Induction and expansion of human PRRX1+ limb-bud-like mesenchymal cells from pluripotent stem cells.

Current protocols for the differentiation of human pluripotent stem cells (hPSCs) into chondrocytes do not allow for the expansion of intermediate progenitors so as to prospectively assess their chondrogenic potential. Here we report a protocol that leverages PRRX1-tdTomato reporter hPSCs for the selective induction of expandable and ontogenetically defined PRRX1+ limb-bud-like mesenchymal cells under defined xeno-free conditions, and the prospective assessment of the cells' chondrogenic potential via the cell-surface markers CD90, CD140B and CD82. The cells, which proliferated stably and exhibited the potential to undergo chondrogenic differentiation, formed hyaline cartilaginous-like tissue commensurate to their PRRX1-expression levels. Moreover, we show that limb-bud-like mesenchymal cells derived from patient-derived induced hPSCs can be used to identify therapeutic candidates for type II collagenopathy and we developed a method to generate uniformly sized hyaline cartilaginous-like particles by plating the cells on culture dishes coated with spots of a zwitterionic polymer. PRRX1+ limb-bud-like mesenchymal cells could facilitate the mass production of chondrocytes and cartilaginous tissues for applications in drug screening and tissue engineering.

Caged gene-inducer spatially and temporally controls gene expression and plant development in transgenic Arabidopsis plant.

Two new types of caged gene-inducers, caged 17beta-estradiol and caged dexamethazone, were synthesized. Caged gene-inducers were applied to transgenic Arabidopsis plants carrying a steroid hormone-inducible transactivation system. Light uncaged caged gene-inducers and controlled spatial and temporal expression of transgene in the transgenic plant. Furthermore, caged gene-inducers enabled the control of root development by light.