In the body, stem cells are surrounded by a complex 3D network of proteins, called the extracellular matrix, that provides the cells with vital signals that regulate their function. During cell culture, stem cells are removed from this native home, and need to adapt to a relatively foreign environment, that is, tissue culture plastic. Tissue culture plastic is fully synthetic, does not present standard ECM signals and mesenchymal stem cells on tissue culture plastic start to produce proteins to build a new home. Cells are able to assemble an extracellular matrix over the course of two weeks, and this image shows mesenchymal stem cells embedded in complex networks of ECM proteins after ten days of in vitro culture.