Patient-derived ovarian cancer explants: preserved viability and histopathological features in long-term agitation-based cultures

Ovarian carcinoma (OvC) remains a major therapeutic challenge due to its propensity to develop resistance after an initial response to chemotherapy. Interactions of tumour cells with the surrounding microenvironment play a role in tumour survival, invasion capacity and drug resistance. Cancer models that retain tissue architecture and tumour microenvironment components are therefore essential to understand drug response and resistance mechanisms. Herein, our goal was to develop a long-term OvC patient-derived explant (OvC-PDE) culture strategy in which architecture and cell type heterogeneity of the original tumour would be retained. Samples from 25 patients with distinct OvC types and one with a benign tumour, were cultured for 30 days in agitation-based culture systems with 100% success rate. OvC-PDE cultures retained the original tumour architecture and main cellular components: epithelial cells, fibroblasts and immune cells. Epithelial cells kept their original levels of proliferation and apoptosis. Moreover, the major extracellular components, such as collagen-I and -IV, were retained in explants. OvC-PDE cultures were exposed to standard-of-care chemotherapeutics agents for 2 weeks, attesting the ability of the platform for drug assays employing cyclic drug exposure regimens. We established an OvC-PDE dynamic culture in which tumour architecture and cell type heterogeneity were preserved for the different OvC types, replicating features of the original tumour and compatible with long-term drug exposure for drug efficacy and resistance studies.

Abstract 1048: Preservation of tumor architecture and heterogeneity in long-term cultures of patient-derived explants

The tumor microenvironment plays an important role on tumor drug sensitivity; thus the incorporation of microenvironment features on cancer models is expected to improve their predictive power. Patient-Derived Explants (PDE) have been proposed as potential models; however there are typically short term cultures. Our goal was to improve culture longevity and vitality to evaluate efficacy of repeated drug treatments, taking advantage of dynamic culture systems.

Fresh ovarian and colorectal cancer (OC and CRC, respectively) samples were mechanically dissociated into PDE and cultured in dynamic conditions. The cell population dynamics, cell viability and proliferation were assessed by a panel of readouts, e.g. immunohistochemistry, rezasurin reduction capacity, PDE concentration and morphometric measurements.

To this date, 20 OC and 18 CRC were successfully cultured as PDE, retaining the original tumor architecture and main cellular components: epithelial cells, fibroblasts and immune cells for at least 28 days (OC) or 7 days (CRC). OC samples included all main malignant ovarian carcinoma types (endometrioid, clear cell, mucinous, undifferentiated, serous low and high grade) and CRC samples included adenocarcinomas' stage I to IIIB. Epithelial, stromal and immune cells were maintained for the duration of OC PDE cultures For CRC, epithelial neoplastic cells were preserved, in some cases up to 3 months, and stromal components were progressively lost along culture. The status of the original tumors was preserved for the majority of cases in terms of driver mutations of CRC and of microsatellite stability. To validate the model, OC-PDE cultures were exposed to cyclic chemotherapy treatment (paclitaxel, carboplatin and the combination of both). After two cycles (1 cycle of 24h per week), PDE showed low cellularity and cell viability, compared to untreated controls, reflecting the action of the compounds.

Altogether, we established PDE dynamic cultures in which tumor architecture and heterogeneity is preserved, replicating the original tumor features. Moreover, we demonstrated the feasibility of performing ex vivo drug efficacy studies employing cyclic drug exposure regimens.

This work was partially supported by FCT (iNOVA4Health – UID/Multi/04462/2013, PD/BD/105768/2014 and SFRH/BD/52208/2013).

Citation Format: Sofia Abreu, Fernanda Silva, Sara da Mata, Teresa F. Mendes, Marta Teixeira, Bruno Filipe, Sónia Morgado, Inês Francisco, Marta Mesquita, Cristina Albuquerque, Paula Chaves, Ricardo Fonseca, Jacinta Serpa, Isadora Rosa, Ana Felix, Erwin R. Boghaert, Vítor E. Santo, Catarina Brito. Preservation of tumor architecture and heterogeneity in long-term cultures of patient-derived explants [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1048.

Therapeutic angiogenesis induced by human umbilical cord tissue-derived mesenchymal stromal cells in a murine model of hindlimb ischemia

Background

Mesenchymal stem cells derived from human umbilical cord tissue, termed UCX®, have the potential to promote a full range of events leading to tissue regeneration and homeostasis. The main goal of this work was to investigate UCX® action in experimentally induced hindlimb ischemia (HLI).

Methods

UCX®, obtained by using a proprietary technology developed by ECBio (Amadora, Portugal), were delivered via intramuscular injection to C57BL/6 females after unilateral HLI induction. Perfusion recovery, capillary and collateral density increase were evaluated by laser doppler, CD31 immunohistochemistry and diaphonisation, respectively. The activation state of endothelial cells (ECs) was analysed after EC isolation by laser capture microdissection microscopy followed by RNA extraction, cDNA synthesis and quantitative RT-PCR analysis. The UCX®-conditioned medium was analysed on Gallios flow cytometer. The capacity of UCX® in promoting tubulogenesis and EC migration was assessed by matrigel tubule formation and wound-healing assay, respectively.

Results

We demonstrated that UCX® enhance angiogenesis in vitro via a paracrine effect. Importantly, after HLI induction, UCX® improve blood perfusion by stimulating angiogenesis and arteriogenesis. This is achieved through a new mechanism in which durable and simultaneous upregulation of transforming growth factor β2, angiopoietin 2, fibroblast growth factor 2, and hepatocyte growth factor, in endothelial cells is induced by UCX®.

Conclusions

In conclusion, our data demonstrate that UCX® improve the angiogenic potency of endothelial cells in the murine ischemic limb suggesting the potential of UCX® as a new therapeutic tool for critical limb ischemia.