Generation of iPSC lines from primary human amniotic fluid cells

Ethical considerations for advancing research using organoid models derived from the placenta

BACKGROUND

The advent of organoid culture systems has revolutionized our ability to model and study complex tissues in vitro. The placenta is one of the last human organs to have a functional organoid model developed: trophoblast organoids. These 3-dimensional structures, derived from placental tissue, offer researchers a valuable tool for studying previously inaccessible processes that occur within the womb and play a significant role in determining the health of the offspring. While primarily used for research, trophoblast organoids hold promise for clinical applications, including prenatal diagnostics and therapeutic interventions, both of which may have commercial interest. However, to ensure that research with organoid models derived from the placenta is conducted responsibly, the relevant ethics of these models need to be addressed.

OBJECTIVE AND RATIONALE

Ethical considerations related to organoid models derived from the placenta, such as trophoblast organoids are important but remain unexplored in literature. Therefore, the goal of this review is to explore the ethical considerations related to trophoblast organoids.

SEARCH METHODS

Since there is no ethical research specifically addressing organoid models of the placenta to date, we have based our findings on discussions related to other organoid models and research involving fetal tissue, placenta, or umbilical cord blood. We employed a scoping review method to search PubMed, Embase, Medline (all), Bioethics Research Library, and Google Scholar for research articles, books, or other correspondence on ethical issues regarding these indicated topics, with no date limits.

OUTCOMES

Ethical considerations related to trophoblast organoids can be divided into three distinct categories. First, there is a need to assess the moral value of trophoblast organoids, including their potential relational and symbolic dimensions. Second, it is important to understand ethical issues associated with ownership and commercialization of trophoblast organoids. Last, there are considerations related to appropriate informed consent procedures. It is worth noting that these three categories are interconnected, with the second and third being largely dependent on the moral value attributed to trophoblast organoids. Future research should assess the perspectives of various stakeholders, including parents who may donate placental tissue for organoid research.

WIDER IMPLICATIONS

This review offers valuable insights into the ethical landscape surrounding the derivation of tissues or products from pregnancies, and their further application, highlighting areas that require attention and discussion within both the scientific community and the broader society.

REGISTRATION NUMBER

N/A.

Tissue-Restricted Stem Cells as Starting Cell Source for Efficient Generation of Pluripotent Stem Cells: An Overview

Induced pluripotent stem cells (iPSCs) have vast biomedical potential concerning disease modeling, drug screening and discovery, cell therapy, tissue engineering, and understanding organismal development. In the year 2006, a groundbreaking study reported the generation of iPSCs from mouse embryonic fibroblasts by viral transduction of four transcription factors, namely, Oct4, Sox2, Klf4, and c-Myc. Subsequently, human iPSCs were generated by reprogramming fibroblasts as a starting cell source using two reprogramming factor cocktails [(i) OCT4, SOX2, KLF4, and c-MYC, and (ii) OCT4, SOX2, NANOG, and LIN28]. The wide range of applications of these human iPSCs in research, therapeutics, and personalized medicine has driven the scientific community to optimize and understand this reprogramming process to achieve quality iPSCs with higher efficiency and faster kinetics. One of the essential criteria to address this is by identifying an ideal cell source in which pluripotency can be induced efficiently to give rise to high-quality iPSCs. Therefore, various cell types have been studied for their ability to generate iPSCs efficiently. Cell sources that can be easily reverted to a pluripotent state are tissue-restricted stem cells present in the fetus and adult tissues. Tissue-restricted stem cells can be isolated from fetal, cord blood, bone marrow, and other adult tissues or can be obtained by differentiation of embryonic stem cells or trans-differentiation of other tissue-restricted stem cells. Since these cells are undifferentiated cells with self-renewal potential, they are much easier to reprogram due to the inherent characteristic of having an endogenous expression of few pluripotency-inducing factors. This review presents an overview of promising tissue-restricted stem cells that can be isolated from different sources, namely, neural stem cells, hematopoietic stem cells, mesenchymal stem cells, limbal epithelial stem cells, and spermatogonial stem cells, and their reprogramming efficacy. This insight will pave the way for developing safe and efficient reprogramming strategies and generating patient-specific iPSCs from tissue-restricted stem cells derived from various fetal and adult tissues.

A circular RNA map for human induced pluripotent stem cells of foetal origin

BACKGROUND

Adult skin fibroblasts represent the most common starting cell type used to generate human induced pluripotent stem cells (F-hiPSC) for clinical studies. Yet, a foetal source would offer unique advantages, primarily the absence of accumulated somatic mutations. Herein, we generated hiPSC from cord blood multipotent mesenchymal stromal cells (MSC-hiPSC) and compared them with F-hiPSC. Assessment of the full activation of the pluripotency gene regulatory network (PGRN) focused on circular RNA (circRNA), recently proposed to participate in the control of pluripotency.

METHODS

Reprogramming was achieved by a footprint-free strategy. Self-renewal and pluripotency of cord blood MSC-hiPSC were investigated in vitro and in vivo, compared to parental MSC, to embryonic stem cells and to F-hiPSC. High-throughput array-based approaches and bioinformatics analyses were applied to address the PGRN.

FINDINGS

Cord blood MSC-hiPSC successfully acquired a complete pluripotent identity. Functional comparison with F-hiPSC showed no differences in terms of i) generation of mesenchymal-like derivatives, ii) their subsequent adipogenic, osteogenic and chondrogenic commitment, and iii) their hematopoietic support ability. At the transcriptional level, specific subsets of mRNA, miRNA and circRNA (n = 4,429) were evidenced, casting a further layer of complexity on the PGRN regulatory crosstalk.

INTERPRETATION

A circRNA map of transcripts associated to naïve and primed pluripotency is provided for hiPSC of clinical-grade foetal origin, offering insights on still unreported regulatory circuits of the PGRN to consider for the optimization and development of efficient differentiation protocols for clinical translation.

FUNDING

This research was funded by Ricerca Corrente 2012-2018 by the Italian Ministry of Health.

The Impact of Epigenetic Signatures on Amniotic Fluid Stem Cell Fate

Epigenetic modifications play a significant role in determining the fate of stem cells and in directing the differentiation into multiple lineages. Current evidence indicates that mechanisms involved in chromatin regulation are essential for maintaining stable cell identities. There is a tight correlation among DNA methylation, histone modifications, and small noncoding RNAs during the epigenetic control of stem cells' differentiation; however, to date, the precise mechanism is still not clear. In this context, amniotic fluid stem cells (AFSCs) represent an interesting model due to their unique features and the possible advantages of their use in regenerative medicine. Recent studies have elucidated epigenetic profiles involved in AFSCs' lineage commitment and differentiation. In order to use these cells effectively for therapeutic purposes, it is necessary to understand the basis of multiple-lineage potential and elaborate in detail how cell fate decisions are made and memorized. The present review summarizes the most recent findings on epigenetic mechanisms of AFSCs with a focus on DNA methylation, histone modifications, and microRNAs (miRNAs) and addresses how their unique signatures contribute to lineage-specific differentiation.

Cell fate decisions of human iPSC-derived bipotential hepatoblasts depend on cell density

During embryonic development bipotential hepatoblasts differentiate into hepatocytes and cholangiocytes- the two main cell types within the liver. Cell fate decision depends on elaborate interactions between distinct signalling pathways, namely Notch, WNT, TGFβ, and Hedgehog. Several in vitro protocols have been established to differentiate human pluripotent stem cells into either hepatocyte or cholangiocyte like cells (HLC/CLC) to enable disease modelling or drug screening. During HLC differentiation we observed the occurrence of epithelial cells with a phenotype divergent from the typical hepatic polygonal shape- we refer to these as endoderm derived epithelial cells (EDECs). These cells do not express the mature hepatocyte marker ALB or the progenitor marker AFP. However they express the cholangiocyte markers SOX9, OPN, CFTR as well as HNF4α, CK18 and CK19. Interestingly, they express both E Cadherin and Vimentin, two markers that are mutually exclusive, except for cancer cells. EDECs grow spontaneously under low density cell culture conditions and their occurrence was unaffected by interfering with the above mentioned signalling pathways.

Stem cell contributions to neurological disease modeling and personalized medicine

Human induced pluripotent stem cells (iPSCs) represent a revolutionary tool for disease modeling and drug discovery. The generation of tissue-relevant cell types exhibiting a patient's genetic and molecular background offers the ability to develop individual and effective therapies. In this review, we present some major achievements in the neuroscience field using iPSCs and discuss promising perspectives in personalized medicine. In addition to disease modeling, the understanding of the cellular and molecular basis of neurological disorders is explored, including the discovery of new targets and potential drugs. Ultimately, we highlight how iPSC technology, together with genome editing approaches, may bring a deep impact on pre-clinical trials by reducing costs and increasing the success of treatments in a personalized fashion.

Osteogenic Differentiation of Human Amniotic Fluid Mesenchymal Stem Cells Is Determined by Epigenetic Changes

Osteogenic differentiation of human amniotic fluid derived mesenchymal stem cells (AF-MSCs) has been widely studied in vitro and in vivo as a potential tool for regenerative medicine and tissue engineering. While most of the studies analyze changes in transcriptional profile during differentiation to date there is not much information regarding epigenetic changes in AF-MSCs during differentiation. The aim of our study was to evaluate epigenetic changes during osteogenic differentiation of AF-MS cells. Isolated AF-MSCs were characterized morphologically and osteogenic differentiation was confirmed by cell staining and determining expression of alkaline phosphatase and osteopontin by RT-qPCR. Variation in gene expression levels of pluripotency markers and specific microRNAs were also evaluated. Analysis of epigenetic changes revealed that levels of chromatin modifying enzymes such as Polycomb repressive complex 2 (PRC2) proteins (EZH2 and SUZ12), DNMT1, HDAC1, and HDAC2 were reduced after osteogenic differentiation of AF-MSCs. We demonstrated that the level of specific histone markers keeping active state of chromatin (H3K4me3, H3K9Ac, and others) increased and markers of repressed state of chromatin (H3K27me3) decreased. Our results show that osteogenic differentiation of AF-MSCs is conducted by various epigenetic alterations resulting in global chromatin remodeling and provide insights for further epigenetic investigations in human AF-MSCs.