Post-Passage rock inhibition induces cytoskeletal aberrations and apoptosis in Human embryonic stem cells

The culture and application of circulating tumor cell-derived organoids

Circulating tumor cells (CTCs), which have the heterogeneity and histological properties of the primary tumor and metastases, are shed from the primary tumor and/or metastatic lesions into the vasculature and initiate metastases at remote sites. In the clinic, CTCs are used extensively in liquid biopsies for early screening, diagnosis, treatment, and prognosis. Current research focuses on using CTC-derived models to study tumor heterogeneity and metastasis, with 3D organoids emerging as a promising tool in cancer research and precision oncology. However, isolating and enriching CTCs from blood remains challenging due to their scarcity, exacerbated by the lack of an optimized culture medium for CTC-derived organoids (CTCDOs). In this review, we summarize the origin, isolation, enrichment, culture, validation, and clinical application of CTCs and CTCDOs.

Formation of epithelial polarity on the fluorinated-oil microdroplet surface by regulating cell adhesion

Polarized epithelial cells are compartmentalized into apical and basement membranes with asymmetrically distributed proteins. This study aimed to establish a method for culturing epithelial cells at the fluorinated oil (Novec-7500) microdroplet surface for the formation of epithelial polarity, which is desirable for regenerative medicine and drug discovery research. Microdroplet surfaces treated with fibronectin, which regulates a variety of cell behaviors through direct interactions with cell surface integrin receptors, were prepared for culturing epithelial cells. The cells adhered rapidly to the fibronectin-coated fluorinated oil-medium interface and reached confluence. However, as the culture time progressed, the cells began to detach from the microdroplet surface. To promote adhesion to the microdroplet interface, the cells were exposed to the Rho-associated protein kinase inhibitor Y27632, which increased the frequency of microdroplets with cells adhering to the liquid-liquid interface by 1.63-fold. However, continuous exposure to Y27632 caused the cells to detach from the microdroplet surface. When the drug was switched from Y27632 to forskolin, which enhances cell-cell and cell-substrate adhesion, the cells remained as a monolayer on the microdroplet interface. Na+/K+-ATPase and zonula occludens-2 were localized to the apical and lateral membranes of the cells, respectively, while paxillin co-localized with fibronectin at the microdroplet interface. This suggests that the cells exhibited epithelial polarity. These findings indicate that the regulation of cell-cell and cell-substrate adhesion is crucial for establishing epithelial polarity in cells cultured on the microdroplet interface.

Anoikis in cell fate, physiopathology, and therapeutic interventions

The extracellular matrix (ECM) governs a wide spectrum of cellular fate processes, with a particular emphasis on anoikis, an integrin-dependent form of cell death. Currently, anoikis is defined as an intrinsic apoptosis. In contrast to traditional apoptosis and necroptosis, integrin correlates ECM signaling with intracellular signaling cascades, describing the full process of anoikis. However, anoikis is frequently overlooked in physiological and pathological processes as well as traditional in vitro research models. In this review, we summarized the role of anoikis in physiological and pathological processes, spanning embryonic development, organ development, tissue repair, inflammatory responses, cardiovascular diseases, tumor metastasis, and so on. Similarly, in the realm of stem cell research focused on the functional evolution of cells, anoikis offers a potential solution to various challenges, including in vitro cell culture models, stem cell therapy, cell transplantation, and engineering applications, which are largely based on the regulation of cell fate by anoikis. More importantly, the regulatory mechanisms of anoikis based on molecular processes and ECM signaling will provide new strategies for therapeutic interventions (drug therapy and cell-based therapy) in disease. In summary, this review provides a systematic elaboration of anoikis, thus shedding light on its future research.

A retinoid analogue, TTNPB, promotes clonal expansion of human pluripotent stem cells by upregulating CLDN2 and HoxA1

Enzymatic dissociation of human pluripotent stem cells (hPSCs) into single cells during routine passage leads to massive cell death. Although the Rho-associated protein kinase inhibitor, Y-27632 can enhance hPSC survival and proliferation at high seeding density, dissociated single cells undergo apoptosis at clonal density. This presents a major hurdle when deriving genetically modified hPSC lines since transfection and genome editing efficiencies are not satisfactory. As a result, colonies tend to contain heterogeneous mixtures of both modified and unmodified cells, making it difficult to isolate the desired clone buried within the colony. In this study, we report improved clonal expansion of hPSCs using a retinoic acid analogue, TTNPB. When combined with Y-27632, TTNPB synergistically increased hPSC cloning efficiency by more than 2 orders of magnitude (0.2% to 20%), whereas TTNPB itself increased more than double cell number expansion compared to Y-27632. Furthermore, TTNPB-treated cells showed two times higher aggregate formation and cell proliferation compared to Y-27632 in suspension culture. TTNPB-treated cells displayed a normal karyotype, pluripotency and were able to stochastically differentiate into all three germ layers both in vitro and in vivo. TTNBP acts, in part, by promoting cellular adhesion and self-renewal through the upregulation of Claudin 2 and HoxA1. By promoting clonal expansion, TTNPB provides a new approach for isolating and expanding pure hPSCs for future cell therapy applications.

Epigenetic repression of CHCHD2 enhances survival from single cell dissociation through attenuated Rho A kinase activity

During in vitro culture, human pluripotent stem cells (hPSCs) often acquire survival advantages characterized by decreased susceptibility to mitochondrial cell death, known as "culture adaptation." This adaptation is associated with genetic and epigenetic abnormalities, including TP53 mutations, copy number variations, trisomy, and methylation changes. Understanding the molecular mechanisms underlying this acquired survival advantage is crucial for safe hPSC-based cell therapies. Through transcriptome and methylome analysis, we discovered that the epigenetic repression of CHCHD2, a mitochondrial protein, is a common occurrence during in vitro culture using enzymatic dissociation. We confirmed this finding through genetic perturbation and reconstitution experiments in normal human embryonic stem cells (hESCs). Loss of CHCHD2 expression conferred resistance to single cell dissociation-induced cell death, a common stress encountered during in vitro culture. Importantly, we found that the downregulation of CHCHD2 significantly attenuates the activity of Rho-associated protein kinase (ROCK), which is responsible for inducing single cell death in hESCs. This suggests that hESCs may survive routine enzyme-based cell dissociation by downregulating CHCHD2 and thereby attenuating ROCK activity. These findings provide insights into the mechanisms by which hPSCs acquire survival advantages and adapt to in vitro culture conditions.

Mechanical loading intensities affect the release of extracellular vesicles from mouse bone marrow-derived hematopoietic progenitor cells and change their osteoclast-modulating effect

Low-intensity loading maintains or increases bone mass, whereas lack of mechanical loading and high-intensity loading decreases bone mass, possibly via the release of extracellular vesicles by mechanosensitive bone cells. How different loading intensities alter the biological effect of these vesicles is not fully understood. Dynamic fluid shear stress at low intensity (0.7 ± 0.3 Pa, 5 Hz) or high intensity (2.9 ± 0.2 Pa, 1 Hz) was used on mouse hematopoietic progenitor cells for 2 min in the presence or absence of chemical compounds that inhibit release or biogenesis of extracellular vesicles. We used a Receptor activator of nuclear factor kappa-Β ligand-induced osteoclastogenesis assay to evaluate the biological effect of different fractions of extracellular vesicles obtained through centrifugation of medium from hematopoietic stem cells. Osteoclast formation was reduced by microvesicles (10 000× g) obtained after low-intensity loading and induced by exosomes (100 000× g) obtained after high-intensity loading. These osteoclast-modulating effects could be diminished or eliminated by depletion of extracellular vesicles from the conditioned medium, inhibition of general extracellular vesicle release, inhibition of microvesicle biogenesis (low intensity), inhibition of ESCRT-independent exosome biogenesis (high intensity), as well as by inhibition of dynamin-dependent vesicle uptake in osteoclast progenitor cells. Taken together, the intensity of mechanical loading affects the release of extracellular vesicles and change their osteoclast-modulating effect.

Effect of Rho-Associated Kinase Inhibitor on Growth Behaviors of Human Induced Pluripotent Stem Cells in Suspension Culture

Rho-associated protein kinase (ROCK) inhibitors are used for the survival of single-dissociated human induced pluripotent stem cells (hiPSCs); however, their effects on the growth behaviors of hiPSCs in suspension culture are unexplored. Therefore, we investigated the effect of ROCK inhibitor on growth behaviors of two hiPSC lines (Tic and 1383D2) with different formation of aggregate that attached between single cells in suspension culture. The apparent specific growth rate by long-term exposure to Y-27632, a ROCK inhibitor, was maintained throughout the culture. Long-term exposure to ROCK inhibitor led to an increase in cell division throughout the culture in both lines. Immunofluorescence staining confirmed that hiPSCs forming spherical aggregates showed localization of collagen type I on its periphery. In addition, phosphorylated myosin (pMLC) was localized at the periphery in culture under short-term exposure to ROCK inhibitor, whereas pMLC was not detected at whole the aggregate in culture under long-term exposure. Scanning electron microscopy indicated that long-term exposure to ROCK inhibitor blocked the structural alteration on the surface of cell aggregates. These results indicate that pMLC inhibition by long-term ROCK inhibition leads to enhanced growth abilities of hiPSCs in suspension culture by maintaining the structures of extracellular matrices.

Spatially arranged encapsulation of stem cell spheroids within hydrogels for the regulation of spheroid fusion and cell migration

Mesenchymal stem cell spheroids have been encapsulated in hydrogels for various applications because spheroids demonstrate higher cell activity than individual cells in suspension. However, there is limited information on the effect of distance between spheroids (inter-spheroid distance) on fusion or migration in a hydrogel. In this study, we developed temperature-responsive hydrogels with surface microwell patterns to culture adipose-derived stem cell (ASC) spheroids and deliver them into a Matrigel for the investigation of the effect of inter-spheroid distance on spheroid behavior. The ASC spheroids were encapsulated successfully in a Matrigel, denoted as sandwich culture, with a specific inter-spheroid distance ranging from 100 to 400 µm. Interestingly, ASCs migrated from the host spheroid and formed a bridge-like structure between spheroids, denoted as a cellular bridge, only when the inter-spheroid distance was 200 µm. Thus, we performed a sandwich culture of human umbilical vein endothelial cells (HUVECs) and ASCs in co-cultured spheroids in the Matrigel to create a homogeneous endothelial cell network in the hydrogel. The HUVECs sprouted through the ASC cellular bridge and directly interacted with the adjacent spheroid when the inter-spheroid distance was 200 µm. Similar results were obtained from an in vivo study. Thus, our study suggests the appropriate inter-spheroid distance for effective spheroid encapsulation in a hydrogel. STATEMENT OF SIGNIFICANCE: Recently, spheroid-based 3D tissue culture techniques such as spheroid encapsulation or 3D printing are being intensively investigated for various purposes. However, there is limited research regarding the effect of the inter-spheroid distance on spheroid communication. Here, we demonstrate a spatially arranged spheroid encapsulation method within a Matrigel by using a temperature-responsive hydrogel. Human adipose-derived stem cell spheroids are encapsulated with a precisely controlled inter-spheroid distance from 100 to 400 µm and show different tendencies in cell migration and spheroid fusion. Our results suggest that the inter-spheroid distance affects spheroid communication, and thus, the inter-spheroid distance needs to be considered carefully according to the purpose.

Effects of Y-27632 on the osteogenic and adipogenic potential of human dental pulp stem cells in vitro

BACKGROUND

Human dental pulp stem cells (hDPSCs) possess mesenchymal stem cell properties, originating from migrating neural crest cells. hDPSCs have received extensive attention in the field of tissue engineering and regenerative medicine due to their accessibility and ability to differentiate in several cell phenotypes. In this study, we cultured hDPSCs with Y-27632 to observe their biological behaviors changes.

METHODS

The hDPSCs were separately cultured with Y-27632 (0, 0.156, 0.312, 0.625, 1.25, 2.50, 5, 10, 20, 40 μm) for 24, 48, 72 h to select the suitable concentration and time using CCK-8. Then, the hDPSCs were cultured with 2.50 μm Y-27632 for 48 h to analyzed the biological behaviors changes by 5-Ethynyl-2'-deoxyuridine (EdU), plate cloning, transwell, scratch, and Annexin V FITC/PI assays, separately. Additionally, osteogenic calcium nodules and lipid droplets were analyzed using alizarin red staining and oil red O staining, respectively. qRT-PCR was used to analyze the expression of osteogenesis, adipogenesis, stemness maintenance, and inflammation related genes.

RESULTS

The hDPSCs proliferation was significantly enhanced after cultured with 2.50 μm Y-27632 for 48 h, but there was no significant difference in migration and apoptosis. Observation of alkaline phosphatase (ALP) activity, osteogenic and adipogenic differentiation abilities of hDPSCs, Y-27632 treatment clearly decreased the ALP activity and osteogenic differentiation ability, increased the adipogenic differentiation ability. Furthermore, Y-27632 decreased the CD73, CD90, CD105, CD166, TLR4, and NF-κB p65 genes expression, but increased the IL-8 gene expression.

CONCLUSIONS

The biological behaviors of hDPSCs could be changed when they cultured with Y-27632.

RhoGTPase Signalling in Cancer Progression and Dissemination

Rho GTPases are a family of small G proteins that regulate a wide array of cellular processes related to their key roles controlling the cytoskeleton. On the other hand, cancer is a multi-step disease caused by the accumulation of genetic mutations and epigenetic alterations, from the initial stages of cancer development when cells in normal tissues undergo transformation, to the acquisition of invasive and metastatic traits, responsible for a large number of cancer related deaths. In this review, we discuss the role of Rho GTPase signalling in cancer in every step of disease progression. Rho GTPases contribute to tumour initiation and progression, by regulating proliferation and apoptosis, but also metabolism, senescence and cell stemness. Rho GTPases play a major role in cell migration, and in the metastatic process. They are also involved in interactions with the tumour microenvironment and regulate inflammation, contributing to cancer progression. After years of intensive research, we highlight the importance of relevant models in the Rho GTPase field, and we reflect on the therapeutic opportunities arising for cancer patients.

Agarose microgel culture delineates lumenogenesis in naive and primed human pluripotent stem cells

Human periimplantation development requires the transformation of the naive pluripotent epiblast into a polarized epithelium. Lumenogenesis plays a critical role in this process, as the epiblast undergoes rosette formation and lumen expansion to form the amniotic cavity. Here, we present a high-throughput in vitro model for epiblast morphogenesis. We established a microfluidic workflow to encapsulate human pluripotent stem cells (hPSCs) into monodisperse agarose microgels. Strikingly, hPSCs self-organized into polarized epiblast spheroids that could be maintained in self-renewing and differentiating conditions. Encapsulated primed hPSCs required Rho-associated kinase inhibition, in contrast to naive hPSCs. We applied microgel suspension culture to examine the lumen-forming capacity of hPSCs and reveal an increase in lumenogenesis during the naive-to-primed transition. Finally, we demonstrate the feasibility of co-encapsulating cell types across different lineages and species. Our work provides a foundation for stem cell-based embryo models to interrogate the critical components of human epiblast self-organization and morphogenesis.

Maintenance of mouse trophoblast stem cells in KSR-based medium allows conventional 3D culture

Mouse trophoblast stem cells (TSCs) can differentiate into trophoblast cells, which constitute the placenta. Under conventional culture conditions, in a medium supplemented with 20% fetal bovine serum (FBS), fibroblast growth factor 4 (FGF4), and heparin and in the presence of mouse embryonic fibroblast cells (MEFs) as feeder cells, TSCs maintain their undifferentiated, proliferative status. MEFs can be replaced by a 70% MEF-conditioned medium (MEF-CM) or by TGF-ß/activin A. To find out if KnockOut^TM Serum Replacement (KSR) can replace FBS for TSC maintenance, we cultured mouse TSCs in KSR-based, FBS-free medium and investigated their proliferation capacity, stemness, and differentiation potential. The results indicated that fibronectin, vitronectin, or laminin coating was necessary for adhesion of TSCs under KSR-based conditions but not for their survival or proliferation. While the presence of FGF4, heparin, and activin A was not sufficient to support the proliferation of TSCs, the addition of a pan-retinoic acid receptor inverse agonist and a ROCK-inhibitor yielded a proliferation rate comparable to that obtained under the conventional FBS-based conditions. TSCs cultured under the KSR-based conditions had a gene expression and DNA methylation profile characteristic of TSCs and exhibited a differentiation potential. Moreover, under KSR-based conditions, we could obtain a suspension culture of TSCs using extracellular matrix (ECM) coating-free dishes. Thus, we have established here, KSR-based culture conditions for the maintenance of TSCs, which should be useful for future studies.

An updated protocol for the cost-effective and weekend-free culture of human induced pluripotent stem cells

The protocol provided here describes methodologies for making a highly cost-effective, chemically defined medium for culturing hiPSCs we call B8 medium. The typical cost of B8 medium is US$10 per liter, which with modifications included here is more affordable than standard media. We provide simple protocols for making B8 supplement aliquots, making the basal media DMEM/F12, Matrigel-coated plates, thawing, passaging, culturing, and cryopreserving hiPSCs. We show typical differentiation results and provide a comprehensive troubleshooting guide. For complete details on the use and execution of this protocol, please refer to Kuo et al. (2020).

Establishment of an Efficient Primary Culture System for Human Hair Follicle Stem Cells Using the Rho-Associated Protein Kinase Inhibitor Y-27632

Background

Hair follicle tissue engineering is a promising strategy for treating hair loss. Human hair follicle stem cells (hHFSCs), which play a key role in the hair cycle, have potential applications in regenerative medicine. However, previous studies did not achieve efficient hHFSC expansion in vitro using feeder cells. Therefore, there is a need to develop an efficient primary culture system for the expansion and maintenance of hHFSCs.

Methods

The hHFSCs were obtained by two-step proteolytic digestion combined with microscopy. The cell culture dishes were coated with human fibronectin and inoculated with hHFSCs. The hHFSCs were harvested using a differential enrichment procedure. The effect of Rho-associated protein kinase (ROCK) inhibitor Y-27632, supplemented in keratinocyte serum-free medium (K-SFM), on adhesion, proliferation, and stemness of hHFSCs and the underlying molecular mechanisms were evaluated.

Results

The hHFSCs cultured in K-SFM, supplemented with Y-27632, exhibited enhanced adhesion and proliferation. Additionally, Y-27632 treatment maintained the stemness of hHFSCs and promoted the ability of hHFSCs to regenerate hair follicles in vivo. However, Y-27632-induced proliferation and stemness in hHFSCs were conditional and reversible. Furthermore, Y-27632 maintained propagation and stemness of hHFSCs through the ERK/MAPK pathway.

Conclusion

An efficient short-term culture system for primary hHFSCs was successfully established using human fibronectin and the ROCK inhibitor Y-27632, which promoted the proliferation, maintained the stemness of hHFSCs and promoted the ability to regenerate hair follicles in vivo. The xenofree culturing method used in this study provided a large number of high-quality seed cells, which have applications in hair follicle tissue engineering and stem cell therapy.

Generation and Cultivation of Transgene-Free Macaque and Baboon iPSCs Under Chemically Defined Conditions

Non-human primates (NHP), and in particular Old World monkeys including macaques and baboons, are key animal models for the late preclinical testing of novel stem cell-based therapies and other advanced therapy medical products (ATMP) for the treatment of degenerative diseases. These pathologies are characterized by the loss of functional cells in an organ, as in Parkinson's disease, age-related macular degeneration, or after myocardial infarction. For preclinically relevant testing of induced pluripotent stem cell (iPSC)-based therapies, robust, and standardized protocols for the generation, characterization, and differentiation of NHP-iPSCs are required. Since the discovery of iPSCs by Takahashi and Yamanaka in 2006, human reprogramming protocols have been continuously refined. However, the generation of integration-free NHP-iPSC lines and a stable feeder- and serum-free long-term culture turned out to be difficult or even impossible with the current protocols established for human iPSCs. Here, we provide a robust protocol for the generation of transgene-free Old World monkey (and human) iPSCs and long-term cultivation under chemically defined conditions. This protocol was successfully applied to generate human, baboon (Papio anubis), rhesus (Macaca mulatta), and cynomolgus macaque (Macaca fascicularis) iPSCs from skin fibroblasts. The resulting NHP-iPSCs provide a valuable resource for the preclinical testing of regenerative therapies in NHP.