysis and cryopreserved for somatic cell nuclear transfer (SCNT). All colonies were analysed by PCR for CMAH gene and their resulting products were digested with HindIII (HindIII-RFLP). Colonies that lost wild-type HindIII as a consequence of Talens effected deletion were PCR characterised for GGTA1, selecting those that had detectable Indels after gel electrophoresis and finally analysed by PCR for B4GalNT2. All PCR products were validated by sequencing for all the 3 genes of interest (TopoTA, Thermo Fisher Scientific). Selected colonies were used as nuclear donors for SCNT (Lagutina et al., 2006). Eight DPT we obtained 3.45 ×106 cells. About 6.0 × 103 Gal-negative cells (0.17%) were collected from the supernatant after magnetic beads separation. Eighteen DPT, 120 colonies were picked up and their HindIII-RFLP analyses on CMAH gene revealed that 22 colonies (18.3%) were KO for both CMAH alleles. Of these 22 colonies following electrophoretic analyses of GGTA1-PCR products, 13 colonies had detectable Indels. These 13 colonies were finally PCR analysed and sequenced for B4GalNT2 and sequenced. Final sequencing results confirmed that 2 colonies (1.6%) resulted in KO for the 3 genes. Three different zona-free SCNT experiments were done and 579 reconstructed embryos were obtained. On Day 7, 322 morulae or blastocysts (56%) were transferred in 3 synchronised sows and 2 (66%) became pregnant. In conclusion, after gene editing with programmable nucleases, combining beads-mediated selection with well-designed molecular analyses, we developed a multistep assay that can be used efficiently to detect desired gene edited events in cell colonies suitable for the SCNT. Embryos generated after SCNT were able to establish pregnancies at a high rate. This work is supported by European FP7 grants Translink (n° 603049) and Xenoislet (n° 601827).

Differential Response of Human Embryonic Stem and Somatic Cells to Non-Cytotoxic Hydrogen Peroxide Exposure: An Attempt to Model In Vitro the Effects of Oxidative Stress on the Early Embryo

Human Embryonic Stem Cells (hESCs) potentially offer a unique in vitro model to study how an adverse environment during the early developmental stages post-fertilization can affect the physiology of the undifferentiated embryonic stem cells existing in the early embryo and predispose to long term effects on the offspring, according to the Developmental Origins of Health and Disease (DOHaD) concept. A number of unfavourable conditions can affect the development of the early embryo inducing oxidative stress both in vivo, for instance in gestational diabetes and in vitro, when embryos are derived from Assisted Reproductive Technologies (ART). Therefore, the aim of this study was the development of a novel in vitro model to analyse the effects of oxidative stress and the antioxidant response against Reactive Oxygen Species (ROS) in embryonic stem cells in comparison with somatic cells, fibroblasts and endothelial cells. To this purpose we designed an in vitro protocol based on hydrogen peroxide (H₂O₂) treatment of 72 h, in order to better resemble the period of embryonic development from the early cleavages to the blastocyst stage. We demonstrate that H₂O₂ treatment induces the modification of crucial oxidative stress biomarkers like ROS and lipid peroxidation levels, and mobilizes several antioxidant enzymes through NFkβ translocation. Moreover we show differences between somatic and embryonic cells in their antioxidant response towards H₂O₂ induced damage. Therefore this study presents a promising in vitro model to investigate the effects of oxidative stress conditions on early human embryonic cells.

Isolation and in vitro characterization of bovine amniotic fluid derived stem cells at different trimesters of pregnancy

Amniotic fluid (AF) is a source of multipotent mesenchymal stem cells (MSCs), very promising cells for tissue engineering in clinical application. The aim of this work was to isolate and characterize cells isolated from bovine AF as alternative sources of primitive multipotent stem cells in a species that could be a large-animal model for biomedical and biotechnology researches. Samples were recovered, at slaughterhouse, from 39 pregnant cows at different trimesters of pregnancy and cells were cultured in vitro. At passages (P) 3 and 7 differentiation towards chondrogenic, osteogenic and adipogenic lineages was induced. Flow cytometry analysis for CD90, CD105, CD73, CD44, CD34, CD45 and CD14 was performed, immunocytochemistry (ICC) for Oct4, SSEA4, α-SMA, Vimentin, N- and E- Cadherin and CK and qPCR analysis for OCT4, NANOG and SOX2 were carried out. The cell yield was significantly higher in the first trimester compared to the second and the third one (P < 0.05). Cells were isolated from 25/39 samples and cell population appeared heterogeneous. Two main cell types were identified in samples from all trimesters: round- (RS) and spindle-shaped (SS) cells. 17/25 samples showed both populations (mixed, MX). Both cell types showed MSC-markers and differentiation capability with some variability related to the passages. The SS-population also expressed low levels of stemness markers such as NANOG and SSEA4 but not OCT4. Bovine AF shows a heterogeneous cell population containing also MSCs, multipotent cells that represent an intermediate stage between embryonic stem cells and adult ones.

215 LIVE PIGLETS GENERATED BY SOMATIC CELL NUCLEAR TRANSFER FOLLOWING TARGETING OF A PORCINE ENHANCED GREEN FLUORESCENT PROTEIN LINE MEDIATED BY ZINC-FINGER NUCLEASES TO ESTABLISH CLONED HYGROMYCIN-RESISTANT PRIMARY CELL LINES SUITABLE FOR Cre-MEDIATED RECOMBINASE-MEDIATED CASSETTE EXCHANGE

Recently, site-specific nucleases (zinc-finger nucleases, ZFN; TAL effector nucleases; and CRISPR) emerged as powerful tools for gene modification of different cells types and enhanced green fluorescent protein (EGFP)-specific ZFN were successfully used in the rat (Geurtz et al. 2010) and in the pig (Watanabe et al. 2010; Whyte et al. 2010). Previously (Brunetti et al. 2008 Clon. Stem Cells), we generated an EGFP transgenic porcine line (Verro2GFP) characterised by a single integration of pCAGGS-EGFP cassette, high ubiquitous EGFP expression, Mendelian transgene transmission, and expression in F1. The aim of this work was to modify a transcriptionally active GFP-locus into one suitable for Cre-mediated recombinase-mediated cassette exchange (RMCE), using EGFP-specific ZFN. Homology arms for promoter-less targeting vector were derived from pCAGGS-EGFP vector (promoter fragment = left-homology-arm = LHA; polyA sequence = right-homology-arm = RHA). Cloning floxed (lox2272/lox5171) hygromycin resistance coding sequence between LHA and RHA sequences, we generated the targeting/RMCE vector (pB5′3′Hygro-PL) and its positive control (C+) for PCR set-up (100–1000 plasmid copies). Verro2GFP fibroblasts cultured in DMEM+M199(1 : 1) + 10% FCS, bFGF in 5% CO2, 5% O2, were transfected using Nucleofector (V-024 program). In ZFN-mediated gene targeting, 2 μg of each ZFN coding vector (Sigma-CompoZr®) and 2 μg of pB5′3′Hygro-PL/KpnI vector were used to “nucleofect” 1.4 × 106 Verro2GFP fibroblasts in 2 experiments. Transfected cells were plated in 20 Petri dishes (Ø = 150 mm) and cultured under hygromycin selection (200 μg mL–1) for 15 days. After 12 days of drug selection, 82 resistant colonies were picked up and expanded in 24 multiwell plates for SCNT. All colonies were PCR screened and 45 (54.9%) colonies were positive. Four colonies were used in zona-free SCNT experiments with 140 Day 6 compacted morulae/blastocysts transferred into 2 synchronized sows that both became pregnant. One pregnancy went to term and delivered 5 live animals and 5 stillborn with correct hygromycin cassette integration, detected by PCR. The PCR products were sequenced in 7 animals to verify integration of promoterless targeting vector and in all 7 sequenced samples we obtained a correct insertion without any substitution/deletion. Using hygromycin selection in these experiments, we demonstrated that ZFN-mediated gene targeting can be easily done with high efficiency and is compatible with living animals. Moreover, we have validated a feasible SCNT-tested platform for further Cre-mediated site-specific gene modifications. This work is supported by a grant (Superpig) co-financed by Lombardy Region through the Fund for Promoting Institutional Agreements.

Modeling amyotrophic lateral sclerosis in hSOD1 transgenic swine

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that occurs in two clinically indistinguishable forms: sporadic (SALS) and familial (FALS), the latter linked to several gene mutations, mostly inheritable in a dominant manner. Nearly 20% of FALS forms are linked to mutations in the Cu/Zn superoxide dismutase (SOD1) gene. Research on ALS relies on transgenic models and particularly on mice carrying a glycine-to-alanine conversion at the 93rd codon (G93A) of the hSOD1 gene. Although G93A transgenic mice have been widely employed in clinical trials and basic research, doubts have been recently raised from numerous reliable sources about their suitability to faithfully reproduce human disease. Besides, the scientific community has already foreseen swine as an attractive and alternative model to nonhuman primates for modeling human diseases due to closer anatomical, physiological and biochemical features of swine rather than rodents to humans. On this basis, we have produced the first swine ALS model by in vitro transfection of cultured somatic cells combined with somatic cell nuclear transfer (SCNT). To achieve this goal we developed a SOD1(G93A) (superoxide dismutase 1 mutated in Gly93-Ala) vector, capable of promoting a high and stable transgene expression in primary porcine adult male fibroblasts (PAF). After transfection, clonal selection and transgene expression level assessment, selected SOD1(G93A) PAF colonies were used as nuclei donors in SCNT procedures. SOD1(G93A) embryos were transferred in recipient sows, and pregnancies developed to term. A total of 5 piglets survived artificial hand raising and weaning and developed normally, reaching adulthood. Preliminary analysis revealed transgene integration and hSOD1(G93A) expression in swine tissues and 360° phenotypical characterization is ongoing. We believe that our SOD1(G93A) swine would provide an essential bridge between the fundamental work done in rodent models and the reality of treating ALS.

34 PRE-IMPLANTATION DEVELOPMENT OF HORSE SOMATIC CELL NUCLEAR TRANSFER EMBRYOS ORIGINATED FROM METAPHASE I OOCYTES

Because of the limited availability of horse oocytes and their wide maturation window that leads to the existence of a subpopulation of oocytes with significantly longer maturation period, horse cloning would benefit from the possibility of also using metaphase I oocytes (Choi et al. 2009 Cloning Stem Cells). The scope of this work was to compare the developmental ability of cloned horse embryos constructed using oocytes in metaphase I (MI) and II (MII). Oocytes of slaughtered mares were matured for 27 h in DMEM/F12 with 10% FCS, 1 µL mL–1 of insulin-transferrin-selenium (ITS), 1 mM sodium pyruvate, 50 ng mL–1 of long-epidermal growth factor, 100 ng mL–1 of long-insulin-like growth factor-I, and 0.1 IU mL–1 each of FSH and LH, denuded of cumulus and enucleated using a zona-free method (Lagutina et al. 2005 Reproduction). Oocytes with a visible polar body were classified as MII and those with no polar body as potential MI. During enucleation, oocytes having a metaphase plate only were confirmed as MI; oocytes in anaphase and telophase were classified as MII. Adult skin fibroblasts of passages 2 to 10 were cultured in TCM 199/DMEM with 10% FCS and serum starved for 1 to 2 days before NT. Nuclear-transfer embryos were constructed after washing of zona-free oocytes in 400 µg mL–1 of phytohemagglutinin P and attachment of each to a single cell in HEPES-SOF by fusion with 2 direct-current (DC) pulses of 1.2 kV cm–1 applied for 30 µs in fusion medium. One hour after fusion, embryos were activated by 5 µM ionomycin for 4 min, followed by culture in 5 µg mL–1 of cycloheximide and 1 mM DMAP in SOFaa for 3 h. Embryos were cultured in SOFaa in 5% CO2 and 5% O2 at 38.5°C. Half of the medium was renewed on Day 3 and replaced on Day 5 with DMEM/F12 with 5% FCS and 5% serum replacement. Cleavage was assessed 48 h after activation and the rate of blastocyst formation was recorded at Day 8. The data were compared by chi-square test. The development ability of MI embryos assessed by cleavage and blastocyst formation was significantly lower than of MII embryos (Table 1). The obtained MI blastocysts were smaller than their MII counterparts. These data demonstrate that MI oocytes account for 20% of the total oocytes after 27 h of maturation, have a lower developmental competence to form blastocysts after NT, and the blastocysts obtained are of smaller size and likely less viable. Therefore, the use of MI oocytes can only marginally improve the outcome of horse cloning. Table 1.Embryo development after SCNT using oocytes in metaphase I or II

184 INTERCELLULAR COUPLING AND CHROMATIN CONFIGURATION STATE IN HORSE OOCYTE - CUMULUS CELL COMPLEXES OF DIFFERENT ORIGINS

Fewer follicles and of variable size are found at any time on the mare ovary compared with other livestock species, also influenced by seasonal variation. This is reflected on the population of cumulus–oocyte complexes (COC) collected that is characterised by a high heterogeneity. Recovered immature oocytes presumably need different culture conditions. The main factors contributing to this high heterogeneity are the follicle diameter, the status of the cumulus oophorus, and the reproductive seasonality. Therefore, the aim of the present study was to assess the nuclear chromatin configuration and the oocytes–cumulus cell gap junction-mediated communication (GJC) functionality in COC of different origins because these parameters are indicative of the oocyte’s metabolic state and should be taken into account when designing IVM strategies. The COC with compact (Cp) or expanded (Ex) cumulus oophorus were collected from follicles of different diameters (<1, 1–2, and >2 cm) in October–November, January–February, and April–May. The GCJ functionality was assessed by Lucifer Yellow microinjection and chromatin configuration was evaluated by Hoechst and Lacmoid staining, after cumulus cells removal. Data were obtained from a total of 1003 oocytes and were analysed by chi-squared test. Overall, GJC functionality was impaired in the majority of Ex COC in each follicle category, even though a certain proportion of them had open GJC (% of Ex COC with open GJC was 39.7, 29.3, and 39.3 in <1, 1–2, and >2 cm follicles, respectively). Moreover, the proportion of Ex COC with open GJC did not differ significantly between periods (% of Ex COCs with open GJC in October–November, January–February, and April–May was, respectively, 43.3, 28.6, and 41.7 in <1 cm follicles; 45.5, 19.3, and 26.47 in 1–2 cm follicles; 66.7, 50, and 16.7 in >2 follicles). On the contrary, the majority of Cp COC from follicles <1 and 1–2 cm, showed open GCJ in October–November and April–May, whereas they decreased significantly in January–February. This tendency was not maintained in Cp COC from follicles >2 cm, where GJC functionality did not differ significantly between periods (% of Cp COC with open GJC in October–November, January–February, and April–May was, respectively, 74.4, 35.7, and 75 in <1 cm follicles; 73.8, 42.1, and 67.7 in 1–2 cm follicles; 58.3, 58.3, and 68.6 in >2-cm follicles). Chromatin configuration analysis revealed that the highest proportion (23.9%) of oocytes with fibrillar chromatin was found in Cp oocytes from <1 cm follicles, whereas the proportion of oocytes with fibrillar chromatin ranged from 5.4 to 12.5% in the other groups. Moreover, the increase in follicle diameter was generally associated with an increase of chromatin condensation in Cp COC. Interestingly, the chromatin configuration distribution did not differ significantly among seasons. Our data could be useful in setting up new in vitro cultural strategies aimed to improve horse-assisted reproductive technology efficiency as well as in the understanding of horse oocyte biology. Funding: Grant no. 26096200 ‘Ex Ovo Omnia’ from Regione Sardegna & Lombardia and ‘Dote Ricerca Applicata’ (VL and IT).

Somatic cell nuclear transfer and transgenesis in large animals: current and future insights

Somatic cell nuclear transfer (SCNT) was first developed in livestock for the purpose of accelerating the widespread use of superior genotypes. Although many problems still exist now after fifteen years of research owing to the limited understanding of genome reprogramming, SCNT has provided a powerful tool to make copies of selected individuals in different species, to study genome pluripotency and differentiation, opening new avenues of research in regenerative medicine and representing the main route for making transgenic livestock. Besides well-established methods to deliver transgenes, recent development in enzymatic engineering to edit the genome provides more precise and reproducible tools to target-specific genomic loci especially for producing knockout animals. The interest in generating transgenic livestock lies in the agricultural and biomedical areas and it is, in most cases, at the stage of research and development, with few exceptions that are making the way into practical applications.

Characterisation of a neural teratogenicity assay based on human ESCs differentiation following exposure to valproic acid

The development of in vitro testing strategies for chemical and drug screening is a priority need in order to protect human health, to increase safety, to reduce the number of animals required for conventional testing methods and finally to meet the deadlines of current legislations. The aim of this work was to design an alternative testing method based on human embryonic stem cells for the detection of prenatal neural toxicity. For this purpose we have created a model based on the generation of neural rosettes, reproducing in vitro the gastrulation events recapitulating the formation of the neural tube in vivo. To validate the model we have exposed this complex cell system to increasing concentrations of valproic acid, a known teratogenic agent, to analyse the morphological and molecular changes induced by the toxicant. Specific assays were applied to discriminate between cytotoxicity and specific neural toxicity. Transcriptomic analysis was performed with a microarray Affimetrix platform and validated by quantitative real time RT-PCR for the expression of genes involved in early neural development, neural tube formation and neural cells migration, key biological processes in which the effect of valproic acid is most relevant. The results demonstrated that neural rosette cells respond to valproic acid exposure with molecular and morphological changes similar to those observed in vivo, indicating that this method represents a promising alternative test for the detection of human prenatal neural toxicity.

157 PREGNANCIES AND CALVES AFTER TRANSFER OF IN VITRO-PRODUCED RIVER BUFFALO EMBRYOS AFTER CRYOPRESERVATION

In the buffalo, the use of embryo-based biotechnologies for breeding and genetic improvement is still very limited because multiple-ovulation embryo transfer delivers poor results compared with cattle and in vitro embryo production has been used mainly for research purposes. At present, very few reports are available on the transfer of in vitro-produced (IVP) and cryopreserved buffalo embryos. Therefore, the scope of this work was to perform a pilot study to evaluate the viability of frozen-thawed IVP embryos by nonsurgical embryo transfer to recipients in an IVF-embryo transfer program on a farm located on the north coast of Colombia, South America. Buffalo oocytes were recovered at the slaughterhouse from selected donors, matured in vitro for 18 to 20 h in TCM-199 + 10% FCS and 0.5 IU of FSH and 0.5 IU of LH in 5% CO2 at 38.5°C. Four different bulls were used for IVF. After thawing, the semen was separated on a Percoll® gradient and then diluted into SOF-IVF media supplemented with 1 μg mL–1 of heparin and phenylalanine. Presumptive zygotes were cultured in modified SOF supplemented with MEM amino acids for 6 days. Half of the medium was replaced on Day 4 and 6. Developing embryos were selected for freezing on Day 6 and 7. Grade 1 embryos were frozen at the blastocyst stage by slow cooling in 10% glycerol or 1.5 M ethylene glycol. Recipients (heifers n = 79 and uniparous cows n = 17) were synchronized using the CIDR-Synch protocol: on Day 0, gonadotropin-releasing hormone was injected and a CIDR was inserted; on Day 7, prostaglandin F2α was administered; on Day 9, the CIDR was removed; on Day 11, a second injection of gonadotropin-releasing hormone was given; and on Day 17, the embryo was transferred. Each female received, nonsurgically, 1 or 2 embryos in the ipsilateral horn to the functional corpus luteum evaluated by ultrasonography. Pregnancies were evaluated by ultrasonography 30 days after transfer and confirmed by rectal palpation 30 days later. This work was performed in 2 successive experiments during the breeding seasons (January and December, respectively). Overall, 96 recipients were transferred, with 136 embryos obtaining 23 pregnancies (24.2%). There were no statistical differences in pregnancy rate between heifers and cows (25.3 vs 17.7%) and between single (n = 56) and double (n = 39) embryo transfers (21.4 vs 27.5%) by chi square test (P > 0.05). To date, 4 females and 5 males have been born by spontaneous calving (1 stillborn male due to dystocia), 3 pregnancies have been aborted (13%) and 11 pregnancies are ongoing (>7 months). The pregnancy rate obtained in this study in farm conditions (24.2%) is lower than generally obtained with frozen IVP cattle embryos, but it is still a good result in buffalo, where even conventional AI provides a lower success rate as compared with cattle. Finally, this work demonstrates that in vitro embryo production can be successfully implemented in buffalo breeding programs for the exploitation of superior genetics. This work was supported by Regione Lombardia, Por Fers 2007–2013, n°13827741, InnovaB.

234 EFFICIENT EXPRESSION OF HUMAN ENDOTHELIAL PROTEIN C RECEPTOR AND HUMAN THROMBOMODULIN IN TRANSFECTED PIG PRIMARY hCD55+-GAL–/– FIBROBLASTS USING F2A EXPRESSION VECTOR

The genetic engineering of the pig genome for xenotransplantation studies requires the insertion of different transgenes to create multi-transgenic pigs. In order to simultaneously add more transgene in a single genetic insertion, we constructed a polycistronic vector using the F2A self-cleaving peptide. Moreover, this solution has the added advantages of preventing possible segregation during breeding of the animals and of guaranteeing an equimolar production of chosen transgenes. The scope of this work was the construction and validation of an ubiquitous F2A-bicistronic expression vector for human thrombomodulin (hTM) and human endothelial protein C receptor (hEPCR) genes in pig primary hCD55-GAL–/– cells to establish transgenic fibroblasts colonies, to be used for somatic cell nuclear transfer (SCNT) to generate pigs for xenotransplantation research. The expression vector consisted of pCAGGS promoter (CMV-IE+chicken β actin) followed by hEPCR-furinF2A-hTM coding sequence. The resulting expression cassette was inserted between 2 insulators obtained from the 5′ MAR region of chicken lysozyme. Outside of this insulated structure, there is a loxable puromycin selection cassette. The resulting purified and linearized expression vector (pEFTM/Lgu I = 5 μg) was transfected into hCD55-GAL–/– primary fibroblasts (1 × 106), using Nucleofector (Amaxa, Lonza, Cologne, Germany), in parallel for comparative purposes we cotransfected the 2 pCAGGS-monocistronic vectors for the same transgenes (hEPCR and hTM = 1:3, 5 μg). Transfected cells were selected with puromycin (1 μg mL–1) for 15 days. After 8 days of selection, resistant colonies were picked up and expanded into 24-well plates for cryopreservation and analyses. Bicistronic transfection produced 20 clones and cotransfection only 8 clones that were analysed by Western blot (WB) and by immunocytochemistry (ICC) using polyclonal antibody anti-EPCR (1:250, R&D) and monoclonal antibody ab6980-Abcam (1:5000, Abcam, Cambridge, UK) in WB; polyclonal antibody RCR252 (1:100, Sigma-Aldrich, St. Louis, MO, USA) and monoclonal antibody ab6980-Abcam (1:100, Abcam) for ICC. Seventeen bicistronic clones (85%) and 2 cotransfected monocistronic clones (25%) were positive for both transgenes using WB. After ICC analyses, only 11 bicistronic colonies (55%) and 1 cotransfected colony (12.5%) uniformly expressed the desired transgenes and were selected for SCNT. The pCAGGS promoter maintained its strong expression also using the hEPCR-FurinF2A-hTM coding sequence and this bicistronic solution permitted us to improve our results obtained with co-transfection. Availability of hEPCR+ hTM+ hCD55+-GAL–/– colonies will allow us to obtain a new transgenic background for future xenotransplantation projects. This study was supported by EU grant no. LSHB-CT-2006-037377 (Xenome) and by Regione Lombardia (Superpig project).

Embryonic genotype and inbreeding affect preimplantation development in cattle

Infertility in cattle herds is a growing problem with multifactorial causes. Embryonic genotype and level of inbreeding are among the many factors that can play a role on reproductive efficiency. To investigate this issue, we produced purebred and crossbred bovine embryos by in vitro techniques from Holstein oocytes and Holstein or Brown Swiss semen and analyzed several cellular and molecular features. In the first experiment, purebred and crossbred embryos, obtained from abattoir oocytes, were analyzed for cleavage, development to morula/blastocyst stages, amino acid metabolism and gene expression of developmentally important genes. The results indicated significant differences in the percentage of compacted morulae, in the expression of three genes at the blastocyst stage (MNSOD, GP130 and FGF4) and in the utilization of serine, asparagine, methionine and tryptophan in day 6 embryos. In the second experiment, bovine oocytes were collected by ovum pick up from ten Holstein donors and fertilized with the semen of the respective Holstein sires or with Brown Swiss semen. The derived embryos were grown in vitro up to day 7, and were then transferred to synchronized recipients and recovered on day 12. We found that purebred/inbred embryos had lower blastocyst rate on days 7-8, were smaller on day 12 and had lower expression of the trophoblast gene PLAC8. Overall, these results indicate reduced and delayed development of purebred embryos compared with crossbred embryos. In conclusion, this study provides evidence that embryo genotype and high inbreeding can affect amino acid metabolism, gene expression, preimplantation development and therefore fertility in cattle.

43 SHORT- AND LONG-LASTING EFFECTS OF TRICHOSTATIN A TREATMENT OF SCNT EMBRYOS IN CATTLE

Both preimplantation and full-term development of mouse somatic cell nuclear transfer (SCNT) embryos are significantly enhanced by treatment with trichostatin A (TSA), an inhibitor of histone deacetylase (Kishigami et al. 2006 Biochem. Biophys. Res. Commun. 340, 183–189; Rybouchkin et al. 2006 Biol. Reprod. 74, 1083–1089). The present study was designed to examine the effect of TSA treatment on preimplantation and full-term development of bovine cloned embryos. To investigate the effect of TSA on bovine NT embryos development, we treated them with 50 nM TSA during the first 10 h after activation. Bovine NT-embryos were reconstructed using adult fibroblasts of 2 female donors (A and B) with significantly different in vitro cloning efficiency (respectively, 84/245; 34.3% v. 155/298; 52.1% blastocyst D7, P ≤ 0.05, chi-square test). TSA treatment significantly improved blastocyst rate in A, however did not affect development in B (56.3% and 50.5%, respectively). The level of acetylated histone H3K9 10 h after activation detected by anti-acH3K9 antibody was significantly increased after TSA-treatment in A (P ≤ 0.05, Student’s t-test) but did not change in B, thus demonstrating that the levels of histone acetylation in cloned embryos correlate with their in vitro developmental potential. To evaluate the long-lasting effect of TSA-treatment on the full-term development of cloned embryos, SCNT embryos derived from 4 female donor animals were reconstructed. 196 TSA-treated embryos at the blastocyst stage were transferred into 98 recipients and 2 calves (2%) were born. In the control group, 167 embryos were transferred into 141 recipients and 3 calves (2.1%) were born. Our data show that cell lines demonstrate different susceptibility to TSA that may affect reprogramming of the somatic genome with low level of acetylation resulting in higher in vitro embryo development. However, TSA does not improve overall cloning efficiency in cattle, measured as full-term development. Project partly supported by EU grants Plurisys (n 22348), Xenome (LSHB-CT-2006-037377) and Regione Lombardia.

377 EMBRYO PRODUCTION BY OVUM PICKUP-INTRACYTOPLASMIC SPERM INJECTION-IVC IN AN EQUINE OVUM PICKUP PROGRAM USING SEMEN FROM FERTILE AND INFERTILE STALLIONS

The introduction in equine reproduction of ovum pickup (OPU) combined with intracytoplasmic sperm injection (ICSI), IVC, and embryo transfer, has allowed for the production of offspring from donors and stallions that could not reproduce by conventional techniques. For this reason, we used in our OPU-ICSI-IVC program both fertile stallions and stallions with field records of low or no fertility. Overall, 805 and 584 OPU oocytes were fertilized with sperm from fertile and infertile stallions, respectively. Cleavage rate was statistically lower in the latter group (65.94 v. 59.24%, chi square test; P < 0.05) but embryo development was similar (11.67 v. 8.20% blastocysts/injected oocytes, chi-square test). In order to further investigate the stallion effect on embryo development, we selected 3 stallions with low (A) or no (B, C) fertility in the field and we compared the results of the OPU program with embryo development obtained using oocytes recovered from abattoir ovaries and matured, fertilized, and cultured in vitro as the OPU oocytes. Part of the abattoir oocytes was fertilized with a stallion with known high fertility both in vivo and in vitro (abattoir fertile). Overall, the results (shown in the table) suggest a reduction in the efficiency of stallions A, B, and C compared with to the fertile stallion used as control (10.79, 7.69, and 5.0% v. 17.35%, respectively). For stallions A and B, the efficiency was further reduced in the OPU setting, indicating that the female component can play a role in the overall efficiency of the procedure. In particular, 4 mares out of 8 had a history of no pregnancy and all mares had some rate of inbreeding with the respective stallion used for the ICSI. Instead, the oocytes from the abattoir ovaries were collected in large pools from several mares, representing an average oocyte quality, and the mares were of different breed than the stallions. All data were analyzed by chi-square test and significance was set at P < 0.05. In conclusion, we demonstrated that, for those stallions in which fertility in the field is low or absent, OPU-ICSI-IVP is a suitable choice to obtain embryos, although the efficiency is variable depending not only on the stallion but also on the origin of the oocytes. Table 1.Stallion effect on embryo development of ovum pickup (OPU) and abattoir oocytes This work was supported by Fondazione Cariplo and Regione Lombardia.

Protective effects of the cumulus-corona radiata complex during vitrification of horse oocytes

Vitrifying oocytes is a potentially valuable means of preserving the female germ line, but significantly compromises oocyte developmental competence. This study examined the hypothesis that the cumulus complex protects the oocyte during vitrification. Vitrified-warmed immature cumulus oocyte complexes (COCs) were labelled with a plasma membrane impermeant DNA marker (ethidium homodimer-1) to examine the percentage and location of dead cumulus cells, and to investigate the effect of the proportion of dead cells (+1,+2 or +3) on the success of in vitro maturation (IVM). Further, oocytes were labelled for connexin-43 or injected with Lucifer yellow dye to determine whether the integrity of the gap junctions between an oocyte and its cumulus was compromised by vitrification. Finally, the effect of denuding immature and mature oocytes on their ability to withstand vitrification was examined. Cryopreserving immature COCs increased the number of dead cumulus cells (13 vs 2.6% for controls; P<0.05). However, an increased proportion of dead cumulus cells did not affect post-warming maturation rates (∼30% MII) presumably because dead cells were located at the periphery of the cumulus mass and cumulus-oocyte gap junction communication was not disrupted. Moreover, cumulus removal prior to IVM or vitrification indicated that while the cumulus does protect immature oocytes during vitrification it does so by mechanisms other than support during maturation. Cumulus presence was also found to protect mature equine oocytes against vitrification-induced damage since cumulus-enclosed MII oocytes preserved their meiotic spindle quality better during vitrification than denuded oocytes (38.1 vs 3.1% normal spindles; P<0.05).

262 ICSI OF EQUINE OOCYTES WITH SEX-SORTED FROZEN-THAWED SEMEN RESULTS IN LOW CLEAVAGE RATE BUT NORMAL EMBRYO DEVELOPMENT AND PREGNANCIES

Sorting of sperm by flow cytometer has allowed selection of offspring of predetermined sex in several species by artificial insemination, although the success rate is often lower than with non-sexed semen. In horses, the problem was partially overcome with hysteroscopic insemination using sex-sorted fresh sperm. However, when sex-sorted frozen–thawed sperm were used the pregnancy rate was heavily reduced in comparison with non-sexed frozen–thawed semen. Because it has been demonstrated that in vitro assisted reproductive techniques, namely intracytoplasmic sperm injection (ICSI), has permitted live foals to be obtained using sperm with low fertility in the field, in this study we investigated the possibility of using ICSI with sexed-sorted frozen–thawed sperm for equine embryo production in vitro. Briefly, semen was collected from two Standardbred stallions of proven fertility (Stallions A, B), sorted using a MoFlo SX flow cytometer and frozen (Johnson LA and Welch GR 1999 Theriogenology 52, 1323–1341). Sex-sorted and control non-sexed frozen semen (two stallions of in vitro proven fertility: C, D) was thawed, centrifuged on a Percoll gradient, washed and diluted 1:1 in PVP before ICSI. Oocytes were collected from ovaries of slaughtered mares and matured in vitro. Metaphase II oocytes were injected with sperm, subsequently cultured up to the blastocyst stage and frozen conventionally in 10% of glycerol (Galli et al. 2002 Theriogenology 58, 713–715). Six embryos from sexed-sorted sperm were thawed and non-surgically transferred in naturally cycling synchronous recipient mares. Results are summarized in Table 1. Overall, 70 and 58 (stallion A, B) and 30 and 15 (stallion C, D) oocytes were injected with sex-sorted or control frozen–thawed sperm, respectively. Mean cleavage rates were 20.3% for sorted sexed sperm and 71.1% for control, showing a significantly lower cleavage rate for sexed sperm. This difference was reflected in the number of blastocysts obtained (4.7% v. 20.0%). From the 6 frozen–thawed embryos derived from sexed sperm, that were transferred, 4 pregnancies resulted. One pregnancy was lost around 21 days, a second was pharmacologically aborted, and two were maintained (one from male and one from female sorted semen are currently in the 11th month of gestation). In conclusion, this study demonstrates that ICSI with sex-sorted sperm can be used for producing equine blastocysts able to establish pregnancies at a high rate following embryo transfer. However, the overall efficiency of the system is limited due to the very low cleavage rate obtained with sexed-sorted frozen–thawed sperm. Table 1.Development of embryos produced by ICSI with sorted and non-sorted frozen–thawed semen This work was supported by an RFO (ex 60%) and Camera di Commercio Cremona grant. The Authors wish to thank Società Italiana Produttori Sementi.

300 HEMIZYGOUS PRION PROTEIN GENE (PRNP) KNOCKOUT IN CATTLE FIBROBLASTS

Bovine spongiform encephalopathy (BSE) represents a real threat for human health, as has been demonstrated by the causal link with the variant form of Creutzfeldt-Jakob disease. The aim of our project is to create a bovine strain knockout for the prion protein gene (PRNP) that should be resistant to BSE infection. We combined the use of homologous recombination by PRNP targeting vectors in bovine fibroblasts with the subsequent use of nuclear transfer (NT). We transfected fetal (male) and adult (female) bovine fibroblasts by nucleofection, using targeting vectors disrupting the PRNP by means of loxP flanked cassettes. They expressed resistance to different drugs driven by a PGK or TK promoter and the thymidine kinase gene as a negative selection marker. We screened, by PCR, 907 drug-resistant colonies, from which we identified 8 Neo-resistant colonies with a recombined PRNP allele (overall efficiency 3.2%; 7/108 from fetal, 1/145 from adult; P < 0.5). Fibroblasts PRNP+/– Neo were used to produce NT blastocysts from which neural precursors cell lines were established (Lazzari et al. 2006 Stem Cells 24, 2514–2521). These lines were capable of extensive proliferation (over 120 doublings during 4 months of culture) and provided unlimited material for Southern blot analysis to confirm PCR findings. Three clones (2 from fetal and 1 from adult) were further analyzed and confirmed PRNP+/– by Southern blot and were subsequently used for NT to generate blastocysts for transfer to recipient heifers. On Day +40 of gestation, the pregnancy rate was 33.3% (9/30) for the fetal line and 50% (2/4) for the adult line. One of the fetuses originating from fetal fibroblasts was removed on Day +45 to establish a rejuvenated fibroblast cell line used for a second round of gene targeting to obtain a PRNP –/– clone. We nucleofected these fibroblasts with Puro, Hygro, and promoterless Hygro cassette-carrying targeting vectors. We screened 625 drug-resistant colonies by PCR but none tested positive for the second targeting. In conclusion, we have obtained heterozygous PRNP+/– fibroblasts with the Neo vector both in fetal and adult fibroblasts, but failed with other vectors. In the first targeting, the efficiency was 10 times greater in fetal v. adult fibroblasts. The derivation of neural precursor cell lines from cloned blastocysts is a useful procedure to have sufficient material for molecular analysis without the need of rejuvenating the cell through the production of a fetus. None of the vectors used for the targeting of the second allele was successful.

170 EXPRESSION PATTERN OF THE Sox2 GENE IN BOVINE OOCYTES AND IN VITRO-DERIVED EMBRYOS

Sox2 is a member of the Sox (SRY-related HMGbox) family. It acts to maintain developmental potential and marks the pluripotent lineage of the early mouse embryo; in particular, as in the case of Oct-4 and Nanog, Sox2 is expressed specifically in the inner cell mass (ICM) and in the epiblast of this species. Moreover, it plays an important role in the transcription network that maintains stem cell pluripotency, interacting with other factors such as Oct-4 and Nanog. Little information is available on this gene in bovine; therefore aims of the present study were: a) to identify and characterize the Sox2 expression profile in bovine oocytes and preimplantation embryos; and b) to investigate its expression pattern in ICM and trophectoderm (TE). Bovine oocytes and embryos were obtained by in vitro maturation and fertilization; blastocysts at Day 7 post-insemination underwent microsurgery to separate TE from ICM. mRNA was isolated from 3 pools, each consisting of 5 MII oocytes, 2-, 4-, 8-, and 16-cell embryos, morulae, blastocysts, ICMs, and TEs. Semi-quantitative analysis of Sox2 expression was performed in the exponential phase of PCR amplification using rabbit globin as exogenous control. Data were analyzed with one-way ANOVA, followed by multiple pairwise comparisons with Tukey test (SigmaStat 2.03, SPSS, Inc., Chicago, IL, USA). Values are presented as mean � SEM and differences of P ≤ 0.05 are considered significant. In order to rule out false negative results, PCR amplifications of isolated ICMs and TEs were extended to the plateau phase. Fragment identity was confirmed by sequencing. Comparison of bovine Sox2 cDNA sequence (EMBL AM774325) with databases revealed a 98%, 93%, and 87% homology with sheep, human, and mouse, respectively. Sox2 mRNA was detectable in oocytes as well as in embryos at the different developmental stages analyzed. Semi-quantitative expression studies revealed that Sox2 was present as both maternal and embryonic transcript; in particular, a statistically significant increase from the 8-cell stage, concomitant with embryo genome activation, was observed. Differently from the mouse, Sox2 was expressed in both bovine ICM and TE, resembling the profile previously shown for Oct-4 (van Eijk et al. 1999 Biol. Reprod. 60, 1093–1103), and suggesting that Sox2 expression might be regulated by Oct-4 also in bovine, as described in mouse and human. These findings also suggest that its expression may become restricted to the ICM only at the expanded hatched stage, as previously described for Oct-4 in pig embryos (Vejlsted et al. 2006 Mol. Reprod. Dev. 73, 709–718). This work was supported by PRIN 2006, FIRST 2005, TECLA-MIUR, and EUROSTELLS-ESF.

257 EXPRESSION PROFILING OF GENES CRUCIAL FOR LINEAGE DETERMINATION IN IN VITRO-DERIVED EARLY BOVINE EMBRYOS

In the early blastocyst, lineage segregation depends on the expression of several key specific transcription factors. In the mouse, commitment to inner cell mass (ICM), lineage is positively regulated by Oct-4, a repressor of trophectoderm (TE) cell fate, and Nanog, which inhibits the formation of extra-embryonic and primitive endoderm. Cdx2, a caudal-type homeodomain protein, is specifically expressed in the nascent TE. The mechanisms that drive Cdx2 segregation to the outside cells are still unclear. However, the expression of Fgf Receptor 2 (FgfR2), restricted to the outside cells, and the role for its ligand, Fgf4, in promoting TE development, suggest that this signalling pathway may act upstream or in parallel with Cdx2. Little information is available on these genes in bovine; therefore the aims of the present study were as follows: (a) to identify and characterize the expression profiles of Cdx2 and FgfR2 variants (IIIc and IIIb) in bovine oocytes and pre-implantation embryos; and (b) to compare their expression patterns in ICM and TE with that of Oct-4 and Nanog. Bovine oocytes and embryos were obtained by in vitro maturation and fertilization; blastocysts at Day 7 post-insemination underwent microsurgery to separate TE from ICM. RNA was isolated from MII oocytes; 2-, 4-, 8-, and 16-cell embryos; morulae; blastocysts; ICMs; and TEs. Semi-quantitative analysis of Cdx2 and FgfR2 expression in oocytes and embryos was performed in the exponential phase of PCR amplification with rabbit globin as exogenous control. In order to exclude false negative results, PCR amplification in isolated TE and ICM was extended to the plateau phase for all genes considered. Fragment identity was confirmed by sequencing. Comparison of bovine Cdx2 cDNA sequence (EMBL AM293662) with databases revealed a 91% and 87% homology with human and mouse, respectively. Cdx2 expression was not detectable in MII oocytes, but increased in 2-cell embryos. Transcript levels decreased at the 4- and 8-cell stages and then increased again in the blastocyst. FgfR2 variants were present as both maternal and embryonic transcripts, because they were detectable throughout pre-implantation development. Cdx2 and FgfR2 IIIc and IIIb expression was restricted to TE cells. Nanog was detected only in ICM, whereas Oct-4 was expressed in both lineages, as previously described in bovine (van Eijk et al. 1999 Bio. Reprod. 60, 1093-1103). In conclusion, the expression profiles of Nanog, Cdx2, and FgfR2 in bovine pre-implantation embryos follow the pattern previously described in the mouse. Their differentially segregated expression is consistent with their role as selector factors of ICM vs. TE fates. The significance of Oct-4 ubiquitous distribution still remains to be elucidated. This work was supported by FIRB RBNE01HPMX_005, TECLA-MIUR, and EUROSTELLS-ESF.

Effect of cumulus morphology and maturation stage on the cryopreservability of equine oocytes

Oocyte cryopreservation is a potentially valuable way of preserving the female germ line. However, the developmental competence of cryopreserved oocytes is presently poor. This study investigated whether the morphology of the cumulus complex surrounding an immature equine oocyte and/or the oocyte’s stage of maturation affect its cryopreservability. Compact (Cp) and expanded (Ex) cumulus oocyte complexes (COCs) were vitrified either shortly after recovery (germinal vesicle stage, GV) or after maturationin vitro(IVM); cryoprotectant-treated and -untreated non-frozen oocytes served as controls. In Experiment I, oocytes maturedin vitroand then vitrified, or vice versa, were examined for maturation stage and meiotic spindle quality. Cp and Ex COCs vitrified at the GV stage matured at similar rates during subsequent IVM (41 vs 46% MII), but meiotic spindle quality was better for Cp than Ex (63 vs 33% normal spindles). Vitrifying oocytes after IVM resulted in disappointing post-warming spindle quality (32 vs 28% normal for Cp vs Ex). In Experiment II, oocytes from Cp and Ex COCs vitrified at the GV or MII stages were fertilized by intracytoplasmic sperm injection (ICSI) and monitored for cleavage and blastocyst formation. Oocytes vitrified prior to IVM yielded higher cleavage rates (34 and 27% for Cp and Ex COCs) than those vitrified after IVM (16 and 4%). However, only one blastocyst was produced from a sperm-injected vitrified–warmed oocyte (0.4 vs 9.3% and 13% blastocysts for cryoprotectant-exposed and -untreated controls). It is concluded that, when vitrification is the chosen method of cryopreservation, Cp equine COCs at the GV stage offer the best chance of an MII oocyte with a normal spindle and the potential for fertilization; however, developmental competence is still reduced dramatically.

Developmental competence of equine oocytes and embryos obtained by in vitro procedures ranging from in vitro maturation and ICSI to embryo culture, cryopreservation and somatic cell nuclear transfer

Development of assisted reproductive technologies in horses has been relatively slow compared to other domestic species, namely ruminants and pigs. The scarce availability of abattoir ovaries and the lack of interest from horse breeders and breed associations have been the main reasons for this delay. Progressively though, the technology of oocyte maturation in vitro has been established followed by the application of ICSI to achieve fertilization in vitro. Embryo culture was initially performed in vivo, in the mare oviduct or in the surrogate sheep oviduct, to achieve the highest embryo development, in the range of 18-36% of the fertilised oocytes. Subsequently, the parallel improvement of in vitro oocyte maturation conditions and embryo culture media has permitted high rates of embryo development from in vitro matured and in vitro cultured ICSI embryos, ranging from 5 to 10% in the early studies to up to 38% in the latest ones. From 2003, with the birth of the first cloned equids, the technology of somatic cell nuclear transfer has also become established due to improvement of the basic steps of embryo production in vitro, including cryopreservation. Pregnancy and foaling rates are still estimated based on a small number of in vitro produced equine embryos transferred to recipients. The largest set of data on non-surgical embryo transfer of in vitro produced embryos, from ICSI of both abattoir and in vitro-matured Ovum Pick Up (OPU) oocytes, and from somatic cell nuclear transfer, has been obtained in our laboratory. The data demonstrate that equine embryos produced by OPU and then cryopreserved can achieve up to 69% pregnancy rate with a foaling rate of 83%. These percentages are reduced to 11 and 23%, respectively, for cloned embryos. In conclusion, extensive evidence exists that in vitro matured equine oocytes can efficiently develop into viable embryos and offspring.

QSAR study for a novel series of ortho disubstituted phenoxy analogues of α1-adrenoceptor antagonist WB4101

On the basis of the affinities at the alpha1a-, alpha1b- and alpha1d-adrenoceptors and the 5-HT1A receptor of a previous series of sixteen 2-[(2-phenoxyethyl)aminomethyl]-1,4-benzodioxanes ortho monosubstituted at the phenoxy moiety, a number of ortho disubstituted analogues were designed, synthesized in both the enantiomeric forms and tested in binding assays on the same receptors. The affinity values of the new compounds 1-11 were compared with those of the enantiomers of the 2,6-dimethoxyphenoxy analogue, the well-known alpha1 antagonist WB4101, and of the ortho monosubstituted derivatives, suggesting some distinctive aspects of the interaction of the phenoxy moiety, in particular with the alpha1a-AR and the 5-HT1A receptor, of the monosubstituted and the disubstituted compounds. A classical quantitative structure-activity relationship (Hansch) analysis was applied to the whole set of the S enantiomers of the ortho mono- and disubstituted WB4101 analogues (26 compounds), finding a very good correlation for the alpha1a affinity. For this latter, a significant parabolic relationship was also found with the volume of the two ortho substituents. Diametrically opposite, the same relationships for the 5-HT1A exhibit low or insignificant correlation coefficients.

25 MATERNAL-TO-EMBRYONIC TRANSITION FOLLOWING NUCLEAR TRANSFER OR PARTHENOGENETIC ACTIVATION

The successful development of embryos generated by somatic cell nuclear transfer (SCNT) requires the ooplasm to reprogram the nucleus. This establishes the gene expression pattern necessary for full development by mechanisms that are currently being clarified. The ooplasm action on somatic nuclei shows many common aspects to the process that leads to the creation of a functional embryonic genome from the differentiated sperm and egg genomes. In order to investigate this aspect we studied a critical phase of early embryonic development: the maternal to embryonic transition (MET). We compared the pattern and level of gene expression between bovine embryos derived from in vitro fertilization (IVF), from nuclear transfer of adult fibroblasts (NT), or from parthenogenetic activation (PG). The study was performed in cattle because MET, in this species, occurs over four cell cycles, making it easier to detect even small deviations. Oocytes, matured for 22 h and fertilized in vitro or after cumulus removal, were enucleated and fused to fibroblast cells. Nuclear transfer and Met II oocytes were activated at 24-26 h of maturation with ionomycin (5 �M) for 5 min and 6DMAP (2 mM) for 4 h and then cultured in mSOFaa. Embryos were harvested at the required time for analysis at the 2-, 4-, 8-, and 16-cell; morula; and blastocyst stages and stored snap-frozen in a minimal volume of medium in groups of 5-10 embryos. Semiquantitative RT-PCR was used to study the expression of Nanog, Oct-4, Zar-1, and Par-3, because these genes are directly involved in early embryo development and have a specific expression pattern during MET. Data were analyzed with one-way ANOVA followed by Student-Newman-Keuls All Pairwise Multiple Comparison. No difference in pre-implantation development was observed among the three groups. The Nanog expression pattern was unchanged in all three groups, becoming detectable from the 8-16-cell stage onward. Oct-4 mRNA was detected at all stages in every group, but only in NT embryos did a significant increase occur at the 16-cell stage, suggesting the onset of an anticipated embryonic transcription. the Zar-1 expression pattern, with the characteristic de-novo transcription peak at the 4-cell stage, was observed in both IVF and NT embryos but not in PG embryos. In this group, Zar-1 mRNA levels were significantly higher at the 2- and 4-cell stage than in all of the following stages. The Par-3 gene showed the biggest differences among groups: IVF embryos expressed this gene from the 8-cell stage onward, whereas NT embryos showed high levels of Par-3 mRNA already at the 2-cell stage. Surprisingly, PG embryos showed no detectable Par-3 levels at any stages. The results indicate that, although in vitro development was not affected, gene-specific expression differences during MET occurred among groups. Relating the specific functions exerted by each of these genes in early development to the changes observed following the different manipulations provides useful data toward a better understanding of the role of these genes and of the mechanisms of nuclear reprogramming. This work was supported by FIRB RBNE01HPMX, FIRST 2004, and ESF-EuroStells.

246 EXPRESSION PATTERN OF NANOG AND Par3 GENES IN IN VITRO-DERIVED BOVINE EMBRYOS

Homeobox genes have been demonstrated to be important in patterning and lineage specification during early embryogenesis. Nanog belongs to the family of DNA-binding transcription factors and has been shown to maintain pluripotency of embryonic stem cells, both in murine and human. Par3 plays an essential role in determining cell fate of the early mouse embryo, leading to the generation of the inner cell mass and the trophectoderm. No information is available on these genes in the bovine; therefore, the aim of the present study was to identify and characterize Nanog and Par3 expression in bovine embryos. Oocytes recovered from slaughterhouse ovaries were matured for 22 h, fertilized in vitro and then cultured in mSOFaa medium. RNA was extracted from pools of five oocytes and embryos at different stages of development (2-, 4-, 8-, 16-cell, morula and blastocyst). It was then reverse transcribed, and PCR runs were carried out with primers specifically designed for Nanog and Par3, based on the sequence data bank available. The amplified products were separated on a 2% TAE agarose gel, purified, sequenced and aligned using Clustal W. Comparison of the bovine Nanog cDNA sequence (EMBL AM039957) with databases revealed a 84% degree of homology with the human, 97% with the mouse, and 82% with the goat genes. IVF bovine embryos express Nanog only upon genome activation, becoming detectable from the 8-cell stage onward indicating that Nanog is zygotically expressed in the bovine similar to what happens in mouse, pig and goat. Bovine Par3 cDNA sequence (EMBL AM039956) shows a high degree of homology with human (83%), mouse (81%), and rat (79%). Also Par3 is expressed only upon the maternal to embryonic transition (MET) at the 8-cell stage. As opposed to the expression patterns of other early embryo genes, like Oct-4 and Zar-1, Nanog and Par3 expression patterns in bovine embryos closely resemble those described in the mouse. Since both are absent in the ooplasm and before MET, they represent useful markers for genome activation. This work was supported by FIRB RBNE01HPMX, FIRST 2004 and ESF-EuroStells.

Establishment, differentiation, electroporation, viral transduction, and nuclear transfer of bovine and porcine mesenchymal stem cells

Mesenchymal stem cells (MSCs) reside in the bone marrow and have the potential for multilineage differentiation, into bone, cartilage, and fat, for example. In this study, bovine and porcine MSCs were isolated, cultured to determine their replication ability, and differentiated with osteogenic medium and 5-azacytine. Both bovine and porcine undifferentiated MSCs were electroporated and virally transduced to test the efficiency of genetic modification and the maintainance of differentiation ability thereafter. Nuclear transfer experiments were carried out with bovine and porcine MSCs, both at the undifferentiated state and following differentiation. Our results indicate that bovine and porcine MSCs have limited lifespans in vitro--approximately 50 population doublings. They can be efficiently differentiated and characterized along the osteogenic lineage by morphology, alkaline phosphatase, Von Kossa, oil red stainings, and RT-PCR. Electroporation and selection induce high levels of EGFP expression in porcine but not in bovine MSCs. Following genetic modification, MSCs retain their pluridifferentiation ability as parental cells. Cloned embryos derived from bovine and porcine undifferentiated MSCs and their derivatives along the osteogenic lineage give rise to consistently high preimplantation development comparable to adult fibroblasts.

Susceptibility of bovine mesenchymal stem cells to bovine herpesvirus 4

Bovine herpesvirus 4 (BoHV-4) is a gamma herpesvirus with no clear disease association. Previous studies have demonstrated that macrophages can harbour persistent BoHV-4. Since mesenchymal stem cells in bone marrow regulate the differentiation and proliferation of adjacent haematopoietic precursors, such as macrophages, the interaction between BoHV-4 and mesenchymal stem cells was investigated. Primary bovine mesenchymal stem cells were highly permissive to support full replication of BoHV-4. This finding could be considered a new important step in studies on the potential pathogenesis related to BoHV-4.

Expression pattern of the maternal factor zygote arrest 1 (Zar1) in bovine tissues, oocytes, and embryos

Zygote arrest 1 (Zar1) is an ovary-specific maternal factor that plays an essential role during the oocyte-to-embryo transition in mouse. In this species, Zar1 expression is strictly limited to the oocyte, the zygote and, at a lower level, the 2-cell embryo. Aim of the present study was to analyze the presence and the expression pattern of the Zar1 ortholog in bovine tissues and embryos. Reverse transcription (RT)-polymerase chain reaction (PCR) analysis was performed in a panel of bovine tissues, in oocytes and pre-implantation in vitro produced embryos. The results demonstrated that a Zar1 ortholog is present in cattle. In the adult, the gene is expressed in ovary, testis, muscle, and myocardium. The gene is also expressed in the oocyte, the zygote, and in all the stages of embryonic development until blastocyst formation. A semi-quantitative RT-PCR analysis revealed that Zar1 levels are constant through in vitro development with the exception of the 4-cell stage, when a significant increase is observed. The exposure of fertilized oocytes to the RNA polymerase II inhibitor alpha-amanitin was able to suppress this Zar1 increase indicating that transcription of this gene occurs at the 4-cell stage. Zar1 is conserved in cattle but has an expression pattern different from the mouse. In particular, Zar1 expression in the adult is not limited to the ovary and in the embryo is expressed well beyond the oocyte to embryo transition. Moreover, the identification of Zar1 transcription at the 4-cell stage represents the first characterization of one of the genes expressed in cattle embryos before the major onset of embryonic transcription.

91 EMBRYO DEVELOPMENT AFTER ICSI OF EQUINE OOCYTES VITRIFIED BEFORE AND AFTER IVM

Vitrification has proven to be the method of choice for cryopreservation of mammalian oocytes. In this study, we evaluated in vitro embryonic developmental competence of equine oocytes, vitrified before and after IVM, and fertilized by ICSI. The benefits of the interaction between Naloxone (Nx) and endogenous opioids peptide receptors in different conditions of cellular stress have already been demonstrated (Sheu et al. 1997 Biochem. Biophys. Res. Comm. 231, 12–16). In this study we determined whether addition of Nx to the vitrification solutions can limit the oocyte's damages. COCs collected April to June from abattoir ovaries were: (1) vitrified immediately after recovery (PREM) or (2) matured for 24 h in TCM 199 (Galli et al. 2002 Theriogenology 58, 705–708) before vitrification (POSTM). Half of the oocytes of the two groups were vitrified using solutions supplemented with 10−8 M Nx. Cryoprotectants were loaded in three steps as reported by Maclellan et al. (2002 Theriogenology 58, 911–919). Oocytes were placed on a nylon cryoloop (Hampton Research, Laguna Niguel, CA, USA) and immediately plunged into liquid nitrogen. Oocytes were thawed by immersing the loop sequentially in 0.25 M, 0.188 M, and 0.125 M sucrose in HEPES synthetic oviductal fluid (HSOF) for 30 s per step. PREM oocytes were subjected to 24 h IVM, POSTM were cultured 2–3 h after thawing. Matured oocytes, as assessed by the presence of the first polar body, underwent ICSI. Frozen semen was separated over a discontinuous Percoll gradient and denuded oocytes were injected with a single spermatozoon. Non-vitrified oocytes matured under the same conditions were used as a control. Injected oocytes were cultured in SOFaa until Day 9 (Day 0 day of ICSI). Vitrification was done in five replicates and all oocytes were injected on the same day. Chi-square test was used for statistical analysis (Statistica for Windows; Stat Soft, Inc., Tulsa, OK, USA); significance was assessed at P < 0.05. Results are reported in Table 1. The number of degenerated oocytes and the cleavage rates were not significantly different among treatments (P > 0.05). Within vitrified COCs, only those with Nx in the vitrification solutions reached the blastocyst stage at Day 9; because of the low number of oocytes used in this work, blastocyst rate was not different among treatments. Further studies are needed to evaluate the benefits of adding Nx to oocyte vitrification solutions. Table 1. Embryo development after ICSI of vitrified equine oocytes This research was funded by MIUR Cofin PRIN 2003.

173 EFFECT OF CULTURE SYSTEM FOR IVM-IVF PIG EMBRYOS ON THE ICMS ABILITY TO PRODUCE OUTGROWTHS FOR EMBRYONIC STEM CELL DERIVATION

Attempts to derive true embryonic stem cells in large farm animals rely on the supply of good quality embryos. In these species, including the pig, pre-implantation-stage embryos can be produced by in vitro techniques from slaughterhouse ovaries. The objective of this study was to evaluate the ability of the inner cell masses (ICMs) of pig embryos, produced in vitro by different methods, to provide viable initial outgrowths of ICM cells that could be subsequently subcultured and expanded. Porcine oocytes were recovered from slaughtered donors and matured in vitro for 40–44 h in DMEM-F12 supplemented with 10% FCS, 0.05 IU LH and FSH (Menogon, Ferring, Milan, Italy), 0.3 mM cystine, 0.5 mM cysteamine, 50 ng/mL long-EGF, 100 ng/mL long-IGF1, 5 ng/mL bFGF (Sigma-Aldrich, Milan, Italy) in 5% CO2 at 38.5°C. Boar frozen-thawed semen was separated on a percoll gradient and diluted in TALP medium with PHE (penicillamine, hypotaurine, epinefrine) to a concentration ranging from 0.05 to 0.1 million sperm per mL. Oocytes were partially decumulated, co-incubated with sperm for 24 h, and finally denuded and cultured in microdrops of mSOFaa or NCSU. After cleavage, approximately half of the cleaved embryos were surgically transferred into the sheep oviduct for 4 days of in vivo culture and the remaining embryos were left in vitro in the two media. On Day +6 in vivo-cultured embryos were recovered from the sheep oviduct. Blastocyst formation and quality were comparatively evaluated in the three culture groups. Quality specifically referred to the morphology/size of the ICM according to the following criteria: ICM A (large/prominent), ICM B (flat), and ICM C (non-visible). All embryos with a visible inner cell mass were subjected to microdissection with needles to recover the ICMs that were then plated on feeder-layers of mitomycin-treated STO fibroblasts. Attachment and outgrowth was evaluated 48–72 h post-plating. Results are presented in Table 1. Our data indicate that in vivo culture of pig embryos in the sheep oviduct greatly enhance both blastocyst development and ICM quality. As a consequence the efficiency of outgrowth formation, following plating for ES cell derivation, was significantly higher with ICMs derived from IVM-IVF pig embryos cultured in vivo as compared to their in vitro-cultured counterparts. Within the two culture media tested for in vitro culture, SOF and NCSU, the rate of blastocyst formation was similar but the quality of SOF-cultured embryos is higher. In conclusion, embryo/ICM quality represents a fundamental requirement for the derivation of ES cell lines, and in vivo culture in the sheep oviduct provides the most efficient source of high quality IVM-IVF pig embryos. Table 1. Blastocyst development and ICM quality of in vitro-produced pig embryos This work was supported by the Istituto Superiore di Sanità, Programma Nazionale Cellule Staminali, Rome, Italy, grant No. CS 11.

Cumulus-Oocyte Communications in the Horse: Role of the Breeding Season and of the Maturation Medium

Horse is a seasonal breeder and information on oocyte quality outside the breeding season is very limited. Ovaries obtained at the slaughterhouse are a convenient but often limited source of oocytes in this species. As the low quantity of ovaries leads to an intensive use of all available material, it would be useful to know whether ovaries collected during the non-breeding season are suitable for in vitro maturation (IVM). In an attempt to characterize the effect of season on oocyte quality, we investigated the permeability of the gap junctions (GJ) present between cumulus cells and oocytes because of their important role in oocyte growth and maturation. We also compared the effect of supplementing the maturation medium with bovine serum albumin (BSA) or oestrus mare serum (EMS). A total of 645 oocytes isolated from 158 and 154 ovaries collected during the breeding and the non-breeding season, respectively, were used in this study. Oocytes were matured for 30 h in TCM 199 supplemented either with 10% EMS or with 4 mg/ml BSA. The presence of permeable GJs between cumulus cells and oocytes was investigated with the injection of a 3% solution of the fluorescent dye Lucifer yellow into the ooplasm. No differences in efficiency of oocyte retrieval or oocyte meiotic competence were detected between oocytes collected during the breeding and non-breeding season. The vast majority (90%) of the oocytes collected during the breeding season had fully functional communications with their surrounding cumulus cells but such communications were completely interrupted in 55.3% of the oocytes collected during the non-breeding season. During the non-breeding season, the proportion of oocytes whose communications with cumulus cells were classified as closed or intermediate at the end of maturation was lower in the group matured with BSA than with EMS (71.4 vs 97.7, p < 0.05). The same trend, although not statistically significant, was observed during the breeding season also. The presence of BSA caused an incomplete cumulus expansion during both seasons. Our data indicate that oocytes collected during the non-breeding season do not show any meiotic deficiency but lack active communication with the surrounding cumulus cells at the time of their isolation from the ovary. No data are available at present for determining the consequences on the developmental competence even if data from other species suggest that this is likely.

258ULTRASTRUCTURAL STUDY OF STALLION SPERM FOLLOWING THAWING, CAPACITATING AND IVF PROCEDURES: EFFECT OF THE PRESENCE OF CUMULUS-ENCLOSED OOCYTES

The use of IVF in horses has a limited efficiency, reflecting low oocyte developmental competence and inadequate sperm capacitation procedures. In a preliminary study, using carboxyfluorescein diacetate/propidium iodide staining, we determined that the freezing-thawing procedure left only 56.6±3.4 % of the sperm cells with an intact membrane. The following incubation in TALP-IVF induced membrane damage at high rates with only 9.58±1.8 % of them intact after 18h. However, the presence of at least four cumulus-enclosed oocytes (CEO) in the medium significantly increased the number of membrane-intact spermatozoa at the end of incubation (53.87±1.99%). This indicated that the sperm thawing and capacitating procedures can damage the cell membrane but the presence of four or more CEO in TALP-IVF could prevent further damages. The aim of the study was to investigate in detail the membrane damages and to analyze the differences induced by the presence of CEO. Spermatozoa were thawed in water at 37°C, and centrifuged for 30 minutes at 600g in a 45–90% Percoll gradient made with modified Tyrode’s medium. The sperm pellet was washed once in the same medium and diluted to a final concentration of 1×106 spermatozoa/ml TALP supplemented with 0.6% (w/v) BSA fatty acid free and 12μgmL−1 heparin (TALP-IVF). Sperm cells were incubated with 0 or 4 in vitro-matured CEO. Sperm cells were examined after thawing, 0, 2 and 18h from the beginning of incubation in TALP-IVF. Each experiment was replicated at least 3 times. Both scanning and transmission electron microscopy were performed on sperm samples fixed in 2.5% glutaraldehyde in 0.1M phosphate buffer, pH 7.2, using standard procedures. Specimens for scanning electron microscopy were examined under a field emission gun JEOL JSM 6301 microscope. For transmission electron microscopy the samples were examined with a JEOL JEM 100 SX. A minimum of 25 cells were analyzed for each group. Immediately after thawing, damaged spermatozoa showed, on the surface of their heads, small vesicles correlated to a progressive process of vacuolisation and degeneration of membrane integrity. The same lesions were visible at all the successive time points taken into account. Moreover, a loss of the acrosome integrity with acrosomal swelling and a decrease of content homogeneity were observed particularly in the spermatozoa cultured for 18 h without CEO. When CEO were present in the IVF medium lesions were visible in a lower percentage of spermatozoa but the type of lesions did not differ from those observed in their absence. These observations confirmed our previous data and gave more details on the lesions that occur during the IVF procedures in the horse. Supported by MURST COFIN grant n. 2001078849.

Production and Quality of Bovine Oocytes and Embryos

Many factors influence the efficiency of the in vitro embryo production technology in cattle but the most important are the physiological conditions of the donor and the culture protocols for oocyte maturation and fertilization and for embryo culture from zygote to blastocyst. Therefore, general factors such as age, body conditions and herd management play a pivotal role together with more specific factors such as reproductive soundness and ovarian cyclicity. Given that good quality and competent oocytes are available a complex series of processes, including oocyte maturation, fertilization and culture of the derived zygotes, must be completed to generate viable embryos.

Bovine embryo technologies

Embryo technologies are a combination of assisted reproduction, cellular and molecular biology and genomic techniques. Their classical use in animal breeding has been to increase the number of superior genotypes but with advancement in biotechnology and genomics they have become a tool for transgenesis and genotyping. Multiple ovulation and embryo transfer (MOET) has been well established for many years and still accounts for the majority of the embryos produced worldwide. However, no progress has been made in the last 20 years to increase the number of transferable embryos and to reduce the side effects on the reproductive performance of the donors. In vitro embryo production (IVP) is a newer and more flexible approach, although it is technically more demanding and requires specific laboratory expertise and equipment that are most important for the quality of the embryos produced. Somatic cell cloning is a rapidly developing area and a very valuable technique to copy superior genotypes and to produce or copy transgenic animals. More knowledge in oocyte and embryo biology is expected to shed new light on the early developmental events, including epigenetic changes and their long lasting effect on the newborn.Embryo technologies are here to stay and their use will increase as advances in the understanding of the mechanisms governing basic biological processes are made.

Xenogeneic serum promotes leukocyte-endothelium interaction under flow through two temporally distinct pathways: role of complement and nuclear factor-kappaB

Endothelial cell activation and mononuclear cell infiltration are consistent features of discordant xenograft rejection. This study evaluated whether xenogeneic serum--as a source of xenoreactive natural antibodies and complement--induced endothelial activation with consequent leukocyte adhesion and transmigration under flow conditions. Porcine aortic endothelial cells (PAEC) were incubated for 30 min, 1 h 30 min, or 5 h with 10% human serum or 10% porcine serum and then perfused with human leukocytes in a parallel plate flow chamber under flow (1.5 dynes/cm2). Adherent and transmigrated cells were counted by digital image analysis. Results showed that human serum significantly (P < 0.01) increased over time the number of adherent leukocytes compared with porcine serum. Stimulation of PAEC with human serum also promoted a progressive increase in leukocyte transmigration that reached statistical significance (P < 0.01) at 1 h 30 min and at 5 h compared with porcine serum. Studying the role of complement in leukocyte-endothelium interaction in xenogeneic conditions, a marked complement C3 deposition on PAEC exposed to human serum was shown by immunofluorescence, whereas cells incubated with porcine serum were negative. Next, it was documented that human serum decomplemented by heating and C3-deficient human serum failed to promote both leukocyte adhesion and transmigration, results that were comparable to porcine serum. To elucidate the intracellular mediators involved in endothelial cell activation by xenogeneic serum, this study focused on transcriptional factor nuclear factor-kappaB (NF-kappaB), a central regulator for the induction of different genes, including adhesive molecules and chemoattractants. Positive nuclear staining of NF-kappaB (p65 subunit) found by confocal fluorescence microscopy of PAEC exposed to human serum was taken to reflect NF-kappaB activation. NF-kappaB was instead strictly localized in the cell cytoplasm in PAEC incubated with the homologous serum. Heat-inactivated human serum failed to activate NF-kappaB. Electrophoretic mobility shift assay of nuclear extracts from PAEC exposed to human serum revealed an intense NF-kappaB activation that was inhibited by the NF-kappaB inhibitor pyrrolidinedithiocarbamate. The NF-kappaB inhibitors pyrrolidinedithiocarbamate and tosyl-phe-chloromethylketone did not affect the number of adherent and transmigrated leukocytes in PAEC exposed to human serum for 30 min and 1 h 30 min. Both inhibitors instead significantly reduced leukocyte adhesion and transmigration induced by human serum at 5 h. Confocal fluorescence microscopy studies showed that human serum induced an increase in the expression of vascular cell adhesion molecule-1 and intercellular adhesion molecule-1. Functional blocking of these adhesive molecules with the corresponding antibodies significantly inhibited xenogeneic serum-induced leukocyte adhesion. These data suggest that leukocyte adhesion and transmigration are directly dependent on complement deposited on PAEC in the early phase of cell activation (30 min and 1 h 30 min) induced by xenogeneic serum, whereas leukocyte adhesive events observed after 5 h of incubation of endothelial cells with xenogeneic serum are possibly regulated by transcription of NF-kappaB-dependent genes. The finding that xenogeneic serum promotes leukocyte-endothelial interaction depending on NF-kappaB activation might be relevant for designing future therapeutic strategies intended to prolong xenograft survival.

Protein overload stimulates RANTES production by proximal tubular cells depending on NF-kappa B activation

Abnormal traffic of proteins through the glomerular capillary has an intrinsic renal toxicity possibly linked to the subsequent process of proximal tubular reabsorption. Here we investigated in vitro the effect of protein overload on proximal tubular cell production of RANTES, a nuclear factor-kappa B (NF-kappa B)-dependent chemokine with potent chemotactic activity for monocytes/macrophages and T lymphocytes. Confluent pig LLC-PK1 cells were incubated for 24 and 48 hours with Eagle's MEM plus 0.5% FCS containing bovine serum albumin (BSA, 1 to 30 mg/ml). Tumor necrosis factor-alpha (TNF-alpha; 100 U/ml) was used as a positive control. RANTES was measured in cell supernatants by ELISA. Bovine serum albumin (BSA) induced a time- and dose-dependent increase in proximal tubular cell RANTES production. Selected experiments using transwells showed that the RANTES release was predominantly basolateral. The stimulatory effect on tubular RANTES was not specific to albumin but was shared by immunoglobulin (Ig) G. We then explored the role of NF-kappa B on BSA-induced RANTES. The NF-kappa B inhibitors pyrrolidine dithiocarbamate (PDTC; 25 microM) and sodium salicylate (10 mM) significantly reduced BSA-induced RANTES production. Electrophoretic mobility shift assay of nuclear extracts of LLC-PK1 exposed to BSA revealed an intense NF-kappa B activation as early as 30 minutes in a dose-dependent fashion, which was inhibited by PDTC. Supershift analysis revealed that the protein subunits of activated NF-kappa B were p65/p65 homodimer, p65/cRel, p50/p65 heterodimers. Given its chemotactic activity, RANTES released into the interstitium might promote inflammatory cell recruitment and contribute to interstitial inflammation and renal disease progression.