Generation of a tumor spheroid in a microgravity environment as a 3D model of melanoma.

An in vitro 3D model was developed utilizing a synthetic microgravity environment to facilitate studying the cell interactions. 2D monolayer cell culture models have been successfully used to understand various cellular reactions that occur in vivo. There are some limitations to the 2D model that are apparent when compared to cells grown in a 3D matrix. For example, some proteins that are not expressed in a 2D model are found up-regulated in the 3D matrix. In this paper, we discuss techniques used to develop the first known large, free-floating 3D tissue model used to establish tumor spheroids. The bioreactor system known as the High Aspect Ratio Vessel (HARVs) was used to provide a microgravity environment. The HARVs promoted aggregation of keratinocytes (HaCaT) that formed a construct that served as scaffolding for the growth of mouse melanoma. Although there is an emphasis on building a 3D model with the proper extracellular matrix and stroma, we were able to develop a model that excluded the use of matrigel. Immunohistochemistry and apoptosis assays provided evidence that this 3D model supports B16.F10 cell growth, proliferation, and synthesis of extracellular matrix. Immunofluorescence showed that melanoma cells interact with one another displaying observable cellular morphological changes. The goal of engineering a 3D tissue model is to collect new information about cancer development and develop new potential treatment regimens that can be translated to in vivo models while reducing the use of laboratory animals.