Totipotency: what it is and what it is not

Transverse and vertical incisions affect the viability of in vitro-produced embryos submitted to a simplified microsurgery approach

Integrating in vitro embryo production with embryonic microsurgery facilitates the generation of monozygotic twins. However, despite their potential benefits, these methods have not been widely adopted in commercial settings because of their substantial costs. Hence, there is a need to streamline the bisection procedure while ensuring efficient production of viable demi-embryos. In this study, we investigated the impact of different orientations of microsurgical incisions in relation to inner cell mass on embryonic development, morphology, viability, and expression of cell fate protein markers using a simplified microsurgery approach. Ovaries were transported from the slaughterhouse to the laboratory and aspirated to obtain oocytes that were selected and subjected to in vitro embryo production. The selected expanded blastocysts (n = 204) underwent microsurgery. The blastocysts were immobilized to facilitate incision using an adapted microblade, yielding demi-embryos (vertical incision) and viable embryonic fragments (transverse incision). The structures were then re-cultured for 12 h. Viability was assessed by measuring the re-expansion rate after re-culture, followed by immunofluorescence analysis of proteins (CDX2 and NANOG) and apoptosis analysis using terminal deoxynucleotyl transferase dUTP nick end-labeling (TUNEL). Microsurgically derived embryos exhibited remarkable plasticity, as evidenced by a slight reduction (P < 0.05) in the re-expansion rate (transverse 64.2 % and vertical 57.2 %) compared to that of the control group (blastocysts without microsurgery) (86.7 %). They also demonstrated the ability of morphological reconstitution after culturing. Despite the anticipated decrease (P < 0.05) in the total number of cells and embryo volume, microsurgery did not result in a significant increase (P > 0.05) in the number of apoptotic cells. Furthermore, microsurgery led to higher (P < 0.05) expression of markers associated with pluripotency, indicating its efficiency in preserving regenerative capacity. Moreover, microsurgery, whether followed by immunosurgery or not, made the isolation of embryonic cells easier. In conclusion, both transverse and vertical microsurgery incisions enabled the production of identical demi-embryos and served as tools for isolating embryonic cells without compromising the resumption of development and the apoptotic index.

Organelle Ca2+/CAM1-SELTP confers somatic cell embryogenic competence acquisition and transformation in plant regeneration

Somatic cell totipotency in plant regeneration represents the forefront of the compelling scientific puzzles and one of the most challenging problems in biology. How somatic embryogenic competence is achieved in regeneration remains elusive. Here, we discover uncharacterized organelle-based embryogenic differentiation processes of intracellular acquisition and intercellular transformation, and demonstrate the underlying regulatory system of somatic embryogenesis-associated lipid transfer protein (SELTP) and its interactor calmodulin1 (CAM1) in cotton as the pioneer crop for biotechnology application. The synergistic CAM1 and SELTP exhibit consistent dynamical amyloplast-plasmodesmata (PD) localization patterns but show opposite functional effects. CAM1 inhibits the effect of SELTP to regulate embryogenic differentiation for plant regeneration. It is noteworthy that callus grafting assay reflects intercellular trafficking of CAM1 through PD for embryogenic transformation. This work originally provides insight into the mechanisms responsible for embryogenic competence acquisition and transformation mediated by the Ca2+/CAM1-SELTP regulatory pathway, suggesting a principle for plant regeneration and cell/genetic engineering.

Hallmarks of totipotent and pluripotent stem cell states

Though totipotency and pluripotency are transient during early embryogenesis, they establish the foundation for the development of all mammals. Studying these in vivo has been challenging due to limited access and ethical constraints, particularly in humans. Recent progress has led to diverse culture adaptations of epiblast cells in vitro in the form of totipotent and pluripotent stem cells, which not only deepen our understanding of embryonic development but also serve as invaluable resources for animal reproduction and regenerative medicine. This review delves into the hallmarks of totipotent and pluripotent stem cells, shedding light on their key molecular and functional features.

[Using 2C-like cells to understand embryonic totipotency]

Totipotency is the ability of a cell to generate a whole organism, a property that characterizes the first embryonic cells, such as the zygote and the blastomeres. This review provides a retrospective on the progress made in the last decade in the study of totipotency, especially with the discovery of mouse ES cells expressing markers of the 2-cell stage (2C-like cells). This model has greatly contributed to a better understanding of the molecular mechanisms involved in totipotency (pioneer factors, epigenetic regulation, splicing, nuclear maturation). 2C-like cells have also paved the way for the development of new cellular models of human totipotency.

Update on Mesenchymal Stem Cells: A Crucial Player in Cancer Immunotherapy

The idea of cancer immunotherapy has spread, and it has made tremendous progress with the advancement of new technology. Immunotherapy, which serves to assist the natural defenses of the body in eradicating cancerous cells, is a remarkable achievement that has revolutionized both cancer research and cancer treatments. Currently, the use of stem cells in immunotherapy is widespread and shares a special characteristic, including cancer cell migration, bioactive component release, and immunosuppressive activity. In the context of cancer, mesenchymal stem cells (MSCs) are rapidly being identified as vital stromal regulators of tumor progression. MSCs therapy has been implicated in treating a wide range of diseases, including bone damage, autoimmune diseases, and particularly hematopoietic abnormalities, providing stem cell-based therapy with an extra dimension. Moreover, the implication of MSCs does not have ethical concerns, and the complications known in pluripotent and totipotent stem cells are less common in MSCs. MSCs have a lot of distinctive characteristics that, when coupled, make them excellent for cellular-based immunotherapy and as vehicles for gene and drug delivery in a variety of inflammations and malignancies. MSCs can migrate to the inflammatory site and exert immunomodulatory responses via cell-to-cell contacts with lymphocytes by generating soluble substances. In the current review, we discuss the most recent research on the immunological characteristics of MSCs, their use as immunomodulatory carriers, techniques for approving MSCs to adjust their immunological contour, and their usages as vehicles for delivering therapeutic as well as drugs and genes engineered to destroy tumor cells.

High Temperature-Induced m6A Epigenetic Changes Affect Early Porcine Embryonic Developmental Competence in Pigs

N6-methyladenosine (m6A), the most prevalent modification in eukaryotic messenger RNA (mRNA), plays a key role in various developmental processes in mammals. Three proteins that affect RNA m6A modification have been identified: methyltransferases, demethylases, and m6A-binding proteins, known as "writer," "eraser," and "reader" proteins, respectively. However, changes in the m6A modification when early porcine embryos are exposed to stress remain unclear. In this study, we exposed porcine oocytes to a high temperature (HT, 41°C) for 10 h, after which the mature oocytes were parthenogenetically activated and cultured for 7 days to the blastocyst stage. HT significantly decreased the rates of the first polar body extrusion and blastocyst formation. Further detection of m6A modification found that HT can lead to increased expression levels of "reader," YTHDF2, and "writer," METTL3, and decreased expression levels of "eraser," FTO, resulting in an increased level of m6A modification in the embryos. Additionally, heat shock protein 70 (HSP70) is upregulated under HT conditions. Our study demonstrated that HT exposure alters m6A modification levels, which further affects early porcine embryonic development.

Recent advancement in therapeutic strategies for Alzheimer's disease: Insights from clinical trials

Alzheimer's disease (AD) is the most prevalent form of dementia, characterized by the presence of plaques of amyloid beta and Tau proteins. There is currently no permanent cure for AD; the only medications approved by the FDA for mild to moderate AD are cholinesterase inhibitors, NMDA receptor antagonists, and immunotherapies against core pathophysiology, that provide temporary relief only. Researchers worldwide have made significant attempts to find new targets and develop innovative therapeutic molecules to treat AD. The FDA-approved drugs are palliative and couldn't restore the damaged neuron cells of AD. Stem cells have self-differentiation properties, making them prospective therapeutics to treat AD. The promising results in pre-clinical studies of stem cell therapy for AD seek attention worldwide. Various stem cells, mainly mesenchymal stem cells, are currently in different phases of clinical trials and need more advancements to take this therapy to the translational level. Here, we review research from the past decade that has identified several hypotheses related to AD pathology. Moreover, this article also focuses on the recent advancement in therapeutic strategies for AD treatment including immunotherapy and stem cell therapy detailing the clinical trials that are currently undergoing development.

Molecular mechanisms underlying totipotency

Numerous efforts to understand pluripotency in mammals, using pluripotent stem cells in culture, have enabled the generation of artificially induced pluripotent stem cells, which serve as a valuable source for regenerative medicine and the creation of disease models. In contrast to these tremendous successes in the pluripotency field in the past few decades, our understanding of totipotency, which is highlighted by its broader plasticity than pluripotency, is still limited. This is largely attributable to the scarcity of available materials and the lack of in vitro models. However, recent technological advances have unveiled molecular features that characterize totipotent cells. Single-cell or low-input sequencing technologies allow the dissection of pre- and post-fertilization developmental processes at the molecular level with high resolution. In this review, we describe some of the key findings in understanding totipotency and discuss how totipotency is acquired at the beginning of life.

In Vitro Embryogenesis and Gastrulation Using Stem Cells in Mice and Humans

During early mammalian embryonic development, fertilized one-cell embryos develop into pre-implantation blastocysts and subsequently establish three germ layers through gastrulation during post-implantation development. In recent years, stem cells have emerged as a powerful tool to study embryogenesis and gastrulation without the need for eggs, allowing for the generation of embryo-like structures known as synthetic embryos or embryoids. These in vitro models closely resemble early embryos in terms of morphology and gene expression and provide a faithful recapitulation of early pre- and post-implantation embryonic development. Synthetic embryos can be generated through a combinatorial culture of three blastocyst-derived stem cell types, such as embryonic stem cells, trophoblast stem cells, and extraembryonic endoderm cells, or totipotent-like stem cells alone. This review provides an overview of the progress and various approaches in studying in vitro embryogenesis and gastrulation in mice and humans using stem cells. Furthermore, recent findings and breakthroughs in synthetic embryos and gastruloids are outlined. Despite ethical considerations, synthetic embryo models hold promise for understanding mammalian (including humans) embryonic development and have potential implications for regenerative medicine and developmental research.

The mammalian preimplantation embryo: Its role in the environmental programming of postnatal health and performance

During formation of the preimplantation embryo several cellular and molecular milestones take place, making the few cells forming the early embryo vulnerable to environmental stressors than can impair epigenetic reprogramming and controls of gene expression. Although these molecular alterations can result in embryonic death, a significant developmental plasticity is present in the preimplantation embryo that promotes full-term pregnancy. Prenatal epigenetic modifications are inherited during mitosis and can perpetuate specific phenotypes during early postnatal development and adulthood. As such, the preimplantation phase is a developmental window where developmental programming can take place in response to the embryonic microenvironment present in vivo or in vitro. In this review, the relevance of the preimplantation embryo as a developmental stage where offspring health and performance can be programmed is discussed, with emphasis on malnutrition and assisted reproductive technologies; two major environmental insults with important implications for livestock production and human reproductive medicine.

Unlocking the potential of stem cells: Their crucial role in the production of cultivated meat

Cellular agriculture is an emerging research field of agribiotechnology that aims to produce agricultural products using stem cells, without sacrificing animals or cultivating crops. Cultivated meat, as a representative cellular product of cellular agriculture, is being actively researched due to global food insecurity, environmental, and ethical concerns. This review focuses on the application of stem cells, which are the seeds of cellular agriculture, for the production of cultivated meat, with emphasis on deriving and culturing muscle and adipose stem cells for imitating fresh meat. Establishing standards and safety regulations for culturing stem cells is crucial for the market entry of cultured muscle tissue-based biomaterials. Understanding stem cells is a prerequisite for creating reliable cultivated meat and other cellular agricultural biomaterials. The techniques and regulations from the cultivated meat industry could pave the way for new cellular agriculture industries in the future.

The impact of epigenetic modifications on allogeneic hematopoietic stem cell transplantation

The field of epigenetics studies the complex processes that regulate gene expression without altering the DNA sequence itself. It is well established that epigenetic modifications are crucial to cellular homeostasis and differentiation and play a vital role in hematopoiesis and immunity. Epigenetic marks can be mitotically and/or meiotically heritable upon cell division, forming the basis of cellular memory, and have the potential to be reversed between cellular fate transitions. Hence, over the past decade, there has been increasing interest in the role that epigenetic modifications may have on the outcomes of allogeneic hematopoietic transplantation and growing enthusiasm in the therapeutic potential these pathways may hold. In this brief review, we provide a basic overview of the types of epigenetic modifications and their biological functions, summarizing the current literature with a focus on hematopoiesis and immunity specifically in the context of allogeneic hematopoietic stem cell transplantation.

A program of successive gene expression in mouse one-cell embryos

At the moment of union in fertilization, sperm and oocyte are transcriptionally silent. The ensuing onset of embryonic transcription (embryonic genome activation [EGA]) is critical for development, yet its timing and profile remain elusive in any vertebrate species. We here dissect transcription during EGA by high-resolution single-cell RNA sequencing of precisely synchronized mouse one-cell embryos. This reveals a program of embryonic gene expression (immediate EGA [iEGA]) initiating within 4 h of fertilization. Expression during iEGA produces canonically spliced transcripts, occurs substantially from the maternal genome, and is mostly downregulated at the two-cell stage. Transcribed genes predict regulation by transcription factors (TFs) associated with cancer, including c-Myc. Blocking c-Myc or other predicted regulatory TF activities disrupts iEGA and induces acute developmental arrest. These findings illuminate intracellular mechanisms that regulate the onset of mammalian development and hold promise for the study of cancer.

Adipose Stem Cells in Modern-Day Ophthalmology

Stem cells (SCs) have evolved as an interesting and viable factor in ophthalmologic patient care in the past decades. SCs have been classified as either embryonic, mesenchymal, tissue-specific, or induced pluripotent cells. Multiple novel management techniques and clinical trials have been established to date. While available publications are predominantly animal-model-based, significant material is derived from human studies and case-selected scenarios. This possibility of explanting cells from viable tissue to regenerate/repair damaged tissue points to an exciting future of therapeutic options in all fields of medicine, and ophthalmology is surely not left out. Adipose tissue obtained from lipo-aspirates has been shown to produce mesenchymal SCs that are potentially useful in different body parts, including the oculo-visual system. An overview of the anatomy, physiology, and extraction process for adipose-tissue-derived stem cells (ADSC) is important for better understanding the potential therapeutic benefits. This review examines published data on ADSCs in immune-modulatory, therapeutic, and regenerative treatments. We also look at the future of ADSC applications for ophthalmic patient care. The adverse effects of this relatively novel therapy are also discussed.

Comparative single-cell transcriptomic profiles of human androgenotes and parthenogenotes during early development

OBJECTIVE

To unravel the differential transcriptomic behavior of human androgenotes (AGs) and parthenogenotes (PGs) throughout the first cell cycles, analyze the differential expression of genes related to key biologic processes, and determine the time frame for embryonic genome activation (EGA) in AGs and PGs.

DESIGN

Laboratory study.

SETTING

Private fertility clinic.

PATIENT(S)

Mature oocytes were retrieved from healthy donors and subjected to artificial oocyte activation using calcium ionophore and puromycin to generate PGs (n = 6) or enucleated and subjected to intracytoplasmic sperm injection to generate AGs (n = 10).

INTERVENTION(S)

Uniparental constructs at different early stages of development were disaggregated into constituent single cells (we suggest the terms parthenocytes and androcytes) to characterize the single-cell transcriptional landscape using next-generation sequencing.

MAIN OUTCOMES MEASURE(S)

Transcriptomic profiles comparison between different stages of early development in AGs and PGs.

RESULT(S)

The uniparental transcriptomic profiles at the first cell cycle showed 68 down-regulated and 26 up-regulated differentially expressed genes (DEGs) in PGs compared with AGs. During the third cell cycle, we found 60 up-regulated and 504 down-regulated DEGs in PGs compared with AGs. In the fourth cell cycle, 1,771 up-regulated and 1,171 down-regulated DEGs were found in PGs compared with AGs. The AGs and PGs had reduced EGA profiles during the first 3 cell cycles, and a spike of EGA at the fourth cell cycle was observed in PGs.

CONCLUSION(S)

Transcriptomic analysis of AGs and PGs revealed their complementary behavior until the fourth cell cycle. Androgenotes undergo a low wave of transcription during the first cell cycle, which reflects the paternal contribution to cell cycle coordination, mechanics of cell division, and novel transcription regulation. Maternal transcripts are most prominent in the third and fourth cell cycles, with amplification of transcription related to morphogenic progression and embryonic developmental competence acquisition. Regarding EGA, in PGs, a primitive EGA begins at the 1-cell stage and gradually progresses until the 4-cell stage, when crucial epigenetic reprogramming (through methylation) is up-regulated. In addition, our longitudinal single-cell transcriptomic analysis challenges that the zygote and early cleavage stages are the only totipotent entities, by revealing potential totipotency in cleavage-stage AGs and implications of paternal transcripts.

Induction of Somatic Embryogenesis in Plants: Different Players and Focus on WUSCHEL and WUS-RELATED HOMEOBOX (WOX) Transcription Factors

In plants, other cells can express totipotency in addition to the zygote, thus resulting in embryo differentiation; this appears evident in apomictic and epiphyllous plants. According to Haberlandt's theory, all plant cells can regenerate a complete plant if the nucleus and the membrane system are intact. In fact, under in vitro conditions, ectopic embryos and adventitious shoots can develop from many organs of the mature plant body. We are beginning to understand how determination processes are regulated and how cell specialization occurs. However, we still need to unravel the mechanisms whereby a cell interprets its position, decides its fate, and communicates it to others. The induction of somatic embryogenesis might be based on a plant growth regulator signal (auxin) to determine an appropriate cellular environment and other factors, including stress and ectopic expression of embryo or meristem identity transcription factors (TFs). Still, we are far from having a complete view of the regulatory genes, their target genes, and their action hierarchy. As in animals, epigenetic reprogramming also plays an essential role in re-establishing the competence of differentiated cells to undergo somatic embryogenesis. Herein, we describe the functions of WUSCHEL-RELATED HOMEOBOX (WOX) transcription factors in regulating the differentiation-dedifferentiation cell process and in the developmental phase of in vitro regenerated adventitious structures.

Integrated transcriptomic and metabolic analyses provide insights into the maintenance of embryogenic potential and the biosynthesis of phenolic acids and flavonoids involving transcription factors in Larix kaempferi (Lamb.) Carr

Somatic embryogenesis (SE) techniques have been established for micropropagation or basic research related to plant development in many conifer species. The frequent occurrence of non-embryogenic callus (NEC) during SE has impose constraints on the application of somatic embryogenesis SE in Larix kaempferi (Lamb.) Carr, but the potential regulatory mechanisms are poorly understood. In this study, integrated transcriptomic and metabolomic analyses were performed in embryogenic callus (EC) and NEC originating from a single immature zygotic embryo to better decipher the key molecular and metabolic mechanisms required for embryogenic potential maintenance. The results showed that a total of 13,842 differentially expressed genes (DEGs) were found in EC and NEC, among which many were enriched in plant hormone signal transduction, starch and sucrose metabolism, phenylpropanoid biosynthesis, flavonoid biosynthesis, and the biosynthesis of amino acids pathways. Metabolite profiling showed that 441 differentially accumulated metabolites (DAMs) were identified in EC and NEC. Both EC and NEC had vigorous primary metabolic activities, while most secondary metabolites were upregulated in NEC. Many totipotency-related transcription factor (TF) genes such as BBMs, WUSs, and LEC1 showed higher expression levels in EC compared with NEC, which may result in the higher accumulation of indole 3-acetic acid (IAA) in EC. NEC was characterized by upregulation of genes and metabolites associated with stress responses, such as DEGs involved in jasmonic acid (JA) and ethylene (ETH) biosynthesis and signal transduction pathways, and DEGs and DAMs related to phenylpropanoid and flavonoid biosynthesis. We predicted and analyzed TFs that could target several key co-expressed structural DEGs including two C4H genes, two CcoAOMT genes and three HCT genes involved in phenylpropanoid and flavonoid biosynthesis. Based on the targeted relationship and the co-expression network, two ERFs (Lk23436 and Lk458687), one MYB (Lk34626) and one C2C2-dof (Lk37167) may play an important role in regulating phenolic acid and flavonoid biosynthesis by transcriptionally regulating the expression of these structural genes. This study shows an approach involving integrated transcriptomic and metabolic analyses to obtain insights into molecular events underlying embryogenic potential maintenance and the biosynthesis mechanisms of key metabolites involving TF regulation, which provides valuable information for the improvement of SE efficiency in L. kaempferi.

The initiation of mammalian embryonic transcription: to begin at the beginning

Gamete (sperm and oocyte) genomes are transcriptionally silent until embryonic genome activation (EGA) following fertilization. EGA in humans had been thought to occur around the eight-cell stage, but recent findings suggest that it is triggered in one-cell embryos, by fertilization. Phosphorylation and other post-translational modifications during fertilization may instate transcriptionally favorable chromatin and activate oocyte-derived transcription factors (TFs) to initiate EGA. Expressed genes lay on cancer-associated pathways and their identities predict upregulation by MYC and other cancer-associated TFs. One interpretation of this is that the onset of EGA, and the somatic cell trajectory to cancer, are mechanistically related: cancer initiates epigenetically. We describe how fertilization might be linked to the initiation of EGA and involve distinctive processes recapitulated in cancer.

An integrative perspective on the role of touch in the development of intersubjectivity

Touch concerns a fundamental component of sociality. In this review, we examine the hypothesis that somatomotor development constitutes a crucial psychophysiological element in the ontogeny of intersubjectivity. An interdisciplinary perspective is provided on how the communication channel of touch contributes to the sense of self and extends to the social self. During gestation, the transformation of random movements into organized sequences of actions with sensory consequences parallels the development of the brain's functional architecture. Brain subsystems shaped by the coordinated activity of somatomotor circuits to support these first body-environment interactions are the first brain functional arrangements to develop. We propose that tactile self-referring behaviour during gestation constitutes a prototypic mode of interpersonal exchange that supports the subsequent development of intersubjective exchange. The reviewed research suggests that touch constitutes a pivotal bodily experience that in early stages builds and later filters self-other interactions. This view is corroborated by the fact that aberrant social-affective touch experiences appear fundamentally associated with attachment anomalies, interpersonal trauma, and personality disorders. Given the centrality of touch for the development of intersubjectivity and for psychopathological conditions in the social domain, dedicated research is urged to elucidate the role of touch in the evolution of subjective self-other coding.

Multicellularity in animals: The potential for within-organism conflict

Metazoans function as individual organisms but also as “colonies” of cells whose single-celled ancestors lived and reproduced independently. Insights from evolutionary biology about multicellular group formation help us understand the behavior of cells: why they cooperate, and why cooperation sometimes breaks down. Current explanations for multicellularity focus on two aspects of development which promote cooperation and limit conflict among cells: a single-cell bottleneck, which creates organisms composed of clones, and a separation of somatic and germ cell lineages, which reduces the selective advantage of cheating. However, many obligately multicellular organisms thrive with neither, creating the potential for within-organism conflict. Here, we argue that the prevalence of such organisms throughout the Metazoa requires us to refine our preconceptions of conflict-free multicellularity. Evolutionary theory must incorporate developmental mechanisms across a broad range of organisms—such as unusual reproductive strategies, totipotency, and cell competition—while developmental biology must incorporate evolutionary principles. To facilitate this cross-disciplinary approach, we provide a conceptual overview from evolutionary biology for developmental biologists, using analogous examples in the well-studied social insects.

Cambial meristematic cell culture: a sustainable technology toward in vitro specialized metabolites production

Cambial meristematic cells (CMCs) culture has received a fair share of scientific and industrial attention among the trending topics of plant cell culture, especially their potential toward secondary metabolites production. However, the conventional plant cell culture is often not commercially feasible because of difficulties associated with culture dedifferentiated cells. Several reports have been published to culture CMCs and bypass the dedifferentiation process in plant cell culture. Numerous mitochondria, multiple vacuoles, genetic stability, self-renewal, higher biomass, and stable metabolites accumulation are the characteristics features of CMCs compared with dedifferentiated cells (DDCs) culture. The CMCs culture has a broader application to produce large-scale natural compounds for: pharmaceuticals, food, and cosmetic industries. Cutting-edge progress in plant cellular and molecular biology has allowed unprecedented insights into cambial stem cell culture and its fundamental processes. Therefore, regarding sustainability and natural compound production, cambial cell culture ranks among the most vital biotechnological interventions for industrial and economic perspectives. This review highlights the recent advances in plant stem cell culture and understands the cambial cells induction and culture mechanisms that affect the growth and natural compounds production.

Advances in stem cell therapy in Alzheimer's disease: a comprehensive clinical trial review

Alzheimer's disease (AD) is the most common type of dementia responsible for more than 121,499 deaths from AD in 2019 making AD the sixth-leading cause in the United States. AD is a progressive neurodegenerative disorder characterized by decline of memory, behavioral impairments that affects a person's ability to function independently ultimately leading to death. The current pressing need for a treatment for (AD) and advances in the field of cell therapy, has rendered stem cell therapeutics a promising field of research. Despite advancements in stem cell technology, confirmed by encouraging pre-clinical utilization of stem cells in AD animal models, the number of clinical trials evaluating the efficacy of stem cell therapy is limited, with the results of many ongoing clinical trials on cell therapy for AD still pending. Mesenchymal stem cells (MSCs) have been the main focus in these studies, reporting encouraging results concerning safety profile, however their efficacy remains unproven. In the current article we review the latest advances regarding different sources of stem cell therapy and present a comprehensive list of every available clinical trial in national and international registries. Finally, we discuss drawbacks arising from AD pathology and technical limitations that hinder the transition of stem cell technology from bench to bedside. Our findings emphasize the need to increase clinical trials towards uncovering the mode of action and the underlying therapeutic mechanisms of transplanted cells as well as the molecular mechanisms controlling regeneration and neuronal microenvironment.

Buckwheat in Tissue Culture Research: Current Status and Future Perspectives

Buckwheat is a member of a genus of 23 species, where the two most common species are Fagopyrum esculentum (common buckwheat) and Fagopyrum tataricum (Tartary buckwheat). This pseudocereal is a source of micro and macro nutrients, such as gluten-free proteins and amino acids, fatty acids, bioactive compounds, dietary fibre, fagopyrins, vitamins and minerals. It is gaining increasing attention due to its health-promoting properties. Buckwheat is widely susceptible to in vitro conditions which are used to study plantlet regeneration, callus induction, organogenesis, somatic embryogenesis, and the synthesis of phenolic compounds. This review summarises the development of buckwheat in in vitro culture and describes protocols for the regeneration of plantlets from various explants and differing concentrations of plant growth regulators. It also describes callus induction protocols as well as the role of calli in plantlet regeneration. Protocols for establishing hairy root cultures with the use of Agrobacterium rhizogens are useful in the synthesis of secondary metabolites, as well as protocols used for transgenic plants. The review also focuses on the future prospects of buckwheat in tissue culture and the challenges researchers are addressing.

Auxin biosynthesis maintains embryo identity and growth during BABY BOOM-induced somatic embryogenesis

Somatic embryogenesis is a type of plant cell totipotency where embryos develop from nonreproductive (vegetative) cells without fertilization. Somatic embryogenesis can be induced in vitro by auxins, and by ectopic expression of embryo-expressed transcription factors like the BABY BOOM (BBM) AINTEGUMENTA-LIKE APETALA2/ETHYLENE RESPONSE FACTOR domain protein. These different pathways are thought to converge to promote auxin response and biosynthesis, but the specific roles of the endogenous auxin pathway in somatic embryogenesis induction have not been well-characterized. Here we show that BBM transcriptionally regulates the YUCCA3 (YUC3) and YUC8 auxin biosynthesis genes during BBM-mediated somatic embryogenesis in Arabidopsis (Arabidopsis thaliana) seedlings. BBM induced local and ectopic YUC3 and YUC8 expression in seedlings, which coincided with increased DR5 auxin response and indole-3-acetic acid (IAA) biosynthesis and with ectopic expression of the WOX2 embryo reporter. YUC-driven auxin biosynthesis was required for BBM-mediated somatic embryogenesis, as the number of embryogenic explants was reduced by ca. 50% in yuc3 yuc8 mutants and abolished after chemical inhibition of YUC enzyme activity. However, a detailed YUC inhibitor time-course study revealed that YUC-dependent IAA biosynthesis is not required for the re-initiation of totipotent cell identity in seedlings. Rather, YUC enzymes are required later in somatic embryo development for the maintenance of embryo identity and growth. This study resolves a long-standing question about the role of endogenous auxin biosynthesis in transcription factor-mediated somatic embryogenesis and also provides an experimental framework for understanding the role of endogenous auxin biosynthesis in other in planta and in vitro embryogenesis systems.

Stem Cell-Based Therapies: What Interventional Radiologists Need to Know

As the basic units of biological organization, stem cells and their progenitors are essential for developing and regenerating organs and tissue systems using their unique self-renewal capability and differentiation potential into multiple cell lineages. Stem cells are consistently present throughout the entire human development, from the zygote to adulthood. Over the past decades, significant efforts have been made in biology, genetics, and biotechnology to develop stem cell-based therapies using embryonic and adult autologous or allogeneic stem cells for diseases without therapies or difficult to treat. Stem cell-based therapies require optimum administration of stem cells into damaged organs to promote structural regeneration and improve function. Maximum clinical efficacy is highly dependent on the successful delivery of stem cells to the target tissue. Direct image-guided locoregional injections into target tissues offer an option to increase therapeutic outcomes. Interventional radiologists have the opportunity to perform a key role in delivering stem cells more efficiently using minimally invasive techniques. This review discusses the types and sources of stem cells and the current clinical applications of stem cell-based therapies. In addition, the regulatory considerations, logistics, and potential roles of interventional Radiology are also discussed with the review of the literature.

Developmental capacity is unevenly distributed among single blastomeres of 2-cell and 4-cell stage mouse embryos

During preimplantation development, mammalian embryo cells (blastomeres) cleave, gradually losing their potencies and differentiating into three primary cell lineages: epiblast (EPI), trophectoderm (TE), and primitive endoderm (PE). The exact moment at which cells begin to vary in their potency for multilineage differentiation still remains unknown. We sought to answer the question of whether single cells isolated from 2- and 4-cell embryos differ in their ability to generate the progenitors and cells of blastocyst lineages. We revealed that twins were often able to develop into blastocysts containing inner cell masses (ICMs) with PE and EPI cells. Despite their capacity to create a blastocyst, the twins differed in their ability to produce EPI, PE, and TE cell lineages. In contrast, quadruplets rarely formed normal blastocysts, but instead developed into blastocysts with ICMs composed of only one cell lineage or completely devoid of an ICM altogether. We also showed that quadruplets have unequal capacities to differentiate into TE, PE, and EPI lineages. These findings could explain the difficulty of creating monozygotic twins and quadruplets from 2- and 4-cell stage mouse embryos.

Avoiding the potentiality trap: thinking about the moral status of synthetic embryos

Research ethics committees must sometimes deliberate about objects that do not fit nicely into any existing category. This is currently the case with the "gastruloid," which is a self-assembling blob of cells that resembles a human embryo. The resemblance makes it tempting to group it with other members of that kind, and thus to ask whether gastruloids really are embryos. But fitting an ambiguous object into an existing category with well-worn pathways in research ethics, like the embryo, is only a temporary fix. The bigger problem is that we no longer know what an embryo is. We haven't had a non-absurd definition of 'embryo' for several decades and without a well-defined comparison class, asking whether gastruloids belong to the morally relevant class of things we call embryos is to ask a question without an answer. What's the alternative? A better approach needs to avoid what I'll refer to as "the potentiality trap" and, instead, rely on the emergence of morally salient facts about gastruloids and other synthetic embryos.

Stem Cells: Innovative Therapeutic Options for Neurodegenerative Diseases?

Neurodegenerative diseases are characterized by the progressive loss of structure and/or function of both neurons and glial cells, leading to different degrees of pathology and loss of cognition. The hypothesis of circuit reconstruction in the damaged brain via direct cell replacement has been pursued extensively so far. In this context, stem cells represent a useful option since they provide tissue restoration through the substitution of damaged neuronal cells with exogenous stem cells and create a neuro-protective environment through the release of bioactive molecules for healthy neurons, as well. These peculiar properties of stem cells are opening to potential therapeutic strategies for the treatment of severe neurodegenerative disorders, for which the absence of effective treatment options leads to an increasingly socio-economic burden. Currently, the introduction of new technologies in the field of stem cells and the implementation of alternative cell tissues sources are pointing to exciting frontiers in this area of research. Here, we provide an update of the current knowledge about source and administration routes of stem cells, and review light and shadows of cells replacement therapy for the treatment of the three main neurodegenerative disorders (Amyotrophic lateral sclerosis, Parkinson’s, and Alzheimer’s disease).

Patentability challenges associated with emerging pharmaceutical technologies

According to the recent patent filing trends, it has been observed that certain pharmaceutical technologies are more popular than others and are commonly referred to as emerging technologies. The emerging technologies in the pharmaceutical sector include artificial intelligence, big data and certain advanced biological therapies such as personalized medicine and stem cell therapy. These trends have various applications in the medicine and healthcare industry. Since these technologies are relatively new and each of them is very unique in its own way, current patent laws are inadequate to deal with the complex challenges associated with them. A brief analysis of the challenges associated with these emerging technologies and their applications is discussed in this paper.

Stem Cell-Derived Exosomes: a New Strategy of Neurodegenerative Disease Treatment

Short-term symptomatic treatment and dose-dependent side effects of pharmacological treatment for neurodegenerative diseases have forced the medical community to seek an effective treatment for this serious global health threat. Therapeutic potential of stem cell for treatment of neurodegenerative disorders was identified in 1980 when fetal nerve tissue was used to treat Parkinson's disease (PD). Then, extensive studies have been conducted to develop this treatment strategy for neurological disease therapy. Today, stem cells and their secretion are well-known as a therapeutic environment for the treatment of neurodegenerative diseases. This new paradigm has demonstrated special characteristics related to this treatment, including neuroprotective and neurodegeneration, remyelination, reduction of neural inflammation, and recovery of function after induced injury. However, the exact mechanism of stem cells in repairing nerve damage is not yet clear; exosomes derived from them, an important part of their secretion, are introduced as responsible for an important part of such effects. Numerous studies over the past few decades have evaluated the therapeutic potential of exosomes in the treatment of various neurological diseases. In this review, after recalling the features and therapeutic history, we will discuss the latest stem cell-derived exosome-based therapies for these diseases.

Biological Responses of Stem Cells to Photobiomodulation Therapy

BACKGROUND

Stem cells have attracted the researchers interest, due to their applications in regenerative medicine. Their self-renewal capacity for multipotent differentiation, and immunomodulatory properties make them unique to significantly contribute to tissue repair and regeneration applications. Recently, stem cells have shown increased proliferation when irradiated with low-level laser therapy or Photobiomodulation Therapy (PBMT), which induces the activation of intracellular and extracellular chromophores and the initiation of cellular signaling. The purpose of this study was to evaluate this phenomenon in the literature.

METHODS

The literature investigated the articles written in English in four electronic databases of PubMed, Scopus, Google Scholar and Cochrane up to April 2019. Stem cell was searched by combining the search keyword of "low-level laser therapy" OR "low power laser therapy" OR "low-intensity laser therapy" OR "photobiomodulation therapy" OR "photo biostimulation therapy" OR "LED". In total, 46 articles were eligible for evaluation.

RESULTS

Studies demonstrated that red to near-infrared light is absorbed by the mitochondrial respiratory chain. Mitochondria are significant sources of reactive oxygen species (ROS). Mitochondria play an important role in metabolism, energy generation, and are also involved in mediating the effects induced by PBMT. PBMT may result in the increased production of (ROS), nitric oxide (NO), adenosine triphosphate (ATP), and cyclic adenosine monophosphate (cAMP). These changes, in turn, initiate cell proliferation and induce the signal cascade effect.

CONCLUSION

The findings of this review suggest that PBMT-based regenerative medicine could be a useful tool for future advances in tissue engineering and cell therapy.

Totipotency of mouse zygotes extends to single blastomeres of embryos at the four-cell stage

In multicellular organisms, oocytes and sperm undergo fusion during fertilization and the resulting zygote gives rise to a new individual. The ability of zygotes to produce a fully formed individual from a single cell when placed in a supportive environment is known as totipotency. Given that totipotent cells are the source of all multicellular organisms, a better understanding of totipotency may have a wide-ranging impact on biology. The precise delineation of totipotent cells in mammals has remained elusive, however, although zygotes and single blastomeres of embryos at the two-cell stage have been thought to be the only totipotent cells in mice. We now show that a single blastomere of two- or four-cell mouse embryos can give rise to a fertile adult when placed in a uterus, even though blastomere isolation disturbs the transcriptome of derived embryos. Single blastomeres isolated from embryos at the eight-cell or morula stages and cultured in vitro manifested pronounced defects in the formation of epiblast and primitive endoderm by the inner cell mass and in the development of blastocysts, respectively. Our results thus indicate that totipotency of mouse zygotes extends to single blastomeres of embryos at the four-cell stage.

A Comparative Analysis of Hippo Signaling Pathway Components during Murine and Bovine Early Mammalian Embryogenesis

The time required for successful blastocyst formation varies among multiple species. The formation of a blastocyst is governed by numerous molecular cell signaling pathways, such as the Hippo signaling pathway. The Hippo signaling pathway is initiated by increased cell-cell contact and via apical polarity proteins (AMOT, PARD6, and NF2) during the period of preimplantation embryogenesis. Cell-cell contact and cell polarity activate (phosphorylates) the core cascade components of the pathway (mammalian sterile twenty like 1 and 2 (MST1/2) and large tumor suppressor 1 and 2 (LATS1/2)), which in turn phosphorylate the downstream effectors of the pathway (YAP1/TAZ). The Hippo pathway remains inactive with YAP1 (Yes Associated protein 1) present inside the nucleus in the trophectoderm (TE) cells (polar blastomeres) of the mouse blastocyst. In the inner cell mass (ICM) cells (apolar blastomeres), the pathway is activated with p-YAP1 present in the cytoplasm. On the contrary, during bovine embryogenesis, p-YAP1 is exclusively present in the nucleus in both TE and ICM cells. Contrary to mouse embryos, transcription co activator with PDZ-binding motif (TAZ) (also known as WWTR1) is also predominantly present in the cytoplasm in all the blastomeres during bovine embryogenesis. This review outlines the major differences in the localization and function of Hippo signaling pathway components of murine and bovine preimplantation embryos, suggesting significant differences in the regulation of this pathway in between the two species. The variance observed in the Hippo signaling pathway between murine and bovine embryos confirms that both of these early embryonic models are quite distinct. Moreover, based on the similarity of the Hippo signaling pathway between bovine and human early embryo development, bovine embryos could be an alternate model for understanding the regulation of the Hippo signaling pathway in human embryos.

Transcriptomic profiles of non-embryogenic and embryogenic callus cells in a highly regenerative upland cotton line (Gossypium hirsutum L.)

Background

Genotype independent transformation and whole plant regeneration through somatic embryogenesis relies heavily on the intrinsic ability of a genotype to regenerate. The critical genetic architecture of non-embryogenic callus (NEC) cells and embryogenic callus (EC) cells in a highly regenerable cotton genotype is unknown.

Results

In this study, gene expression profiles of a highly regenerable Gossypium hirsutum L. cultivar, Jin668, were analyzed at two critical developmental stages during somatic embryogenesis, non-embryogenic callus (NEC) cells and embryogenic callus (EC) cells. The rate of EC formation in Jin668 is 96%. Differential gene expression analysis revealed a total of 5333 differentially expressed genes (DEG) with 2534 genes upregulated and 2799 genes downregulated in EC. A total of 144 genes were unique to NEC cells and 174 genes were unique to EC. Clustering and enrichment analysis identified genes upregulated in EC that function as transcription factors/DNA binding, phytohormone response, oxidative reduction, and regulators of transcription; while genes categorized in methylation pathways were downregulated. Four key transcription factors were identified based on their sharp upregulation in EC tissue; LEAFY COTYLEDON 1 (LEC1), BABY BOOM (BBM), FUSCA (FUS3) and AGAMOUS-LIKE15 with distinguishable subgenome expression bias.

Conclusions

This comparative analysis of NEC and EC transcriptomes gives new insights into the genes involved in somatic embryogenesis in cotton.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12861-020-00230-4.

From pluripotency to totipotency: an experimentalist's guide to cellular potency

Embryonic stem cells (ESCs) are derived from the pre-implantation mammalian blastocyst. At this point in time, the newly formed embryo is concerned with the generation and expansion of both the embryonic lineages required to build the embryo and the extra-embryonic lineages that support development. When used in grafting experiments, embryonic cells from early developmental stages can contribute to both embryonic and extra-embryonic lineages, but it is generally accepted that ESCs can give rise to only embryonic lineages. As a result, they are referred to as pluripotent, rather than totipotent. Here, we consider the experimental potential of various ESC populations and a number of recently identified in vitro culture systems producing states beyond pluripotency and reminiscent of those observed during pre-implantation development. We also consider the nature of totipotency and the extent to which cell populations in these culture systems exhibit this property.

The molecular and cellular features of 2-cell-like cells: a reference guide

Currently, two main cell culture models predominate pluripotent stem cell research: embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). Thanks to their ability to contribute to and form all tissues within the body, ESCs and iPSCs have proven invaluable in understanding pluripotent states, early embryonic development and cell differentiation, as well as in devising strategies for regenerative medicine. Comparatively little is known about totipotency - a cellular state with greater developmental potential. In mice, only the zygote and the blastomeres of the 2-cell-stage embryo are truly totipotent, as they alone can develop to form the embryo and all of its supportive extra-embryonic tissues. However, the discovery of a rare subpopulation of cells in murine ESC cultures, possessing features of 2-cell embryo blastomeres and expanded cell fate potential, has provided a biochemically tractable model to enable the in vitro study of totipotency. Here, we summarize current known features of these 2-cell-like cells (2CLCs) in an effort to provide a reference for the community, and to clarify what we know about their identity so far.

Common principles of early mammalian embryo self-organisation

Pre-implantation mammalian development unites extreme plasticity with a robust outcome: the formation of a blastocyst, an organised multi-layered structure ready for implantation. The process of blastocyst formation is one of the best-known examples of self-organisation. The first three cell lineages in mammalian development specify and arrange themselves during the morphogenic process based on cell-cell interactions. Despite decades of research, the unifying principles driving early mammalian development are still not fully defined. Here, we discuss the role of physical forces, and molecular and cellular mechanisms, in driving self-organisation and lineage formation that are shared between eutherian mammals.

Expanded potential: the key to synthetic embryo?

How does an embryo acquire totipotency and develop into an adult is a fundamental scientific question. Stem cells derived from pre-implantation embryos or reprogrammed from somatic cells with totipotency features have been established. They have enriched molecular features, including transcription, epigenetic modification, chromatin structure and metabolism, similar to early embryos from 2 cell (2C) to morula. Functionally, they display a broader developmental potential to differentiate into cell types in the embryonic and extraembryonic tissues. The expanded developmental potential was further demonstrated by inducing these stem cells into embryo-like structures alone or aggregating with other embryo-derived stem cells. The synthetic embryo-like structures not only facilitate the dissection of key events in early embryonic development, but also serve as a model for investigating pregnancy related complications.

On Mammalian Totipotency: What Is the Molecular Underpinning for the Totipotency of Zygote?

The mammalian zygote is described as a totipotent cell in the literature, but this characterization is elusive ignoring the molecular underpinnings. Totipotency can connote genetic totipotency, epigenetic totipotency, or the reprogramming capacity of a cell to epigenetic totipotency. Here, the implications of these concepts are discussed in the context of the properties of the zygote. Although genetically totipotent as any diploid somatic cell is, a zygote seems not totipotent transcriptionally, epigenetically, or functionally. Yet, a zygote may retain most of the key factors from its parental oocyte to reprogram an implanted differentiated genome or the zygote genome toward totipotency. This totipotent reprogramming process may extend to blastomeres in the two-cell-stage embryo. Thus, a revised alternative model of mammalian cellular totipotency is proposed, in which an epigenetically totipotent cell exists after the major embryonic genome activation and before the separation of the first two embryonic lineages.

A Survey of Essential Genome Stability Genes Reveals That Replication Stress Mitigation Is Critical for Peri-Implantation Embryogenesis

Murine development demands that pluripotent epiblast stem cells in the peri-implantation embryo increase from approximately 120 to 14,000 cells between embryonic days (E) 4.5 and E7.5. This is possible because epiblast stem cells can complete cell cycles in under 3 h in vivo. To ensure conceptus fitness, epiblast cells must undertake this proliferative feat while maintaining genome integrity. How epiblast cells maintain genome health under such an immense proliferation demand remains unclear. To illuminate the contribution of genome stability pathways to early mammalian development we systematically reviewed knockout mouse data from 347 DDR and repair associated genes. Cumulatively, the data indicate that while many DNA repair functions are dispensable in embryogenesis, genes encoding replication stress response and homology directed repair factors are essential specifically during the peri-implantation stage of early development. We discuss the significance of these findings in the context of the unique proliferative demands placed on pluripotent epiblast stem cells.

Does in vitro fertilization affect the expression of miRNAs and their biogenesis pathway in preimplantation mouse embryos?

BACKGROUND

In vitro fertilization (IVF) is a well-accepted procedure which has been utilized for the treatment of infertile patients. As embryos at early stages of development are very vulnerable, the IVF conditions may influence genetic and epigenetic regulation of preimplantation mouse embryo.

METHODS

We assessed the effect of IVF on the expression of developmental and implantation related miRNAs (miR-21, miR-93, miR-24, and let-7a), their common presumptive target (Stat3), and miRNA biogenesis pathway genes (Drosha, Dgcr8, Exportin-5, Dicer, and Ago2). in vivo 8-cell and blastocysts were compared to IVF embryos. Expression levels of miRNAs, Stat3, and miRNA biogenesis pathway genes were evaluated by qRT-PCR in in vivo (n = 8) and IVF (n = 4) embryos.

RESULTS

The expression levels of let-7a and Stat3 were significantly reduced in IVF blastocyst when compared with in vivo (p = .004 and p = .009, respectively). Nevertheless, the IVF procedure did not influence the expression levels of miRNA biogenesis pathway components in 8-cell and blastocyst embryos.

CONCLUSIONS

Downregulation of let-7a and developmental related transcription factor, Stat3, in IVF mouse blastocysts may affect preimplantation development and implantation of embryos. Moreover, the genes of the miRNA biogenesis pathway were not changed in preimplantation mouse embryos through the IVF procedure.

Induced Pluripotent Stem Cell-Derived T Cells for Cancer Immunotherapy

Adoptive T cell therapy for solid malignancies is limited because obtaining sufficient numbers of less-differentiated tumor-specific T cells is difficult. This roadblock can be theoretically overcome by the use of induced pluripotent stem cells (iPSCs), which self-renew and provide unlimited numbers of autologous less-differentiated T cells. iPSCs can generate less-differentiated antigen-specific T cells that harbor long telomeres and increased proliferative capacity, and exhibit potent antitumor efficacy. Although this strategy holds great promise for adoptive T cell therapy, highly reproducible and robust differentiation protocols are required before the translation of iPSC technology into the clinical setting.

Toward a Reconceptualization of Stem Cells from Cellular Plasticity

The slow progress in clinical applications of stem cells and the bewildering mechanisms involved have puzzled many researchers. Recently, the increasing evidences have indicated that cells have superior plasticity in vivo or in vitro, spontaneously or under extrinsic specific inducers. The concept of stem cells may be challenged, or even replaced by the concept of cell plasticity when cell reprogramming technology is progressing rapidly. The characteristics of stem cells are manifestations of cellular plasticity. Incorrect understanding of the concept of stem cells hinders the clinical application of so-called stem cells. Understanding cellular plasticity is important for understanding and treating disease. The above issues will be discussed in detail to prove the reconceptualization of stem cells from cellular plasticity.

Arrayed functional genetic screenings in pluripotency reprogramming and differentiation

Thoroughly understanding the molecular mechanisms responsible for the biological properties of pluripotent stem cells, as well as for the processes involved in reprograming, differentiation, and transition between Naïve and Primed pluripotent states, is of great interest in basic and applied research. Although pluripotent cells have been extensively characterized in terms of their transcriptome and miRNome, a comprehensive understanding of how these gene products specifically impact their biology, depends on gain- or loss-of-function experimental approaches capable to systematically interrogate their function. We review all studies carried up to date that used arrayed screening approaches to explore the function of these genetic elements on those biological contexts, using focused or genome-wide genetic libraries. We further discuss the limitations and advantages of approaches based on assays with population-level primary readouts, derived from single-parameter plate readers, or cell-level primary readouts, obtained using multiparametric flow cytometry or quantitative fluorescence microscopy (i.e., high-content screening). Finally, we discuss technical limitation and future perspectives, highlighting how the integration of screening data may lead to major advances in the field of stem cell research and therapy.

Can epigenetics translate environmental cues into phenotypes?

Living organisms are constantly exposed to wide ranges of environmental cues. They react to these cues by undergoing a battery of phenotypic responses, such as by altering their physiological and behavioral traits, in order to adapt and survive in the changed environments. The adaptive response of a species induced by environmental cues is typically thought to be associated with its genetic diversity such that higher genetic diversity provides increased adaptive potential. This originates from the general consensus that phenotypic traits have a genetic basis and are subject to Darwinian natural selection and Mendelian inheritance. There is no doubt about the validity of these principles, supported by the successful introgression of specific traits during (selective) breeding. However, a range of recent studies provided fascinating evidences suggesting that environmental effects experienced by an organism during its lifetime can have marked influences on its phenotype, and additionally the organism can pass on the acquired phenotypes to its subsequent generations through non-genetic mechanisms (also termed as epigenetic mechanism) - a notion that dates back to Lamarck and has been controversial ever since. In this review, we describe how the epigenetics has reshaped our long perception about the inheritance/development of phenotypes within organisms, contrasting with the classical gene-based view of inheritance. We particularly highlighted recent developments in our understanding of inheritance of parental environmental induced phenotypic traits in multicellular organisms under different environmental conditions, and discuss how modifications of the epigenome contribute to the determination of the adult phenotype of future generations.

Potential Clinical Applications of Stem Cells in Regenerative Medicine

The field of regenerative medicine is looking for a pluripotent/multipotent stem cell able to differentiate across germ layers and be safely employed in therapy. Unfortunately, with the exception of hematopoietic stem/progenitor cells (HSPCs) for hematological applications, the current clinical results with stem cells are somewhat disappointing. The potential clinical applications of the more primitive embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) have so far been discouraging, as both have exhibited several problems, including genomic instability, a risk of teratoma formation, and the possibility of rejection. Therefore, the only safe stem cells that have so far been employed in regenerative medicine are monopotent stem cells, such as the abovementioned HSPCs or mesenchymal stem cells (MSCs) isolated from postnatal tissues. However, their monopotency, and therefore limited differentiation potential, is a barrier to their broader application in the clinic. Interestingly, results have accumulated indicating that adult tissues contain rare, early-development stem cells known as very small embryonic-like stem cells (VSELs), which can differentiate into cells from more than one germ layer. This chapter addresses different sources of stem cells for potential clinical application and their advantages and problems to be solved.

Callus, Dedifferentiation, Totipotency, Somatic Embryogenesis: What These Terms Mean in the Era of Molecular Plant Biology?

Recent findings call for the critical overview of some incorrectly used plant cell and tissue culture terminology such as dedifferentiation, callus, totipotency, and somatic embryogenesis. Plant cell and tissue culture methods are efficient means to preserve and propagate genotypes with superior germplasm as well as to increase genetic variability for breading. Besides, they are useful research tools and objects of plant developmental biology. The history of plant cell and tissue culture dates back to more than a century. Its basic methodology and terminology were formulated preceding modern plant biology. Recent progress in molecular and cell biology techniques allowed unprecedented insights into the underlying processes of plant cell/tissue culture and regeneration. The main aim of this review is to provide a theoretical framework supported by recent experimental findings to reconsider certain historical, even dogmatic, statements widely used by plant scientists and teachers such as "plant cells are totipotent" or "callus is a mass of dedifferentiated cells," or "somatic embryos have a single cell origin." These statements are based on a confused terminology. Clarification of it might help to avoid further misunderstanding and to overcome potential "terminology-raised" barriers in plant research.

Stem cells technology: a powerful tool behind new brain treatments

Stem cell research has recently become a hot research topic in biomedical research due to the foreseen unlimited potential of stem cells in tissue engineering and regenerative medicine. For many years, medicine has been facing intense challenges, such as an insufficient number of organ donations that is preventing clinicians to fulfill the increasing needs. To try and overcome this regrettable matter, research has been aiming at developing strategies to facilitate the in vitro culture and study of stem cells as a tool for tissue regeneration. Meanwhile, new developments in the microfluidics technology brought forward emerging cell culture applications that are currently allowing for a better chemical and physical control of cellular microenvironment. This review presents the latest developments in stem cell research that brought new therapies to the clinics and how the convergence of the microfluidics technology with stem cell research can have positive outcomes on the fields of regenerative medicine and high-throughput screening. These advances will bring new translational solutions for drug discovery and will upgrade in vitro cell culture to a new level of accuracy and performance. We hope this review will provide new insights into the understanding of new brain treatments from the perspective of stem cell technology especially regarding regenerative medicine and tissue engineering.