Xenotransplantation of cryopreserved human ovarian tissue into murine back muscle.

BACKGROUND: Ovarian tissue (OT) cryopreservation and transplantation are options for fertility preservation in young female cancer patients. METHODS: We investigated xenotransplantation of human OT into back muscle (B) of severe combined immunodeficiency mice. OT follicle content was evaluated by stereomicroscopy and pre-transplantation. Xenograft survival, follicular development (with/without FSH administration), apoptosis and vascularization were compared in B- versus K-site (under the kidney capsule) several times after grafting using histology, immunohistochemistry and magnetic resonance imaging. In vitro maturation (IVM) was also performed. RESULTS: Anastomoses which developed from existing human and invading murine vessels were seen in OT at both sites, but angiogenesis was more prominent at the B- than K-site (P < 0.001). Vascularization and follicle size were correlated in the B-group (Spearman's coefficient 0.73; P < 0.001). FSH increased early (8 days) micro-vessel formation in B but not in K grafts (P < 0.0001, versus no FSH). B-site grafts showed a better histological morphology and survival (P = 0.0084), formation of larger antral follicles (P = 0.005), more metaphase-II (MII) oocytes, growing follicles (P = 0.028) and slightly fewer apoptotic follicles than K grafts. One MI oocyte from B underwent IVM and reached MII stage next day. CONCLUSIONS: To our knowledge, this is the first report of MII and IVM-MII oocytes obtained from B xenografts. We report the largest oval-shaped antral follicles containing an MII oocyte obtained after OT xenotransplantation to date. Xenografting in the mouse B should be further explored as a method for human OT transplantation.

Reduced amounts and abnormal forms of phospholipase C zeta (PLCzeta) in spermatozoa from infertile men.

BACKGROUND: In mammals, oocyte activation at fertilization is thought to be induced by the sperm-specific phospholipase C zeta (PLCzeta). However, it still remains to be conclusively shown that PLCzeta is the endogenous agent of oocyte activation. Some types of human infertility appear to be caused by failure of the sperm to activate and this may be due to specific defects in PLCzeta. METHODS AND RESULTS: Immunofluorescence studies showed PLCzeta to be localized in the equatorial region of sperm from fertile men, but sperm deficient in oocyte activation exhibited no specific signal in this same region. Immunoblot analysis revealed reduced amounts of PLCzeta in sperm from infertile men, and in some cases, the presence of an abnormally low molecular weight form of PLCzeta. In one non-globozoospermic case, DNA analysis identified a point mutation in the PLCzeta gene that leads to a significant amino acid change in the catalytic region of the protein. Structural modelling suggested that this defect may have important effects upon the structure and function of the PLCzeta protein. cRNA corresponding to mutant PLCzeta failed to induce calcium oscillations when microinjected into mouse oocytes. Injection of infertile human sperm into mouse oocytes failed to activate the oocyte or trigger calcium oscillations. Injection of such infertile sperm followed by two calcium pulses, induced by assisted oocyte activation, activated the oocytes without inducing the typical pattern of calcium oscillations. CONCLUSIONS: Our findings illustrate the importance of PLCzeta during fertilization and suggest that mutant forms of PLCzeta may underlie certain types of human male infertility.

Back muscle as a promising site for ovarian tissue transplantation, an animal model.

BACKGROUND: The aim of this study was to evaluate the optimal transplantation site for ovarian tissue fragments in murine hosts. We compared the transplantation to the back muscle (B) versus the kidney capsule (K) in a mouse allograft model. METHODS: Hemi-ovaries from 12-day-old mice were allografted into B and K of bilaterally ovariectomized same strain recipients which had undergone gonadotrophin stimulation (n = 15). Graft survival after 27 days, angiogenesis and follicle development were scored and compared to age-matched control ovaries (38-day old, n = 5). The ability of oocytes to be fertilized was studied after IVF, ICSI and embryos were transferred to recipient mothers. Anti-mouse CD 31+ antibody was used to evaluate neo-vascularization in grafts. RESULTS: Primordial follicle survival was higher (P < 0.01) and vascular support was better (P < 0.01) in B- than in K-grafts. From 34 oocytes retrieved from B-grafts (15 metaphase I, of which 14 matured in vitro, and 19 collected at metaphase II), 18 morulae were obtained. Transfer of 12 embryos obtained by ICSI led to three live offspring, and transfer of six IVF embryos to another recipient mother yielded four offspring, one of which was born dead and one showed placental anomalies. CONCLUSIONS: The back muscle is a promising site for ovarian allografts in mice. This is the first report of live offspring obtained after back muscle grafting using both IVF and ICSI.