Tuning the 3D microenvironment of reprogrammed tubule cells enhances biomimetic modeling of polycystic kidney disease.

Renal tubular cells frequently lose differentiation markers and physiological properties when propagated in conventional cell culture conditions. Embedding cells in 3D microenvironments or controlling their 3D assembly by bioprinting can enhance their physiological properties, which is beneficial for modeling diseases in vitro. A potential cellular source for modeling renal tubular physiology and kidney diseases in vitro are directly reprogrammed induced renal tubular epithelial cells (iRECs). iRECs were cultured in various biomaterials and as bioprinted tubular structures. They showed high compatibility with the embedding substrates and dispensing methods. The morphology of multicellular aggregates was substantially influenced by the 3D microenvironment. Transcriptomic analyses revealed signatures of differentially expressed genes specific to each of the selected biomaterials. Using a new cellular model for autosomal-dominant polycystic kidney disease, Pkd1-/- iRECs showed disrupted morphology in bioprinted tubules and a marked upregulation of the Aldehyde dehydrogenase 1a1 (Aldh1a1). In conclusion, 3D microenvironments strongly influence the morphology and expression profiles of iRECs, help to unmask disease phenotypes, and can be adapted to experimental demands. Combining a direct reprogramming approach with appropriate biomaterials will facilitate construction of biomimetic kidney tubules and disease models at the microscale.

Heteroplasmy and atrazine resistance in Chenopodium album and Senecio vulgaris.

Atrazine-resistant weeds are well known, and the resistance is primarily caused by a point mutation in the psbA chloroplast gene encoding the photosystem II D1 protein. Heteroplasmy, the presence of different types of chloroplasts in an individual plant, is also very common. Thus, atrazine-resistant weeds may also partly possess the atrazine-binding sequence and vice versa. The region of the psbA gene containing the mutation was sequenced from atrazine-resistant and atrazine-sensitive Chenopodium album and Senecio vulgaris plants. In atrazine-sensitive C. album plants, the expected AGT triplet was found. The atrazine-resistant plants contained the expected base substitution (AGT to GGT); however, in addition the AGT triplet was found. The atrazine-resistant S. vulgaris plants contained the expected GGT sequence, whereas the atrazine-sensitive plants contained both the AGT and GGT sequences. This clearly indicates that in addition to Gly264 also Ser264 is present in atrazine-resistant plants, and vice versa in atrazine-sensitive plants, indicating heteroplasmy in these weeds.