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Herbal medicines have been increasingly used in the last three decades. Despite their popularity, safety issues with herbal products need to be addressed. We performed a feasibility study of the toxic responses of human induced pluripotent stem cell-derived hepatocytes (iHep cells) to phytochemicals in comparison with hepatoblasoma-derived HepG2 cells and long-term human hepatocytes (LTHHs). The iHep cells expressed typical hepatocyte markers cytochrome P450 3A4 (CYP3A4), hepatocyte nuclear factor 4α, and albumin despite the expression of immature markers α-fetoprotein and cytokeratin 19. We studied the responses of iHep cells to phytochemicals saikosaponin D, triptolide, deoxycalyciphylline B, and monocrotaline with different mode of toxicity employing MTS and lactate dehydrogenase (LDH) assays. Saikosaponin D and triptolide caused dose-dependent cytotoxicity in the iHep cells, which were more sensitive than LTHHs and HepG2 cells. Saikosaponin D-induced cytotoxicity tightly correlated with increased LDH leakage in the iHep cells. Although deoxycalyciphylline B did not exhibit toxic effect on the iHep and HepG2 cells when compared with LTHHs, it decreased CYP3A7 expression in the iHep cells and increased CYP1A2 expression in HepG2 cells. We hereby show the feasibility of using iHep cells to detect toxic effects of phytochemicals., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Open Science is encouraged by the European Union and many other political and scientific institutions. However, scientific practice is proving slow to change. We propose, as early career researchers, that it is our task to change scientific research into open scientific research and commit to Open Science principles.

Three-dimensional (3D) cell cultures produce more in vivo-like multicellular structures such as spheroids that cannot be obtained in two-dimensional (2D) cell cultures. Thus, they are increasingly employed as models for cancer and drug research, as well as tissue engineering. It has proven challenging to stabilize spheroid architectures for detailed morphological examination. Here we overcome this issue using a silica bioreplication (SBR) process employed on spheroids formed from human pluripotent stem cells (hPSCs) and hepatocellular carcinoma HepG2 cells cultured in the nanofibrillar cellulose (NFC) hydrogel. The cells in the spheroids are more round and tightly interacting with each other than those in 2D cultures, and they develop microvilli-like structures on the cell membranes as seen in 2D cultures. Furthermore, SBR preserves extracellular matrix-like materials and cellular proteins. These findings provide the first evidence of intact hPSC spheroid architectures and similar fine structures to 2D-cultured cells, providing a pathway to enable our understanding of morphogenesis in 3D cultures.

Human embryonic stem cells and induced pluripotent stem cells have great potential in research and therapies. The current in vitro culture systems for human pluripotent stem cells (hPSCs) do not mimic the three-dimensional (3D) in vivo stem cell niche that transiently supports stem cell proliferation and is subject to changes which facilitate subsequent differentiation during development. Here, we demonstrate, for the first time, that a novel plant-derived nanofibrillar cellulose (NFC) hydrogel creates a flexible 3D environment for hPSC culture. The pluripotency of hPSCs cultured in the NFC hydrogel was maintained for 26 days as evidenced by the expression of OCT4, NANOG, and SSEA-4, in vitro embryoid body formation and in vivo teratoma formation. The use of a cellulose enzyme, cellulase, enables easy cell propagation in 3D culture as well as a shift between 3D and two-dimensional cultures. More importantly, the removal of the NFC hydrogel facilitates differentiation while retaining 3D cell organization. Thus, the NFC hydrogel represents a flexible, xeno-free 3D culture system that supports pluripotency and will be useful in hPSC-based drug research and regenerative medicine.

Over the recent years, various materials have been introduced as potential 3D cell culture scaffolds. These include protein extracts, peptide amphiphiles, and synthetic polymers. Hydrogel scaffolds without human or animal borne components or added bioactive components are preferred from the immunological point of view. Here we demonstrate that native nanofibrillar cellulose (NFC) hydrogels derived from the abundant plant sources provide the desired functionalities. We show 1) rheological properties that allow formation of a 3D scaffold in-situ after facile injection, 2) cellular biocompatibility without added growth factors, 3) cellular polarization, and 4) differentiation of human hepatic cell lines HepaRG and HepG2. At high shear stress, the aqueous NFC has small viscosity that supports injectability, whereas at low shear stress conditions the material is converted to an elastic gel. Due to the inherent biocompatibility without any additives, we conclude that NFC generates a feasible and sustained microenvironment for 3D cell culture for potential applications, such as drug and chemical testing, tissue engineering, and cell therapy., (Copyright © 2012 Elsevier B.V. All rights reserved.)