An Engineered N-Cadherin Substrate for Differentiation, Survival, and Selection of Pluripotent Stem Cell-Derived Neural Progenitors.

For stem cell-based treatment of neurodegenerative diseases a better understanding of key developmental signaling pathways and robust techniques for producing neurons with highest homogeneity are required. In this study, we demonstrate a method using N-cadherin-based biomimetic substrate to promote the differentiation of mouse embryonic stem cell (ESC)- and induced pluripotent stem cell (iPSC)-derived neural progenitor cells (NPCs) without exogenous neuro-inductive signals. We showed that substrate-dependent activation of N-cadherin reduces Rho/ROCK activation and ß-catenin expression, leading to the stimulation of neurite outgrowth and conversion into cells expressing neural/glial markers. Besides, plating dissociated cells on N-cadherin substrate can significantly increase the differentiation yield via suppression of dissociation-induced Rho/ROCK-mediated apoptosis. Because undifferentiated ESCs and iPSCs have low affinity to N-cadherin, plating dissociated cells on N-cadherin-coated substrate increase the homogeneity of differentiation by purging ESCs and iPSCs (~30%) from a mixture of undifferentiated cells with NPCs. Using this label-free cell selection approach we enriched differentiated NPCs plated as monolayer without ROCK inhibitor. Therefore, N-cadherin biomimetic substrate provide a powerful tool for basic study of cell-material interaction in a spatially defined and substrate-dependent manner. Collectively, our approach is efficient, robust and cost effective to produce large quantities of differentiated cells with highest homogeneity and applicable to use with other types of cells.

Ligand-induced internalization, recycling, and resensitization of adrenomedullin receptors depend not on CLR or RAMP alone but on the receptor complex as a whole.

Adrenomedullins (AM) is a multifaceted distinct subfamily of peptides that belongs to the calcitonin gene-related peptide (CGRP) superfamily. These peptides exert their functional activities via associations of calcitonin receptor-like receptors (CLRs) and receptor activity-modifying proteins (RAMPs) RAMP2 and RAMP3. Recent studies established that RAMPs and CLRs can modify biochemical properties such as trafficking and glycosylation of each other. However there is very little or no understanding regarding how RAMP or CLR influence ligand-induced events of AM-receptor complex. In this study, using pufferfish homologs of CLR (mfCLR1-3) and RAMP (mfRAMP2 and mfRAMP3), we revealed that all combinations of CLR and RAMP quickly underwent ligand-induced internalization; however, their recycling rates were different as follows: mfCLR1-mfRAMP3>mfCLR2-mfRAMP3>mfCLR3-mfRAMP3. Functional receptor assay confirmed that the recycled receptors were resensitized on the plasma membrane. In contrast, a negligible amount of mfCLR1-mfRAMP2 was recycled and reconstituted. Immunocytochemistry results indicated that the lower recovery rate of mfCLR3-mfRAMP3 and mfCLR1-mfRAMP2 was correlated with higher proportion of lysosomal localization of these receptor complexes compared to the other combinations. Collectively our results indicate, for the first time, that the ligand-induced internalization, recycling, and reconstitution properties of RAMP-CLR receptor complexes depend on the receptor-complex as a whole, and not on individual CLR or RAMP alone.

Multiarray formation of CHO spheroids cocultured with feeder cells for highly efficient protein production in serum-free medium.

Functional proteins like antibody, cytokine and growth factor have been widely used for basic biological research, diagnosis and cancer therapy. Particularly, antibody drugs as attractive biopharmaceuticals will be expected to create an enormous new market. Chinese hamster ovay (CHO) cells are being increasingly used in industry for the production of recombinant therapeutic proteins including antibody drugs. Although three-dimensional culture is preferred to two-dimensional monolayer culture for the efficient large scale culture of CHO cells and subsequent mass production of recombinant proteins, it has the limitation of low protein production. Therefore, a new cell culture em essentially required for an efficient protein production. Here we report on a new three-dimensional cell culture system as a spheroid cell culture on the micropattern array for efficient production of protein in CHO cells. Furthermore, cocultivation of CHO spheroids with feeder cells including bovine aortic endothelial cells (BAEC) and NIH 3T3 was essential to more increase a protein production. The results indicated that CHO heterospheroids cocultured with BAECs were much superior to either CHO monolayers or CHO homospheroids in protein production. Significantly, the above cocultured spheroids in the serum-free medium drastically enhanced protein expression level up to 3-fold compared with CHO spheroids in serum medium, suggesting that a coculture of spheroid system with feeder layer cells is a promising method to enhance protein production under serum-free condition. The spheroid array constructed here is highly usuful as a platform of biopharmaceutical manufacturing as well as tissue and cell based biosensors to detect a wide variety of clinically active compounds through a cellular physiological response.

Chondrocyte spheroids on microfabricated PEG hydrogel surface and their noninvasive functional monitoring.

A two-dimensional microarray of 10 000 (100 × 100) chondrocyte spheroids was constructed with a 100 µm spacing on a micropatterned gold electrode that was coated with poly(ethylene glycol) (PEG) hydrogels. The PEGylated surface as a cytophobic region was regulated by controlling the gel structure through photolithography. In this way, a PEG hydrogel was modulated enough to inhibit outgrowth of chondrocytes from a cell adhering region in the horizontal direction, which is critical for inducing formation of three-dimensional chondrocyte aggregations (spheroids) within 24 h. We further report noninvasive monitoring of the cellular functional change at the cell membrane using a chondrocyte-based field effect transistor. This measurement is based on detection of extracellular potential change induced as a result of the interaction between extracellular matrix protein secreted from spheroid and substrate at the cell membrane. The interface potential change at the cell membrane/gate interface can be monitored during the differentiation of spheroids without any labeling materials. Our measurements of the time evolution of the interface potential provide important information for understanding the uptake kinetics for cellular differentiation.

Self-association of PAR-3-mediated by the conserved N-terminal domain contributes to the development of epithelial tight junctions.

PAR-3 is a scaffold-like PDZ-containing protein that forms a complex with PAR-6 and atypical protein kinase C (PAR-3-atypical protein kinase C-PAR-6 complex) and contributes to the establishment of cell polarity in a wide variety of biological contexts. In mammalian epithelial cells, it localizes to tight junctions, the most apical end of epithelial cell-cell junctions, and contributes to the formation of functional tight junctions. However, the mechanism by which PAR-3 localizes to tight junctions and contributes to their formation remains to be clarified. Here we show that the N-terminal conserved region, CR1-(1-86), and the sequence 937-1,024 are required for its recruitment to the most apical side of the cell-cell contact region in epithelial Madin-Darby canine kidney cells. We also show that CR1 self-associates to form an oligomeric complex in vivo and in vitro. Further, overexpression of CR1 in Madin-Darby canine kidney cells disturbs the distribution of atypical protein kinase C and PAR-6 as well as PAR-3 and delays the formation of functional tight junctions. These results support the notion that the CR1-mediated self-association of the PAR-3-containing protein complex plays a role during the formation of functional tight junctions.