[Show abstract][Hide abstract] ABSTRACT: Large animal models that accurately mimic human hemophilia A (HA) are in great demand for developing and testing novel therapies to treat HA.
To re-establish a line of sheep exhibiting a spontaneous bleeding disorder closely mimicking severe human HA, fully characterize their clinical presentation, and define the molecular basis for disease.
Sequential reproductive manipulations were performed with cryopreserved semen from a deceased affected ram. The resultant animals were examined for hematologic parameters, clinical symptoms, and responsiveness to human FVIII (hFVIII). The full coding region of sheep FVIII mRNA was sequenced to identify the genetic lesion.
The combined reproductive technologies yielded 36 carriers and 8 affected animals. The latter had almost non-existent levels of FVIII:C and extremely prolonged aPTT, with otherwise normal hematologic parameters. These animals exhibited bleeding from the umbilical cord, prolonged tail and nail cuticle bleeding time, and multiple episodes of severe spontaneous bleeding, including hemarthroses, muscle hematomas and hematuria, all of which responded to hFVIII. Inhibitors of hFVIII were detected in four treated animals, further establishing the preclinical value of this model. Sequencing identified a premature stop codon and frame-shift in exon 14, providing a molecular explanation for HA. Given the decades of experience using sheep to study both normal physiology and a wide array of diseases and the high homology between human and sheep FVIII, this new model will enable a better understanding of HA and facilitate the development and testing of novel treatments that can directly translate to HA patients.
Full-text · Article · Nov 2009 · Journal of Thrombosis and Haemostasis
[Show abstract][Hide abstract] ABSTRACT: The objectives of the present study were to investigate the relationship between the morphological status of cumulus cells surrounding canine oocytes after maturation culture and the meiotic stage of the oocytes. In addition, the effect of the removal of cumulus cells from canine cumulus-oocyte complexes (COCs) during maturation culture on their meiotic competence was examined. Canine COCs were collected from bitches at the anoestrous and dioestrous stages and only COCs with >110 microm in vitelline diameter were cultured in medium 199 with 10% canine serum for 72 h. In the first experiment, the relation between the morphological status of cumulus cells surrounding oocytes cultured for 72 h and their meiotic stages was examined. At the end of maturation culture, the proportions of intact, partially nude and completely nude oocytes were 65.2%, 22.9% and 11.9%, respectively. The proportion of maturation to metaphase II of completely nude oocytes was highest among the oocytes with different morphological status of cumulus cells. In the second experiment, the cumulus cells were partially or completely removed from COCs at 48 h after the start of maturation culture and the oocytes were cultured for a further 24 h. The proportion of oocytes reaching metaphase II in the completely denuded oocytes was significantly higher than that in the control oocytes without the removal treatment of cumulus cells. The results indicate that morphological status of cumulus cells surrounding oocytes may be related to the nuclear maturation of canine oocytes, and the removal of cumulus cells from COCs during maturation culture can promote the completion of oocyte meiotic maturation.
No preview · Article · Apr 2007 · Reproduction in Domestic Animals
[Show abstract][Hide abstract] ABSTRACT: Tissue banking and animal cloning represent a powerful tool for conserving and regenerating valuable animal genomes. Here we report an example involving cattle and the rescue of a genome affording natural disease resistance. During the course of a 2-decade study involving the phenotypic and genotypic analysis for the functional and genetic basis of natural disease resistance against bovine brucellosis, a foundation sire was identified and confirmed to be genetically resistant to Brucella abortus. This unique animal was utilized extensively in numerous animal breeding studies to further characterize the genetic basis for natural disease resistance. The bull died in 1996 of natural causes, and no semen was available for AI, resulting in the loss of this valuable genome. Fibroblast cell lines had been established in 1985, cryopreserved, and stored in liquid nitrogen for future genetic analysis. Therefore, we decided to utilize these cells for somatic cell nuclear transfer to attempt the production of a cloned bull and salvage this valuable genotype. Embryos were produced by somatic cell nuclear transfer and transferred to 20 recipient cows, 10 of which became pregnant as determined by ultrasound at d 40 of gestation. One calf survived to term. At present, the cloned bull is 4.5 yr old and appears completely normal as determined by physical examination and blood chemistry. Furthermore, in vitro assays performed to date indicate this bull is naturally resistant to B. abortus, Mycobacterium bovis, and Salmonella typhimurium, as was the original genetic donor.
Full-text · Article · Feb 2007 · Journal of Animal Science
[Show abstract][Hide abstract] ABSTRACT: The objective of this study was to restore a line of sheep that exhibits spontaneous X-linked factor VIII deficiency closely mimicking human hemophilia A. Six straws of frozen semen from an affected Alpine White male were obtained from Switzerland. In the first experiment the straw of semen thawed was of poor quality. Two ewes were synchronized for use as embryo donors (MOET) by means of CIDRs for 14 days and superovulated with declining doses of FSH (184 mg) twice daily for 3 days. PMSG (200 IU) was given with the final dose of FSH and 1000 IU of hCG 12 h post-CIDR removal. The ewes were surgically inseminated 24 h later. Oviducts were flushed 48 h post-insemination producing 13 unfertilized ova (UFO). Spermatozoa were used for intracytoplasmic sperm injection (ICSI) utilizing oocytes collected from superstimulated ewes by laporatomy. These ewes were synchronized with CIDRs (15 days) and superovulated with a declining dose of FSH (204 mg) twice daily for 3.5 days. Utilizing 236 oocytes, ICSI produced 189 embryos, an 80% embryo/oocyte rate. Embryos were transferred surgically to the oviducts of 17 synchronized recipients. Recipients were synchronized using sponges (Ovakron; Heriot Agvet, Rowville, Victoria, Australia) containing 30 mg of flugestone acetate (14 days) and given PMSG (400 IU) at sponge removal, followed by 1000 IU of hCG 12 h post-sponge removal. Eleven recipients produced 17 lambs for a lamb/embryo rate of 8.9%. The straw of semen utilized for the second experiment was of higher quality. Three ewes were superstimulated for use as MOET donors, as above, with increased doses of FSH (228 mg) and PMSG (500 IU). Donors were surgically inseminated and oviductal flushes were performed 40 h post-insemination, yielding 19 UFO and 12 embryos for an embryo/oocyte rate of 38.7%. Embryos were transferred to four recipients, synchronized as above with an increased dose of PMSG (600 IU). These MOET recipients produced nine lambs for a lamb/embryo rate of 75%. Semen was used to produce embryos via in vitro fertilization (IVF) using oocytes collected from superstimulated ewes (as above with an increase of FSH to 252 mg). IVF produced 91 embryos from 247 oocytes for an embryo/oocyte rate of 36.8%. Embryos were transferred to 20 recipients 24 to 48 h post-fertilization. Seven recipients maintained pregnancy and produced 10 lambs with a lamb/embryo rate of 11%. ICSI was also utilized, producing 54 embryos from 98 oocytes, an embryo/oocyte rate of 55.1%. Embryos were transferred to eight recipients; none maintained pregnancy. Through the use of multiple reproductive technologies, 36 lambs (22 carriers) were produced from two straws of semen. Carriers will be bred back to their sire in a similar program to produce affected lambs.
The authors would like to acknowledge J. Liu and M. Ridha for their contributions. This work was supported by NIH Grant HL073737-12.
Full-text · Article · Jan 2006 · Reproduction Fertility and Development
[Show abstract][Hide abstract] ABSTRACT: This study was conducted to determine a suitable ratio of oocytes to medium for in vitro maturation (IVM) of cumulus-oocyte complexes (COCs) collected from bitches at anoestrus and dioestrus and to examine the meiotic competence of COCs cultured singly or in different group sizes. In the first experiment, different numbers of COCs (5, 10, 15 and 20 per drop) were cultured for 72 h in 100 microl drops of maturation medium. The meiotic competence of oocytes from ovaries at anoestrus was affected by the number of COCs incubated, whereas at dioestrus, the incubation number of COCs had no effect. In the second experiment, COCs were cultured singly or in different group sizes for 72 h by suitable oocyte density according to the reproductive cycle of the donor. In the anoestrous group, 1, 5 and 10 COCs were cultured in 10, 50 and 100 microl drops of the medium (10 microl per COC), respectively. In the dioestrous group, 1, 5 and 15 COCs were cultured in 7, 35 and 105 microl drops of the medium (7 microl per COC), respectively. There were no differences in the proportions of oocytes reaching metaphase II among the different group sizes in each stage of the reproductive cycle of the donor. The results indicate that the influence of oocyte density on the meiotic competence of oocytes differs according to the stage of the reproductive cycle of the donor. Moreover, the group sizes have no effect on the meiotic competence of oocytes cultured at suitable oocyte density according to the reproductive cycle of the donor.
Full-text · Article · Jan 2003 · Reproduction (Cambridge, England)
[Show abstract][Hide abstract] ABSTRACT: The objective of this research was to evaluate if DNA hypomethylation in cells used as karyoplasts would improve development of bovine nuclear transplantation (NT) embryos. DNA from serum-fed (SF), serum-starved (SS), and 1, or 5 microM 5-azacytidine (5-aza-CR) treated cells was digested with a methylation sensitive enzyme, and evaluated for DNA methylation. A significant reduction in DNA methylation was observed in cells cultured for 48 or 72 hr in SS medium as well as in cells cultured for 48 hr in the presence of 5 microM 5-aza-CR when compared to cells cultured in SF medium. All other comparisons contained no significant differences when compared to controls. When donor cells were cultured in 5-aza-CR, SF, or SS treatment media for 48 hr, no significant difference was observed (P = 0.06) in blastocyst development rates after NT. One embryo produced by donor cells treated with 5-aza-CR established a pregnancy. Four pregnancies resulted from embryos produced by SS donor cell NT and 3 resulted from embryos produced by SF donor cell NT. Supplementation of the donor cell culture medium with 5-aza-CR was not beneficial for increasing blastocyst rate or establishing pregnancy after NT.
No preview · Article · Oct 2001 · Molecular Reproduction and Development
[Show abstract][Hide abstract] ABSTRACT: Cloned sheep, cattle, goats, pigs and mice have now been produced using somatic cells for nuclear transplantation. Animal cloning is still very inefficient with on average less than 10% of the cloned embryos transferred resulting in a live offspring. However successful cloning of a variety of different species and by a number of different laboratory groups has generated tremendous interest in reproducing desired genotypes. Some of these specific genotypes represent animal cell lines that have been genetically modified. In other cases there is a significant demand for cloning animals characterized by their inherent genetic value, for example prize livestock, household pets and rare or endangered species. A number of different variables may influence the ability to reproduce a specific genotype by cloning. These include species, source of recipient ova, cell type of nuclei donor, treatment of donor cells prior to nuclear transfer, and the techniques employed for nuclear transfer. At present, there is no solid evidence that suggests cloning will be limited to only a few specific animals, and in fact, most data collected to date suggests cloning will be applicable to a wide variety of different animals. The ability to reproduce any desired genotype by cloning will ultimately depend on the amount of time and resources invested in research.
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to determine whether nuclear transplantation could be used to clone a dog using donor nucleus cells collected from an adult female. Fibroblasts obtained from skin biopsies were fused with enucleated bovine or canine oocytes. The resulting cloned embryos were cultured in vitro to monitor embryonic development. A proportion of the resulting embryos was transferred into surrogate bitches for development to term. When canine oocytes were used as recipient ova for canine fibroblasts, 23% of the resulting embryos cleaved at least once after culture in vitro. Five cloned embryos were transferred into three synchronized recipient bitches, but no pregnancies resulted. When bovine oocytes were used as recipinets for canine fibroblasts, 38% cleaved to the two- to four-cell stage and 43% cleaved to the eight- to 16-cell stage. Forty-seven of these embryos were transferred into four recipient females, resulting in a single conceptus that ceased development at about day 20 of gestation. The desire for cloned dogs is considerable and will undoubtedly incite the development of successful methods for cloning companion animals. However, significant investment into additional research is required, especially in the areas of in vitro maturation of oocytes and control of the oestrous cycle of bitches.
No preview · Article · Feb 2001 · Journal of reproduction and fertility. Supplement