Identification of cryosensitive niches and a targetable FOS/AP‑1 program in the human ovarian cortex by single‑cell and spatial transcriptomics.

The ovary is a vital and dynamic reproductive organ. Ovarian tissue cryopreservation (OTC) plays a vital role in preserving female fertility. However, the cellular subtypes most susceptible to cryoinjury and the molecular mechanisms underlying cryopreservation-associated damage remain poorly understood. This study aimed to identify cell populations vulnerable to freezing-thawing and to elucidate the key transcriptomic alterations and signaling pathways associated with ovarian cryoinjury at the single-cell and spatial levels. Ovarian cortical tissues from patients undergoing three gender reassignment surgery (GRS) were divided into fresh and vitrification-rapid warming groups. Following collagenase IV digestion, 10x Genomics single-cell RNA-seq was used for dissociated ovarian cell suspensions (27,185 fresh and 25,480 frozen-thawed cells). Eight major cell clusters were identified. Additionally, 110 oocytes (66 fresh, 44 vitrification-rapid warming) were isolated and analyzed using the Smart-seq2 platform. Spatial transcriptomics was performed via BGI Stereo-seq. Molecular validation was performed via β-galactosidase staining, immunofluorescence, and qRT-PCR. Cryopreservation significantly altered the activity of pathways related to focal adhesion, oxidative stress, and apoptosis, particularly in stromal and perivascular cells. The number of FOS-positive perivascular cells was notably increased after vitrification-rapid warming, whereas the number of PTGDS-positive stromal cells decreased. Oocyte analysis revealed that cryopreservation primarily disrupted pathways involved in the cell cycle and meiosis, although the damage was not irreversible, supporting the relative safety of long-term cryostorage. Spatial transcriptomics and functional validation further confirmed the rapid and robust activation of the FOS/AP-1 pathway after vitrification-rapid warming, particularly in perivascular and granulosa cells. Treatment with T-5224 (a FOS/AP-1 inhibitor) significantly rescued the morphology and function of cultured frozen-thawed ovaries. Stromal and perivascular cells are the main cell types that are sensitive to ovarian cryopreservation. The FOS/AP-1 pathway is markedly activated after, suggesting the exacerbation of metabolic impairment. In oocytes within the ovarian cortex, the cell cycle and meiosis-related physiological processes were the primary processes affected.