Effect of initial seeding density on cell behavior-driven epigenetic memory and preferential lineage differentiation of human iPSCs

Systematic optimization of culture media for maintenance of human induced pluripotent stem cells using the response surface methodology

The application of human induced pluripotent stem cells (hiPSCs) provides tremendous opportunities in cell therapy. However, culturing these cells faces many practical challenges, including costs associated with cell culture media and the optimization of cell culture conditions. Providing an optimized culture platform for hiPSCs to maintain pluripotency and self-renewal and generate cost-effective and robust therapeutics is an immediate requirement. This study used the design of experiments and the response surface methodology, a powerful statistical tool, to generate empirical models for predicting the optimal culture conditions of the hiPSCs. Pluripotency and cell proliferation were applied as read-outs to determine the optimal concentration of basic fibroblast growth factor (bFGF) and cell density. One model was defined to predict pluripotency and cell proliferation in terms of the predictor variables of the bFGF concentration and cell seeding density. Predicted culture conditions to maximize maintaining cell pluripotency were successfully validated. The present study's findings provide a novel approach that can potentially allow controllable hiPSC culture routine in translational research.

Stable and efficient generation of functional iPSC-derived neural progenitor cell rosettes through regulation of collective cell-cell behavior

Although the potential of stem cells to differentiate into several cell types has shown promise in regenerative medicine, low differentiation efficiency and poor reproducibility significantly limit their practical application. We developed an effective and robust differentiation strategy for the efficient and robust generation of neural progenitor cell rosettes from induced pluripotent stem cells (iPSCs) incorporating botulinum hemagglutinin (HA). Treatment with HA suppressed the spontaneous differentiation of iPSCs cultured under undirected differentiation conditions, resulting in the preservation of their pluripotency. Moreover, treatment with HA during neural progenitor differentiation combined with dual SMAD inhibition generated a highly homogeneous population of PAX6-and SOX1-expressing neural progenitor cells with 8.4-fold higher yields of neural progenitor cells than untreated control cultures. These neural progenitor cells formed radially organized rosettes surrounding the central lumen. This differentiation method enhanced the generation of functional iPSC-derived neural progenitor cell rosettes throughout the culture vessel, suggesting that the regulation of collective cell-cell behavior using HA plays a morphogenetically important role in rosette formation and maturation. These findings show the significance of HA in the suppression of spontaneous differentiation through spatial homogeneity. The study proposes a novel methodology for the efficient derivation of functional iPSC-derived neural progenitor cell rosettes.

Comparison of miRNA transcriptome of exosomes in three categories of somatic cells with derived iPSCs

Somatic cells can be reprogrammed into induced pluripotent stem cells (iPSCs) through epigenetic manipulation. While the essential role of miRNA in reprogramming and maintaining pluripotency is well studied, little is known about the functions of miRNA from exosomes in this context. To fill this research gap,we comprehensively obtained the 17 sets of cellular mRNA transcriptomic data with 3.93 × 1010 bp raw reads and 18 sets of exosomal miRNA transcriptomic data with 2.83 × 107 bp raw reads from three categories of human somatic cells: peripheral blood mononuclear cells (PBMCs), skin fibroblasts(SFs) and urine cells (UCs), along with their derived iPSCs. Additionally, differentially expressed molecules of each category were identified and used to perform gene set enrichment analysis. Our study provides sets of comparative transcriptomic data of cellular mRNA and exosomal miRNA from three categories of human tissue with three individual biological controls in studies of iPSCs generation, which will contribute to a better understanding of donor cell variation in functional epigenetic regulation and differentiation bias in iPSCs.

Novel strategy to improve hepatocyte differentiation stability through synchronized behavior-driven mechanical memory of iPSCs

Cellular homeostasis is assumed to be regulated by the coordination of dynamic behaviors. Lack of efficient methods for synchronizing large quantities of cells makes studying cell culture strategies for bioprocess development challenging. Here, we demonstrate a novel application of botulinum hemagglutinin (HA), an E-cadherin function-blocking agent, to synchronize behavior-driven mechanical memory in human induced pluripotent stem cell (hiPSC) cultures. Application of HA to hiPSCs resulted in a decrease in actin bundling and disruption of colony formation in a concentration-and time-dependent manner. Interestingly, cytoskeleton rearrangement in cells with prolonged exposure to HA resulted in mechanical memory synchronization with Yes-associated protein, which increased pluripotent cell homogeneity. Synchronized hiPSCs have higher capability to differentiate into functional hepatocytes than unsynchronized hiPSCs, resulting in improved efficiency and robustness of hepatocyte differentiation. Thus, our strategy for cell behavior synchronization before differentiation induction provides an approach against the instability of differentiation of pluripotent cells.

Cell Behavioral Dynamics as a Cue in Optimizing Culture Stabilization in the Bioprocessing of Pluripotent Stem Cells

Pluripotent stem cells (PSCs) are important for future regenerative medicine therapies. However, in the production of PSCs and derivatives, the control of culture-induced fluctuations in the outcome of cell quality remains challenging. A detailed mechanistic understanding of how PSC behaviors are altered in response to biomechanical microenvironments within a culture is necessary for rational bioprocessing optimization. In this review, we discuss recent insights into the role of cell behavioral and mechanical homeostasis in modulating the states and functions of PSCs during culture processes. We delineate promising ways to manipulate the culture variability through regulating cell behaviors using currently developed tools. Furthermore, we anticipate their potential implementation for designing a culture strategy based on the concept of Waddington's epigenetic landscape that may provide a feasible solution for tuning the culture quality and stability in the bioprocessing space.