Stem cells supporting other stem cells

Chigno/CG11180 and SUMO are Chinmo-interacting proteins with a role in Drosophila testes somatic support cells

Stem cells are critical for replenishment of cells lost to death, damage or differentiation. Drosophila testes are a key model system for elucidating mechanisms regulating stem cell maintenance and differentiation. An intriguing gene identified through such studies is the transcription factor, chronologically inappropriate morphogenesis (Chinmo). Chinmo is a downstream effector of the Jak-STAT signaling pathway that acts in testis somatic stem cells to ensure maintenance of male stem cell fate and sexual identity. Defects in these processes can lead to infertility and the formation of germ cell tumors. While Chinmo's effect on testis stem cell behavior has been investigated in detail, there is still much to be learned about its structure, function, and interactions with other proteins. Using a two-hybrid screen, we find that Chinmo interacts with itself, the small ubiquitin-like modifier SUMO, the novel protein CG11180, and four other proteins (CG4318, Ova (ovaries absent), Taf3 (TBP-associated factor 3), and CG18269). Since both Chinmo and CG11180 contain sumoylation sites and SUMO-interacting motifs (SIMs), we analyzed their interaction in more detail. Using site-directed mutagenesis of a unique SIM in CG11180, we demonstrate that Chinmo's interaction with CG11180 is SUMO-dependent. Furthermore, to assess the functional relevance of both SUMO and CG11180, we performed RNAi-mediated knockdown of both proteins in somatic cells of the Drosophila testis. Using this approach, we find that CG11180 and SUMO are required in somatic cells of adult testes, and that reduction of either protein causes formation of germ cell tumors. Overall, our work suggests that SUMO may be involved in the interaction of Chinmo and CG11180 and that these genes are required in somatic cells of the adult Drosophila testis. Consistent with the CG11180 knockdown phenotype in male testes, and to underscore its connection to Chinmo, we propose the name Chigno (Childless Gambino) for CG11180.

The Drosophila histone methyl-transferase SET1 coordinates multiple signaling pathways in regulating male germline stem cell maintenance and differentiation

Many cell types come from tissue-specific adult stem cells that maintain the balance between proliferation and differentiation. Here, we study how the H3K4me3 methyltransferase, Set1, regulates early-stage male germ cell proliferation and differentiation in Drosophila. Early-stage germline-specific knockdown of set1 results in a temporally progressed defects, arising as germ cell loss and developing to overpopulated early-stage germ cells. These germline defects also impact the niche architecture and cyst stem cell lineage in a non-cell-autonomous manner. Additionally, wild-type Set1, but not the catalytically inactive Set1, could rescue the set1 knockdown phenotypes, highlighting the functional importance of the methyl-transferase activity of the Set1 enzyme. Further, RNA-seq experiments reveal key signaling pathway components, such as the JAK-STAT pathway gene stat92E and the BMP pathway gene mad, that are upregulated upon set1 knockdown. Genetic interaction assays support the functional relationships between set1 and JAK-STAT or BMP pathways, as mutations of both the stat92E and mad genes suppress the set1 knockdown phenotypes. These findings enhance our understanding of the balance between proliferation and differentiation in an adult stem cell lineage. The germ cell loss followed by over-proliferation phenotypes when inhibiting a histone methyl-transferase raise concerns about using their inhibitors in cancer therapy.

Differentiation of Human Wharton Jelly Mesenchymal Stem Cells into Germ-Like Cells; emphasis on evaluation of Germ-long non-coding RNAs

BACKGROUND

The proliferation and differentiation of stem cells into Germ-Like Cells (GLCs) is mediated by several growth factors and specific genes, of which some are related to long non-coding RNAs (lncRNAs). We have developed a modified differentiation process and identified a panel of GermlncRNAs related to GLCs.

METHODS

Human Wharton Jelly Mesenchymal Stem Cells were treated with 25 ng/ml Bone Morphogenetic Protein (BMP)-4 and 10^- 5 M all-trans retinoic acid to differentiate them into germ-like cells. To confirm the differentiation, changes in the expression of Oct-4, C-kit, Stella, and Vasa genes were assessed using quantitative Real-Time PCR (qPCR) and immunocytochemistry. QPCR was also used before and after differentiation to evaluate the changes in a lncRNA panel, using a 96-well array. Statistical analysis of the data was performed by SPSS 21.

RESULTS

After 21 days of induction, the HWJ-MSCs derived germ-like cells were formed. Also, qPCR and immunocytochemistry showed that the pluripotent Oct4 marker was expressed in the undifferentiated HWJ-MSCs, but its expression gradually decreased in the differentiated cells. C-kit was expressed on days 7, 14, and 21 of differentiation. Both GLC markers of Stella and Vasa genes/proteins were present only in differentiated cells. Of the 44 lncRNA genes array, 36 of them showed an increase and eight genes showed a decrease.

CONCLUSION

Our study showed that BMP4 and RA are effective in inducing HWJ-MSCs differentiation into GLCs. In addition, our study for the first time showed changes in the lncRNAs expression during the differentiation of HWJ-MSCs into GLCs by using BMP4 and RA.

The Vascular Niche for Adult Cardiac Progenitor Cells

Research on cardiac progenitor cell populations has generated expectations about their potential for cardiac regeneration capacity after acute myocardial infarction and during physiological aging; however, the endogenous capacity of the adult mammalian heart is limited. The modest efficacy of exogenous cell-based treatments can guide the development of new approaches that, alone or in combination, can be applied to boost clinical efficacy. The identification and manipulation of the adult stem cell environment, termed niche, will be critical for providing new evidence on adult stem cell populations and improving stem-cell-based therapies. Here, we review and discuss the state of our understanding of the interaction of adult cardiac progenitor cells with other cardiac cell populations, with a focus on the description of the B-CPC progenitor population (Bmi1+ cardiac progenitor cell), which is a strong candidate progenitor for all main cardiac cell lineages, both in the steady state and after cardiac damage. The set of all interactions should be able to define the vascular cardiac stem cell niche, which is associated with low oxidative stress domains in vasculature, and whose manipulation would offer new hope in the cardiac regeneration field.

Mir-106b Cluster Regulates Primordial Germ Cells Differentiation from Human Mesenchymal Stem Cells

Objective

Numerous evidence indicates that microRNAs (miRNAs) are critical regulators in the spermatogenesis process. The aim of this study was to investigate Mir-106b cluster regulates primordial germ cells (PGCs) differentiation from human mesenchymal stem cells (MSCs).

Materials and Methods

In this experimental study, samples containing male adipose (n: 9 samples- age: 25-40 years) were obtained from cosmetic surgeries performed for the liposuction in Imam Khomeini Hospital. The differentiation of MSCs into PGCs was accomplished by transfection of a lentivector expressing miR-106b. The transfection of miR- 106b was also confirmed by the detection of a clear green fluorescent protein (GFP) signal in MSCs. MSCs were treated with bone morphogenic factor 4 (BMP4) protein, as a putative inducer of PGCs differentiation, to induce the differentiation of MSCs into PGCs (positive control). After 4 days of transfection, the expression of miR-106b, STELLA, and FRAGILIS genes was evaluated by real-time polymerase chain reaction (PCR). Also, the levels of thymocyte differentiation antigen 1 (Thy1) protein was assessed by the western blot analysis. The cell surface expression of CD90 was also determined by immunocytochemistry method. The cytotoxicity of miR-106b was examined in MSCs after 24, 48, and 72 hours using the MTT assay.

Results

MSCs treated with BMP4 or transfected by miR-106b were successfully differentiated into PGCs. The results of this study also showed that the expression of miR-106b was significantly increased after 48 hours from transfection. Also, we showed STELLA, FARGILIS, as well as the protein expression of Thy1, was significantly higher in MSCs transfected by lentivector expressing miR-106b in comparison with MSCs treated with BMP4 (P≤0.05). MTT assay showed miR-106b was no toxic during 72 hours in 1 µg/ml dose, that this amount could elevated germ cells marker significantly higher than other experimental groups (P≤0.05).

Conclusion

According to this findings, it appears that miR-106b plays an essential role in the differentiation of MSCs into PGCs.

Nanocurcumin versus mesenchymal stem cells in ameliorating the deleterious effects in the cadmium-induced testicular injury: A crosstalk between oxidative and apoptotic markers

Cadmium (Cd), a grave occupational pollutant, can result in; testicular damage. This study was designed to distinguish the potential effect of bone marrow-derived mesenchymal stem cells (BM-MSCs) versus that of curcumin nanoemulsion on Cd-induced testicular damage. Fifty adult male Sprague Dawley rats were distributed into five groups; control, sham control, Cd-treated, stem cell-treated and nanocurcumin-treated groups. Histological, immune histochemical; caspase 3 and proliferating cell nuclear antigen (PCNA) and CD 68, testosterone levels, nitric oxide, malondialdehyde (MDA)/glutathione (GSH) superoxide, dismutase (SOD), Western blot; B-cell lymphoma (Bcl-2), BCL2-Associated X Protein (BAX), BAX/Bcl-2 ratio and morphometry were done. Cadmium-treated group showed degenerated, detached seminiferous tubules, vacuolations and wide interstitial spaces containing fluid exudates. The same group revealed increased expression of BAX, BAX/Bcl-2 ratio, caspase 3, CD 68 and increased mean values of MDA, NO. Concomitantly, Cd has significant reduction in PCNA, Bcl-2 and sperm cell count when compared to control group. BM-MSCs- and nanocurcumin-treated groups revealed well-structured tubules and were perceived to expressively enhance the deleterious changes induced by Cd. The injurious changes on the testis induced by Cd were obviously improved when treated with either MSCs or nano-curcumin. BM-MSCs exerted more ameliorative changes.

Spermatogenesis Recovery Potentials after Transplantation of Adipose Tissue-Derived Mesenchymal Stem Cells Cultured with Growth Factors in Experimental Azoospermic Mouse Models

Objective

Approximately 1% of the male population suffers from obstructive or non-obstructive azoospermia. Previous in vitro studies have successfully differentiated mesenchymal stem cells (MSCs) into germ cells. Because of immune- modulating features, safety, and simple isolation, adipose tissue-derived MSCs (AT-MSCs) are good candidates for such studies. However, low availability is the main limitation in using these cells. Different growth factors have been investigated to overcome this issue. In the present study, we aimed to comparatively assess the performance of AT-MSCs cultured under the presence or absence of three different growth factors, epidermal growth factor (EGF), leukemia inhibitory factor (LIF) and glial cell line-derived neurotrophic factor (GDNF), following transplantation in testicular torsion-detorsion mice

Materials and Methods

This was an experimental study in which AT-MSCs were first isolated from male Naval Medical Research Institute (NMRI) mice. Then, the mice underwent testicular torsion-detorsion surgery and received bromodeoxyuridine (BrdU)-labeled AT-MSCs into the lumen of seminiferous tubules. The transplanted cells had been cultured in different conditioned media, containing the three growth factors and without them. The expression of germ cell-specific markers was evaluated with real-time polymerase chain reaction (PCR) and western-blot. Moreover, immunohistochemical staining was used to trace the labeled cells.

Results

The number of transplanted AT-MSCs resided in the basement membrane of seminiferous tubules significantly increased after 8 weeks. The expression levels of Gcnf and Mvh genes in the transplanted testicles by AT-MSCs cultured in the growth factors-supplemented medium was greater than those in the control group (P<0.001 and P<0.05, respectively). The expression levels of the c-Kit and Scp3 genes did not significantly differ from the control group.

Conclusion

Our findings showed that the use of EGF, LIF and GDNF to culture AT-MSCs can be very helpful in terms of MSC survival and localization.

The Dlg Module and Clathrin-Mediated Endocytosis Regulate EGFR Signaling and Cyst Cell-Germline Coordination in the Drosophila Testis

Tissue homeostasis and repair relies on proper communication of stem cells and their differentiating daughters with the local tissue microenvironment. In the Drosophila male germline adult stem cell lineage, germ cells proliferate and progressively differentiate enclosed in supportive somatic cyst cells, forming a small organoid, the functional unit of differentiation. Here we show that cell polarity and vesicle trafficking influence signal transduction in cyst cells, with profound effects on the germ cells they enclose. Our data suggest that the cortical components Dlg, Scrib, Lgl and the clathrin-mediated endocytic (CME) machinery downregulate epidermal growth factor receptor (EGFR) signaling. Knockdown of dlg, scrib, lgl, or CME components in cyst cells resulted in germ cell death, similar to increased signal transduction via the EGFR, while lowering EGFR or downstream signaling components rescued the defects. This work provides insights into how cell polarity and endocytosis cooperate to regulate signal transduction and sculpt developing tissues.

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Dlg, Scrib, Lgl, and clathrin-mediated endocytosis (CME) attenuate EGFR signaling

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Knockdown of Dlg module or CME results in cell non-autonomous germ cell death

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Dlg module and CME control MAPK activation and the levels of the PIP₂ phospholipid

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PIP₂ and its synthesizing kinase Sktl/dPIP5K mediate MAPK activation

Heterochromatin Protein 1 (HP1) inhibits stem cell proliferation induced by ectopic activation of the Jak/STAT pathway in the Drosophila testis

Stem cells can divide asymmetrically with respect to cell fate, producing a copy of themselves (self-renewal), while giving rise to progeny that will differentiate along a specific lineage. Mechanisms that bias the balance towards self-renewal or extend the proliferative capacity of the differentiating progeny can result in tissue overgrowth and, eventually, the formation of tumors. Recent work has explored the role of heterochromatin and heterochromatin-associated proteins in the regulation of stem cell behavior under homeostatic conditions, but less is known about their possible roles in potentiating or suppressing stem cell overproliferation. Here we used ectopic activation of the Jak/STAT pathway in germline and somatic stem cells of the D. melanogaster testis as an in vivo model to probe the function of Heterochromatin Protein 1 (HP1) in stem cell overproliferation. Forced expression of HP1 in either early germ or somatic cells suppressed the overgrowth of testes in response to ectopic Jak/STAT activation. Interestingly, HP1 expression led to distinct phenotypes, depending on whether it was overexpressed in somatic or germ cells, possibly reflecting different cell-autonomous and non-autonomous effects in each cell type. Our results provide a new framework for further in vivo studies aimed at understanding the interactions between heterochromatin and uncontrolled stem cell proliferation, as well as the complex cross-regulatory interactions between the somatic and germline lineages in the Drosophila testis.

Application of induced pluripotent stem cell and embryonic stem cell technology to the study of male infertility

Stem cells (SCs) are classes of undifferentiated biological cells existing only at the embryonic, fetal, and adult stages that can divide to produce specialized cell types during fetal development and remain in our bodies throughout life. The progression of regenerative and reproductive medicine owes the advancement of respective in vitro and in vivo biological science on the stem cell nature under appropriate conditions. The SCs are promising therapeutic tools to treat currently of infertility because of wide sources and high potency to differentiate. Nevertheless, no effective remedies are available to deal with severe infertility due to congenital or gonadotoxic stem cell deficiency in prepubertal childhood. Some recent solutions have been developed to address the severe fertility problems, including in vitro formation of germ cells from stem cells, induction of pluripotency from somatic cells, and production of patient-specific pluripotent stem cells. There is a possibility of fertility restoration using the in vitro formation of germ cells from somatic cells. Accordingly, the present review aimed at studying the literature published on the medical application of stem cells in reproductive concerns.

Inhibition of the Activin Receptor Type-2B Pathway Restores Regenerative Capacity in Satellite Cell-Depleted Skeletal Muscle

Degenerative myopathies typically display a decline in satellite cells coupled with a replacement of muscle fibers by fat and fibrosis. During this pathological remodeling, satellite cells are present at lower numbers and do not display a proper regenerative function. Whether a decline in satellite cells directly contributes to disease progression or is a secondary result is unknown. In order to dissect these processes, we used a genetic model to reduce the satellite cell population by ~70–80% which leads to a nearly complete loss of regenerative potential. We observe that while no overt tissue damage is observed following satellite cell depletion, muscle fibers atrophy accompanied by changes in the stem cell niche cellular composition. Treatment of these mice with an Activin receptor type-2B (AcvR2B) pathway blocker reverses muscle fiber atrophy as expected, but also restores regenerative potential of the remaining satellite cells. These findings demonstrate that in addition to controlling fiber size, the AcvR2B pathway acts to regulate the muscle stem cell niche providing a more favorable environment for muscle regeneration.

Hyperbranched poly(ϵ-lysine) substrate presenting the laminin sequence YIGSR induces the formation of spheroids in adult bone marrow stem cells

Unlike the fibroblast-like cells formed upon monolayer culture of human mesenchymal stem cells, the natural stem cell niche of the bone marrow and other types of tissues favours the formation of 3-dimensional (3D) cell clusters. The structuring and biological activity of these clusters are regulated by the contacts established by cells with both the basement membrane and neighbour cells and results in their asymmetric division and the consequent maintenance of both a stem population and a committed progeny. The present work demonstrates the potential of a synthetic substrate to mimic the stem cell niche in vitro. The side amino groups of a linear Poly-L-lysine were modified with hyperbranched poly-(ϵ-lysine) peptides, named as dendrons, tethered with the laminin-mimicking sequence, YIGSR. These dendrons presented the YIGSR sequence at the uppermost molecular branching ensuring a controlled spacing of the bioligand. When used to coat the surface of tissue culture plates in a serum-free in vitro cell culture system, the substrate was able to mimic the most relevant features of the basement membrane of the stem cell niche, i.e. the mesh structure of Collagen Type IV and the availability of laminin bioligands relevant to integrin biorecognition. The substrate biomimetic properties were tested for their ability to support the formation of human bone marrow mesenchymal stem cells (hMSCs) 3D spheroids similar to those observed in the natural stem cell niches and their ability to maintain stem cell pluripotency markers. These features were related to the substrate-specific expression and localisation of (i) cell adhesion receptors (i.e. β-integrin and N-cadherin), (ii) transcription factors of pluripotency markers and cytoskeleton protein and (iii) regulators of cell migration throughout cell culture passages 2 to 4. The results clearly demonstrate the formation of 3D spheroids starting from the asymmetric division of substrate-adhering spread cells, the clustering of relevant integrins and the expression of specific intracellular pathways controlling cytoskeleton formation suggesting their potential use as a substrate for the handling of stem cells prior to transplantation procedures.

Enhancer of polycomb coordinates multiple signaling pathways to promote both cyst and germline stem cell differentiation in the Drosophila adult testis

Stem cells reside in a particular microenvironment known as a niche. The interaction between extrinsic cues originating from the niche and intrinsic factors in stem cells determines their identity and activity. Maintenance of stem cell identity and stem cell self-renewal are known to be controlled by chromatin factors. Herein, we use the Drosophila adult testis which has two adult stem cell lineages, the germline stem cell (GSC) lineage and the cyst stem cell (CySC) lineage, to study how chromatin factors regulate stem cell differentiation. We find that the chromatin factor Enhancer of Polycomb [E(Pc)] acts in the CySC lineage to negatively control transcription of genes associated with multiple signaling pathways, including JAK-STAT and EGF, to promote cellular differentiation in the CySC lineage. E(Pc) also has a non-cell-autonomous role in regulating GSC lineage differentiation. When E(Pc) is specifically inactivated in the CySC lineage, defects occur in both germ cell differentiation and maintenance of germline identity. Furthermore, compromising Tip60 histone acetyltransferase activity in the CySC lineage recapitulates loss-of-function phenotypes of E(Pc), suggesting that Tip60 and E(Pc) act together, consistent with published biochemical data. In summary, our results demonstrate that E(Pc) plays a central role in coordinating differentiation between the two adult stem cell lineages in Drosophila testes.

Tissue maintenance and repair rely on adult stem cells, which can divide to generate new stem cells as well as cells committed for becoming specific cell types. Stem cell activity needs to be tightly controlled because insufficient or unlimited stem cell division may lead to tissue degeneration or tumorigenesis. This control depends not only on stem cells themselves, but also on the microenvironment where stem cells reside. The chromatin structure of stem cells is crucial to determine their activities. The signaling pathways connecting stem cells with their microenvironment is also important. Here we ask how chromatin factors interact with signaling pathways in determining stem cell activity. We use Drosophila adult testis as a model system, in which two types of stem cells co-exist and interact: germline stem cells and somatic stem cells. We find that a chromatin regulator called Enhancer of Polycomb [E(Pc)] acts in somatic cells to promote germ cell differentiation and maintain germ cell fate. This regulation is mediated by several signaling pathways, such as EGF and JAK-STAT pathways. E(Pc) also works with another chromatin regulator, the histone acetyltransferase Tip60, in somatic cells. Insufficient activity of the E(Pc) homolog in human leads to cancers. Our studies of E(Pc) may help understanding its roles as a tumor suppressor.

Therapeutic Application of Adult Stem Cells in the Heart

Cell therapies have been explored as a potential treatment avenue to treat heart diseases, such as myocardial infarction, doxorubicin-induced cardiomyopathy, and heart failure. Embryonic and adult stem cells (ASCs) have been examined in animal and clinical settings. Unlike embryonic and induced pluripotent stem cells, ASCs do not pose a threat to form teratomas, nor do they have immune system concerns, making them ideal for therapeutic use in humans. In this review, we will investigate different characteristics and sources of adult stem cells and progenitor cells, as well as determine their efficacy in cell transplantation in experimental and clinical trials. In addition, we will propose other research avenues that may promote further understanding and use of ASCs in therapeutic designs.

The Regenerative Effect of Bone Marrow-Derived Stem Cells in Spermatogenesis of Infertile Hamster

BACKGROUND

Infertility is a serious social problem in advanced nations, with male factor in half of all cases of infertility. This study was conducted to determine the regenerative effect of bone marrow-derived stem cells in spermatogenesis of infertile hamster.

METHODS

Twelve adult male hamsters were equally divided into azoospermic and control groups. Busulfan was intraperitoneally used for induction of azoospermia, while the right testis was treated with bone marrow-derived stem cells (10⁶ BM-SCs), labeled with sterile trypan blue, 35 days after busulfan injection. The left testis served as positive control for azoospermia. Sixty days after cell transplantation, the animals were euthanized and both testes were removed and evaluated histologically.

RESULTS

BM-SCs were spindle-shaped, adherent to the culture flasks and had positive expression of CD29 and CD73 and negative expression of CD45. Alcian blue staining confirmed differentiation of BM-SCs into chondrocytes. Karyotyping denoted to stability of chromosomes. Treatment with busulfan in seminiferous tubules resulted into distruption of spermatogenesis. After two months in busulfan treatment group, seminiferous tubular atrophy and germinal epitheliums degenerations were noticed with no spermatozoa in epididymis. After treatment of busulfan group with BM-SCs, spermatogonia, primary spermatocytes, spermatids and sperms were present in seminiferous tubules.

CONCLUSION

As cell transplantation in seminiferous tubules resulted into a rapid repair of pathological changes, BM-SCs can be recommended an effective treatment measure in azoospermia. It seems that more studies are necessary to confirm the use of this technique in treatment of azoospermia and infertility in human.

Histomorphometric evaluation of treatment of rat azoosper-mic seminiferous tubules by allotransplantation of bone marrow-derived mesenchymal stem cells

OBJECTIVES

Bone marrow-derived mesenchymal stem cells (BM-MSCs) potentials make them appropriate for cell therapy including ability of differentiation and release of anti-inflammatory cytokines and growth factors secreta. For treatment of azoospermia to induce proliferation and differentiation of germ cells, MSCs transplantation has been introduced. The aim of the present experimental case-control study was to histomorphometric evaluation of the germinal cells in seminiferous tubules of azoospermic rats before and after BM-MSCs allotransplantation.

MATERIALS AND METHODS

In the present study, BM-MSCs were isolated from six male rats and confirmed. Their testes also served as intact negative controls. The recipient rats (n=6) were received two doses of 10 mg/kg of busulfan with 21 days interval to induce azoospermia. After cessation of spermatogenesis, the rats were allotransplanted with the BM-MSCs into efferent duct of right testes. Thirty-five days later, the right cell-treated testes were compared to left azoospermic ones.

RESULTS

Histomorphometric analyses showed that the seminiferous tubules treated with BM-MSCs had normal morphology in comparison with azoospermic testes, which were without germinal layer. In most BM-MSCs-treated seminiferous tubules, spermatogenesis was observed.

CONCLUSION

The allotransplanted BM-MSCs could induce spermatogenesis in seminiferous tubules of azoospermic rats.

Apontic regulates somatic stem cell numbers in Drosophila testes

BACKGROUND

Microenvironments called niches maintain resident stem cell populations by balancing self-renewal with differentiation, but the genetic regulation of this process is unclear. The niche of the Drosophila testis is well-characterized and genetically tractable, making it ideal for investigating the molecular regulation of stem cell biology. The JAK/STAT pathway, activated by signals from a niche component called the hub, maintains both germline and somatic stem cells.

RESULTS

This study investigated the molecular regulation of the JAK/STAT pathway in the stem cells of the Drosophila testis. We determined that the transcriptional regulator Apontic (Apt) acts in the somatic (cyst) stem cells (CySCs) to balance differentiation and maintenance. We found Apt functions as a negative feedback inhibitor of STAT activity, which enables cyst cell maturation. Simultaneous loss of the STAT regulators apt and Socs36E, or the Stat92E-targeting microRNA miR-279, expanded the somatic stem cell-like population.

CONCLUSIONS

Genetic analysis revealed that a conserved genetic regulatory network limits JAK/STAT activity in the somatic stem cells of Drosophila testis. In these cells, we determined JAK/STAT signaling promotes apt expression. Then, Apt functions through Socs36E and miR-279 to attenuate pathway activation, which is required for timely CySC differentiation. We propose that Apt acts as a core component of a STAT-regulatory circuit to prevent stem cell overpopulation and allow stem cell maturation.

Biology of the eyelash hair follicle: an enigma in plain sight

Because of their crucial impact on our perception of beauty, eyelashes constitute a prime target for the cosmetic industry. However, when compared with other hair shafts and the mini-organs that produce them [eyelash hair follicles (ELHFs)], knowledge on the biology underlying growth and pigmentation of eyelashes is still rudimentary. This is due in part to the extremely restricted availability of human ELHFs for experimental study, underappreciation of their important sensory and protective functions and insufficient interest in understanding why they are distinct from scalp hair follicles (HFs) (e.g. ELHFs produce shorter hair shafts, do not possess an arrector pili muscle, have a shorter hair cycle and undergo greying significantly later than scalp HFs). Here we synthesize the limited current knowledge on the biology of ELHFs, in humans and other species, their role in health and disease, the known similarities with and differences from other HF populations, and their intrinsic interethnic variations. We define major open questions in the biology of these intriguing mini-organs and conclude by proposing future research directions. These include dissecting the molecular and cellular mechanisms that underlie trichomegaly and the development of in vitro models in order to interrogate the distinct molecular controls of ELHF growth, cycling and pigmentation and to probe novel strategies for the therapeutic and cosmetic manipulation of ELHFs beyond prostaglandin receptor stimulation.

Stem Cells and Organ Transplantation: Resetting Our Biological Clocks

The human body has only a limited ability to repair itself. Illness, injury, and aging can overwhelm its built-in capability to replace dysfunctional, damaged, or destroyed tissues. We can at best only partly regenerate our organs and cannot grow back a whole limb.

Induction of Spermatogenesis by Bone Marrow-derived Mesenchymal Stem Cells in Busulfan-induced Azoospermia in Hamster

Background

Bone marrow-derived mesenchymal stem cells (BM-MSCs) have potential of differentiation and they secrete anti-inflammatory cytokines and growth factors which make them appropriate for cell therapy.

Aim of the Work

Were to evaluate the healing effect of BM-MSCs transplantation on germinal cells of busulfan-induced azoospermic hamsters.

Material and Methods

In the present experimental case control study, BM-MSCs were isolated from bone marrow of donor albino hamsters. Five mature male recipient hamsters received two doses of 10 mg/kg of busulfan with 21 days interval to stop endogenous spermatogenesis. After induction of azoospermia, right testis of hamsters was injected with 10⁶ BM-MSCs via efferent duct and the left one remained as azoospermia control testis. Five normal mature hamsters were selected as normal intact control. After 35 days, testes and epididymis of three groups were removed for histological evaluation.

Results

Histomorphological analyses of BM-MSCs treated testes and epididymis showed the epithelial tissue of seminiferous tubules had normal morphology and spermatozoa were present in epididymis tubes. Spermatogenesis was observed in most cell-treated seminiferous tubules. The untreated seminiferous tubules were empty.

Conclusion

Transplanted BM-MSCs could successfully induce spermatogenesis in seminiferous tubules of azoospermic hamster. Therefore, BM-MSCs can be an attractive candidate in cell transplantation of azoospermia.

Adipose tissue-derived mesenchymal stem cells repair germinal cells of seminiferous tubules of busulfan-induced azoospermic rats

CONTEXT:

Adipose tissue-derived mesenchymal stem cells (AT-MSCs) are less invasive than bone marrow mesenchymal stem cells to obtain for cell therapy.

AIMS:

The aims of this study were to evaluate the germinal cells characteristics and repairs in seminiferous tubules of busulfan-induced azoospermic rats after AT-MSCs transplantation.

SETTINGS AND DESIGN:

Experimental case-control study.

MATERIALS AND METHODS:

In the present experimental study, donors AT-MSCs were isolated from subcutaneous adipose tissue of two Sprague-Dawley rats. The recipients (n = 5) were received two doses of 10 mg/kg of busulfan with 21 days interval to stop endogenous spermatogenesis. After induction of azoospermia by busulfan, rats were injected with the AT-MSCs into the efferent duct of right testes. After 60 days, the right testes were injected AT-MSCs were compared to left azoospermic testes. Five untreated male rats served as negative control.

STATISTICAL ANALYSIS USED:

Stereological indices were analyzed by one-way ANOVA and LSD post-hoc test. The spermatogenesis index was compared using Mann–Whitney U test.

RESULTS:

After stereological analyses, the seminiferous tubules treated with AT-MSCs had normal morphology. The untreated seminiferous tubules were empty. Spermatogenesis was observed in most cell-treated seminiferous tubules.

CONCLUSIONS:

The testis of busulfan-induced azoospermic rats accepted transplanted AT-MSCs. The transplanted AT-MSCs could induce spermatogenesis in seminiferous tubules of the rat.

Purinergic signaling: a common pathway for neural and mesenchymal stem cell maintenance and differentiation

Extracellular ATP, related nucleotides and adenosine are among the earliest signaling molecules, operating in virtually all tissues and cells. Through their specific receptors, namely purinergic P1 for nucleosides and P2 for nucleotides, they are involved in a wide array of physiological effects ranging from neurotransmission and muscle contraction to endocrine secretion, vasodilation, immune response, and fertility. The purinergic system also participates in the proliferation and differentiation of stem cells from different niches. In particular, both mesenchymal stem cells (MSCs) and neural stem cells are endowed with several purinergic receptors and ecto-nucleotide metabolizing enzymes, and release extracellular purines that mediate autocrine and paracrine growth/proliferation, pro- or anti-apoptotic processes, differentiation-promoting effects and immunomodulatory actions. Here, we discuss the often opposing roles played by ATP and adenosine in adult neurogenesis in both physiological and pathological conditions, as well as in adipogenic and osteogenic MSC differentiation. We also focus on how purinergic ligands produced and released by transplanted stem cells can be regarded as ideal candidates to mediate the crosstalk with resident stem cell niches, promoting cell growth and survival, regulating inflammation and, therefore, contributing to local tissue homeostasis and repair.

Potential interactions between pericytes and oligodendrocyte precursor cells in perivascular regions of cerebral white matter

Pericytes are embedded within basal lamina and play multiple roles in the perivascular niche in brain. Recently, oligodendrocyte precursor cells (OPCs) have also been reported to associate with cerebral endothelium. Is it possible that within this gliovascular locus, there may also exist potential spatial and functional interactions between pericytes and OPCs? Here, we demonstrated that in the perivascular region of cerebral white matter, pericytes and OPCs may attach and support each other. Immunostaining showed that pericytes and OPCs are localized in close contact with each other in mouse white matter at postnatal days 0, 60 and 240. Electron microscopic analysis confirmed that pericytes attached to OPCs via basal lamina in the perivascular region. The close proximity between these two cell types was also observed in postmortem human brains. Functional interaction between pericytes and OPCs was assessed by in vitro media transfer experiments. When OPC cultures were treated with pericyte-conditioned media, OPC number increased. Similarly, pericyte number increased when pericytes were maintained in OPC-conditioned media. Taken together, our data suggest a potential anatomical and functional interaction between pericytes and OPCs in cerebral white matter.

Pericytes in the myovascular niche promote post-natal myofiber growth and satellite cell quiescence

The satellite cells, which serve as adult muscle stem cells, are both located beneath myofiber basement membranes and closely associated with capillary endothelial cells. We observed that 90% of capillaries were associated with pericytes in adult mouse and human muscle. During post-natal growth, newly formed vessels with their neuroglial 2 proteoglycan (NG2)-positive pericytes became progressively associated with the post-natal muscle stem cells, as myofibers increased in size and satellite cells entered into quiescence. In vitro, human muscle-derived pericytes promoted myogenic cell differentiation through insulin-like growth factor 1 (IGF1) and myogenic cell quiescence through angiopoietin 1 (ANGPT1). Diphtheria toxin-induced ablation of muscle pericytes in growing mice led both to myofiber hypotrophy and to impaired establishment of stem cells quiescence. Similar effects were observed following conditional in vivo deletion of pericyte Igf1 and Angpt1 genes, respectively. Our data therefore demonstrate that, by promoting post-natal myogenesis and stem cell quiescence, pericytes play a key role in the microvascular niche of satellite cells.

Potential spermatogenesis recovery with bone marrow mesenchymal stem cells in an azoospermic rat model

Non-obstructive azoospermia is the most challenging type of male infertility. Stem cell based therapy provides the potential to enhance the recovery of spermatogenesis following cancer therapy. Bone marrow-derived mesenchymal stem cells (BMSCs) possess the potential to differentiate or trans-differentiate into multi-lineage cells, secrete paracrine factors to recruit the resident stem cells to participate in tissue regeneration, or fuse with the local cells in the affected region. In this study, we tested whether spermatogenically-induced BMSCs can restore spermatogenesis after administration of an anticancer drug. Allogeneic BMSCs were co-cultured in conditioned media derived from cultured testicular Sertoli cells in vitro, and then induced stem cells were transplanted into the seminiferous tubules of a busulfan-induced azoospermatic rat model for 8 weeks. The in vitro induced BMSCs exhibited specific spermatogonic gene and protein markers, and after implantation the donor cells survived and located at the basement membranes of the recipient seminiferous tubules, in accordance with what are considered the unique biological characteristics of spermatogenic stem cells. Molecular markers of spermatogonial stem cells and spermatogonia (Vasa, Stella, SMAD1, Dazl, GCNF, HSP90α, integrinβ1, and c-kit) were expressed in the recipient testis tissue. No tumor mass, immune response, or inflammatory reaction developed. In conclusion, BMSCs might provide the potential to trans-differentiate into spermatogenic-like-cells, enhancing endogenous fertility recovery. The present study indicates that BMSCs might offer alternative treatment for the patients with azoospermatic infertility after cancer chemotherapy.