Validation of an automated technique for ovarian cortex dissociation: isolation of viable ovarian cells and their qualification by multicolor flow cytometry

Minimal Infiltrative Disease Identification in Cryopreserved Ovarian Tissue of Girls with Cancer for Future Use: A Systematic Review

BACKGROUND

Ovarian tissue cryopreservation and transplantation are the only available fertility techniques for prepubertal girls with cancer. Though autotransplantation carries a risk of reintroducing malignant cells, it can be avoided by identifying minimal infiltrative disease (MID) within ovarian tissue.

METHODS

A broad search for peer-reviewed articles in the PubMed database was conducted in accordance with PRISMA guidelines up to March 2023. Search terms included 'minimal residual disease', 'cryopreservation', 'ovarian', 'cancer' and synonyms.

RESULTS

Out of 542 identified records, 17 were included. Ovarian tissues of at least 115 girls were evaluated and categorized as: hematological malignancies (n = 56; 48.7%), solid tumors (n = 42; 36.5%) and tumors of the central nervous system (n = 17; 14.8%). In ovarian tissue of 25 patients (21.7%), MID was detected using RT-qPCR, FISH or multicolor flow cytometry: 16 of them (64%) being ALL (IgH rearrangements with/without TRG, BCL-ABL1, EA2-PBX1, TEL-AML1 fusion transcripts), 3 (12%) Ewing sarcoma (EWS-FLI1 fusion transcript, EWSR1 rearrangements), 3 (12%) CML (BCR-ABL1 fusion transcript, FLT3) and 3 (12%) AML (leukemia-associated immunophenotypes, BCR-ABL1 fusion transcript) patients.

CONCLUSION

While the majority of malignancies were found to have a low risk of containing malignant cells in ovarian tissue, further studies are needed to ensure safe implementation of future fertility restoration in clinical practice.

Minimal residual disease detection by multicolor flow cytometry in cryopreserved ovarian tissue from leukemia patients

Background

Cryopreservation of ovarian tissue is a fertility-preservation option for women before gonadotoxic treatments. However, cryopreserved ovarian tissue transplantation must be performed with caution in women with malignancies that may metastasize to the ovaries. For this purpose, detecting minimal residual disease (MRD) in the ovarian cortex using sensitive methods is a crucial step. We developed an automated ovarian tissue dissociation method to obtain ovarian cell suspensions.

Results

We assessed MRD by multicolor flow cytometry (MFC) in cryopreserved ovarian cortex of 15 leukemia patients: 6 with B-cell acute lymphoblastic leukemia (B-ALL), 2 with T-cell acute lymphoblastic leukemia (T-ALL) and 7 with acute myeloid leukemia (AML). Ovarian MRD was positive in 5 of the 15 leukemia patients (one T-ALL and 4 AML). No B-ALL patient was positive by MFC. Quantitative reverse-transcribed polymerase chain reaction was performed when a molecular marker was available, and confirmed the MFC results for 3 patients tested. Xenografts into immunodeficient mice were also performed with ovarian cortical tissue from 10 leukemia patients, with no evidence of leukemic cells after the 6-month grafting period.

Conclusions

In conclusion, this is the first study using MFC to detect MRD in ovarian cortical tissue from acute leukemia patients. MFC has been accepted in clinical practice for its ease of use, the large number of parameters available simultaneously, and high throughput analysis. We demonstrate here that MFC is a reliable method to detect MRD in cryopreserved ovarian tissue, with a view to controlling the oncological risk before ovarian tissue transplantation in leukemia patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13048-021-00936-4.

Post-thawing and culture comparison of three routine slow freezing methods for human ovarian tissue cryopreservation: Histological, molecular, and hormonal aspects

To find the gold standard out of three pre-established routine slow freezing (SF) methods, ovarian cortex tissues of nine transsexual individuals were cryopreserved and compared to each other, as well as the control (fresh) samples. Histological, genomic, and endocrinological effects of the SFs were assessed post-thawing and after a seven-day culture period. SF1 included 10% dimethyl-sulfoxide (Me2SO) in the base medium (BM), SF2 had 1.5 M/L ethylene-glycol (EG) and 0.1 M/L sucrose in the BM, and SF3 consisted of 6% Me2SO, 6% EG and 0.15 M/L sucrose in the BM. The cortical tissue strips went under a programmed cooling process and were stored in liquid nitrogen. Histological criteria (tissue damage and follicular quality), as well as gene expression levels, were assessed in the thawed and control tissues. Half of the thawed and control tissues were cultured for seven days and their histology, genetic profile, and hormonal status were examined as the reflection of the avascular tension effect. Post-thawing tissue damage was similar between all groups but significantly increased post-culture (P < 0.05). The percentages of high-quality follicles diminished in all SFs after thawing and culture (P < 0.05) except for the similarity of post-thawing SF3, compared to control. The genetic profile of the tissue after thawing and culture suggested quiescence/activation balance in SF1 and 2 and significant down-regulation in SF3, compared to the control specimens (P < 0.05). Post-thawing BAX:BCL2 was higher than control in SF1 and SF3 (P < 0.05), while this ratio in SF2 was similar to the control. However, after culture this ratio was similar to that of control in SF3 and diminished in SF1 and 2 (P < 0.05). The expression levels of gap-junction genes showed dramatic pre- and post-thawing fluctuations in all groups. After culture, estradiol in SF3 was significantly higher than SF1 and 2 (P < 0.05). In addition, progesterone in SF3 was similar to control but significantly lower in SF1 and 2 (P < 0.05). In conclusion, all SFs showed advantages and disadvantages, and the follicular quality and its function depend on the type of cryoprotectant and the speed of thawing. The effects of freezing/thawing continue to appear during the seven days of culture. According to the results of this study, SF3 seems to be more promising in keeping the follicles functional and safe from cell damage during culture.

New method of FACS analyzing and sorting of intact whole ovarian fragments (COPAS) after long time (24 h) cooling to 5 °C before cryopreservation

As recently announced by the American Society for Reproductive Medicine (ASRM), human ovarian tissue cryopreservation is an established option for fertility preservation in prepubertal girls and young women undergoing gonadotoxic treatments for cancer as well as some autoimmune diseases. Proper ovarian tissue assessment before and after cryopreservation is essential to increase success rates. Ovarian fragments from 16 patients were divided into small pieces in form of cortex with medulla, and randomly divided into the following two groups. Pieces of Group 1 (n = 16) were frozen immediately after operation, thawed and just after thawing their quality was analyzed. Group 2 pieces (n = 16) after operation were cooled to 5 °C for 24 h, then frozen after 24 h pre-cooling to 5 °C, thawed and just after thawing their quality was analyzed. The effectiveness of the pre-freezing cooling of tissue was evaluated by the development and viability of follicles (Calcein-AM and Propidium Iodide) using complex object parametric analyzer and sorter machine (COPAS). Positive effect of cooling of cells to low supra-zero temperatures on their future development after re-warming has been observed. New flow cytometry- technique is suitable for the evaluation and sorting of cryopreserved whole human whole intact ovarian fragments. Long time (24 h) cooling of ovarian tissue to 5 °C before cryopreservation has a trend of a cell viability increasing.

A protocol to isolate and qualify purified human preantral follicles in cases of acute leukemia, for future clinical applications

Background

Autotransplantation of cryopreserved ovarian cortex can be associated with a risk of cancer cell reseeding. This issue could be eliminated by grafting isolated preantral follicles. Collagenase NB6 is an enzyme produced under good manufacturing practices (GMP) in compliance with requirements for tissue engineering and transplantation in humans and thus can be used to isolate preantral follicles from ovarian tissue in the framework of further clinical applications. Multicolor flow cytometry is an effective tool to evaluate the potential contamination of follicular suspensions by leukemic cells.

Methods

The efficiency of collagenase NB6 was evaluated in comparison to collagenase type IA and Liberase DH, in terms of yield, morphology and viability. A short-term in vitro culture of follicles isolated with collagenase NB6 was conducted for 3 days in a fibrin matrix. A modelization procedure was carried out to detect the presence of leukemic cells in follicular suspensions using multicolor flow cytometry (MFC).

Results

No statistical differences were found between collagenase NB6, Liberase DH (p = 0.386) and collagenase type IA (p = 0.171) regarding the number of human preantral follicles isolated. The mean diameter of isolated follicles was significantly lower with collagenase NB6 (p < 0.0001). The survival rate of isolated follicles was 93.4% (n = 272) using collagenase NB6 versus 94.9% (n = 198) with Liberase DH and 92.6% (n = 298) using collagenase type IA. Even after 3 days of in vitro culture in a fibrin scaffold, most of the isolated follicles were still alive after using collagenase NB6 (90.7% of viable follicles; n = 339). The rate of isolated Ki67-positive follicles was 29 ± 9.19% before culture and 45 ± 1.41% after 3 days. In 23 out of 24 follicular suspensions analyzed, the detection of leukemic cells by MFC was negative. The purification had no significant impact on follicle viability.

Conclusion

The isolation and purification of human preantral follicles were performed following good manufacturing practices for cell therapy. Multicolor flow cytometry was able to confirm that final follicular suspensions were free from leukemic cells. This safe isolation technique using collagenase NB6 can be considered for future clinical applications.