fixation of ovarian cancer organoids for long-term storage

Standardizing Ovarian Cancer Organoid Biobanking

Clinical management of patients with epithelial ovarian cancer remains challenging due to its heterogeneous clinical presentation at advanced stages and high recurrence rates1. Improving our understanding of ovarian cancer development and biological behavior requires research approaches that address the patient-specific variability during the course of the disease, treatment response, and histopathological as well as molecular features2.
Biobanking, characterized by the systematic collection and long-term preservation of tumor samples derived from ovarian cancer patients along with their clinical information offers the preservation of a large patient cohort in different disease stages, including tumor samples from primary debulking surgeries, after neoadjuvant chemotherapy and from recurrent disease. It holds valuable potential for advancing cancer research serving as a resource of promising prognostic biomarkers and therapeutic targets3. However, conventional biobanking methods, such as formalin fixation and freezing, are not amenable to conducting functional studies on the original tumor samples due to the loss of viability and the disruption of the native three-dimensional tissue architecture4,5.
Studies of molecular mechanisms, in oncology and beyond, crucially depend on the use of appropriate experimental models that faithfully reflect the biology of the disease and maintain in vitro properties of the tissue observed in vivo. Patient-derived organoids, based on the preservation of the renewal potential, reproduce in the lab the original structure and function of the epithelium and allow testing in a patient-specific context. Therefore, they have emerged as highly promising tools for cancer research and personalized medicine, bridging the gap between clinical diversity and laboratory research6,7,8,9. Tailored therapeutic strategies based on individual drug responses of organoid lines and testing of the functional relevance of molecular profiles, can potentially be directly applied to patient care10,11. The possibility of long-term cultivation including patient-specific characteristics and the collection of relevant prospective clinical data over time holds great promise to identify novel prognostic and predictive factors involved in disease progression and resistance mechanisms3,9.
Nonetheless, building a biobank that includes organoids from different tumor samples requires a combination of strict adherence to complex methodology and setting up protocols for easy maintenance12. Process standardization ensures that the biobank can be established and maintained efficiently by trained staff even at high turnover, while at the same time adhering to the highest quality standards13. Several studies reported the successful generation of stable ovarian cancer organoid lines corresponding to the mutational and phenotypical profile of the original tumor with varying efficiency rates. Still, routine bio banking remains challenging in practice, particularly for long-term stable growth of lines, which is a prerequisite for large-scale expansion or successful genomic editing.
In particular, the issue of expandability remains vaguely defined in the field as organoids that show slow and limited growth potential are occasionally counted as established lines. As initially demonstrated by Hoffmann et al., a study whose principal findings provided the basis for this further developed protocol, optimal handling of ovarian cancer tissue requires a unique strategy to accommodate heterogeneity14. Phenotypic characterization of the organoids obtained by this method and close similarity with parental tumor tissue were confirmed by panel DNA sequencing and transcriptomics analysis of mature cultures (4-10 months of cultivation) demonstrating the stability of the model8,9,12,14.
In contrast to the paracrine environment that regulates the homeostasis in the healthy fallopian tubes, the epithelial layer, which likely yields high-grade serous ovarian cancer (HGSOC), cancer regeneration potential, and organoid formation capacity, is less dependent on exogenous Wnt supplementation. Moreover, active Bone Morphogenetic Protein (BMP) signaling, characterized by the absence of Noggin in organoid medium, proved to be beneficial for the establishment of long-term cultures from ovarian cancer solid tissue deposits14,15. During systematic biobanking of solid deposits of ovarian cancer, we have confirmed these findings and set up the pipeline, with details outlined in this protocol that ensures sustained long-term expansion in the majority of cases. We find that parallel testing of different media compositions and seeding modalities when working with primary isolates are essential to improve the establishment of long-term stable organoid lines and to increase yields enabling robust propagation and expansion to multi-well formats required for downstream experiments16.
Furthermore, the purity and quality of the samples collected during surgery are of crucial importance for the translational potential of ovarian cancer organoids in basic research and molecular diagnostics. The complexity of the clinical presentation of HGSOC requires close cooperation between the surgeons, oncologists, and the scientists in the lab to ensure that relevant material is correctly identified, transport conditions are kept constant, and organoid lines are generated with high efficiency representing the most important characteristics of the disease of each patient. This protocol provides a standardized but adaptable framework to capture the full potential of ovarian cancer organoids, considering the heterogeneity that characterizes ovarian cancer16,17. Notably, this protocol enables reliable biobanking of the broad spectrum of ovarian cancer clinical presentation, including different histological types (high-grade and low-grade ovarian cancer, LGSOC), different deposits from the same patients who exhibit differences in stemness regulation, tissues from surgeries in post neoadjuvant setting, biopsy material, and samples from surgeries in the recurrent phase of disease progression.

Author Spotlight: Advancing Personalized Medicine in Ovarian Cancer 

Strategy for Biobanking of Ovarian Cancer Organoids: Addressing the Interpatient Heterogeneity across Histological Subtypes and Disease Stages

The best clinical management in cutting-edge translational research for patients with advanced ovarian cancer has highest priority at our institution. With the biobanking of patient-derived organoids, we have achieved major progress towards individually-tailored management. This enables us to evaluate patient-specific characteristics and to identify predictive biomarkers.We have made significant advances in recent years in improving radical multivisceral surgery, chemotherapy, anti-angiogenic therapy, and also PARP inhibitor therapy in patients with advanced ovarian cancer and improved survival rates even with that. Now, the next big step would be to better predict which patient would benefit from which specific treatment. Currently, clinical treatment decisions are based on general histopathological features and on information on homologous recommendation deficiency or tested in paraffin-embedded tumor tissue.Biologic models that evaluate specific responses to chemotherapy and to targeted treatments have not yet been implemented in clinical routine. We have identified key characteristics of ovarian cancer tissue, specifically the culture requirements necessary to sustain its renewal potential in vitro, and use this knowledge to achieve robust long-term growth of organoid lines and establish biobank from samples at various stages of the disease. Our day-to-day experience in biobanking of ovarian cancer organoids effectively shows a remarkable heterogeneity in the biology of this malignancy, which could pave the way to new classification or provide the basis for new therapeutic solutions targeting STEMI's potential.

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Fixation of Ovarian Cancer Organoids for Long-Term Storage

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Research

JoVE Journal

Cancer Research

177 Views.  University Hospital, Ludwig-Maximilian-University (LMU) Munich. Fixation of Ovarian Cancer Organoids for Long-Term Storage