Abstract

Organotypic 3-dimensional Spheroid Cultures: Pre-clinical Testing Paradigms

Wendy Purcell, Chair, National Council for Healthcare Science in Higher Education

The principles of the 3Rs (reduction, refinement and replacement) alternatives to in vivo testing are being aggressively pursued across the globe for reasons of cost and speed as well as science and ethics. Primary cells in particular express many of the differentiated cellular structures and functions of their source tissues, however short culture periods and loss of organotypic functionality limit their use especially for chronic toxicity studies. 2-D in vitro culture methods such as primary tissue culture and immortalised or transformed cell lines have been used extensively to elucidate specific toxic or biological responses in target or surrogate organs. But these conventional culture methods do not fully represent the growth conditions or 3-D architecture of in vivo tissues. 3-D in vitro studies can provide some of the vital mechanistic knowledge of the functions of different cell types. Instead of keeping cells in a suspension, or plating them out into a film of material in a Petri dish, spheroids are prepared by gyrotatory and other means to form a ‘ball’. Within these ‘balls’ the cells then begin to connect to each other and form a mini-organ or micro-tissue known as a spheroids. The functionality of mature spheroids is similar to that of the tissue in vivo, and the longevity improves up to ten-fold compared to primary cells. Characterisation via a range of assay measures is possible and the models may offer the potential for stem cell studies alongside their pre-clinical applications in toxicity testing and mechanistic studies.