Can you imagine a supermarket where doctors could just go and pick the cells they need to cure their patients? Just like a pharmacy…or a blood bank?
Well, this is the dream most stem cell biologists are working towards. In order to make this dream a reality, scientists are trying (with more or less success!) to develop protocols with which they could use a stock of stem cells and differentiate them towards a cell fate of interest in order to obtain functional specialized cells…which ideally could then be used for cell replacement therapies and drug screenings.
In a recent study published in Development by S. Ogawa and colleagues, human pluripotent stem cells (hPSCs; ie: stem cells that can become any tissue of the body) were successfully differentiated into mature liver cells. To this end, the authors developed an elaborate in vitro liver differentiation protocol that consists of successive steps that recapitulate liver development. First, hPSC are differentiated into definitive endoderm and then to hepatoblasts (immature liver cells), a process dependent on activin/nodal signalling. Subsequently, 3D cell aggregation and cAMP signalling are required to obtain hepatocyte-like cells, hepatocytes being mature liver cells.
In this picture, one can observe 3D cell aggregates the scientists produced from hPSCs. Cells express the proteins ASGR1 (in green in the picture) and ALBUMIN (ALB, in red in the picture), a combination that is specific to hepatocytes.
So in the future, if these cells are proven to function properly, they could potentially be used in therapies against all sorts of liver diseases, in drug screening studies or to produce bio-artificial liver devices!
S. Ogawa et al., Three-dimensional culture and cAMP signaling promote the maturation of human pluripotent stem cell-derived hepatocytes. Development 140, 3285 (August 2013). doi: 10.1242/dev.090266