Figure 1. In vitro differentiation of putative β-cells from mouse embryonic stem cells (MESC).

A: Genetic manipulation. i: Soria et al. (2001) used a 'cell-trapping' protocol to select for insulin-producing cells expressing the β-geo gene under the control of the human Insulin gene promoter [84]. This strategy was later refined by placing the β-geo gene under the control of the promoter of Nkx6.1 (ii). iii: Enforced expression of Pax4 or Pdx1 increased the frequency with which insulin-producing cells were isolated from differentiating MESC. B: Cell culture manipulation of ES cells. Lumelsky et al. (2001) developed a five-step protocol based on methods known to promote the generation of neural cell types from MESC [94]. Nestin-expressing cells were cultured in B27/N2 neurobasal medium went on to form cell clusters. Although the nature of insulin-staining cells derived by this method remains controversial, other groups have successfully used variations on this procedure to generate similar cell types. EB: embryoid bodies.