interact grow in three dimensions three dimensional 3d cell culturing methods are understood in the art and can include methods associated with apparatuses such as extracellular scaffolds bioreactors micro carriers magnetic levitation hanging drop plates magnetic bio printing and modified surfaces for example 3d culturing of stem cells can occur when the cells are conditioned in a bioreactor a bioreactor is any manufactured or engineered device or system that supports a biologically active environment in some instances the bioreactor is a vessel in which a chemical biochemical process is carried out which involves contact with organisms or biochemically active substances derived from such organisms such processes can either be aerobic or made anaerobic such bioreactors are commonly cylindrical ranging in size from 2 liters to 10000 liters and often made of stainless steel a bioreactor may also refer to a device or system meant to grow cells or tissues in the context of cell culture such devices are seen in tissue engineering or biochemical engineering see e g john w haycock ed 3d cell culture methods and protocols methods in molecular biology vol 695 doi 10 1007 978 1 60761 984 0 u2014 1 springer science business media llc 2011 compared to cells grown in two dimensional 2d cultures the use of three dimensional 3d cell cultures provides a closer mimicking of natural tissues and organs in 2d cultures cells are grown on flat dishes made of polystyrene plastic that is very stiff and unnatural the cells adhere and spread on the plastic surface and form unnatural cell attachments to proteins that are deposited and.