S. Wood

Development of Human Cloned Blastocysts Following Somatic Cell Nuclear Transfer with Adult Fibroblasts

Nuclear transfer stem cells hold considerable promise in the field of regenerative medicine and cell‐based drug discovery. In this study, a total of 29 oocytes were obtained from three young (20–24 years old) reproductive egg donors who had been successful in previous cycles. These oocytes, deemed by intended parents to be in excess of their reproductive needs, were donated for research without financial compensation by both the egg donor and intended parents after receiving informed consent. All intended parents successfully achieved ongoing pregnancies with the oocytes retained for reproductive purposes. Mature oocytes, obtained within 2 hours following transvaginal aspiration, were enucleated using one of two methods, extrusion or aspiration, after 45 minutes of incubation in cytochalasin B. Rates of oocyte lysis or degeneration did not differ between the two methods. Somatic cell nuclear transfer (SCNT) embryos were constructed using two established adult male fibroblast lines of normal karyotype. High rates of pronuclear formation (66%), early cleavage (47%), and blastocyst (23%) development were observed following incubation in standard in vitro fertilization culture media. One cloned blastocyst was confirmed by DNA and mitochondrial DNA fingerprinting analyses, and DNA fingerprinting of two other cloned blastocysts indicated that they were also generated by SCNT. Blastocysts were also obtained from a limited number of parthenogenetically activated oocytes. This study demonstrates, for the first time, that SCNT can produce human blastocyst‐stage embryos using nuclei obtained from differentiated adult cells and provides new information on methods that may be needed for a higher level of efficiency for human nuclear transfer.

Effect of human corticotropin-releasing hormone on gonadotropin secretion in cycling and postmenopausal women

OBJECTIVE To test the hypothesis that corticotropin-releasing hormone (CRH) is linked to stress-associated reproductive dysfunction in the human by determining if the administration of human corticotropin-releasing hormone (hCRH) results in an inhibition of gonadotropin secretion. DESIGN Twenty-four-hour prospective study with frequent (every 10 minutes) blood sampling. SETTING University Clinical Research Center. INTERVENTIONS Sequential 8-hour infusions of normal saline, hCRH (1 to 5 micrograms/kg per hour), and hCRH plus naloxone (2 mg/h). SUBJECTS Four normal cycling women and four postmenopausal women. MAIN OUTCOME MEASURES Plasma luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin (PRL), and adrenal and ovarian steroids. RESULTS In response to hCRH, a prompt and sustained rise in cortisol (F) was noted in both normal cycling women and postmenopausal women. No inhibition of LH or FSH was noted during either the hCRH or hCRH plus naloxone infusion in either group of women. Unexpectedly, elevations in the mean LH peak amplitude and the transverse mean LH concentration were noted in the postmenopausal women during the infusion of hCRH as compared with saline. The infusion of hCRH had no apparent effect on concentrations of PRL, FSH, and gonadal and adrenal steroids (except for F). CONCLUSIONS Under these conditions, intravenously administered hCRH has no inhibitory effect on gonadotropin secretion in either premenopausal or postmenopausal women. The mechanism by which stress exerts its deleterious effect on reproductive function in the human remains unknown.