Conceptualization of an Ex Vivo Organ Culture (EVOC) Model for Human Seminoma: A Pilot Study

Personalized treatment strategies for seminoma, a germ cell tumor, are crucial due to inherent tumor heterogeneity. Existing in vitro models often inadequately represent the native tumor microenvironment. Ex vivo organ culture (EVOC) offers a potential solution by preserving the tumor's original architecture and cellular interactions. This study presents the pilot study for adaptation of the EVOC platform specifically for non-metastatic seminoma, focusing on short-term tissue maintenance and an assessment of viability markers, examining intraoperative biopsies from 12 patients with non-metastatic seminoma (cT1-2, cN0-3, M0) undergoing orchifuniculectomy. Tissues were cultured in DMEM/F12 medium supplemented with fetal bovine serum and antibiotics. Histological and immunohistochemical analyses were performed on days 0, 3, 7, and 10. We analyzed the proliferative index (PI), using Ki-67; total cell number (OCN); and tumor cell number (TCN; PLAP-positive cells). The area under the curve (AUC) for PI was calculated to evaluate tumor viability. Statistical analyses included repeated measures ANOVA and post-hoc tests. Histological examination confirmed the preservation of the native seminoma histoarchitecture up to day 7. OCN showed a median decrease of 32.6% on day 7 (p = 0.002) and 55.1% on day 10 (p = 0.0004) compared with the baseline. TCN showed a median decrease of 27.5% on day 7 (p = 0.0033) and 53.2% on day 10 (p = 0.00018) compared with the baseline. The PI decreased significantly from day 3 to day 10 (p < 0.05). The AUC for PI was identified as a representative marker of tumor viability. An "EVOC score" calculation method was proposed to compare the effects of different treatments. This proof-of-concept work confirms that seminoma tissue can be maintained ex vivo for up to ten days under optimized conditions. The EVOC system developed here will serve as a methodological basis for further improving culture stability and exploring its broader applications in tumor biology and pharmacological testing.