Abstract
BackgroundAutotransplantation 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.MethodsThe 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).ResultsNo 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.ConclusionThe 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.
Highlights
Autotransplantation of cryopreserved ovarian cortex can be associated with a risk of cancer cell reseeding
Freezing/thawing of ovarian tissue Cortical fragments were transferred in 1.8 ml cryovials (VWR, France) containing 1.5 ml of a freezing solution composed of 1.5 M dimethyl sulfoxide (DMSO; Sigma Aldrich, France) and 0.1 M sucrose (Pharmacy of Besançon University Hospital, France) in Leibovitz L-15® supplemented with 10% decomplemented AB human serum (Etablissement Francais du Sang, Bourgogne FrancheComté, France)
In order to validate our isolation technique, we first compared collagenase IA, which was previously used by our team, to collagenase NB6, which can be used in the clinic using the same concentration and incubation time
Summary
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. Over the past 30 years, the survival rate of cancer patients has drastically improved thanks to early diagnosis, advances in surgery procedures and adjuvant therapies [1, 2]. In some cases of malignant disease, ovarian tissue transplantation is associated with a high risk of cancer reseeding [9,10,11,12,13]. Culturing isolated follicles separates them from surrounding stromal elements like capillaries, white blood cells and nerves and protects them from the risk of contamination with malignant cells, as cancerous cells are not located inside follicles but in the stroma [41]
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