In vitro metastatic colonization of human ovarian cancer cells to the omentum.

Despite the potentially crucial contributions of the omentum in the regulation of ovarian cancer metastatic growth, it remains a poorly understood organ. Due to its anatomic location and structural fragility, the omentum presents inherent challenges to mechanism-based in vivo studies. Thus, the availability of an ex vivo omental model would, in part, address some of these difficulties posed. Here we describe a technique for identifying, isolating and maintaining ex vivo cultures of omenta from immune-compromised and -competent mice. Ex vivo culture conditions were developed that maintain tissue viability, architecture, and function for up to 10 days. Further experiments demonstrate that the ex vivo culture conditions allow for the proliferation of ovarian cancer cells in vitro and support a similar pattern of microscopic lesions after either intraperitoneal injection of ovarian cancer cells or co-culture of ovarian cancer cells with the omentum. In agreement with previous studies from our laboratory, histologic evaluation of these specimens found that ovarian cancer cells, as well as other peritoneal cancer cells, preferentially accumulate in, and colonize, omental areas rich in immune cells. We now recognize that these are specific, functional structures referred to as milky spots. In sum, these are foundational studies of a readily accessible model, which is easily manipulated and can be immediately used to study the dynamic process of omental colonization. It is hoped that investigators will use the data herein as a starting point for refinements and modifications which will enable them to tailor the model to the specific needs of the experimental question(s) they wish to pursue.