Orthotopic transplantation of cryopreserved mouse ovaries and gonadotrophin releasing hormone analogues in the restoration of function following chemotherapy-induced ovarian damage

Investigation on revascularization time and initial damage after transplantation of fresh and cryopreserved ovarian tissue in domestic cats

The present study evaluated revascularization time of fresh and cryopreserved cat ovarian tissue after transplantation to subcutaneous tissue. Ovaries of five cats were used and eight pieces of ovarian tissue were taken from each pair of ovaries. Immediately after removal, three pieces were transplanted and one fixed for fresh control. The remaining four pieces were cryopreserved and, after thawing, one was fixed for cryopreservation control and three were transplanted. Grafts were recovered on days 2 (D2), 4 (D4) and 6 (D6) post-transplantation. Blood vessels were identified by immunohistochemistry and doppler ultrasound. Immunohistochemistry showed that the percentages of total tissue area occupied by blood vessels were similar (P > 0.05) in fresh and cryopreserved tissues. In both cases, blood vessel area was significantly higher (P < 0.05) on D4 and D6 compared to D0. Ultrasound analysis showed vascularization improvement on the periphery of grafts from D2 to D4 and from D4 to D6, both in fresh and cryopreserved tissue samples. Nonetheless, there was a significant decrease (P < 0.05) in the percentage of morphologically normal follicles (MNF) after transplantation compared to non-transplanted tissue (D0), both for fresh and cryopreserved samples. Moreover, the number of follicles found in samples was considerably smaller after grafting. In conclusion, revascularization of ovarian tissue autotransplanted to subcutaneous tissue in domestic cats occurs within 4 days after transplantation, both for fresh and cryopreserved tissue. However, large follicular loss has been observed in the first days post-transplantation, especially in cryopreserved tissues.

The growth and development conditions in mouse offspring derived from ovarian tissue cryopreservation and orthotopic transplantation

PURPOSE

To investigate the potential development or metabolic risk in offspring derived from mice with transplanted frozen-thawed ovarian tissue.

METHODS

Mice ovaries were intervened by vitrification (group V) and slow-freezing (group S) cryopreservation and orthotopic transplantation. Orthotopic transplantation of fresh ovarian (group F) and natural mating (group C) served as control groups. The fertility restoration and health conditions of generations were assessed by offspring counts, anti-fatigue and motor ability, and organ morphology. The methylation rate and expression level of imprinted genes (IGF2R, H19, SNRPN, and PLAGL1) were used to predict the potential risk of development in transplanted generations.

RESULTS

Both the percentage of normal morphological follicles in different developmental periods and the litter size of receipt mice were comparable in all three transplanted groups. There was no significant difference in offspring mice's birth defects, body weight gain, anti-fatigue ability, or exercise capacity among the four groups. The methylation rate of IGF2R, H19, and PLAGL1 showed a significant variation in cryopreservation groups as compared with control groups, as well as a difference in gene expression. The SNRPN appeared to be stable in methylation status. There were no differences in mRNA expression in all groups.

CONCLUSIONS

The different ovarian tissue cryopreservation methods did not influence either maternal fertility function or offspring growth. However, these technologies could affect the methylation rate and expression level of some development-related imprinting genes in the offspring, which may lead to some indeterminacy risk.

Both in vivo FSH depletion and follicular exposure to Gonadotrophin-releasing hormone analogues in vitro are not effective to prevent follicular depletion during chemotherapy in mice

STUDY QUESTION

Does fertility preservation using gonadotrophin-releasing hormone (GnRH) analogues during chemotherapy act through a direct effect on the ovary or through inhibition of FSH secretion?

SUMMARY ANSWER

The absence of FSH in vivo and the direct exposition of ovarian follicles to GnRH analogues in vitro did not prevent chemotherapy-induced ovarian damage.

WHAT IS KNOWN ALREADY

The potential mechanisms of action of GnRH analogues in protecting ovaries against chemotherapy damage remain poorly understood. We previously showed that GnRH analogues have a limited inhibitory effect on gonadotropin secretion and follicular growth in mice.

STUDY DESIGN SIZE, DURATION

Mouse models were developed to independently evaluate (i) the indirect effect of FSH depletion on chemotherapy-induced ovarian damage using Fshb-deficient (-/-) mice to mimic the profound inhibition of FSH secretion during GnRH analogues treatment and (ii) the direct in vitro effect of GnRH agonist and antagonist in follicles exposed to chemotherapy using a follicular culture system.

PARTICIPANTS/MATERIALS, SETTING, METHODS

To assess the indirect effect of GnRH analogues through FSH inhibition, Fshb-/- mice were treated with 1 IU pregnant mare serum gonadotropin (control group) or saline (study group) for 7 days and with cyclophosphamide (200 mg/kg) on Day 5. Ovaries were collected 48 h post-cyclophosphamide to evaluate ovarian reserve, cellular apoptosis and proliferation. To evaluate the direct effects of GnRH analogues on growing follicles, isolated preantral follicles from prepubertal mice were cultured in vitro for 13 days with 1 μM GnRH analogues and 20 μM of 4-hydroperoxycyclophosphamide or not at Day 4. Oocytes were matured by adding epidermal growth factor (EGF)/hCG on Day 12. Follicular development, follicular survival, oocyte maturation rates, cAMP production, and steroidogenesis were evaluated. To assess the direct GnRH analogues effects on follicular reserve, whole neonatal ovaries were cultured in vitro under the same conditions for 2 days. Ovaries were processed 24 h post-chemotherapy for ovarian reserve, cellular apoptosis and proliferation analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

Cyclophosphamide induced a significant follicular loss of more than 50% in Fshb-/- mice regardless of previous treatment with gonadotropins and no difference was observed in cell proliferation or apoptosis. In vitro experiments on growing follicles showed that 4-hydroperoxycyclophosphamide significantly decreased preantral follicle survival and maturation rates (55% and 37%, respectively) and delayed follicular development, regardless of the presence of GnRH analogues. Chemotherapy reduced granulosa cell numbers in all groups, while no change in cAMP production/106 granulosa cells was observed. Similarly, 4-hydroperoxycyclophosphamide induced apoptosis and significant follicular loss in cultured neonatal ovaries irrespective of GnRH analogues exposure.

LIMITATIONS REASONS FOR CAUTION

As ovarian GnRH receptors expression differs in humans and mice, further studies are needed to validate our results in human ovaries.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings demonstrate that ovarian damage occurred even in the absence of FSH, suggesting that inhibition of the pituitary-gonadal axis is not involved in ovarian protection during GnRH analogues treatment. Using in vitro models, no evidence for direct protective effect of GnRH analogues against cyclophosphamide metabolite damage was observed. At present, clinical efficiency of GnRH analogues to prevent chemotherapy-induced ovarian damage remains highly debated and these experimental results reinforced the question as they did not bring evidence of direct or indirect mechanisms of protection.

LARGE SCALE DATA

N/A.

STUDY FUNDING AND COMPETING INTEREST(S)

This work was supported by the Belgian FNRS, 'Le Fonds Emile DEFAY', and 'La Fondation Rose et Jean Hoguet'. Authors have no conflict of interest to declare.

Human amnion-derived mesenchymal stem cell (hAD-MSC) transplantation improves ovarian function in rats with premature ovarian insufficiency (POI) at least partly through a paracrine mechanism

Background

Chemotherapy can induce premature ovarian insufficiency (POI) and reduce fertility in young female patients. Currently, there is no effective therapy for POI. Human amnion-derived mesenchymal stem cells (hAD-MSCs) may be a promising seed cell for regenerative medicine. This study investigated the effects and mechanisms of hAD-MSC transplantation on chemotherapy-induced POI in rats.

Methods

Chemotherapy-induced POI rat models were established by intraperitoneal injection of cyclophosphamide. Seventy-two female SD rats were randomly divided into control, POI, and hAD-MSC-treated groups. hAD-MSCs were labeled with PKH26 and injected into the tail veins of POI rats. To examine the underlying mechanisms, the differentiation of transplanted hAD-MSCs in the POI ovaries was analyzed by immunofluorescent staining. The in vitro expression of growth factors secreted by hAD-MSCs in hAD-MSC-conditioned media (hAD-MSC-CM) was analyzed by ELISA. Sixty female SD rats were divided into control, POI, and hAD-MSC-CM-treated groups, and hAD-MSC-CM was injected into the bilateral ovaries of POI rats. After hAD-MSC transplantation or hAD-MSC-CM injection, serum sex hormone levels, estrous cycles, ovarian pathological changes, follicle counts, granulosa cell (GC) apoptosis, and Bcl-2, Bax, and VEGF expression in ovaries were examined.

Results

PKH26-labeled hAD-MSCs mainly homed to ovaries after transplantation.

hAD-MSC transplantation reduced ovarian injury and improved ovarian function in rats with POI. Transplanted hAD-MSCs were only located in the interstitium of ovaries, rather than in follicles, and did not express the typical markers of oocytes and GCs, which are ZP3 and FSHR, respectively. hAD-MSCs secreted FGF2, IGF-1, HGF, and VEGF, and those growth factors were detected in the hAD-MSC-CM. hAD-MSC-CM injection improved the local microenvironment of POI ovaries, leading to a decrease in Bax expression and an increase in Bcl-2 and endogenous VEGF expression in ovarian cells, which inhibited chemotherapy-induced GC apoptosis, promoted angiogenesis and regulated follicular development, thus partly reducing ovarian injury and improving ovarian function in rats with POI.

Conclusions

hAD-MSC transplantation can improve ovarian function in rats with chemotherapy-induced POI at least partly through a paracrine mechanism. The presence of a paracrine mechanism accounting for hAD-MSC-mediated recovery of ovarian function might be attributed to the growth factors secreted by hAD-MSCs.