Embryonic and induced pluripotent stem cells: understanding, creating, and exploiting the nano-niche for regenerative medicine

Toward the latest advancements in cardiac regeneration using induced pluripotent stem cells (iPSCs) technology: approaches and challenges

A novel approach to treating heart failures was developed with the introduction of iPSC technology. Knowledge in regenerative medicine, developmental biology, and the identification of illnesses at the cellular level has exploded since the discovery of iPSCs. One of the most frequent causes of mortality associated with cardiovascular disease is the loss of cardiomyocytes (CMs), followed by heart failure. A possible treatment for heart failure involves restoring cardiac function and replacing damaged tissue with healthy, regenerated CMs. Significant strides in stem cell biology during the last ten years have transformed the in vitro study of human illness and enhanced our knowledge of the molecular pathways underlying human disease, regenerative medicine, and drug development. We seek to examine iPSC advancements in disease modeling, drug discovery, iPSC-Based cell treatments, and purification methods in this article.

Exploring Parental Knowledge, Attitudes, and Factors Influencing Decision-Making in Stem Cell Banking: Rising the Future of Medical Treatment

BACKGROUND AND OBJECTIVES

Stem cell banking (SCB) is a promising area of modern medicine with the potential to yield innovative treatments and cures. To effectively educate parents and implement laws and regulations that address parental concerns and encourage informed decision-making, it is imperative to emphasize parental viewpoints and their consequences for future healthcare. The study aims to establish the Saudi Arabian population's level of understanding regarding SCB and to comprehend the elements influencing parental knowledge, attitudes, and SCB decision-making processes.

METHODOLOGY

A cross-sectional study was conducted among the population in the Makkah region of Saudi Arabia. Demographic data, knowledge levels, attitudes, and decision-making variables were gathered from 380 respondents.

RESULTS

The study reveals a lack in their comprehension of the objectives and possible uses of SCB, together with the main sources of information on those banks and conveniently available banking choices. It showed varied results regarding attitudes about considering an SCB for their children. In addition, the majority of respondents had not made a consent decision about SCB for their children. It also illuminates the factors that could influence participants' decisions about SCB for their children and shows that a lack of information and understanding is the main obstacle faced by parents regarding SCB. It highlights that participants were generally in favor of learning more about SCB for their children.

CONCLUSIONS

This study broadens our understanding of parental decision-making toward SCB and clarifies the elements influencing parents' opinions and worries and offers significant ramifications for lawmakers, medical professionals, and SCB. These implications can be utilized to enhance communication strategies, create instructional programs, and ease the fears of concerned parents.

The ad hoc chemical design of random PBS-based copolymers influences the activation of cardiac differentiation while altering the HYPPO pathway target genes in hiPSCs

Cardiac tissue engineering is a cutting-edge technology aiming to replace irreversibly damaged cardiac tissue and restore contractile functionality. However, cardiac tissue engineering porous and perfusable scaffolds to enable oxygen supply in vitro and eventually promote angiogenesis in vivo are still desirable. Two fully-aliphatic random copolymers of poly(butylene succinate) (PBS), poly(butylene succinate/Pripol), P(BSBPripol), and poly(butylene/neopentyl glycol succinate), P(BSNS), containing two different subunits, neopentyl glycol and Pripol 1009, were successfully synthesized and then electrospun in tridimentional fibrous mats. The copolymers show different thermal and mechanical behaviours as result of their chemical structure. In particular, copolymerization led to a reduction in crystallinity and consequently PBS stiffness, reaching values of elastic modulus very close to those of soft tissues. Then, to check the biological suitability, human induced Pluripotent Stem Cells (hiPSCs) were directly seeded on both PBS-based copolymeric scaffolds. The results confirmed the ability of both the scaffolds to sustain cell viability and to maintain their stemness during cell expansion. Furthermore, gene expression and immunofluorescence analysis showed that P(BSBPripol) scaffold promoted an upregulation of the early cardiac progenitor and later-stage markers with a simultaneously upregulation of HYPPO pathway gene expression, crucial for mechanosensing of cardiac progenitor cells. These results suggest that the correct ad-hoc chemical design and, in turn, the mechanical properties of the matrix, such as substrate stiffness, together with surface porosity, play a critical role in regulating the behaviour of cardiac progenitors, which ultimately offers valuable insights into the development of novel bio-inspired scaffolds for cardiac tissue regeneration.

The enhanced generation of motor neurons from mESCs by MgAl layered double hydroxide nanoparticles

The committed differentiation of stem cells into neurons is a promising therapeutic strategy for neurological diseases. Predifferentiation of transplanted stem cells into neural precursors could enhance their utilization and control the direction of differentiation. Embryonic stem cells with totipotency can differentiate into specific nerve cells under appropriate external induction conditions. Layered double hydroxide (LDH) nanoparticles have been proven to regulate the pluripotency of mouse ESCs (mESCs), and LDH could be used as carrier in neural stem cells for nerve regeneration. Hence, we sought to study the effects of LDH without loaded factors on mESCs neurogenesis in this work. A series of characteristics analyses indicated the successful construction of LDH nanoparticles. LDH nanoparticles that may adhere to the cell membranes had insignificant effect on cell proliferation and apoptosis. The enhanced differentiation of mESCs into motor neurons by LDH was systematically validated by immunofluorescent staining, quantitative real-time PCR analysis and western blot analysis. In addition, transcriptome sequencing analysis and mechanism verification elucidated the significant regulatory roles of focal adhesion signaling pathway in the enhanced mESCs neurogenesis by LDH. Taken together, the functional validation of inorganic LDH nanoparticles promoting motor neurons differentiation provide a novel strategy and therapeutic prospect for the clinical transition of neural regeneration.

Systemic proteomics and miRNA profile analysis of exosomes derived from human pluripotent stem cells

BACKGROUND

Increasing studies have reported the therapeutic effect of mesenchymal stem cell (MSC)-derived exosomes by which protein and miRNA are clearly characterized. However, the proteomics and miRNA profiles of exosomes derived from human embryonic stem cells (hESCs) and human-induced pluripotent stem cells (hiPSCs) remain unclear.

METHODS

In this study, we isolated exosomes from hESCs, hiPSCs, and human umbilical cord mesenchymal stem cells (hUC-MSCs) via classic ultracentrifugation and a 0.22-μm filter, followed by the conservative identification. Tandem mass tag labeling and label-free relative peptide quantification together defined their proteomics. High-throughput sequencing was performed to determine miRNA profiles. Then, we conducted a bioinformatics analysis to identify the dominant biological processes and pathways modulated by exosome cargos. Finally, the western blot and RT-qPCR were performed to detect the actual loads of proteins and miRNAs in three types of exosomes.

RESULTS

Based on our study, the cargos from three types of exosomes contribute to sophisticated biological processes. In comparison, hESC exosomes (hESC-Exos) were superior in regulating development, metabolism, and anti-aging, and hiPSC exosomes (hiPSC-Exos) had similar biological functions as hESC-Exos, whereas hUC-MSCs exosomes (hUC-MSC-Exos) contributed more to immune regulation.

CONCLUSIONS

The data presented in our study help define the protein and miRNA landscapes of three exosomes, predict their biological functions via systematic and comprehensive network analysis at the system level, and reveal their respective potential applications in different fields so as to optimize exosome selection in preclinical and clinical trials.

Biophysical Approaches for Applying and Measuring Biological Forces

Over the past decades, increasing evidence has indicated that mechanical loads can regulate the morphogenesis, proliferation, migration, and apoptosis of living cells. Investigations of how cells sense mechanical stimuli or the mechanotransduction mechanism is an active field of biomaterials and biophysics. Gaining a further understanding of mechanical regulation and depicting the mechanotransduction network inside cells require advanced experimental techniques and new theories. In this review, the fundamental principles of various experimental approaches that have been developed to characterize various types and magnitudes of forces experienced at the cellular and subcellular levels are summarized. The broad applications of these techniques are introduced with an emphasis on the difficulties in implementing these techniques in special biological systems. The advantages and disadvantages of each technique are discussed, which can guide readers to choose the most suitable technique for their questions. A perspective on future directions in this field is also provided. It is anticipated that technical advancement can be a driving force for the development of mechanobiology.

Mesenchymal Stem Cells Influence Activation of Hepatic Stellate Cells, and Constitute a Promising Therapy for Liver Fibrosis

Liver fibrosis is a common feature of chronic liver disease. Activated hepatic stellate cells (HSCs) are the main drivers of extracellular matrix accumulation in liver fibrosis. Hence, a strategy for regulating HSC activation is crucial in treating liver fibrosis. Mesenchymal stem cells (MSCs) are multipotent stem cells derived from various post-natal organs. Therapeutic approaches involving MSCs have been studied extensively in various diseases, including liver disease. MSCs modulate hepatic inflammation and fibrosis and/or differentiate into hepatocytes by interacting directly with immune cells, HSCs, and hepatocytes and secreting modulators, thereby contributing to reduced liver fibrosis. Cell-free therapy including MSC-released secretomes and extracellular vesicles has elicited extensive attention because they could overcome MSC transplantation limitations. Herein, we provide basic information on hepatic fibrogenesis and the therapeutic potential of MSCs. We also review findings presenting the effects of MSC itself and MSC-based cell-free treatments in liver fibrosis, focusing on HSC activation. Growing evidence supports the anti-fibrotic function of either MSC itself or MSC modulators, although the mechanism underpinning their effects on liver fibrosis has not been established. Further studies are required to investigate the detailed mechanism explaining their functions to expand MSC therapies using the cell itself and cell-free treatments for liver fibrosis.

DNA Damage-Induced Inflammatory Microenvironment and Adult Stem Cell Response

Adult stem cells ensure tissue homeostasis and regeneration after injury. Due to their longevity and functional requirements, throughout their life stem cells are subject to a significant amount of DNA damage. Genotoxic stress has recently been shown to trigger a cascade of cell- and non-cell autonomous inflammatory signaling pathways, leading to the release of pro-inflammatory factors and an increase in the amount of infiltrating immune cells. In this review, we discuss recent evidence of how DNA damage by affecting the microenvironment of stem cells present in adult tissues and neoplasms can affect their maintenance and long-term function. We first focus on the importance of self-DNA sensing in immunity activation, inflammation and secretion of pro-inflammatory factors mediated by activation of the cGAS-STING pathway, the ZBP1 pathogen sensor, the AIM2 and NLRP3 inflammasomes. Alongside cytosolic DNA, the emerging roles of cytosolic double-stranded RNA and mitochondrial DNA are discussed. The DNA damage response can also initiate mechanisms to limit division of damaged stem/progenitor cells by inducing a permanent state of cell cycle arrest, known as senescence. Persistent DNA damage triggers senescent cells to secrete senescence-associated secretory phenotype (SASP) factors, which can act as strong immune modulators. Altogether these DNA damage-mediated immunomodulatory responses have been shown to affect the homeostasis of tissue-specific stem cells leading to degenerative conditions. Conversely, the release of specific cytokines can also positively impact tissue-specific stem cell plasticity and regeneration in addition to enhancing the activity of cancer stem cells thereby driving tumor progression. Further mechanistic understanding of the DNA damage-induced immunomodulatory response on the stem cell microenvironment might shed light on age-related diseases and cancer, and potentially inform novel treatment strategies.

Cell Transdifferentiation and Reprogramming in Disease Modeling: Insights into the Neuronal and Cardiac Disease Models and Current Translational Strategies

Cell transdifferentiation and reprogramming approaches in recent times have enabled the manipulation of cell fate by enrolling exogenous/artificial controls. The chemical/small molecule and regulatory components of transcription machinery serve as potential tools to execute cell transdifferentiation and have thereby uncovered new avenues for disease modeling and drug discovery. At the advanced stage, one can believe these methods can pave the way to develop efficient and sensitive gene therapy and regenerative medicine approaches. As we are beginning to learn about the utility of cell transdifferentiation and reprogramming, speculations about its applications in translational therapeutics are being largely anticipated. Although clinicians and researchers are endeavoring to scale these processes, we lack a comprehensive understanding of their mechanism(s), and the promises these offer for targeted and personalized therapeutics are scarce. In the present report, we endeavored to provide a detailed review of the original concept, methods and modalities enrolled in the field of cellular transdifferentiation and reprogramming. A special focus is given to the neuronal and cardiac systems/diseases towards scaling their utility in disease modeling and drug discovery.

Mechanical and Physical Regulation of Fibroblast-Myofibroblast Transition: From Cellular Mechanoresponse to Tissue Pathology

Fibroblasts are cells present throughout the human body that are primarily responsible for the production and maintenance of the extracellular matrix (ECM) within the tissues. They have the capability to modify the mechanical properties of the ECM within the tissue and transition into myofibroblasts, a cell type that is associated with the development of fibrotic tissue through an acute increase of cell density and protein deposition. This transition from fibroblast to myofibroblast-a well-known cellular hallmark of the pathological state of tissues-and the environmental stimuli that can induce this transition have received a lot of attention, for example in the contexts of asthma and cardiac fibrosis. Recent efforts in understanding how cells sense their physical environment at the micro- and nano-scales have ushered in a new appreciation that the substrates on which the cells adhere provide not only passive influence, but also active stimulus that can affect fibroblast activation. These studies suggest that mechanical interactions at the cell-substrate interface play a key role in regulating this phenotype transition by changing the mechanical and morphological properties of the cells. Here, we briefly summarize the reported chemical and physical cues regulating fibroblast phenotype. We then argue that a better understanding of how cells mechanically interact with the substrate (mechanosensing) and how this influences cell behaviors (mechanotransduction) using well-defined platforms that decouple the physical stimuli from the chemical ones can provide a powerful tool to control the balance between physiological tissue regeneration and pathological fibrotic response.

Application of Nanotechnology in Stem-Cell-Based Therapy of Neurodegenerative Diseases

In addition to adverse health outcomes, neurological disorders have serious societal and economic impacts on patients, their family and society as a whole. There is no definite treatment for these disorders, and current available drugs only slow down the progression of the disease. In recent years, application of stem cells has been widely advanced due to their potential of self-renewal and differentiation to different cell types which make them suitable candidates for cell therapy. In particular, this approach offers great opportunities for the treatment of neurodegenerative disorders. However, some major issues related to stem-cell therapy, including their tumorigenicity, viability, safety, metastases, uncontrolled differentiation and possible immune response have limited their application in clinical scales. To address these challenges, a combination of stem-cell therapy with nanotechnology can be a solution. Nanotechnology has the potential of improvement of stem-cell therapy by providing ideal substrates for large scale proliferation of stem cells. Application of nanomaterial in stem-cell culture will be also beneficial to modulation of stem-cell differentiation using nanomedicines. Nanodelivery of functional compounds can enhance the efficiency of neuron therapy by stem cells and development of nanobased techniques for real-time, accurate and long-lasting imaging of stem-cell cycle processes. However, these novel techniques need to be investigated to optimize their efficiency in treatment of neurologic diseases.

Functional Relationship between Osteogenesis and Angiogenesis in Tissue Regeneration

Bone tissue renewal can be outlined as a complicated mechanism centered on the interaction between osteogenic and angiogenic events capable of leading to bone formation and tissue renovation. The achievement or debacle of bone regeneration is focused on the primary role of vascularization occurrence; in particular, the turning point is the opportunity to vascularize the bulk scaffolds, in order to deliver enough nutrients, growth factors, minerals and oxygen for tissue restoration. The optimal scaffolds should ensure the development of vascular networks to warrant a positive suitable microenvironment for tissue engineering and renewal. Vascular Endothelial Growth Factor (VEGF), a main player in angiogenesis, is capable of provoking the migration and proliferation of endothelial cells and indirectly stimulating osteogenesis, through the regulation of the osteogenic growth factors released and through paracrine signaling. For this reason, we concentrated our attention on two principal groups involved in the renewal of bone tissue defects: the cells and the scaffold that should guarantee an effective vascularization process. The application of Mesenchymal Stem Cells (MSCs), an excellent cell source for tissue restoration, evidences a crucial role in tissue engineering and bone development strategies. This review aims to provide an overview of the intimate connection between blood vessels and bone formation that appear during bone regeneration when MSCs, their secretome-Extracellular Vesicles (EVs) and microRNAs (miRNAs) -and bone substitutes are used in combination.

Flow-enhanced priming of hESCs through H2B acetylation and chromatin decondensation

BACKGROUND

Distinct mechanical stimuli are known to manipulate the behaviors of embryonic stem cells (ESCs). Fundamental rationale of how ESCs respond to mechanical forces and the potential biological effects remain elusive. Here we conducted the mechanobiological study for hESCs upon mechanomics analysis to unravel typical mechanosensitive processes on hESC-specific fluid shear.

METHODS

hESC line H1 was subjected to systematically varied shear flow, and mechanosensitive proteins were obtained by mass spectrometry (MS) analysis. Then, function enrichment analysis was performed to identify the enriched gene sets. Under a steady shear flow of 1.1 Pa for 24 h, protein expressions were further detected using western blotting (WB), quantitative real-time PCR (qPCR), and immunofluorescence (IF) staining. Meanwhile, the cells were treated with 200 nM trichostatin (TSA) for 1 h as positive control to test chromatin decondensation. Actin, DNA, and RNA were then visualized with TRITC-labeled phalloidin, Hoechst 33342, and SYTO® RNASelect™ green fluorescent cell stain (Life Technologies), respectively. In addition, cell stiffness was determined with atomic force microscopy (AFM) and annexin V-PE was used to determine the apoptosis with a flow cytometer (FCM).

RESULTS

Typical mechanosensitive proteins were unraveled upon mechanomics analysis under fluid shear related to hESCs in vivo. Functional analyses revealed significant alterations in histone acetylation, nuclear size, and cytoskeleton for hESC under shear flow. Shear flow was able to induce H2B acetylation and nuclear spreading by CFL2/F-actin cytoskeletal reorganization. The resulting chromatin decondensation and a larger nucleus readily accommodate signaling molecules and transcription factors.

CONCLUSIONS

Shear flow regulated chromatin dynamics in hESCs via cytoskeleton and nucleus alterations and consolidated their primed state.

Lens epithelial cells-induced pluripotent stem cells as a model to study epithelial-mesenchymal transition during posterior capsular opacification

The overall goal was to generate an epithelial-mesenchymal transition (EMT) model using lens epithelial cells-induced pluripotent stem cells to elucidate EMT-regulatory factors during posterior capsular opacification (PCO). For this purpose, the mouse lens epithelial cells-derived mesenchymal cells were reprogrammed to induced pluripotent stem cells (iPSC) and differentiated to lens epithelial cells to be used to determine regulatory factors during EMT. Lens epithelial cells from one-month-old C57BL/6 mice were transitioned to mesenchymal cells in culture, and were reprogrammed to iPSC by delivering reprogramming factors in a single polycistronic lentiviral vector (co-expressing four transcription factors, Oct 4, Sox2, Klf4, and Myc). iPSC were differentiated to epithelial cells by a three-step process using noggin, basic fibroblast growth factor (bFGF), bone morphogenetic protein 4 (BMP4) and Wnt-3. At various time points, the cells/clones were immunocytochemically analyzed for epithelial cell markers (Connexin-43 and E-cadherin), mesenchymal cell markers (Alpha-smooth muscle actin), stem cell markers (Sox1, Oct4, SSEA4 and Tra60) and lens-specific epithelial cell markers (αA- and βA3/A1-crystallins).

By increasing the number of genetic transductions, the time needed for generating iPSC from lens mesenchymal cells was reduced, successfully reprogrammed epithelial/mesenchymal cells into iPSC, and retransformed iPSC into lens epithelial cells by the growth factors’ treatment. The epithelial cells could serve as a model system to elucidate regulatory factors involved during EMT to therapeutically stop it.

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By increasing the number of genetic transductions, reduced the time needed for generating iPSC from lens mesenchymal cells.

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We successfully reprogrammed iPSC, and also differentiated iPSC into lens epithelial cells by the growth factors.

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Our model could elucidate regulatory factors involved in epithelial mesenchymal transition to therapeutically stop it.

Effect of EDTA-treated dentin on the differentiation of mouse iPS cells into osteogenic/odontogenic lineages in vitro and in vivo

To investigate the effect of EDTA-treated dentin on the differentiation of mouse induced pluripotent stem (iPS) cells. Dentin discs were prepared from bovine incisors and treated with 17% EDTA. Embryoid bodies (EBs) formed from mouse iPS cells were seeded on the dentin discs for the experiment. The roughness of the EDTA-treated dentin surface, Sa and Sdr, was higher and collagen fibrillike structures were observed by the scanning electron microscopy (SEM) in vitro. In RT-PCR, the mRNA levels of the osteoblast markers Bsp and Ocn were significantly higher in the experimental group. Expression of the DMP1, DSP, and BSP proteins were more notable in the experimental group by immunofluorescence (ICF) study. In vivo study, cartilage and bone-like tissue were observed adjacent to the EDTA-treated dentin. The study demonstrates that the dentin treated with 17% EDTA induces mouse iPS cells to differentiate into the osteo/odontogenesis.

N-acetylcysteine attenuates PM2.5-induced apoptosis by ROS-mediated Nrf2 pathway in human embryonic stem cells

While the effects of fine particulate matter (PM_2.5) on embryonic toxicity are widely accepted, its exact mechanisms have not yet been fully elucidated, which partially attribute to lack of ideal research model. Embryonic stem cells (ESCs) have the capacity to differentiate into all cell types of three germ layers. Thus, they are ideal resources for the reproductive toxicity assessment in vitro. In the present study, we investigated the effects of PM_2.5 exposure on the oxidative stress and apoptosis of human ESCs (hESCs) and its possible mechanism. Our results showed that strong cytotoxicity high reactive oxygen species (ROS) level and fragmentation of nuclei were observed in the PM_2.5-treated hESCs. Meanwhile, up-regulation of apoptosis as well as down-regulation of Nrf2 signaling pathway were also observed after PM_2.5 treatment. However, we did not detect significant expression change or phosphorylation of Akt and Erk in PM_2.5-treated hESCs. Interestingly, scavenging of PM_2.5-induced ROS by N-acetylcysteine (NAC) could block cell apoptosis and rescue the activity of Nrf2 signaling pathway. In conclusion, we demonstrate that PM_2.5 is toxic to hESCs by inhibition of ROS-mediated Nrf2 pathway activity. Our findings suggest activation of Nrf2 pathway will help develop new strategies for the prevention and treatment of PM_2.5-associated disease.

Amniotic cells share clusters of differentiation of fibroblasts and keratinocytes, influencing their ability to proliferate and aid in wound healing while impairing their angiogenesis capability

An alternative to cultured skin cell grafts usage in burn treatment is the graft of allogenic stem cells. We verified whether amniotic stem cells are better than the present therapeutic standard: grafts of autologous keratinocytes and fibroblasts along with autologous adipose-derived stem cells, and whether amniotic stem cells can support the growth of autologous keratinocytes and fibroblasts in the culture. The study was performed on the material from 18 amnia. Skin cells were obtained from 3 patients. In order to assess the influence of stem cells on keratinocytes and fibroblasts, the following experiments were performed: impact on viability and cell cycle, wound healing capability, angiogenesis capability, influence on the proliferation speed and capability to differentiate into skin cells. We demonstrated that human amniotic membrane-derived mesenchymal stem cells (hAMMSCs) share amniotic proteins with skin cells. Amniotic stem cells may replace skin fibroblasts in grafts due to the close similarity in their surface antigens, with significantly larger proliferative potential and ability to stimulate wound healing. It was shown that adding amniotic cells to both keratinocytes and fibroblast cultures accelerates directional migration by ≥ 40%. We confirmed in this study the influence of amniotic cells on the proliferation and cell cycle of fibroblasts and keratinocytes. Amniotic stem cells can be successfully used not only as a first choice graft but also to replace 3T3 line cells, supporting the proliferation of the cells during the culturing, as well as a supplementary graft supporting an autologous graft of keratinocytes and fibroblasts.

Identification of endogenous migratory MSC-like cells and their interaction with the implant materials guiding osteochondral defect repair

Abundant BMSCs and MSC-like cells move up to the defect area and interact with the implant materials, guiding the osteochondral defect repair.

Heterostructured Silk-Nanofiber-Reduced Graphene Oxide Composite Scaffold for SH-SY5Y Cell Alignment and Differentiation

Stem cell therapy is promising for treating traumatic injuries of the central nervous system, where a major challenge is to effectively differentiate neural stem cells into neurons with uniaxial alignment. Recently, controlling stem cell fate by modulating biophysical cues (e.g., stiffness, conductivity, and patterns) has emerged as an attractive approach. Herein, we report a new heterostructure composite scaffold to induce cell-oriented growth and enhance the neuronal differentiation of SH-SY5Y cells. The scaffold is composed of aligned electrospinning silk nanofibers coated on reduced graphene paper with high conductivity and good biocompatibility. Our experimental results demonstrate that the composite scaffold can effectively induce the oriented growth and enhance neuronal differentiation of SH-SY5Y cells. Our study develops a novel scaffold for enhancing the differentiation of SH-SY5Y cells into neurons, which holds great potential in the treatment of neurological diseases and injuries.

Osteogenic Potential of Graphene in Bone Tissue Engineering Scaffolds

Scaffolds are physical substrates for cell attachments, proliferation, and differentiation, ultimately leading to tissue regeneration. Current literature validates tissue engineering as an emerging tool for bone regeneration. Three-dimensionally printed natural and synthetic biomaterials have been traditionally used for tissue engineering. In recent times, graphene and its derivatives are potentially employed for constructing bone tissue engineering scaffolds because of their osteogenic and regenerative properties. Graphene is a synthetic atomic layer of graphite with SP2 bonded carbon atoms that are arranged in a honeycomb lattice structure. Graphene can be combined with natural and synthetic biomaterials to enhance the osteogenic potential and mechanical strength of tissue engineering scaffolds. The objective of this review is to focus on the most recent studies that attempted to explore the salient features of graphene and its derivatives. Perhaps, a thorough understanding of the material science can potentiate researchers to use this novel substitute to enhance the osteogenic and biological properties of scaffold materials that are routinely used for bone tissue engineering.

Harnessing Nanotopography to Enhance Osseointegration of Clinical Orthopedic Titanium Implants-An in Vitro and in Vivo Analysis

Despite technological advancements, further innovations in the field of orthopedics and bone regeneration are essential to meet the rising demands of an increasing aging population and associated issues of disease, injury and trauma. Nanotopography provides new opportunities for novel implant surface modifications and promises to deliver further improvements in implant performance. However, the technical complexities of nanotopography fabrication and surface analysis have precluded identification of the optimal surface features to trigger osteogenesis. We herein detail the osteoinductive potential of discrete nanodot and nanowire nanotopographies. We have examined the ability of modified titanium and titanium alloy (Ti64) surfaces to induce bone-specific gene activation and extracellular matrix protein expression in human skeletal stem cells (SSCs) in vitro, and de novo osteogenic response within a murine calvarial model in vivo. This study provides evidence of enhanced osteogenic response to nanowires 300 surface modifications, with important implications for clinical orthopedic application.

Nanomechanical Force Mapping of Restricted Cell-To-Cell Collisions Oscillating between Contraction and Relaxation

Contact-mediated cell migration strongly determines the invasiveness of the corresponding cells, collective migration, and morphogenesis. The quantitative study of cellular response upon contact relies on cell-to-cell collision, which rarely occurs in conventional cell culture. Herein, we developed a strategy to activate a robust cell-to-cell collision within smooth muscle cell pairs. Nanomechanical traction force mapping reveals that the collision process is promoted by the oscillatory modulations between contraction and relaxation and orientated by the filopodial bridge composed of nanosized contractile machinery. This strategy can enhance the occurrence of cell-to-cell collision, which renders it advantageous over traditional methods that utilize micropatterned coating to confine cell pairs. Furthermore, modulation of the balance between cell tugging force and traction force can determine the repolarization of cells and thus the direction of cell migration. Overall, our approach could help to reveal the mechanistic contribution in cell motility and provide insights in tissue engineering.

The role of nanomaterials in cell delivery systems

In more than one decade, cell transplantation has created an important strategy to treat a wide variety of diseases characterized by tissue and cell dysfunctions. In this course of action, cell delivery to target site has been always one of the most important constraints and complications, as only a small proportion of the cells are housed in the target sites. Nanotechnology and nanoscale biomaterials have been helpful for cell transplantation in various fields of regenerative medicine including diagnosis, delivery systems for the cell, drug or gene, and cells protection system. In this study, the basic concepts and recently studied aspects of cell delivery systems based on nanoscale biomaterials for transplantation and clinical applications are highlighted. Nanomaterials may be used in combination with cell therapy to control the release of drugs or special factors of engineered cells after transplantation.

Delayed Mesoderm and Erythroid Differentiation of Murine Embryonic Stem Cells in the Absence of the Transcriptional Regulator FUBP1

The transcriptional regulator far upstream binding protein 1 (FUBP1) is essential for fetal and adult hematopoietic stem cell (HSC) self-renewal, and the constitutive absence of FUBP1 activity during early development leads to embryonic lethality in homozygous mutant mice. To investigate the role of FUBP1 in murine embryonic stem cells (ESCs) and in particular during differentiation into hematopoietic lineages, we generated Fubp1 knockout (KO) ESC clones using CRISPR/Cas9 technology. Although FUBP1 is expressed in undifferentiated ESCs and during spontaneous differentiation following aggregation into embryoid bodies (EBs), absence of FUBP1 did not affect ESC maintenance. Interestingly, we observed a delayed differentiation of FUBP1-deficient ESCs into the mesoderm germ layer, as indicated by impaired expression of several mesoderm markers including Brachyury at an early time point of ESC differentiation upon aggregation to EBs. Coculture experiments with OP9 cells in the presence of erythropoietin revealed a diminished differentiation capacity of Fubp1 KO ESCs into the erythroid lineage. Our data showed that FUBP1 is important for the onset of mesoderm differentiation and maturation of hematopoietic progenitor cells into the erythroid lineage, a finding that is supported by the phenotype of FUBP1-deficient mice.

Peptide-Coated Semiconductor Polymer Dots for Stem Cells Labeling and Tracking

Stem cell therapy is rapidly moving toward translation to clinical application. To elucidate the therapeutic effect, a robust method that allows tracking of the stem cells over an extended period of time is required. Herein, semiconducting polymer dots (Pdots) are demonstrated for their use in bright labeling and tracking of human mesenchymal stem cells (MSCs) in vitro and in vivo. The Pdots coated with a cell-penetrating peptide (R8) showed remarkable endocytic uptake efficiency that was 15 times higher than that of carboxyl Pdots and more than 200 times than that of bare Pdots. The Pdot-labeled MSCs can be traced for 15 generations in vitro and tracked over 2 weeks in vivo after subcutaneous transplantation. The labeled MSCs administered through the tail vein were preferentially accumulated in the lung; this was distinctive from the distribution of free Pdots, which were primarily distributed in the liver. Based on the properties of bright labeling, excellent tracking capability, and great biocompatibility, the Pdots will be valuable in the applications of stem cell biology and regenerative medicine.

The scaffold microenvironment for stem cell based bone tissue engineering

Bone tissue engineering uses the principles and methods of engineering and life sciences to study bone structure, function and growth mechanism for the purposes of repairing, maintaining and improving damaged bone tissue.

Recent progress in nanotechnology for stem cell differentiation, labeling, tracking and therapy

Nanotechnology advancements for stem cell differentiation, labeling, tracking and therapeutic applications in cardiac repair, bone, and liver regeneration are delineated.

The Multifaceted Roles of Primary Cilia in the Regulation of Stem Cell Properties and Functions

Stem cells are a unique class of cells that are capable of self-renewal and differentiation into multiple lineages. An increasing number of studies have suggested that both embryonic and adult stem cells possess primary cilia, antenna-like structures protruding from cell surfaces that are critical for sensing and transducing environmental cues. The primary cilium appears to regulate stem cells in multiple aspects, such as lineage specification and stemness maintenance. Understanding the role of primary cilia in the control of stem cell behavior could lead to the identification of new targets for regenerative therapies. Here, we discuss recent studies investigating the diverse roles of primary cilia in the regulation of stem cell properties and functions. We also propose potential new avenues for exploration in this promising field. J. Cell. Physiol. 232: 935-938, 2017. © 2016 Wiley Periodicals, Inc.

Stem Cell Differentiation Toward the Myogenic Lineage for Muscle Tissue Regeneration: A Focus on Muscular Dystrophy

Skeletal muscle tissue engineering is one of the important ways for regenerating functionally defective muscles. Among the myopathies, the Duchenne muscular dystrophy (DMD) is a progressive disease due to mutations of the dystrophin gene leading to progressive myofiber degeneration with severe symptoms. Although current therapies in muscular dystrophy are still very challenging, important progress has been made in materials science and in cellular technologies with the use of stem cells. It is therefore useful to review these advances and the results obtained in a clinical point of view. This article focuses on the differentiation of stem cells into myoblasts, and their application in muscular dystrophy. After an overview of the different stem cells that can be induced to differentiate into the myogenic lineage, we introduce scaffolding materials used for muscular tissue engineering. We then described some widely used methods to differentiate different types of stem cell into myoblasts. We highlight recent insights obtained in therapies for muscular dystrophy. Finally, we conclude with a discussion on stem cell technology. We discussed in parallel the benefits brought by the evolution of the materials and by the expansion of cell sources which can differentiate into myoblasts. We also discussed on future challenges for clinical applications and how to accelerate the translation from the research to the clinic in the frame of DMD.

Novel Strategies for the Improvement of Stem Cells' Transplantation in Degenerative Retinal Diseases

Currently, there is no cure for the permanent vision loss caused by degenerative retinal diseases. One of the novel therapeutic strategies aims at the development of stem cells (SCs) based neuroprotective and regenerative medicine. The main sources of SCs for the treatment of retinal diseases are the embryo, the bone marrow, the region of neuronal genesis, and the eye. The success of transplantation depends on the origin of cells, the route of administration, the local microenvironment, and the proper combinative formula of growth factors. The feasibility of SCs based therapies for degenerative retinal diseases was proved in the preclinical setting. However, their translation into the clinical realm is limited by various factors: the immunogenicity of the cells, the stability of the cell phenotype, the predilection of SCs to form tumors in situ, the abnormality of the microenvironment, and the association of a synaptic rewiring. To improve SCs based therapies, nanotechnology offers a smart delivery system for biomolecules, such as growth factors for SCs implantation and differentiation into retinal progenitors. This review explores the main advances in the field of retinal transplantology and applications of nanotechnology in the treatment of retinal diseases, discusses the challenges, and suggests new therapeutic approaches in retinal transplantation.

Graphene induces spontaneous cardiac differentiation in embryoid bodies

Graphene was embedded into the structure of mouse embryoid bodies (EBs) using the hanging drop technique. The inclusion of 0.2 mg per mL graphene in the EBs did not affect the viability of the stem cells. However, the graphene decreased the stem cell proliferation, probably by accelerating cell differentiation. The graphene also enhanced the mechanical properties and electrical conductivity of the EBs. Interestingly, the cardiac differentiation of the EB-graphene was significantly greater than that of the EBs at day 5 of culture, as confirmed by high-throughput gene analysis. Electrical stimulation (voltage, 4 V; frequency, 1 Hz; and duration, 10 ms for 2 continuous days) further enhanced the cardiac differentiation of the EBs, as demonstrated by analyses of the cardiac protein and gene expression and the beating activity of the EBs. Taken together, the results demonstrated that graphene played a major role in directing the cardiac differentiation of EBs, which has potential cell therapy and tissue regeneration applications.

Cytokine loaded layer-by-layer ultrathin matrices to deliver single dermal papilla cells for spot-by-spot hair follicle regeneration

Polymer nanocoated dermal papilla cells promoting hair regeneration.

Application of biomaterials to in vitro pluripotent stem cell disease modeling of the skeletal system

Disease-specific pluripotent stem cells can be derived through genetic manipulation of embryonic stem cells or by reprogramming somatic cells (induced pluripotent stem cells).

Titanium nanotubes induce osteogenic differentiation through the FAK/RhoA/YAP cascade

TNT topography restricts cell spreading, impairs the FAK recruitment in FAs, and thereby attenuates RhoA activity as well as cytoskeleton formation, which in turn expels YAP from that cell nucleus to the cytoplasm and initiates osteodifferentiation.

Smart Polymeric Nanoparticles as Emerging Tools for Imaging--The Parallel Evolution of Materials

The field of imaging has developed considerably over the past decade and recent advances in the area of nanotechnology, in particular nanomaterials, have opened new opportunities. Polymeric nanoparticles are particularly interesting and a number of novel materials, characterized by stimuli-responsive characteristics and fluorescent tagging, have allowed visualization, intracellular labeling and real-time tracking. In some of the latest applications the nanoparticles have been used for imagining of tumor cells, both in vivo and ex vivo.

Engineering nanoscale stem cell niche: direct stem cell behavior at cell-matrix interface

Biophysical cues on the extracellular matrix (ECM) have proven to be significant regulators of stem cell behavior and evolution. Understanding the interplay of these cells and their extracellular microenvironment is critical to future tissue engineering and regenerative medicine, both of which require a means of controlled differentiation. Research suggests that nanotopography, which mimics the local, nanoscale, topographic cues within the stem cell niche, could be a way to achieve large-scale proliferation and control of stem cells in vitro. This Progress Report reviews the history and contemporary advancements of this technology, and pays special attention to nanotopographic fabrication methods and the effect of different nanoscale patterns on stem cell response. Finally, it outlines potential intracellular mechanisms behind this response.

Fluorescence Quenching of CdSe/ZnS Quantum Dots by Using Black Hole Quencher Molecules Intermediated With Peptide for Biosensing Application

Quantum dots (QDs) have recently been investigated as fluorescent probes for detecting a very small number of biomolecules and live cells; however, the establishment of molecular imaging technology with on-off control of QD fluorescence remains to be established. Here we have achieved the fluorescence off state of QDs with the conjugation of black hole quencher (BHQ) molecules intermediated with peptide by using streptavidin-QDs585 and biotin-pep-BHQ-1. The fluorescence of streptavidin-QDs585 was decreased by the addition of biotin-pep-BHQ-1 in a dose-dependent manner. It has been suggested that the decrease in QDs585 fluorescence occurred through a Förster resonance energy transfer (FRET) mechanism from the analysis of fluorescence intensity and lifetime of streptavidin-QDs585 and QDs585-pep-BHQ-1. QDs585 fluorescence could be quenched by more than 60% efficiency in this system. The sequence of intermediate peptide (pep) was GPLGVRGK, which can be cleaved by matrix metalloproteinases (MMPs) produced by cancer cells. QDs585-pep-BHQ-1 is thus expected to detect the MMP production by the recovery of QDs585 fluorescence as a new bioanalytical agent for molecular imaging.

Adult Stem Cell Responses to Nanostimuli

Adult or mesenchymal stem cells (MSCs) have been found in different tissues in the body, residing in stem cell microenvironments called "stem cell niches". They play different roles but their main activity is to maintain tissue homeostasis and repair throughout the lifetime of an organism. Their ability to differentiate into different cell types makes them an ideal tool to study tissue development and to use them in cell-based therapies. This differentiation process is subject to both internal and external forces at the nanoscale level and this response of stem cells to nanostimuli is the focus of this review.

Graphene-Based Materials in Regenerative Medicine

Graphene possesses many unique properties such as two-dimensional planar structure, super conductivity, chemical and mechanical stability, large surface area, and good biocompatibility. In the past few years, graphene-based materials have risen as a shining star on the path of researchers seeking new materials for future regenerative medicine. Herein, the recent research advances made in graphene-based materials mostly utilizing the mechanical and electrical properties of graphene are described. The most exciting findings addressing the impact of graphene-based materials on regenerative medicine are highlighted, with particular emphasis on their applications including nerve, bone, cartilage, skeletal muscle, cardiac, skin, adipose tissue regeneration, and their effects on the induced pluripotent stem cells. Future perspectives and emerging challenges are also addressed in this Review article.