Use of stem cells, whether adult or embryonic for clinical applications to treat diseases such as Parkinson's, macular degeneration or Type I diabetes will require a homogenous population of mature, terminally differentiated cells. A current area of intense interest is the development of defined surfaces for stem cell derivation, maintenance, proliferation and subsequent differentiation, which are capable of replicating the complex cellular environment existing in vivo. During development many cellular cues result from integrin signalling induced by the local extracellular matrix. There are 24 known integrin heterodimers comprised of one of 18 α subunits and one of 8 β subunits and these have a diverse range of functions mediating cell-cell adhesion, growth factor receptor responses and intracellular signalling cascades for cell migration, differentiation, survival and proliferation. We discuss here a brief summary of defined conditions for human embryonic stem cell culture together with a description of integrin function and signalling pathways. The importance of integrin expression during development is highlighted as critical for lineage specific cell function and how consideration of the integrin expression profile should be made while differentiating stem cells for use in therapy. In addition this review summarises the known integrin expression profiles for human embryonic stem cells and 3 common adult stem cell types: mesenchymal, haematopoietic and neural. We then outline some of the possible technologies available for investigating cell-extracellular matrix interactions and subsequent integrin mediated cell responses.

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The unique pluripotential characteristic of human embryonic stem cells heralds their use in fields such as medicine, biotechnology, biopharmaceuticals, and developmental biology. However, the current availability of sufficient quantities of embryonic stem cells for such applications is limited, and generating sufficient numbers for downstream therapeutic applications is a key concern. In the absence of feeder layers or their conditioned media, human embryonic stem cells readily differentiate to form embryoid bodies, indicating that trophic factors secreted by the feeder layers are required for long-term proliferation and maintenance of pluripotency. Adding further complexity to the elucidation of the factors required for the maintenance of pluripotency is the variability of different fibroblast feeder layers (of mouse or human origin) to effectively support human embryonic stem cells. Currently, the deficiency of knowledge concerning the exact identity of factors within the pathways for self-renewal illustrates that a number of factors may be required to support pluripotent, undifferentiated growth of human embryonic stem cells. This study utilized a proteomic analysis (multidimensional chromatography coupled to tandem mass spectrometry) to isolate and identify proteins in the conditioned media of three mitotically inactivated fibroblast lines (human fetal, human neonatal, and mouse embryonic fibroblasts) used to support the undifferentiated growth of human embryonic stem cells. One-hundred seventy-five unique proteins were identified between the three cell lines using a