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Monozygotic 24-year-old twins presented with discordant ovarian function. One had had premature ovarian failure at the age of 14 years, whereas her sister had normal ovaries and three naturally conceived children. After unsuccessful egg-donation therapy, the sterile twin received a transplant of ovarian cortical tissue from her sister by means of a minilaparotomy. Within three months after transplantation, the recipient's cycles resumed and serum gonadotropin levels fell to the normal range. During the second cycle, she conceived, and her pregnancy progressed uneventfully. At 38 weeks' gestation, she delivered a healthy-appearing female infant.
Case Report
The patients were 24-year-old twin sisters who were confirmed to be monozygotic by means of genetic fingerprinting at 15 loci. One of the sisters (the donor) had three naturally conceived children and had been using oral contraceptives during the year preceding transplantation. Secondary amenorrhea had developed in the other twin (the recipient) at the age of 14 years, after three years of cycles with scanty menses. She had had no menses for 10 years before the ovarian transplantation. Her serum follicle-stimulating hormone (FSH) level at the age of 15 years ranged from 49 to 104 mIU per milliliter. When she was 20 years old, a laparoscopic examination and ovarian biopsy revealed atrophic, elongated ("streak") gonads with no follicles and a small uterus with an otherwise normal reproductive tract. At the age of 23 years, the sisters underwent two unsuccessful cycles of in vitro fertilization (IVF) at another center. The donor sister received controlled ovarian stimulation with standard doses of hormones for egg donation. A total of 14 oocytes (9 of which were mature) were recovered from 16 preovulatory follicles, and 7 zygotes were generated by IVF. Pregnancy was not achieved after the transfer of two fresh embryos or after the transfer of two cryopreserved embryos in a subsequent cycle of IVF.
The twins declined any further attempts at egg donation. Informed that an attempt could be made to transplant ovarian tissue, they requested that this approach be tried instead to restore fertility to the menopausal sister. The women were in excellent general health, and the donor's ovarian function was considered to be normal on the basis of her reproductive history, peripheral hormone levels, ovarian ultrasonographic findings, and previous ovarian stimulation for IVF. Peripheral hormones measured in the infertile twin one day before the transplantation remained at menopausal levels: 75 mIU of FSH per milliliter, 32 mIU of luteinizing hormone (LH) per milliliter, and 4 pg of estradiol per milliliter.
Methods
Surgery
The surgical procedure was approved by the ethics review committee of St. Luke's Hospital, and both sisters provided written informed consent. They were screened for human immunodeficiency virus type 1 and hepatitis B and C viruses, and the recipient stopped taking oral contraceptives as hormone-replacement therapy two weeks before surgery. The donor underwent laparoscopic removal of her left ovary under general anesthesia. The excised ovary was then dissected ex vivo. The ovarian cortical tissue was trimmed to a thickness of 1 to 2 mm by excising medullary tissue and bursting small antral follicles. This dissection was performed in Leibovitz (L15) medium on ice in less than one hour (Figure 1A).
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Spare cortical and medullary tissues were cultured for cytogenetic analyses according to standard procedures, including G-banding. In addition, enzymatically digested ovarian tissue obtained by direct harvest was examined by fluorescence in situ hybridization. Both women were also evaluated for skewed X-chromosome inactivation at the androgen receptor locus9 and for an increase in the number of CGG repeats in the FMR1 gene (indicative of fragile X syndrome) by means of Southern analysis or the polymerase chain reaction, since these mutations have been associated with premature ovarian failure.10,11 Serum samples were analyzed for FSH, LH, and estradiol with the use of standard immunoassays.
Results
Both patients recovered rapidly and returned to their home state one day after surgery. Seventy-one days after transplantation, a 14-mm follicle had developed in the recipient; the serum estradiol level at this time was 154 pg per milliliter (Table 1) and the uterine-lining thickness was 8 mm. At 80 days, she had her first postoperative menses, although it lasted only a single day. The endocrine profile indicated that her ovaries then remained quiescent until 48 days later (128 days after transplantation), when a 14-mm follicle was again noted sonographically. The thickness of the uterine lining was 10 mm, the estradiol level was 193 pg per milliliter, and the LH level was 123.4 mIU per milliliter. Her basal body temperature then rose from 36.4° to 36.9°C and remained elevated for 13 days. At 141 days after transplantation, her serum FSH and LH had decreased to 9.1 and 4.7 mIU per milliliter, respectively. The following day, a heavy menstrual period began, and her basal body temperature dropped.
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human chorionic gonadotropin level was 828 mIU per milliliter. Ultrasonographic examination five weeks after her second menstrual period (day 176 after transplantation) revealed a normal intrauterine pregnancy with a well-defined secondary yolk sac; the human chorionic gonadotropin level was then 30,289 mIU per milliliter. She had conceived naturally. At seven weeks, ultrasonography verified that she had a normally developing intrauterine pregnancy associated with a fetal heart rate of 148 beats per minute. The 22-week ultrasonogram was normal. She gave birth to a healthy-appearing girl at 38 weeks' gestation by vaginal delivery. The infant's birth weight was 3600 g, and the Apgar scores were 9 at one minute and 10 at five minutes. All specimens (peripheral lymphocytes, ovarian cortex, and ovarian medulla) from both patients had a normal 46,XX karyotype, and G-banding did not reveal any structural chromosomal aberrations. Moreover, dual-colored fluorescence in situ hybridization of 250 cells from each sample of uncultured tissue with the use of probes for two genes on the sex chromosomes (DXZ1 and SRY, Vysis) did not reveal any XX–XY mosaicism. The degree of inactivation of the X chromosome was within normal limits in both patients (50:50 for the donor and 65:35 for the recipient), and neither patient had an increase in the number of CGG repeats in the FMR1 gene that was in the premutation or mutation range.
Tissue sections from each sister were compared. The streak ovaries of the recipient had no detectable follicles (Figure 3). There was extensive fibrosis, including fibrotic remnants of old corpora albicantia presumably dating from the sporadic ovulatory cycles that had last occurred more than a decade earlier. The smaller fragments of tissue from the donor ovary appeared histopathologically normal and contained follicles of various sizes. Tissue from the contralateral ovary of the donor was not available for study, but its size and appearance suggested that this ovary was also normal.
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We describe a successful pregnancy in a prematurely menopausal monozygotic twin who received an ovary from her healthy, fertile twin. The pregnancy was established spontaneously, without ancillary medical assistance. It is extremely unlikely that the restoration of ovarian function in this patient after transplantation was due to residual follicles in the streak ovary of the recipient; she had a decade-long history of amenorrhea with elevated gonadotropin levels on all occasions on which they were measured and no detectable follicles on pathological examination.
Studies in animals have indicated that only primordial follicles survive transplantation-related ischemia,12 but the rapid onset of cyclicity in our patient suggested that at least one growing follicle had survived and grown to maturity. However, follicle recruitment may not have normalized until the second cycle, about three months after transplantation, when serum levels of gonadotropin and estrogen returned to levels characteristic of those in young, fertile women. Endometrial thickness also reached preovulatory dimensions at this time, and an LH surge and elevated basal body temperature indicated that ovulation had occurred. The patient conceived naturally during this cycle.
Grafting of ovarian cortex was chosen because it is minimally invasive and involves substantially less risk and recovery time than a vascular graft (which one of us described in a report of testis transplantation between male homozygous twins discordant for anorchia13). Moreover, cortical grafting (in contrast to vascular anastomosis) affords the opportunity to cryopreserve additional ovarian tissue for a future transplantation, should it be required. To date, whole-ovary cryopreservation has been successful only in rats and would be unlikely to be effective with the much larger human ovary.14 Although heterotopic grafts of human (or monkey) cortical tissue can generate mature oocytes for IVF,15,16,17 we did not pursue that strategy in the present case because the twins had declined further attempts at IVF.
An important technical limitation of cortical grafting, whether orthotopic or heterotopic, is the potential for follicle atresia during the period of ischemia, before the tissue becomes revascularized12,18; such an event might compromise long-term ovarian function. Yet experimental studies suggest that long-term ovarian function may not be compromised by grafting.6 Studies in animals have indicated that a short interval before conception is related to adequate follicular reserves and that the use of grafted ovarian cortex can result in prolonged resumption of fertility.6 In the current case, the recipient's low levels of serum FSH on day 3 of the second cycle (after she had received only two thirds of one ovary from her sister) and the rapid return of normal ovarian function suggest that normal menstrual cycles and fertility may resume in this patient after pregnancy. If, however, ovarian function were not maintained over the long term, the recipient could receive a second graft of remaining cryopreserved tissue.
The procedure we used is based on a simple method that was first described in sheep.19,20,21 In the first reported clinical cases of ovarian autografting, ovarian function was transitory, perhaps because of a paucity of follicles in the grafted tissue as a result of prior chemotherapy.22,23 Recently, a viable pregnancy was reported after ovarian-tissue banking and transplantation in a patient who was thought to be sterile after treatment for Hodgkin's disease.24 However, doubts have been expressed as to whether ovulation in that conception cycle occurred from the grafted tissue or from tissue left in situ and in close proximity to the graft.25 It is impossible to verify the origin of the fertilized egg in that case retrospectively, but the present report provides a compelling demonstration that cortical grafts can restore fertility. Furthermore, our technique involved a single, simple procedure rather than repeated laparoscopic procedures to attach multiple slices of tissue to the pelvic wall. Cryopreservation is not required for this procedure, but if a second transplantation is required, frozen–thawed tissue can be used; experimental evidence suggests that cryopreservation should have only a minor effect on follicular wastage.7 Routine genetic testing revealed no obvious cause for the discordance between these monozygotic twin sisters, nor any obvious cause for concern about the health of future offspring.
Although ovarian transplantation between monozygotic twins will be rare, the demonstration that ovarian function can be restored and that natural conception and successful pregnancy can be achieved after transplantation of ovarian tissue may have broader implications for preserving fertility in young women, such as those who require potentially sterilizing treatment for cancer.
We are indebted to Dr. Braden Richmond for his follow-up care in Alabama, to Julie Heintzelman for assistance in the preparation of the manuscript, and to Debby Grenia for coordination of the studies.
Source Information
From St. Luke's Hospital, St. Louis (S.J.S., K.M.L., D.J.L., J.A.P.); Paternity Testing, Columbia, Md. (K.S.G.); Greenwood Genetic Center, Greenwood, S.C. (M.J.F.); Sentara Hospital Cytogenetics Laboratory, Norfolk, Va. (E.C.C.); and Weill Medical College of Cornell University, New York (R.G.G.).
This article was published at www.nejm.org on June 7, 2005.
Address reprint requests to Dr. Silber at the Infertility Center of St. Louis, St. Luke's Hospital, 224 S. Woods Mill Rd., Suite 730, St. Louis, MO 63017, or at drsherm{at}aol.com or silber{at}infertile.com.
References
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