2011-11-23研究人员用实验鼠干细胞培育出脑垂体.doc

Self-formation of functional adenohypophysis in three-dimensional culture The adenohypophysis (anterior pituitary) is a major centre for systemic hormones. At present, no efficient stem-cell culture for its generation is available, partly because of insufficient knowledge about how the pituitary primordium (Rathke’s pouch) is induced in the embryonic head ectoderm. Here we report efficient self-formation of three-dimensional adenohypophysis tissues in an aggregate culture of mouse embryonic stem (ES) cells. ES cells were stimulated to differentiate into non-neural head ectoderm and hypothalamic neuroectoderm in adjacent layers within the aggregate, and treated with hedgehog signalling. Self-organization of Rathke’s-pouch-like three-dimensional structures occurred at the interface of these two epithelia, as seen in vivo, and various endocrine cells including corticotrophs and somatotrophs were subsequently produced. The corticotrophs efficiently secreted adrenocorticotropic hormone in response to corticotrophin releasing hormone and, when grafted in vivo, these cells rescued the systemic glucocorticoid level in hypopituitary mice. Thus, functional anterior pituitary tissue self-forms in ES cell culture, recapitulating local tissue interactions. Figures at a glance left Figure 1: Adjacent formation of head ectoderm and hypothalamic epithelia in ES cell culture. a, Schematic of pituitary development, sagittal view. A, anterior; D, dorsal; P, posterior; V, ventral. b, In vivo expression of Pitx1 and Rx on embryonic day 13 (E13). c, Little expression of Pitx2 in SFEBq/CDM-cultured ES cells (qPCR; n = 3 experiments). d, day. d, Pitx2 expression in aggregates cultured under the LCA condition (red) or treated with 0.5?nM BMP4 (blue) (n = 3). e, f, Immunostaining of day-6 LCA aggregates for Pitx1 (red), and Rx (green, f). g, Schematic of the result. h, Induction of Lim3 expression by SAG (qPCR; n = 9). i, FACS analysis of the Lim3::venus+ population in day-10 LCA aggregate