Adult Stem Cells Research Articles

The pioneer factor SOX9 competes for epigenetic factors to switch stem cell fates

During development, progenitors simultaneously activate one lineage while silencing another, a feature highly regulated in adult stem cells but derailed in cancers. Equipped to bind cognate motifs in closed chromatin, pioneer factors operate at these crossroads, but how they perform fate switching remains elusive. Here we tackle this question with SOX9, a master regulator that diverts embryonic epidermal stem cells (EpdSCs) into becoming hair follicle stem cells. By engineering mice to re-activate SOX9 in adult EpdSCs, we trigger fate switching. Combining epigenetic, proteomic and functional analyses, we interrogate the ensuing chromatin and transcriptional dynamics, slowed temporally by the mature EpdSC niche microenvironment. We show that as SOX9 binds and opens key hair follicle enhancers de novo in EpdSCs, it simultaneously recruits co-factors away from epidermal enhancers, which are silenced. Unhinged from its normal regulation, sustained SOX9 subsequently activates oncogenic transcriptional regulators that chart the path to cancers typified by constitutive SOX9 expression.

Management of Rheumatoid Arthritis: Possibilities and Challenges of Mesenchymal Stromal/Stem Cell-Based Therapies.

Rheumatoid arthritis (RA) is a highly prevalent, chronic, and progressive autoimmune disorder primarily affecting joints and muscles. The associated inflammation, pain, and motor restriction negatively impact patient quality of life (QOL) and can even contribute to premature mortality. Further, conventional treatments such as antiinflammatory drugs are only symptomatic. Substantial progress has been made on elucidating the etiopathology of overt RA, in particular the contributions of innate and adaptive immune system dysfunction to chronic inflammation. Although the precise mechanisms underlying onset and progression remain elusive, the discovery of new drug targets, early diagnosis, and new targeted treatments have greatly improved the prognosis and QOL of patients with RA. However, a sizable proportion of patients develop severe adverse effects, exhibit poor responses, or cannot tolerate long-term use of these drugs, necessitating more effective and safer therapeutic alternatives. Mounting preclinical and clinical evidence suggests that the transplantation of multipotent adult stem cells such as mesenchymal stromal/stem cells is a safe and effective treatment strategy for controlling chronic inflammation and promoting tissue regeneration in patients with intractable diseases, including RA. This review describes the current status of MSC-based therapies for RA as well as the opportunities and challenges to broader clinical application.

Genome-Wide Association Study Identifies 4 Novel Risk Loci for Small Intestinal Neuroendocrine Tumors Including a Missense Mutation in LGR5

Small intestinal neuroendocrine tumor (SI-NET) is a rare disease, but its incidence has increased over the past 4 decades. Understanding the genetic risk factors underlying SI-NETs can help in disease prevention and may provide clinically beneficial markers for diagnosis. Here the results of the largest genome-wide association study of SI-NETs performed to date with 405 cases and 614,666 controls are reported. Samples from 307 patients with SI-NETs and 287,137 controls in the FinnGen study were used for the identification of SI-NET risk-associated genetic variants. The results were also meta-analyzed with summary statistics from the UK Biobank (n= 98 patients with SI-NET and n= 327,529 controls). We identified 6 genome-wide significant (P < 5× 10-8) loci associated with SI-NET risk, of which 4 (near SEMA6A, LGR5, CDKAL1, and FERMT2) are novel and 2 (near LTA4H-ELK and in KIF16B) have been reported previously. Interestingly, the top hit (rs200138614; P= 1.80× 10-19) was a missense variant (p.Cys712Phe) in the LGR5 gene, a bona-fide marker of adult intestinal stem cells and a potentiator of canonical WNT signaling. The association was validated in an independent Finnish collection of 70 patients with SI-NETs, as well as in the UK Biobank exome sequence data (n= 92 cases and n= 392,814 controls). Overexpression of LGR5 p.Cys712Phe in intestinal organoids abolished the ability of R-Spondin1 to support organoid growth, indicating that the mutation perturbed R-Spondin-LGR5 signaling. Our study is the largest genome-wide association study to date on SI-NETs and reported 4 new associated genome-wide association study loci, including a novel missense mutation (rs200138614, p.Cys712Phe) in LGR5, a canonical marker of adult intestinal stem cells.

An organoid-based CRISPR-Cas9 screen for regulators of intestinal epithelial maturation and cell fate

Generation of functionally mature organs requires exquisite control of transcriptional programs governing cell state transitions during development. Despite advances in understanding the behavior of adult intestinal stem cells and their progeny, the transcriptional regulators that control the emergence of the mature intestinal phenotype remain largely unknown. Using mouse fetal and adult small intestinal organoids, we uncover transcriptional differences between the fetal and adult state and identify rare adult-like cells present in fetal organoids. This suggests that fetal organoids have an inherent potential to mature, which is locked by a regulatory program. By implementing a CRISPR-Cas9 screen targeting transcriptional regulators expressed in fetal organoids, we establish Smarca4 and Smarcc1 as important factors safeguarding the immature progenitor state. Our approach demonstrates the utility of organoid models in the identification of factors regulating cell fate and state transitions during tissue maturation and reveals that SMARCA4 and SMARCC1 prevent precocious differentiation during intestinal development.

Hyperbaric oxygen treatment increases intestinal stem cell proliferation through the mTORC1/S6K1 signaling pathway in Mus musculus

BackgroundHyperbaric oxygen treatment (HBOT) has been reported to modulate the proliferation of neural and mesenchymal stem cell populations, but the molecular mechanisms underlying these effects are not completely understood. In this study, we aimed to assess HBOT somatic stem cell modulation by evaluating the role of the mTOR complex 1 (mTORC1), a key regulator of cell metabolism whose activity is modified depending on oxygen levels, as a potential mediator of HBOT in murine intestinal stem cells (ISCs).ResultsWe discovered that acute HBOT synchronously increases the proliferation of ISCs without affecting the animal’s oxidative metabolism through activation of the mTORC1/S6K1 axis. mTORC1 inhibition by rapamycin administration for 20 days also increases ISCs proliferation, generating a paradoxical response in mice intestines, and has been proposed to mimic a partial starvation state. Interestingly, the combination of HBOT and rapamycin does not have a synergic effect, possibly due to their differential impact on the mTORC1/S6K1 axis.ConclusionsHBOT can induce an increase in ISCs proliferation along with other cell populations within the crypt through mTORC1/S6K1 modulation without altering the oxidative metabolism of the animal’s small intestine. These results shed light on the molecular mechanisms underlying HBOT therapeutic action, laying the groundwork for future studies.

Ex vivo adult stem cell characterization from multiple muscles in ambulatory children with cerebral palsy during early development of contractures

Cerebral palsy (CP) is one of the most common conditions leading to lifelong childhood physical disability. Literature reported previously altered muscle properties such as lower number of satellite cells (SCs), with altered fusion capacity. However, these observations highly vary among studies, possibly due to heterogeneity in patient population, lack of appropriate control data, methodology and different assessed muscle.In this study we aimed to strengthen previous observations and to understand the heterogeneity of CP muscle pathology. Myogenic differentiation of SCs from the Medial Gastrocnemius (MG) muscle of patients with CP (n = 16, 3–9 years old) showed higher fusion capacity compared to age-matched typically developing children (TD, n = 13). Furthermore, we uniquely assessed cells of two different lower limb muscles and showed a decreased myogenic potency in cells from the Semitendinosus (ST) compared to the MG (TD: n = 3, CP: n = 6). Longitudinal assessments, one year after the first botulinum toxin treatment, showed slightly reduced SC representations and lower fusion capacity (n = 4). Finally, we proved the robustness of our data, by assessing in parallel the myogenic capacity of two samples from the same TD muscle.In conclusion, these data confirmed previous findings of increased SC fusion capacity from MG muscle of young patients with CP compared to age-matched TD. Further elaboration is reported on potential factors contributing to heterogeneity, such as assessed muscle, CP progression and reliability of primary outcome parameters.

Consequences of HIV infection in the bone marrow niche.

Dysregulation of the bone marrow niche resulting from the direct and indirect effects of HIV infection contributes to haematological abnormalities observed in HIV patients. The bone marrow niche is a complex, multicellular environment which functions primarily in the maintenance of haematopoietic stem/progenitor cells (HSPCs). These adult stem cells are responsible for replacing blood and immune cells over the course of a lifetime. Cells of the bone marrow niche support HSPCs and help to orchestrate the quiescence, self-renewal and differentiation of HSPCs through chemical and molecular signals and cell-cell interactions. This narrative review discusses the HIV-associated dysregulation of the bone marrow niche, as well as the susceptibility of HSPCs to infection by HIV.

Fundamentals of Skin Bioimpedances.

The bioimpedances of tissues beyond the stratum corneum, which is the outermost layer of skin, contain crucial clinical information. Nevertheless, bioimpedance measurements of both the viable skin and the adipose tissue, though easy and innocuous, are not widely used, mainly because of the complex multi-layered skin structure and of the electrically insulating nature of the stratum corneum. Here, first, we establish a theoretical framework for analyzing the impedances of multi-layered tissues and apply it to skin. Afterwards, we determine strategies for the system-level design of electrodes and electronics which minimize 4-wire (or tetrapolar) measurement errors even in presence of a top insulating tissue, thus enabling non-invasive characterizations of tissues beyond the stratum corneum. As an example, we demonstrate non-invasive measurements of bioimpedances of living tissues which are beyond orders-of-magnitude (e.g., up to 350 times) higher stratum corneum impedances independently on extreme variations of the barrier (tape stripping) or of the skin-electrodes contact impedances (sweat). Our results can advance the development of bioimpedance systems enabling the characterization of viable skin and adipose tissues for several applications, including transdermal drug delivery and the assessment of skin cancer, obesity, dehydration, type 2 diabetes mellitus, cardiovascular risk and multipotent adult stem cells. This article is protected by copyright. All rights reserved.

Body fluid-derived stem cells - an untapped stem cell source in genitourinary regeneration.

Somatic stem cells have been obtained from solid organs and tissues, including the bone marrow, placenta, corneal stroma, periosteum, adipose tissue, dental pulp and skeletal muscle. These solid tissue-derived stem cells are often used for tissue repair, disease modelling and new drug development. In the past two decades, stem cells have also been identified in various body fluids, including urine, peripheral blood, umbilical cord blood, amniotic fluid, synovial fluid, breastmilk and menstrual blood. These body fluid-derived stem cells (BFSCs) have stemness properties comparable to those of other adult stem cells and, similarly to tissue-derived stem cells, show cell surface markers, multi-differentiation potential and immunomodulatory effects. However, BFSCs are more easily accessible through non-invasive or minimally invasive approaches than solid tissue-derived stem cells and can be isolated without enzymatic tissue digestion. Additionally, BFSCs have shown good versatility in repairing genitourinary abnormalities in preclinical models through direct differentiation or paracrine mechanisms such as pro-angiogenic, anti-apoptotic, antifibrotic, anti-oxidant and anti-inflammatory effects. However, optimization of protocols is needed to improve the efficacy and safety of BFSC therapy before therapeutic translation.

Ginsenosides on stem cells fate specification-a novel perspective.

Recent studies have demonstrated that stem cells have attracted much attention due to their special abilities of proliferation, differentiation and self-renewal, and are of great significance in regenerative medicine and anti-aging research. Hence, finding natural medicines that intervene the fate specification of stem cells has become a priority. Ginsenosides, the key components of natural botanical ginseng, have been extensively studied for versatile effects, such as regulating stem cells function and resisting aging. This review aims to summarize recent progression regarding the impact of ginsenosides on the behavior of adult stem cells, particularly from the perspective of proliferation, differentiation and self-renewal.

Dental Pulp-Derived Mesenchymal Stem Cells Increase Axon Numbers in Mental Nerve Repair.

The mental nerve, the extended part of the inferior alveolar nerve, is often injured during dentoalveolar, orthognathic, or tumor surgery. Numerous therapeutic interventions, including surgery and pharmacotherapy, have been used to enhance the recovery of nerve injuries. Dental pulp stem cells (DPSCs) represent an easily accessible source of adult stem cells that can be isolated from the pulp of extracted teeth. This study evaluated the effect of DPSCs on the regeneration of the mental nerve injury model of rabbits. In this presented study, DPSCs were cultured and cell characterizations were performed by using flow cytometry and immunostainings. Bilateral mental nerve injury models of rabbits were created. In the control group (n = 10), saline was applied, and in the study group (n = 10), 2 × 106 DPSCs were applied to the repaired nerve areas. After 3 weeks, animals were killed and histological examination was obtained by using Masson's trichrome staining. An unpaired Student's t test was used when comparing the groups. Differences were considered to be statistically significant at P values of less than 0.05. The DPSCs demonstrated a homogeneous population of mesenchymal stromal cells which expressed cluster of differentiation CD44, CD73, CD90, and CD105 and lack of CD34, CD45, and HLA-DR. Our finding clearly demonstrated that a lower number of cross-sectioned axons were founded in the control group (60.18 ± 2.52) compared to the study group (72.96 ± 2.43) (p = 0.00). DPSCs promote mental nerve axonal regeneration. These results suggest that DPSCs provide an important accessible source of adult stem cells for mental nerve regeneration.

Organoid cultures for cancer modeling.

Organoids derived from adult stem cells (ASCs) and pluripotent stem cells (PSCs) are important preclinical models for studying cancer and developing therapies. Here, we review primary tissue-derived and PSC-derived cancer organoid models and detail how they have the potential to inform personalized medical approaches in different organ contexts and contribute to the understanding of early carcinogenic steps, cancer genomes, and biology. We also compare the differences between ASC- and PSC-based cancer organoid systems, discuss their limitations, and highlight recent improvements to organoid culture approaches that have helped to make them an even better representation of human tumors.

Use of autologous adipose-derived mesenchymal stem cells for ovarian rejuvenation in poor responder IVF patients: a phase 1 randomized placebo-controlled double-blind crossover study

Background: Despite the application of various methods to augment ovarian responsiveness, the management of poor ovarian responders remains challenging and pregnancy rates following in vitro fertilization are poor. Advances in adult stem cell research and their clinical application has prompted interest in their use in assisted reproduction. We report the first double-blind, randomized, placebo-controlled clinical study using autologous human stromal vascular fraction (SVF) containing adipose-derived stem cells (ADSCs) for ovarian rejuvenation. Materials and methods: Thirty patients were recruited. Twenty-one had lower-than-expected reserves for their age and 9 had premature ovarian insufficiency. Patients were randomized into a placebo group (10) and an intervention group (20). SVF was obtained from adipose tissue following abdominal liposuction; the ADSC component was characterized using flow cytometry. Three equal insertions, adjusted based on ovarian volume, were performed at monthly intervals via an ultrasound-guided transvaginal needle puncture. The SVF was not cultured before transplantation. Those in the placebo group were then crossed over to the intervention group and received a single SVF (maximally concentrated) insertion (crossover group). Results: The median viable SVF cell number inserted per patient over 3 months, and the percentage of mesenchymal stem cells (MSC) thereof, was 1.6×106 and 13.2%, respectively. Resulting anti-Mullerian hormone (AMH) changes were variable over the treatment course with a notable placebo effect. Patients with premature ovarian insufficiency showed no change in AMH, both to intervention and placebo. Despite this, a temporary return of menses was noted in a third of patients while on treatment. Patients with low reserves for age showed an increase in AMH, although not statistically significant when compared to placebo. In the crossover group, insertions were limited to one intervention comprising all cells; here a significantly higher median of 3.4×106 SVF cells were injected containing an average of 16.9% MSCs. No significant change in AMH was noted. To date 12 patients have undergone ovarian stimulation and in vitro fertilization after stem cell therapy; of these 9 have had embryo transfers with a resulting pregnancy rate of 33%. There were also 2 spontaneous pregnancies. Conclusion: Although the application of SVF-derived ADSCs for ovarian rejuvenation remains experimental, the current study provides further support for the safety of this approach and presents encouraging results as to its efficacy in assisted reproduction.

CRISPR gene technology—the next best thing in medicine

CRISPR gene technology—the next best thing in medicine

Cell-autonomous and non-cell-autonomous roles of NKCC1 in regulating neural stem cell quiescence in the hippocampal dentate gyrus.

Quiescence is a hallmark of adult neural stem cells (NSCs) in the mammalian brain, and establishment and maintenance of quiescence is essential for life-long continuous neurogenesis. How NSCs in the dentate gyrus (DG) of the hippocampus acquire their quiescence during early postnatal stages and continuously maintain quiescence in adulthood is poorly understood. Here, we show that Hopx-CreERT2-mediated conditional deletion of Nkcc1, which encodes a chloride importer, in mouse DG NSCs impairs both their quiescence acquisition at early postnatal stages and quiescence maintenance in adulthood. Furthermore, PV-CreERT2-mediated deletion of Nkcc1 in PV interneurons in the adult mouse brain leads to activation of quiescent DG NSCs, resulting in an expanded NSC pool. Consistently, pharmacological inhibition of NKCC1 promotes NSC proliferation in both early postnatal and adult mouse DG. Together, our study reveals both cell-autonomous and non-cell-autonomous roles of NKCC1 in regulating the acquisition and maintenance of NSC quiescence in the mammalian hippocampus.

Stem Cell and Oxidative Stress-Inflammation Cycle.

Under a variety of physical and experimental settings, stem cells are able to self-renew and differentiate into specialized adult cells. MSCs (mesenchymal stromal/stem cells) are multipotent stem cells present in a wide range of fetal, embryonic, and adult tissues. They are the progenitors of a variety of specialized cells and are considered crucial tools in tissue engineering. MSCs, derived from various tissues, including cord blood, placenta, bone marrow, and dental tissues, have been extensively examined in tissue repair, immune modulation, etc. Increasing the vitality of MSCs and restoring cellular mechanisms are important factors in treatment success. Oxidative stress harms cellular molecules such as DNA, proteins, and lipids due to the overproduction of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in cells and tissues or insufficiency of antioxidant systems that can inactivate them. Oxidative stress has a close link with inflammation as a pathophysiological process. ROS can mediate the expression of proinflammatory genes via intracellular signaling pathways and initiate the chronic inflammatory state. At the same time, inflammatory cells secrete a large number of reactive species that cause increased oxidative stress at sites of inflammation. In inflammatory diseases, the differentiation of stem cells and the regenerative and wound healing process can be affected differently by the increase of oxidative stress. Recent studies have indicated that dental pulp stem cells (DPSCs), as a resource of adult stem cells, are an attractive option for cell therapy in diseases such as neurological diseases, diabetes, cardiological diseases, etc., as well as its treatment potential in pulp inflammation. The future of oxidative stressinflammation cycle and/or ageing therapies involves the selective elimination of senescent cells, also known as senolysis, which prevents various age-related diseases. Most pathologies are implicated on the effects of ageing without exerting undesirable side effects.

Cell type-specific role of CBX2 and its disordered region in spermatogenesis.

Polycomb group (PcG) proteins maintain the repressed state of lineage-inappropriate genes and are therefore essential for embryonic development and adult tissue homeostasis. One critical function of PcG complexes is modulating chromatin structure. Canonical Polycomb repressive complex 1 (cPRC1), particularly its component CBX2, can compact chromatin and phase-separate in vitro. These activities are hypothesized to be critical for forming a repressed physical environment in cells. While much has been learned by studying these PcG activities in cell culture models, it is largely unexplored how cPRC1 regulates adult stem cells and their subsequent differentiation in living animals. Here, we show in vivo evidence of a critical nonenzymatic repressive function of cPRC1 component CBX2 in the male germline. CBX2 is up-regulated as spermatogonial stem cells differentiate and is required to repress genes that were active in stem cells. CBX2 forms condensates (similar to previously described Polycomb bodies) that colocalize with target genes bound by CBX2 in differentiating spermatogonia. Single-cell analyses of mosaic Cbx2 mutant testes show that CBX2 is specifically required to produce differentiating A1 spermatogonia. Furthermore, the region of CBX2 responsible for compaction and phase separation is needed for the long-term maintenance of male germ cells in the animal. These results emphasize that the regulation of chromatin structure by CBX2 at a specific stage of spermatogenesis is critical, which distinguishes this from a mechanism that is reliant on histone modification.

Metabolic "Sense Relay" in Stem Cells: A Short But Impactful Life of PAS Kinase Balancing Stem Cell Fates.

Tissue regeneration is a complex molecular and biochemical symphony. Signaling pathways establish the rhythmic proliferation and differentiation cadence of participating cells to repair the damaged tissues and repopulate the tissue-resident stem cells. Sensory proteins form a critical bridge between the environment and cellular response machinery, enabling precise spatiotemporal control of stem cell fate. Of many sensory modules found in proteins from prokaryotes to mammals, Per-Arnt-Sim (PAS) domains are one of the most ancient and found in the most diverse physiological context. In metazoa, PAS domains are found in many transcription factors and ion channels; however, PAS domain-containing Kinase (PASK) is the only metazoan kinase where the PAS sensory domain is connected to a signaling kinase domain. PASK is predominantly expressed in undifferentiated, self-renewing embryonic and adult stem cells, and its expression is rapidly lost upon differentiation, resulting in its nearly complete absence from the adult mammalian tissues. Thus, PASK is expressed within a narrow but critical temporal window when stem cell fate is established. In this review, we discuss the emerging insight into the sensory and signaling functions of PASK as an integrator of metabolic and nutrient signaling information that serves to balance self-renewal and differentiation programs during mammalian tissue regeneration.

STEM CELLS IN REGENERATIVE MEDICINE AND THERAPEUTIC POTENTIAL

Stem cells are a form of undifferentiated cell that has the potential to proliferate (self-renew), emerge from a single cell (clonal), and develop into different types of cells and tissues (potent). There are several sources of stem cells of varied potency.Although stem cell research has grown at an exponential rate, medicinal applications have moved considerably more slowly. The study is currently focused on understanding embryonic, adult, and inducible pluripotent stem cells. Adult stem cell research translation has demonstrated a decisive benefit that is larger than the present standard of care in the field of cardiovascular medicine. The future of stem cell research and therapy will continue to open up new diagnostic, therapeutic, and tissue regeneration pathways.In cellular treatment, stem cells can be employed to repair damaged cells or rebuild tissues. Furthermore, stem cells have advanced our understanding of development as well as disease causation. Cell lines that are particular to a disease can also be grown and employed in medication research.Despite considerable improvements in stem cell biology, ethical concerns about embryonic stem cells, tumour growth, and rejection restrict their applicability. However, several of these constraints are being overcome, which might lead to significant advancements in illness management. This article provides an introduction to the world of stem cells, including its definition, origin, and categorization, as well as their uses in regenerative medicine.

Adenovirus F41 infection and liver cytolysis in adult hematopoietic stem cell transplant recipients.

Human adenoviruses (HAdVs) of the F species are commonly responsible for acute gastroenteritis. A few cases of systemic infections have been described in adults or children who have received a hematopoietic stem cell transplant (HSCT), but with no report of liver cytolysis. Since January 2022, several countries have reported an increase in cases of acute hepatitis of unknown cause in children. Adenovirus species F type 41 (HAdV-F41)infection was predominantly identified. The objective of this study is to describe HAdV-F41 infections diagnosed since January 2022 in adult HSCT recipients in two French hospitals. All four patients had diarrhea and liver cytolysis at the time of diagnosis of infection. HAdV viremia was observed in three patients (#1, #3, and #4), but no disseminated disease was reported. HAdV whole genome sequencing and metagenomics characterization were performed on stool and blood samples. The complete HAdV-F41 genome sequence was obtained for three patients and phylogenetic analysis showed that the strains consisted of similar lineage (2b). We did not identify any new HAdV-F41 strains. Metagenomics analysis found adeno-associated virus 2 and torque-teno virus infection in patient #1 and Epstein-Barr virus in patient #4. This is the first case series reporting liver cytolysis during HAdV-F41 infection in adult HSCT patients.