Beta-mercaptoethanol supplementation of in vitro maturation medium does not influence nuclear and cytoplasmic maturation of equine oocytes

In vitro embryo production in the horse is still not as efficient as in other species. Oxidative stress negatively affects oocyte and embryo culture. To attenuate/minimize the oxidative stress, antioxidants such as low-molecular thiol compounds can be added to culture media. Beta-mercaptoethanol (BME) has been shown to improve maturation and embryo development in different species. The aim of this study was to investigate whether the addition to maturation medium of BME at common (0.1 mM) and high (0.7 mM) concentration could improve oocyte maturation also in the horse. Equine oocytes recovered from slaughterhouse ovaries were used. Meiotic configuration after in vitro maturation (IVM) and early embryo production after intracytoplasmic sperm injection (ICSI) were considered as criteria for assessing nuclear and cytoplasmic maturation, respectively. A total of 1,076 oocytes were analysed over two experiments: 848 (control n = 293, BME 0.1 n = 270, BME 0.7 n = 285) were stained with Hoechst 33342 and examined for nuclear stage after 26 hr of IVM, and 228 MII oocytes were fertilized by ICSI (control n = 83, BME 0.1 n = 65, BME 0.7 n = 80). Cleavage rates were determined after 60 hr of culture. Unlike results obtained in other species, the addition of BME did not influence maturation rates (51.9% control vs 55.6% BME 0.1 mM and 55.1% BME 0.7 mM), nor cleavage rates after ICSI (38.6% vs 38.5% and 41.3%, respectively). In conclusion, the addition of BME at 0.1 and 0.7 mM to the maturation medium, in our culture conditions, has no effect on nuclear and cytoplasmic maturation of equine oocytes.

VIABILITY, IN VITRO DIFFERENTIATION AND MOLECULAR CHARACTERIZATION OF EQUINE ADIPOSE TISSUE-DERIVED MESENCHYMAL STEM CELLS CRYOPRESERVED IN SERUM AND SERUM-FREE MEDIUM

BACKGROUND

The effect of freezing-thawing equine adipose tissue-derived mesenchymal stem cells (eATMSCs) have been poorly investigated.

OBJECTIVE

This study is to test the influence of cryopreservation solution and temperature when adding the cryoprotectant for freezing eATMSCs, and to investigate the effects of cryopreservation on their stemness features.

MATERIALS AND METHODS

Four freezing protocols were evaluated. Viability and proliferation ability of cryopreserved cells were investigated by MTT assay. Fresh and frozen thawed eATMSCs were compared for morphology, phenotypic characteristics (flow cytometry), and differentiation potential.

RESULTS

A higher value of viable cells for samples frozen in FBS and a positive effect of CPA equilibration at low temperature in samples frozen in medium were observed. Morphology was similar for fresh and cryopreserved cells, such as CD expression and differentiation potential.

CONCLUSION

eATMSCs can be safely stored for clinical use. FBS is superior to medium for freezing, but CPA equilibration at low temperature is beneficial when freezing in serum- free medium.

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.

Sex-sorted canine sperm cryopreservation: limits and procedural considerations

The aim of this study was to define a protocol to store dog sperm before and after sorting to obtain an insemination dose sufficient to allow the conception by artificial insemination. Experiment 1 and 2 were performed to evaluate the more appropriate extender for preserving at room temperature dog sperm before and after sorting. Four extenders were tested: (1) Tris-fructose-citrate (TFC), (2) Tris-glucose-citrate (TGC), (3) modified Tyrode's albumin lactate pyruvate medium (mTALP), and (4) third fraction of the ejaculate (after centrifugation at 5000× g for 10 minutes; III FRAC). Experiment 3 and 4 were performed to evaluate the ability of dog semen to withstand sex sorting and freezing/thawing. Modified Tyrode's albumin lactate pyruvate medium was the best extender for canine sperm storage at room temperature (20 °C-25 °C) before (total motility: TFC, 8.3 ± 1.7; TGC, 50.0 ± 11.5; mTALP, 70.0 ± 0.1; III FRAC, 25.0 ± 1 0.4; P < 0.05) and after sorting (total motility: TFC, 7.3 ± 1.5; TGC, 10.3 ± 1.5; mTALP, 33.3 ± 6.7; III FRAC, 8.7 ± 5.8; P < 0.05), even if at 24-hour sorted sperm quality was impaired in all extenders tested herein. Sperm quality decreased after sorting (total motility: control, 92.5 ± 0.9; sorted, 52.9 ± 6.0; P < 0.05) and, especially, after freezing/thawing (total motility: frozen control, 25.7 ± 4.1; frozen sorted, 2.4 ± 1.2; P < 0.05). In conclusion, mTALP is an appropriate medium for canine sperm storage before and soon after sorting (hours), but a long storage period of sexed sperm at room temperature is not adequate. Cryopreservation greatly impaired sperm quality, and further studies are needed to optimize the freezing protocol for sexed dog sperm.

Stem cells from foetal adnexa and fluid in domestic animals: an update on their features and clinical application

Over the past decade, stem cell research has emerged as an area of major interest for its potential in regenerative medicine applications. This is in constant need of new cell sources to conceive regenerative medicine approaches for diseases that are still without therapy. Scientists drew the attention towards alternative sources such as foetal adnexa and fluid, as these sources possess many advantages: first of all, cells can be extracted from discarded foetal material and it is non-invasive and inexpensive for the patient; secondly, abundant stem cells can be obtained; and finally, these stem cell sources are free from ethical considerations. Cells derived from foetal adnexa and fluid preserve some of the characteristics of the primitive embryonic layers from which they originate. Many studies have demonstrated the differentiation potential in vitro and in vivo towards mesenchymal and non-mesenchymal cell types; in addition, the immune-modulatory properties make these cells a good candidate for allo- and xenotransplantation. Naturally occurring diseases in domestic animals can be more ideal as disease model of human genetic and acquired diseases and could help to define the potential therapeutic use efficiency and safety of stem cells therapies. This review offers an update on the state of the art of characterization of domestic animals' MSCs derived from foetal adnexa and fluid and on the latest findings in pre-clinical or clinical setting of the stem cell populations isolated from these sources.

280 EFFECTS OF HOT SEASON ON BOVINE OOCYTE QUALITY: HOW TO BYPASS THE POOR OOCYTE QUALITY DURING THIS SEASON?

Many authors attribute the decline of reproductive activity in summer to the heat stress, a multifactorial problem in which hyperthermia affects cellular function in various tissues of the female reproductive tract (Hansen et al. 2001; De Rensis et al. 2003). In particular, the combination of high temperatures and high humidity for a long period causes a reduced blood flow to uterus, oviducts, and ovaries, leading to a rise in the concentration of the degradation products of cellular activity. Therefore, the aim of this work was to elucidate the negative effect of the hot season on bovine oocyte quality and evaluate the influence of different factors on the acquisition of meiotic competence. In particular, meiotic competence of bovine oocytes recovered from animals housed at 44°28′00″ N, 11°26′00″ E during spring (March, 4–13°C) and summer (June, 16–27°C) was evaluated. Likewise, in summer the effect of an antioxidant, myo-inositol, the use of serum replacement (SR), and the use of oocytes recovered from cycling heifers (16–18 months) as compared to cows (>24 months) were tested. A total of 1346 abattoir-derived oocytes, equally divided for different experimental groups (over 6 replicates), were in vitro matured in TCM 199 supplemented with EGF (25 ng mL–1), IGF1 (100 ng mL–1), ITS supplement, pFSH-LH (0.1 IU each), and 10% FBS. Myoinositol was added at a concentration of 0, 15, 30, and 50 mM, while 10% SR was used alternatively to FBS. At the end of maturation period (20–22 h), oocytes were denuded and stained with 10 μg mL–1 of Hoechst 33342 at room temperature in the dark. After 15 min they were mounted on glass slides for evaluation of nuclear status using a Nikon Eclipse E400 microscope equipped with fluorescence filters. Nuclear configurations were classified as (a) germinal vesicle (GV), (b) germinal vesicle breakdown (GVBD), (c) metaphase I (M-I), (d) metaphase II (M-II), and (e) degenerated (DEG). Data are expressed as mean ± s.e.m. and were analysed by ANOVA (IBM SPSS Statistics) considering significance at P < 0.05. Oocyte quality of summer oocytes was significantly lower than spring counterparts as result of a higher rate of DEG (8.2 ± 0.6 v. 0.7 ± 0.6) and GV (5.4 ± 0.3 v. 0.4 ± 0.4, respectively; P < 0.05). Myo-inositol supplementation in IVM medium did not significantly affect either oocyte quality or meiotic competence in the hot season, such as the use of SR. When the oocytes were collected from cycling heifers ovaries during summer, the recovery rate of COC/ovary was significantly higher as compared to cows (4.5 v. 2.0), and a lower rate of DEG (1.8 ± 0.2; 8.2 ± 0.6) and GVBD (0.9 ± 0.6; 6.1 ± 0.3) was found (P < 0.05), even if the rate of GV (22.4 ± 0.1 v. 5.4 ± 0.3) was higher (P < 0.05) compared with cow. In conclusion, the hot season negatively affects oocyte quality, myo-inositol does not affect nuclear maturation, and SR can be used alternatively to FBS. The lower age of oocyte donor positively influenced the number of recoverable oocyte and degeneration rate.

186 BOVINE AMNIOTIC FLUID MESENCHYMAL STEM CELLS CHARACTERIZATION AFTER CULTURE IN VITRO

In recent years, fetal adnexa and fluids have been recognised as important sources of mesenchymal stem cells (MSC). The aim of this study was to characterise cell populations of bovine amniotic fluid, studying phenotypic characterisation, RNA expression, and differentiation potential of samples after in vitro culture for different lengths of time following trypsinization and expansion (passage). Amniotic fluid samples were recovered at the slaughterhouse from 25 pregnant cows and harvested cells were cultured in DMEM-TCM199 (1 : 1) plus 10% fetal bovine serum (FBS) in 5% CO2 at 38.5°C. At passages P3 and P7, a sample for each of the 4 population found was characterised. Immunophenotypic characterisation was performed for MSC (CD90, CD105, CD44) and haematopoietic (CD14, CD34) markers by flow cytometry (FACS). Immunocytochemistry (ICC) was performed for Oct4, SSEA4, and α-SMA and the ratio between positive cells and total nuclei was evaluated. Gene expression profile was analysed by RT–PCR for pluripotency markers (Oct4, Nanog, Sox2). At the same passages chondrogenic, osteogenic and adipogenic differentiation were induced and evaluated morphologically and cytologically using, respectively, Alcian blue to identify cartilage matrix, Von Kossa for extracellular calcium deposition, and Oil Red O for intracellular lipid droplets. Cell population appeared heterogeneous and we could identify 2 main cell types: round (R) and spindle-shaped (S) cells. Each isolated sample was classified into one of the following 4 types depending on percentages of R or S cells: prevalence of S-cells (S), prevalence of R-cells (R), and samples showing both morphologies with ~10% of S-cells (S10) or 40% S-cells (S40). S-cells percentage decreased with passages in S10 and S40. After FACS, all lines were positive for CD90, CD105, CD44, and CD34 and negative for CD14 both at P3 and at P7. After ICC, Oct4 was negative in all samples analysed, few S cells stained for SSEA4 (8%) at P3 but increased at P7 to 22%; R, S10, and S40 did not express SSEA4 both at P3 and at P7. α-SMA was expressed in all samples at P3 (9.4% S; 0.9% R; 2.5% S10; 27% S40) but not at P7 (27.5% S; 0% R; 0% S10; 0% S40). After RT–PCR analyses, Oct4 was negative in all samples; at P3, Nanog was clearly positive in S-cells, weak in S40, and negative in R and S10, but all samples turned negative at P7. Sox2 was weakly expressed (S) or not expressed (S10, S40, R) at P3 and it was negative in all cells at P7. Only S showed high differentiation potential into all 3 lineages at both P3 and P7, R had the lowest differentiation potential, whereas S10 and S40 were intermediate at both end points. In conclusion, bovine amniotic fluid showed heterogeneous cell populations and S-type had the characteristics of MSCs. S10 and S40 showed more MSC markers at P3, when S cells were still present, and this aspect suggests that S population is the presumptive MSC one. Although prevalent, R-type showed only some MSC characteristics. Further studies are under way to improve S-type isolation, purification, and culture, and to determine the lifespan of these cell types. This work was supported by grant PRIN2009.

Effects of mesenchymal stem cells isolated from amniotic fluid and platelet-rich plasma gel on severe decubitus ulcers in a septic neonatal foal

This paper documents the treatment of severe decubitus ulcers with amniotic fluid mesenchymal stem cells and platelets rich plasma (PRP) gel in a septic neonatal foal. The colt needed 25 days of hospitalization: during this period ulcers were treated for 15 days with mesenchymal stem cells (MSCs) plus PRP, PRP gel alone, or aloe gel. Healing was faster using MSCs+PRP, and at 7 months an ulcer treated with aloe gel was still not completely healed.

Evaluation of the effectiveness of intrauterine treatment with formosulphathiazole of clinical endometritis in postpartum dairy cows

In cattle, elimination of bacterial contamination from the uterine lumen after parturition is often delayed or compromised, and pathogenic bacteria can persist, causing uterine disease and infertility. The aim of this study was to compare the clinical and bacteriologic recovery following a single intrauterine administration of formosulphatiazole, cephapirin or placebo in cows with clinical endometritis. Cows (n = 80), no less than 28 days postpartum, with clinical endometritis were enrolled in the study. Endometritis was diagnosed by a complete reproductive examination, including rectal palpation, ultrasonography, vaginoscopy and uterine swab. All cows were randomly assigned to receive one of three intrauterine treatments (T0): 2500 mg of formosulphatiazole (Group A); 500 mg of cephapirin (Group B); placebo (4250 mg of propylene glycol; Group C). Cows were examined at the first estrus after treatment or no more than 30 days after (T1). Bacteria isolated were E. coli, A. pyogenes, Pasteurella spp. and Streptococcus spp. After treatment, in Group A and B only 6/30 (20.0%) and 6/24 (25.0%) cows showed a positive bacteriologic culture (P > 0.05), while in Group C the number of positive animals was significantly higher (19/26; 73.1%; P < 0.05). At T0, total clinical scores were similar between the three groups (Group A: 5.84 ± 1.07; Group B: 5.91 ± 1.0; Group C: 5.62 ± 1.17; P > 0.05) and indicative of clinical endometritis. At T1, endometritis scores were significantly lower than those reported before uterine infusion (P < 0.05); however, Group A and B score, 0.4 ± 0.9 and 1.0 ± 2.1, respectively, correspond to no and slight endometritis, while animals in Group C reported a total endometritis score significantly higher (4.6 ± 3.5; P < 0.05) corresponding to endometritis. In the present study, a commercial formosulphatiazole preparation was as effective as cephapirin and more effective than placebo for the treatment of clinical endometritis.

Isolation, characterization and differentiation of mesenchymal stem cells from amniotic fluid, umbilical cord blood and Wharton's jelly in the horse

Mesenchymal stem cells (MSCs) have been derived from multiple sources of the horse including umbilical cord blood (UCB) and amnion. This work aimed to identify and characterize stem cells from equine amniotic fluid (AF), CB and Wharton's Jelly (WJ). Samples were obtained from 13 mares at labour. AF and CB cells were isolated by centrifugation, while WJ was prepared by incubating with an enzymatic solution for 2  h. All cell lines were cultured in DMEM/TCM199 plus fetal bovine serum. Fibroblast-like cells were observed in 7/10 (70%) AF, 6/8 (75%) CB and 8/12 (66.7%) WJ samples. Statistically significant differences were found between cell-doubling times (DTs): cells isolated from WJ expanded more rapidly (2.0±0.6 days) than those isolated from CB (2.6±1.3 days) and AF (2.3±1.0 days) (P<0.05). Positive von Kossa and Alizarin Red S staining confirmed osteogenesis. Alcian Blue staining of matrix glycosaminoglycans illustrated chondrogenesis and positive Oil Red O lipid droplets staining suggested adipogenesis. All cell lines isolated were positive for CD90, CD44, CD105; and negative for CD34, CD14 and CD45. These findings suggest that equine MSCs from AF, UCB and WJ appeared to be a readily obtainable and highly proliferative cell lines from a uninvasive source that may represent a good model system for stem cell biology and cellular therapy applications in horses. However, to assess their use as an allogenic cell source, further studies are needed for evaluating the expression of markers related to cell immunogenicity.

Gene expression profiling of pluripotency and differentiation-related markers in cat oocytes and preimplantation embryos

During mammalian preimplantation development, two successive differentiation events lead to the establishment of three committed lineages with separate fates: the trophectoderm, the primitive endoderm and the pluripotent epiblast. In the mouse embryo, the molecular mechanisms underlying these two cell fate decisions have been studied extensively, leading to the identification of lineage-specific transcription factors. Species-specific differences in expression patterns of key regulatory genes have been reported, raising questions regarding their role in different species. The aim of the present study was to characterise the gene expression patterns of pluripotency (OCT4, SOX2, NANOG) and differentiation (CDX2, GATA6)-related markers during feline early development using reverse transcription–quantitative polymerase chain reaction. In addition, we assessed the impact of in vitro development on gene expression by comparing transcript levels of the genes investigated between in vitro and in vivo blastocysts. To normalise quantitative data within different preimplantation embryo stages, we first validated a set of stable reference genes. Transcript levels of all genes investigated were present and changed over the course of preimplantation development; a highly significant embryo-stage effect on gene expression was observed. Transcript levels of OCT4 were significantly reduced in in vitro blastocysts compared with their in vivo counterparts. None of the other genes investigated showed altered expression under in vitro conditions. The different gene expression patterns of OCT4, SOX2, CDX2 and GATA6 in cat embryos resembled those described in mouse embryos, indicative of a preserved role for these genes during early segregation. However, because of the absence of any upregulation of NANOG transcription levels after embryonic genome activation, it is unlikely that NANOG is a key regular of lineage segregation. Such results support the hypothesis that the behaviour of early lineage markers can be species specific. The present study also revealed a pool of maternal NANOG mRNA transcripts, the role of which remains to be elucidated. Comparing transcription levels of these genes between in vivo and in vitro blastocysts revealed low levels of OCT4 mRNA in the latter, which may contribute to the reduced developmental competence of embryos under suboptimal conditions.

Isolation, growth and differentiation of equine mesenchymal stem cells: effect of donor, source, amount of tissue and supplementation with basic fibroblast growth factor

Mesenchymal stem cells (MSC) are increasingly used as therapeutical aid for the orthopaedic injuries in the horse. MSC populate different tissues but the most commonly used for clinical purposes are isolated from bone marrow or adipose tissue. The first objective of this study was to investigate if the donor animal, the tissue of origin and the technique of isolation could influence the number of MSC available for transplantation after a short-term expansion. The second aim was to devise a culture system capable of increasing MSC lifespan and we tested the effect of basic fibroblast growth factor (bFGF). Results indicate that MSC can be efficiently isolated from both sources and supplementation of bFGF enhances proliferation rate maintaining differentiation potential. In addition, this study shows that collection, expansion and storage of frozen MSC can be performed for later therapeutic use.

308 ISOLATION, DIFFERENTIATION, AND IMMUNOPHENOTYPIC CHARACTERIZATION OF MESENCHYMAL STEM CELLS DERIVED FROM EQUINE ADIPOSE TISSUE AND BONE MARROW

Minimum criteria for the characterisation of human mesenchymal stem cells (MSC) are a) adhesion to the plastic when maintained under culture conditions; b) expression of CD105, CD73, and CD90, and no expression for CD45, CD34, and CD14; and c) differentiation into osteoblasts, adipocytes, and chondroblasts in vitro. One major difficulty in characterising equine MSC is the absence of specific monoclonal antibodies and evidence that certain markers from other species do not cross-react with the equine species. The aim of this work was to isolate, cultivate, differentiate, and conduct cellular characterisation of MSC derived from equine adipose tissue (AT) and bone marrow (BM). Adipose tissue collection was performed at the base of the horses’ tails, and BM was aspirated from the iliac crest. Mononuclear cell fraction was isolated and cultured as previously described by (Colleoni et al. 2009 Vet. Res. Commun. 33, 811–821). Chondrogenic, osteogenic, and adipogenic differentiation were performed in monolayer culture, and evidence for differentiation was made by morphological and cytological evaluations. For molecular characterisation, cells were treated with trypsin, washed with PBS, and fixed with Reagent 1 (Intraprep Kit, Beckman Coulter, Miami, FL, USA), following the manufacturer’s instructions. Samples, after washings, were incubated for 20 min at room temperature with CD105, CD90, CD44, CD45, CD34, CD14, and CD73 mAbs, directly conjugated to fluorescein isothiocyanate, PE, or APC (Beckman Coulter). Appropriate conjugate isotype controls were applied (Beckman Coulter). After staining, cells were washed twice with PBS, and fluorescence intensity was evaluated with a FC500 two-laser equipped cytometer (Beckman Coulter). Results were further analysed with the CXP dedicated program. Samples volumes were 68 ± 23.6 mL for BM and 5.6 ± 1.1 g for AT; in both AT and BM, the isolation rate was 100% (AT: 4/4; BM: 5/5). Undifferentiated cells were passaged up to 8 times for AT and 5 times for BM; population-doubling times (DT) were calculated, and data were analysed by ANOVA (Statistica for Windows, Stat Soft Inc., Tulsa, OK, USA). No significant differences (P > 0.05) were found between DT of all passages. The DT was greater (P < 0.05) for BM (3.2 ± 1.5) than for AT (1.3 ± 0.7). By passage 8, AT MSC underwent 37.3 ± 4.6 cell-doublings (CD); by passage 5, BM MSC underwent 26.2 ± 5.03 CD. Positive von Kossa and Alizarin Red staining confirmed osteogenesis. Alcian blue staining illustrated chondrogenesis, and positive Oil Red O staining suggested adipogenesis. The AT and BM MSC were positive for CD90, CD44, and CD105; all cell lines were negative for haematopoietic markers such as CD34, CD14, and CD45. Although marker CD73 expresses reaction in other studies involving MSC in different species, it did not cross-react with equine AT and BM MSC. Results obtained revealed the immunophenotypic characterisation of the surface of isolated and cultivated MSC, classifying these cells as a promising type of progenitor cells that can be applied in equine cellular therapy.

Successful surgical treatment of a prostatic biphasic tumour (sarcomatoid carcinoma) in a cat

A 12-year-old, neutered male, mixed-breed, domestic cat was presented for dysuria and haematuria accompanied by recurrent dyschezia and constipation. At rectal digital examination a non-painful, globose and relatively immobile mass was detected at the pelvic brim, ventral to the rectum. Abdominal ultrasound showed the prostate replaced by a mass with a regular shape but patchy/non-uniform echogenicity. A prostatectomy followed by prepubic urethrostomy was performed. At histopathology the tumour was composed of epithelial ducts and acini with malignant features, surrounded by proliferating cellular stroma with mitoses and nuclear atypia; an immunohistochemical panel confirmed the biphasic nature of the tumour proliferation. The diagnosis was non-infiltrating malignant mixed tumour, resembling human sarcomatoid carcinoma of the prostate. Two years after surgery the animal has not shown any health problems. To the author's knowledge, this is the first reported case of prostatic tumour with a positive follow-up after surgical treatment in cat.

384 ISOLATION OF MESENCHYMAL STEM CELLS FROM WHARTON'S JELLY, CORD BLOOD, AND AMNIOTIC FLUID IN THE HORSE

The effect of orthopedic injuries on the health of racehorse and racing financials can be dramatic. Bearing this in mind, there is naturally a great interest in new possible treatments for orthopedic injuries. In this study we evaluated equine amniotic fluid (AF), cord blood (CB), and Wharton’s jelly (WJ) as alternative sources of primitive, multipotent stem cells. All chemicals were obtained from Sigma-Aldrich (St. Louis, MO, USA) unless otherwise stated. Samples were recovered at labor from 7 standardbred mares with ages between 6 and 15 years. Wharton’s jelly was incubated with collagenasis at 37°C for at least 2 hr. The resulting cell suspension was centrifuged, and the cell pellet was resuspended in culture medium (DMEM and TCM-199, 1:1) plus 10% FBS (GIBCO®, Invitrogen Corporation, Carlsbad, CA, USA), 100 IU mL-1 penicillin, and 100 μg mL-1 streptomycin). Amniotic fluid and CB were diluted 1:1 in PBS medium supplemented with antibiotic solution and centrifuged for 15 min at 300 x g. The pellet was resuspended in 5 mL of culture medium, placed on 5 mL of 70% Percoll solution, and centrifuged at 1200 x g for 30 min. The interface layer was then aspirated and resuspended in culture medium. All the cell lineages were washed seeded into 25 cm2 flasks and cultured in a 5% CO2 incubator at 38.5°C. Medium was refreshed after 48 h and then twice a week. Adherent fibroblast-like cells were tested for their differentiation potential at passage 3. Chondrogenic differentiation was performed using a micromass culture technique, whereas osteogenic differentiation was induced in monolayer culture (Mizuno H and Hyakusoku H 2003 J. Nippon Med. Sch. 70, 300-306). Evidence for differentiation was made via morphological, biochemical, and cytological evaluations. Sample volume was 15-55 mL for AF, 10-60 mL for CB, and 5-12.6 g for WJ. In 4 out of 6 (66.7%) AF, 5 out of 5 (100%) CB, and 6 out of 7 (85.7%) WJ samples, colonies with the classical mesenchymal stem cell (MSC) morphology of adherent fibroblastoid spindle-shaped cells growing in a monolayer were observed. Undifferentiated cells have been passaged up to 8 times, population-doubling times (DT) were calculated for a subset of cell passages, and data were analyzed by ANOVA (Statistica for Windows, Stat Soft Inc., Tulsa, OK, USA). In all samples, there were no significant differences (P > 0.05) between DT of all passages. The DT was greater (P < 0.05) forCB (2.6 ± 1.3 d) than for AF (2.1 ± 0.8 d) and WJ (1.9 ± 0.5 d). By passage 8, the cells had undergone 39.1 ± 1.2 cell-doubling numbers in AF, 35.1 ± 2.7 in CB, and 37.4 ± 2.0 in WJ. A spheroid structure and positive Alcian blue staining of matrix glycosaminoglycans illustrated chondrogenesis. Cellular morphology and positive von Kossa staining, as well as alkaline phosphatase activity, confirmed osteogenesis. Based on the results obtained, WJ, CB, and for the first time in the horse, AF represent alternative sources of stem cells. Their differentiation into osteocytes and chondrocytes demonstrated that equine MSC from these samples can be induced to form multiple cell types, which underlies their value for regenerative medicine in injured horses.

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.