Laminin 521 Stabilizes the Pluripotency Expression Pattern of Human Embryonic Stem Cells Initially Derived on Feeder Cells

Differentiation of human induced pluripotent stem cells into retinal pigment epithelium cells during culture on peptide-grafted hydrogels

A variety of novel peptide-grafted hydrogels, of which peptides were derived from vitronectin (PQVTRGDVFTMP) or the laminin β4 chain (PMQKMRGDVFSP), were prepared in this study. The peptide-grafted hydrogels promoted the adhesion, proliferation and colony formation of hiPSCs and maintained their pluripotency up to passage 5 under xeno-free conditions. We successfully generated RPE cells from hiPSCs using one of the most suitable xeno-free peptide-grafted hydrogels, KVN2CK (KGCGGKGG-PQVTRGDVFTMP), which was derived from vitronectin, and confirmed the effect of these hiPSC-derived RPE cells in a rat retinal degeneration model (Royal College of Surgeons (RCS) rats) via subretinal transplantation, when we investigated functional improvements in vision in RCS rats after the transplantation of hiPSC-derived RPE cells. Our novel peptide-grafted hydrogels provided a safe and robust platform for generating single-layer hiPSC-derived RPE cells under xeno-free conditions, which indicates the potential of these hydrogels for stem cell therapy for retinal degenerative diseases in the future.

Defined culture conditions robustly maintain human stem cell pluripotency, highlighting a role for Ca2+ signaling

Induced pluripotent stem cells (iPSCs) have significant potential for disease modeling and cell therapies. However, their wide-spread application has faced challenges, including batch-to-batch variabilities, and notable distinctions when compared to embryonic stem cells (ESCs). Some of these disparities can stem from using undefined culture conditions and the reprogramming procedure, however, the precise mechanisms remain understudied. Here, we compared gene expression data from over 100 iPSC and ESC lines cultivated under undefined and defined conditions. Defined conditions significantly reduced inter-PSC line variability, irrespective of PSC cell type, highlighting the importance of standardization to minimize PSC biases. This variability is concurrent with decreased somatic cell marker and germ layer differentiation gene expression and increased Ca2+-binding protein expression. Moreover, SERCA pump inhibition highlighted an important role for intracellular Ca2+ activity in maintaining pluripotency gene expression under defined conditions. Further understanding of these processes can help standardize and improve defined hPSC culture conditions.

Engineered T cells from induced pluripotent stem cells: from research towards clinical implementation

Induced pluripotent stem cell (iPSC)-derived T (iT) cells represent a groundbreaking frontier in adoptive cell therapies with engineered T cells, poised to overcome pivotal limitations associated with conventional manufacturing methods. iPSCs offer an off-the-shelf source of therapeutic T cells with the potential for infinite expansion and straightforward genetic manipulation to ensure hypo-immunogenicity and introduce specific therapeutic functions, such as antigen specificity through a chimeric antigen receptor (CAR). Importantly, genetic engineering of iPSC offers the benefit of generating fully modified clonal lines that are amenable to rigorous safety assessments. Critical to harnessing the potential of iT cells is the development of a robust and clinically compatible production process. Current protocols for genetic engineering as well as differentiation protocols designed to mirror human hematopoiesis and T cell development, vary in efficiency and often contain non-compliant components, thereby rendering them unsuitable for clinical implementation. This comprehensive review centers on the remarkable progress made over the last decade in generating functional engineered T cells from iPSCs. Emphasis is placed on alignment with good manufacturing practice (GMP) standards, scalability, safety measures and quality controls, which constitute the fundamental prerequisites for clinical application. In conclusion, the focus on iPSC as a source promises standardized, scalable, clinically relevant, and potentially safer production of engineered T cells. This groundbreaking approach holds the potential to extend hope to a broader spectrum of patients and diseases, leading in a new era in adoptive T cell therapy.

Truncated vitronectin with E-cadherin enables the xeno-free derivation of human embryonic stem cells

Human embryonic stem cells (hESCs) have unique abilities that enable their use in cell therapy, disease modeling, and drug development. Their derivation is usually performed using a feeder layer, which is undefined and can potentially cause a contamination by xeno components, therefore there is a tendency to replace feeders with xeno-free defined substrates in recent years. Three hESC lines were successfully derived on the vitronectin with a truncated N-terminus (VTN-N) in combination with E-cadherin in xeno-free conditions for the first time, and their undifferentiated state, hESC morphology, and standard karyotypes together with their potential to differentiate into three germ layers were confirmed. These results support the conclusion that the VTN-N/E-cadherin is a suitable substrate for the xeno-free derivation of hESCs and can be used for the derivation of hESCs according to good manufacturing practices.

Genetic manipulation and targeted protein degradation in mammalian systems: practical considerations, tips and tricks for discovery research

Gaining a mechanistic understanding of the molecular pathways underpinning cellular and organismal physiology invariably relies on the perturbation of an experimental system to infer causality. This can be achieved either by genetic manipulation or by pharmacological treatment. Generally, the former approach is applicable to a wider range of targets, is more precise, and can address more nuanced functional aspects. Despite such apparent advantages, genetic manipulation (i.e., knock-down, knock-out, mutation, and tagging) in mammalian systems can be challenging due to problems with delivery, low rates of homologous recombination, and epigenetic silencing. The advent of CRISPR-Cas9 in combination with the development of robust differentiation protocols that can efficiently generate a variety of different cell types in vitro has accelerated our ability to probe gene function in a more physiological setting. Often, the main obstacle in this path of enquiry is to achieve the desired genetic modification. In this short review, we will focus on gene perturbation in mammalian cells and how editing and differentiation of pluripotent stem cells can complement more traditional approaches. Additionally, we introduce novel targeted protein degradation approaches as an alternative to DNA/RNA-based manipulation. Our aim is to present a broad overview of recent approaches and in vitro systems to study mammalian cell biology. Due to space limitations, we limit ourselves to providing the inexperienced reader with a conceptual framework on how to use these tools, and for more in-depth information, we will provide specific references throughout.

Polymerized Laminin-521: A Feasible Substrate for Expanding Induced Pluripotent Stem Cells at a Low Protein Concentration

Laminins (LNs) play a central role in the self-assembly and maintenance of basement membranes and are involved in critical interactions between cells and other extracellular matrix (ECM) proteins. Among the defined, xeno-free ECM culture matrices, LNs-namely LN521-have emerged as promising coating systems for the large-scale expansion of induced pluripotent stem cells (iPSCs). The biologic activity of LNs is enhanced by their acidification-induced self-polymerization into a cell-associated network called polylaminin (polyLN), which can recapitulate the native-like polymeric array in a cell-free system. Here, we show for the first time to our knowledge that polyLN521 displays a native-like hexagonal-like structure and that, at basal and low concentrations, it permits the large-scale expansion of human iPSCs. Human iPSCs expanded with polyLN521 maintained the pluripotent state and showed no impairment of karyotype stability or telomere length. These results suggest that low-concentration polyLN521 is a stable and cost-effective coating for large-scale iPSC expansion.

Poly(vinyl alcohol-co-itaconic acid) hydrogels grafted with several designed peptides for human pluripotent stem cell culture and differentiation into cardiomyocytes

We developed poly(vinyl alcohol-co-itaconic acid) (PV) hydrogels grafted with laminin-derived peptides that had different joint segments and several specific designs, including dual chain motifs. PV hydrogels grafted with a peptide derived from laminin-β4 (PMQKMRGDVFSP) containing a joint segment, dual chain motif and cationic amino acid insertion could attach human pluripotent stem (hPS) cells and promoted high expansion folds in long-term culture (over 10 passages) with low differentiation rates, whereas hPS cells attached poorly on PV hydrogels grafted with laminin-α5 peptides that had joint segments with and without a cationic amino acid or on PV hydrogels grafted with laminin-β4 peptides containing the joint segment only. The inclusion of a cationic amino acid in the laminin-β4 peptide was critical for hPS cell attachment on PV hydrogels, which contributed to the zeta potential shifting to higher values (3-4 mV enhancement). The novel peptide segment-grafted PV hydrogels developed in this study supported hPS cell proliferation, which induced better hPS cell expansion than recombinant vitronectin-coated dishes (gold standard of hPS cell culture dishes) in xeno-free culture conditions. After long-term culture on peptide-grafted hydrogels, hPS cells could be induced to differentiate into specific lineages of cells, such as cardiomyocytes, with high efficiency.

Human induced pluripotent stem cells from two azoospermic patients with Klinefelter syndrome show similar X chromosome inactivation behavior to female pluripotent stem cells

STUDY QUESTION

Does the X chromosome inactivation (XCI) of Klinefelter syndrome (KS)-derived human induced pluripotent stem cells (hiPSCs) correspond to female human pluripotent stem cells (hPSCs) and reflect the KS genotype?

SUMMARY ANSWER

Our results demonstrate for the first time that KS-derived hiPSCs show similar XCI behavior to female hPSCs in culture and show biological relevance to KS genotype-related clinical features.

WHAT IS KNOWN ALREADY

So far, assessment of XCI of KS-derived hiPSCs was based on H3K27me3 staining and X-inactive specific transcript gene expression disregarding the at least three XCI states (XaXi with XIST coating, XaXi lacking XIST coating, and XaXe (partially eroded XCI)) that female hPSCs display in culture.

STUDY DESIGN, SIZE, DURATION

The study used hiPSC lines generated from two azoospermic patients with KS and included two healthy male (HM) and one healthy female donor.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In this study, we derived hiPSCs by reprograming fibroblasts with episomal plasmids and applying laminin 521 as culture substrate. hiPSCs were characterized by karyotyping, immunocytochemistry, immunohistochemistry, quantitative PCR, teratoma formation, and embryoid body differentiation. XCI and KS hiPSC relevance were assessed by whole genome transcriptomics analysis and immunocytochemistry plus FISH of KS, HM and female fibroblast, and their hiPSC derivatives.

MAIN RESULTS AND THE ROLE OF CHANCE

Applying whole genome transcriptomics analysis, we could identify differentially expressed genes (DEGs) between KS and HM donors with enrichment in gene ontology terms associated with fertility, cardiovascular development, ossification, and brain development, all associated with KS genotype-related clinical features. Furthermore, XCI analysis based on transcriptomics data, RNA FISH, and H3K27me3 staining revealed variable XCI states of KS hiPSCs similar to female hiPSCs, showing either normal (XaXi) or eroded (XaXe) XCI. KS hiPSCs with normal XCI showed nevertheless upregulated X-linked genes involved in nervous system development as well as synaptic transmission, supporting the potential use of KS-derived hiPSCs as an in vitro model for KS.

LIMITATIONS, REASONS FOR CAUTION

Detailed clinical information for patients included in this study was not available. Although a correlation between DEGs and the KS genotype could be observed, the biological relevance of these cells has to be confirmed with further experiments. In addition, karyotype analysis for two hiPSC lines was performed at passage 12 but not repeated at a later passage. Nevertheless, since all XCI experiments for those lines were performed between passage 11 and 15 the authors expect no karyotypic changes for those experiments.

WIDER IMPLICATIONS OF THE FINDINGS

As KS patients have variable clinical phenotypes that are influenced by the grade of aneuploidy, mosaicism, origin of the X chromosome, and XCI ‘escapee’ genes, which vary not only among individuals but also among different tissues within the same individual, differentiated KS hiPSCs could be used for a better understanding of KS pathogenesis.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by grants from the Knut and Alice Wallenberg Foundation (2016.0121 and 2015.0096), Ming Wai Lau Centre for Reparative Medicine (2-343/2016), Ragnar Söderberg Foundation (M67/13), Swedish Research Council (2013-32485-100360-69), the Centre for Innovative Medicine (2–388/2016–40), Kronprinsessan Lovisas Förening För Barnasjukvård/Stiftelsen Axel Tielmans Minnesfond, Samariten Foundation, Jonasson Center at the Royal Institute of Technology, Sweden, and Initial Training Network Marie Curie Program ‘Growsperm’ (EU-FP7-PEOPLE-2013-ITN 603568). The authors declare no conflicts of interest.

Matrix decoded - A pancreatic extracellular matrix with organ specific cues guiding human iPSC differentiation

The extracellular matrix represents a dynamic microenvironment regulating essential cell functions in vivo. Tissue engineering approaches aim to recreate the native niche in vitro using biological scaffolds generated by organ decellularization. So far, the organ specific origin of such scaffolds was less considered and potential consequences for in vitro cell culture remain largely elusive. Here, we show that organ specific cues of biological scaffolds affect cellular behavior. In detail, we report on the generation of a well-preserved pancreatic bioscaffold and introduce a scoring system allowing standardized inter-study quality assessment. Using multiple analysis tools for in-depth-characterization of the biological scaffold, we reveal unique compositional, physico-structural, and biophysical properties. Finally, we prove the functional relevance of the biological origin by demonstrating a regulatory effect of the matrix on multi-lineage differentiation of human induced pluripotent stem cells emphasizing the significance of matrix specificity for cellular behavior in artificial microenvironments.

Human Pluripotent Stem Cells in Reproductive Science-a Comparison of Protocols Used to Generate and Define Male Germ Cells from Pluripotent Stem Cells

Globally, fertility-related issues affect around 15% of couples. In 20%–30% of cases men are solely responsible, and they contribute in around 50% of all cases. Hence, understanding of in vivo germ-cell specification and exploring different angles of fertility preservation and infertility intervention are considered hot topics nowadays, with special focus on the use of human pluripotent stem cells (hPSCs) as a source of in vitro germ-cell generation. However, the generation of male germ cells from hPSCs can currently be considered challenging, making a judgment on the real perspective of these innovative approaches difficult. Ever since the first spontaneous germ-cell differentiation studies, using human embryonic stem cells, various strategies, including specific co-cultures, gene over-expression, and addition of growth factors, have been applied for human germ-cell derivation. In line with the variety of differentiation methods, the outcomes have ranged from early and migratory primordial germ cells up to post-meiotic spermatids. This variety of culture approaches and cell lines makes comparisons between protocols difficult. Considering the diverse strategies and outcomes, we aim in this mini-review to summarize the literature regarding in vitro derivation of human male germ cells from hPSCs, while keeping a particular focus on the culture methods, growth factors, and cell lines used.

Advances in Pluripotent Stem Cells: History, Mechanisms, Technologies, and Applications

Over the past 20 years, and particularly in the last decade, significant developmental milestones have driven basic, translational, and clinical advances in the field of stem cell and regenerative medicine. In this article, we provide a systemic overview of the major recent discoveries in this exciting and rapidly developing field. We begin by discussing experimental advances in the generation and differentiation of pluripotent stem cells (PSCs), next moving to the maintenance of stem cells in different culture types, and finishing with a discussion of three-dimensional (3D) cell technology and future stem cell applications. Specifically, we highlight the following crucial domains: 1) sources of pluripotent cells; 2) next-generation in vivo direct reprogramming technology; 3) cell types derived from PSCs and the influence of genetic memory; 4) induction of pluripotency with genomic modifications; 5) construction of vectors with reprogramming factor combinations; 6) enhancing pluripotency with small molecules and genetic signaling pathways; 7) induction of cell reprogramming by RNA signaling; 8) induction and enhancement of pluripotency with chemicals; 9) maintenance of pluripotency and genomic stability in induced pluripotent stem cells (iPSCs); 10) feeder-free and xenon-free culture environments; 11) biomaterial applications in stem cell biology; 12) three-dimensional (3D) cell technology; 13) 3D bioprinting; 14) downstream stem cell applications; and 15) current ethical issues in stem cell and regenerative medicine. This review, encompassing the fundamental concepts of regenerative medicine, is intended to provide a comprehensive portrait of important progress in stem cell research and development. Innovative technologies and real-world applications are emphasized for readers interested in the exciting, promising, and challenging field of stem cells and those seeking guidance in planning future research direction.

Developing defined substrates for stem cell culture and differentiation

Over the past few decades, a variety of different reagents for stem cell maintenance and differentiation have been commercialized. These reagents share a common goal in facilitating the manufacture of products suitable for cell therapy while reducing the amount of non-defined components. Lessons from developmental biology have identified signalling molecules that can guide the differentiation process in vitro, but less attention has been paid to the extracellular matrix used. With the introduction of more biologically relevant and defined matrices, that better mimic specific cell niches, researchers now have powerful resources to fine-tune their in vitro differentiation systems, which may allow the manufacture of therapeutically relevant cell types. In this review article, we revisit the basics of the extracellular matrix, and explore the important role of the cell-matrix interaction. We focus on laminin proteins because they help to maintain pluripotency and drive cell fate specification.This article is part of the theme issue 'Designer human tissue: coming to a lab near you'.

Laminin as a Potent Substrate for Large-Scale Expansion of Human Induced Pluripotent Stem Cells in a Closed Cell Expansion System

The number of high-quality cells required for engineering an adult human-sized bioartificial organ is greater than one billion. Until the emergence of induced pluripotent stem cells (iPSCs), autologous cell sources of this magnitude and with the required complexity were not available. Growing this number of cells in a traditional 2D cell culture system requires extensive time, resources, and effort and does not always meet clinical requirements. The use of a closed cell culture system is an efficient and clinically applicable method that can be used to expand cells under controlled conditions. We aimed to use the Quantum Cell Expansion System (QES) as an iPSC monolayer-based expansion system. Human iPSCs were expanded (up to 14-fold) using the QES on two different coatings (laminin 521 (LN521) and vitronectin (VN)), and a karyotype analysis was performed. The cells were characterized for spontaneous differentiation and pluripotency by RT-PCR and flow cytometry. Our results demonstrated that the QES provides the necessary environment for exponential iPSC growth, reaching 689.75 × 10⁶ ± 86.88 × 10⁶ in less than 7 days using the LN521 coating with a population doubling level of 3.80 ± 0.19. The same result was not observed when VN was used as a coating. The cells maintained normal karyotype (46-XX), expressed pluripotency markers (OCT4, NANOG, LIN28, SOX2, REX1, DPPA4, NODAL, TDGFb, TERT3, and GDF), and expressed high levels of OCT4, SOX2, NANOG, SSEA4, TRA1-60, and TRA1-81. Spontaneous differentiation into ectoderm (NESTIN, TUBB3, and NEFH), mesoderm (MSX1, BMP4, and T), and endoderm (GATA6, AFP, and SOX17) lineages was detected by RT-PCR with both coating systems. We conclude that the QES maintains the stemness of iPSCs and is a promising platform to provide the number of cells necessary to recellularize small human-sized organ scaffolds for clinical purposes.