The effects of 17-β estradiol on enhancing proliferation of human bone marrow mesenchymal stromal cells in vitro

Effect of silk fibroin scaffold loaded with 17-β estradiol on the proliferation and differentiation of BMSCs

In this study, different concentrations of 17-β estradiol silk fibroin (SF)porous scaffolds (SFPS) were prepared using freeze-drying technique, with a hope for optimal concentration and apply it locally to the bone defect area. In this study, the porous scaffold morphology structure was characterized by SEM, FTIR and universal capacity testing machines, and the in vitro cytocompatibility and biological activity of scaffold materials were studied by cell adhesion, viability and proliferation experiments. The results showed that SFPS boasts better physicochemical properties, while 17-β estradiol SF scaffolds with low concentrations of 10-10 mol/L and 10-12 mol/L had more growth and proliferation of SF scaffolds with higher concentrations, and 10-10 mol/L was the optimal concentration of 17-β estradiol SFPS, which was more conducive to cell adhesion and proliferation. On the other hand, after osteogenesis induction of BMSCs inoculated on 17-β estradiol SFPS at different concentrations, it was found that the expression of alkaline phosphatase in BMSCs on different concentrations of 17-β estradiol porous scaffolds was not large. No conflict of interest exits in the submission of this manuscript.

Sex-dependent variation in cartilage adaptation: from degeneration to regeneration

Despite acknowledgement in the scientific community of sex-based differences in cartilage biology, the implications for study design remain unclear, with many studies continuing to arbitrarily assign demographics. Clinically, it has been well-established that males and females differ in cartilage degeneration, and accumulating evidence points to the importance of sex differences in the field of cartilage repair. However, a comprehensive review of the mechanisms behind this trend and the influence of sex on cartilage regeneration has not yet been presented. This paper aims to summarize current findings regarding sex-dependent variation in knee anatomy, sex hormones' effect on cartilage, and cartilaginous degeneration and regeneration, with a focus on stem cell therapies. Findings suggest that the stem cells themselves, as well as their surrounding microenvironment, contribute to sex-based differences. Accordingly, this paper underscores the contribution of both stem cell donor and recipient sex to sex-related differences in treatment efficacy. Cartilage regeneration is a field that needs more research to optimize strategies for better clinical results; taking sex into account could be a big factor in developing more effective and personalized treatments. The compilation of this information emphasizes the importance of investing further research in sex differences in cartilage biology.

Estrogen Signaling Dictates Musculoskeletal Stem Cell Behavior: Sex Differences in Tissue Repair

Sexual dimorphisms in humans and other species exist in visually evident features such as body size and less apparent characteristics, including disease prevalence. Current research is adding to a growing understanding of sex differences in stem cell function and response to external stimuli, including sex hormones such as estrogens. These differences are proving significant and directly impact both the understanding of stem cell processes in tissue repair and the clinical implementation of stem cell therapies. Adult stem cells of the musculoskeletal system, including those used for development and repair of muscle, bone, cartilage, fibrocartilage, ligaments, and tendons, are no exception. Both in vitro and in vivo studies have found differences in stem cell number, proliferative and differentiation capabilities, and response to estrogen treatment between males and females of many species. Maintaining the stemness and reducing senescence of adult stem cells is an important topic with implications in regenerative therapy and aging. As such, this review discusses the effect of estrogens on musculoskeletal system stem cell response in multiple species and highlights the research gaps that still need to be addressed. The following evidence from investigations of sex-related phenotypes in adult progenitor and stem cells are pieces to the big puzzle of sex-related effects on aging and disease and critical information for both fundamental tissue repair and regeneration studies and safe and effective clinical use of stem cells. Impact Statement This review summarizes current knowledge of sex differences in and the effects of estrogen treatment on musculoskeletal stem cells in the context of tissue engineering. Specifically, it highlights the impact of sex on musculoskeletal stem cell function and ability to regenerate tissue. Furthermore, it discusses the varying effects of estrogen on stem cell properties, including proliferation and differentiation, important to tissue engineering. This review aims to highlight the potential impact of estrogens and the importance of performing sex comparative studies in the field of tissue engineering.

DHEA Protects Human Cholangiocytes and Hepatocytes against Apoptosis and Oxidative Stress

Primary biliary cholangitis (PBC) is a rare chronic cholestatic and immune-mediated liver disease of unknown aetiology that targets intrahepatic bile duct cells (cholangiocytes) and primarily affects postmenopausal women, when their estrogen levels sharply decrease. An impaired cholangiocyte response to estrogen characterizes the terminal stage of the disease, as this is when an inefficiency of cholangiocyte proliferation, in balancing the loss of intrahepatic bile ducts, is observed. Here, we report that the estrogen precursor dehydroepiandrosterone (DHEA) and its sulfate metabolites, DHEA-S and 17 β-estradiol, enhance the proliferation of cholangiocytes and hepatocytes in vitro. Flow cytometry analysis showed that DHEA and DHEA-S decreased glyco-chenodeoxycholic acid (GCDC)-driven apoptosis in cholangiocytes. Cell viability assay (MTT) indicated that ER-α, -β, and the G-protein-coupled estrogen receptor, are involved in the protection of DHEA against oxidative stress in cholangiocytes. Finally, immunoblot analysis showed an elevated level of steroid sulfatase and a reduced level of sulfotransferase 1E1 enzymes, involved in the desulfation/sulfation process of estrogens in cirrhotic PBC, and primary sclerosis cholangitis (PSC) liver tissues, another type of chronic cholestatic and immune-mediated liver disease. Taken together, these results suggest that DHEA can prevent the deleterious effects of certain potentially toxic bile acids and reactive oxygen species, delaying the onset of liver disease.

Autologous mesenchymal stem cells in the treatment of spinal aneurysmal bone cyst

PURPOSE

We retrospectively analyzed a cohort of patients treated at our Centre with bone marrow concentrated (BMC) injection for aneurysmal bone cyst (ABC) of the spine, in order to propose this treatment as a valid alternative for the management of ABCs.

METHODS

Fourteen patients (6 male, 8 female) were treated between June 2014 to December 2019 with BMC injection for ABC of the spine. The mean age was 15.5 years. The mean follow up was 37.4 months (range 12-60 months). The dimension of the cyst and the degree of ossification were measured by Computed Tomography (CT) scans before the treatment and during follow-up visits.

RESULTS

Six patients received a single dose of BMC, five patients received two doses and in three patients three doses of BMC were administered. The mean ossification of the cyst (expressed in Hounsfield units) increased statistically from 43.48 ± 2.36 HU to 161.71 ± 23.48 HU during follow-up time and the ossification was associated to an improvement of the clinical outcomes. The mean ossification over time was significantly higher in patients treated with a single injection compared to patients treated with multiple injections. No significant difference in ossification was found between cervical and non-cervical localization of the cyst. Moreover, the initial size of the cyst was not statistically associated with the degree of ossification during follow-up CONCLUSIONS: Results of this paper reinforce our previous evidence on the use of BMC as a valid alternative for spinal ABC management when SAE treatment is contraindicated or ineffective.

Estrogen receptor alpha regulates the expression of adipogenic genes genetically and epigenetically in rat bone marrow-derived mesenchymal stem cells

Regulation of the efficacy of epigenetic modifiers is regarded as an important control mechanism in the determination and differentiation of stem cell fate. Studies are showing that the effect of estrogen is important in the differentiation of mesenchymal stem cells (MSCs) into adipocytes, osteocytes, and chondrocytes. Activation of certain transcription factors and epigenetic modifications in related genes play an active role in the initiation and completion of adipogenic differentiation. Understanding the role of estrogen in diseases such as obesity, which increases with the onset of menopause, will pave the way for more effective use of estrogen as a therapeutic option. Demonstration of the differentiation tendencies of MSCs change in the presence/absence of estrogen, especially the evaluation of reversible epigenetic changes, will provide valuable information for clinical applications. In this study, the effect of estrogen on the expression of genes involved in adipogenic differentiation of MSCs and accompanying epigenetic modifications was investigated. Our results showed that estrogen affects the expression of adipogenesis-related transcription factors such as PPARy, C/EBPα and Adipsin. In addition, after estrogen treatment, increased accumulation of estrogen receptor alpha (ERα) and repressive epigenetic markers such as H3K27me2 and H3K27me3 were observed on the promoter of given transcription factors. By using co-immunoprecipitation experiments we were also able to show that ERα physically interacts with the zeste homolog 2 (EZH2) H3K27 methyltransferase in MSCs. We propose that the increase of H3K27me2 and H3K27me3 markers on adipogenic genes upon estrogen treatment may be mediated by the direct interaction of ERα and EZH2. Taken together, these findings suggest that estrogen has a role as an epigenetic switcher in the regulation of H3K27 methylation leading to suppression of adipogenic differentiation of MSC.

Adipose Tissue- and Bone Marrow-Derived Mesenchymal Stem Cells from Sheep: Culture Characteristics

Simple Summary

Mesenchymal stem cells (MSCs) are available in minuscule numbers in the body or placental tissues. These cells have mostly been harvested from bone marrow and adipose tissue. To broaden the currently available knowledge, the current study provides (a) information on the feasibility of isolation of MSCs at different ambient temperatures, (b) details of MSCs’ culture characteristics with respect to the physiological status of the donor, and (c) information on the viability of cryopreserved cells. Bone marrow harbors a higher mononuclear cell fraction than that of the adipose tissue, although percent adherent cells are comparably more in adipose tissue. MSCs from a pregnant donor show enhanced proliferation and differentiation potential, although further studies are desired. The cryopreserved cells have comparable characteristics to that of the fresh cells. In conclusion, donor animals’ tissue type and physiological status may affect MSCs’ characteristics and should be taken into consideration while applying in clinical settings.

Abstract

The current study demonstrates the culture characteristics of adipose tissue and bone marrow-derived mesenchymal stem cells (MSC). The study evaluates the effect of ambient temperature, physiological status of the donor and the tissue source on sheep (Ovis aries) mesenchymal stem cells. The tissue samples were harvested from full term pregnant female sheep (n = 9) and male sheep (n = 10). Adipose tissue was harvested from n = 9 sheep and bone marrow from n = 10 sheep. The samples (adipose tissue, n = 2; bone marrow, n = 3) transported at cold ambient temperature (<10 °C) failed to yield MSCs while those (n = 14) at higher (>20 °C) ambient temperature successfully yielded MSCs. Bone marrow mononuclear cell (MNC) fraction was higher than the adipose tissue-derived stromal vascular fraction (SVF), but the percent adherent cells (PAC) was higher in the later cell fraction. Adipose tissue-derived MSCs from the full term female sheep had a significantly (p < 0.05) higher proliferation potential as compared to those of the male sheep-derived MSCs. Female sheep MSCs also had rapid differentiation potential. The cryopreserved MSCs had morphological features comparable to that of the fresh cells. In conclusion, the tissue type and physiological status of donor animal may affect MSCs’ characteristics and should be taken into consideration while applying in clinical settings.

Contribution of Bone Marrow-Derived Mesenchymal Stem Cells to Healing of Pulmonary Contusion-Created Rats

BACKGROUND

The most common thoracic injury in children, resulting in trauma, is pulmonary contusion (PC). Bone marrow-derived mesenchymal stem cells (BM-MSCs) are used in wound healing and many other diseases. This study aims to examine the effects of BM-MSCs on PC healing in rats.

MATERIALS AND METHODS

A total of 45 male Wistar albino rats were used. Four groups were formed. BM-MSCs were labeled with the green fluorescent protein. PC was observed in the control group. In group II, PC occured and left to spontaneous healing. In group III, PC formed and BM-MSCs were given. In group IV, BM-MSCs were given without PC formation. Subjects were sacrificed 1 week later. Whether there was any difference in terms of BM-MSC involvement and lung injury score was investigated. Statistical analysis was performed using the Statistical Package for Social Sciences (SPSS), version 17.0, software (SPSS Inc., Chicago, IL), and p value of <0.05 was considered statistically significant.

RESULTS

BM-MSCs were collected much more in the lungs in group III than in group IV. Group III had a lower lung injury score value than group II.

CONCLUSION

The greater involvement of the BM-MSCs in the injury site, and further reductions in lung injury score suggest that BM-MSCs are contributing to the healing of the injury. The use of BM-MSCs in risky patients with diffuse PC may be an alternative treatment to conventional methods.

Engineering the MSC Secretome: A Hydrogel Focused Approach

The therapeutic benefits of exogenously delivered mesenchymal stromal/stem cells (MSCs) have been largely attributed to their secretory properties. However, clinical translation of MSC-based therapies is hindered due to loss of MSC regenerative properties during large-scale expansion and low survival/retention post-delivery. These limitations might be overcome by designing hydrogel culture platforms to modulate the MSC microenvironment. Hydrogel systems could be engineered to i) promote MSC proliferation and maintain regenerative properties (i.e., stemness and secretion) during ex vivo expansion, ii) improve MSC survival, retention, and engraftment in vivo, and/or iii) direct the MSC secretory profile using tailored biochemical and biophysical cues. Herein, it is reviewed how hydrogel material properties (i.e., matrix modulus, viscoelasticity, dimensionality, cell adhesion, and porosity) influence MSC secretion, mediated through cell-matrix and cell-cell interactions. In addition, it is highlighted how biochemical cues (i.e., small molecules, peptides, and proteins) can improve and direct the MSC secretory profile. Last, the authors' perspective is provided on future work toward the understanding of how microenvironmental cues influence the MSC secretome, and designing the next generation of biomaterials, with optimized biophysical and biochemical cues, to direct the MSC secretory profile for improved clinical translation outcomes.

Inhibition of Adipogenic Differentiation of Human Bone Marrow-Derived Mesenchymal Stem Cells by a Phytoestrogen Diarylheptanoid from Curcuma comosa

We investigated the effect of a phytoestrogen, (3R)-1,7-diphenyl-(4E,6E)-4,6-heptadien-3-ol (DPHD), from Curcuma comosa Roxb. (Zingiberaceae family) on the adipogenic differentiation of mesenchymal progenitors, human bone marrow-derived mesenchymal stem cells (hBMSCs). DPHD inhibited adipocyte differentiation of hBMSCs by suppressing the expression of genes involved in adipogenesis. DPHD at concentrations of 0.1, 1, and 10 μM significantly decreased triglyceride accumulation in hBMSCs to 7.1 ± 0.2, 6.3 ± 0.4, and 4.9 ± 0.2 mg/dL, respectively, compared to the nontreated control (10.1 ± 0.9 mg/dL) (p < 0.01). Based on gene expression profiling, DPHD increased the expression of several genes involved in the Wnt/β-catenin signaling pathway, a negative regulator of adipocyte differentiation in hBMSCs. DPHD also increased the levels of essential signaling proteins which are extracellular signal-regulated kinases 1 and 2 (ERK1/2) and glycogen synthase kinase 3 beta (GSK-3β) that link estrogen receptor (ER) signaling to Wnt/β-catenin signaling. In conclusion, DPHD exhibited the anti-adipogenic effect in hBMSCs by suppression of adipogenic markers in hBMSCs through the activation of ER and Wnt/β catenin signaling pathways. This finding suggests the potential role of DPHD in preventing bone marrow adiposity which is one of the major factors that exacerbates osteoporosis in postmenopause.

Mapping human serum-induced gene networks as a basis for the creation of biomimetic periosteum for bone repair

BACKGROUND

The periosteum is a highly vascularized, collagen-rich tissue that plays a crucial role in directing bone repair. This is orchestrated primarily by its resident progenitor cell population. Indeed, preservation of periosteum integrity is critical for bone healing. Cells extracted from the periosteum retain their osteochondrogenic properties and as such are a promising basis for tissue engineering strategies for the repair of bone defects. However, the culture expansion conditions and the way in which the cells are reintroduced to the defect site are critical aspects of successful translation. Indeed, expansion in human serum and implantation on biomimetic materials has previously been shown to improve in vivo bone formation.

AIM

This study aimed to develop a protocol to allow for the expansion of human periosteum derived cells (hPDCs) in a biomimetic periosteal-like environment.

METHODS

The expansion conditions were defined through the investigation of the bioactive cues involved in augmenting hPDC proliferative and multipotency characteristics, based on transcriptomic analysis of cells cultured in human serum.

RESULTS

Master regulators of transcriptional networks were identified, and an optimized periosteum-derived growth factor cocktail (PD-GFC; containing β-estradiol, FGF2, TNFα, TGFβ, IGF-1 and PDGF-BB) was generated. Expansion of hPDCs in PD-GFC resulted in serum mimicry with regard to the cell morphology, proliferative capacity and chondrogenic differentiation. When incorporated into a three-dimensional collagen type 1 matrix and cultured in PD-GFC, the hPDCs migrated to the surface that represented the matrix topography of the periosteum cambium layer. Furthermore, gene expression analysis revealed a down-regulated WNT and TGFβ signature and an up-regulation of CREB, which may indicate the hPDCs are recreating their progenitor cell signature.

CONCLUSION

This study highlights the first stage in the development of a biomimetic periosteum, which may have applications in bone repair.

A comparative study of hBM-MSCs' differentiation toward osteogenic lineage in the presence of progesterone and estrogen hormones separately and concurrently in vitro

Promising cell sources for tissue engineering comprise bone marrow derived-mesenchymal stem cells (BM-MSCs) that have multiple differentiation potentials. Also, sex hormones act as important elements in bone development and maintenance, and the roles of two female sex steroid hormones known as estrogen (17-β estradiol) and progesterone in osteogenic differentiation of human BM-MSCs (hBM-MSCs) are studied. For this purpose, hBM-MSCs were treated with a 1 × 10^-6  M concentration of 17-β estradiol and progesterone separately and simultaneously while the optimum concentrations were obtained by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Osteogenic differentiation tests including measurement of alkaline phosphatase (ALP) enzyme activity, the content of total mineral calcium, mineralized matrix staining by Alizarin Red and Von Kossa solutions, real-time reverse transcription polymerase chain reaction (RT-PCR), and immunofluorescence staining were carried out on Days 7 and 14 of differentiation. To exhibit the morphology of the cells, the BM-MSCs were stained with acridine orange (AO) solution. In this study, the results of ALP activity assay, calcium content and real-time RT-PCR assay and also all tests of differentiation staining have shown that 17-β estradiol has been recognized as an enhancing factor of osteogenic differentiation. Furthermore, MTT assay and AO staining revealed progesterone as a factor that seriously improved the proliferation of hBM-MSCs. Generally, the 17-β estradiol individually or in the presence of progesterone has more effects on BM-MSCs' osteogenic differentiation compared to progesterone alone. In this study, it is indicated that the effect of the 17-β estradiol and progesterone concurrently was the same as individual 17-β estradiol on the differentiation of hBM-MSCs.

The effect of female sex steroid hormones on osteogenic differentiation of endometrial stem cells

Bone regeneration is a significant and crucial health issue worldwide. Tissue bioengineering has shown itself to be the best substitute for common clinical treatment of bone loss. The suitable cell source is human endometrial stem cells (hEnSCs) which have several suitable characteristics for this approach. Since sex steroid hormones are involved in expansion and conservation of the skeleton, the effect of two sex steroid hormones known as estrogen (17-β estradiol) and progesterone on osteogenic differentiation of hEnSCs were examined. For this purpose, hEnSCs were treated with 17-β estradiol and progesterone separately (1 × 10^-6 M) and simultaneously (1 × 10^-7 M). Osteogenic differentiation tests including measurement of total mineral calcium content, Alizarin Red staining, the quantitative expression levels of some osteogenic markers by Real-time RT-PCR, and immunofluorescence staining were performed at 7 and 14 days of differentiation. To exhibit the morphology of the cells in osteogenic and culture medium, the hEnSCs were stained with Acridine Orange (AO) solution. In this research, MTT assay and AO staining revealed progesterone and 17-β estradiol increase the proliferation of hEnSCs in a dose-dependent manner. Furthermore, the results of calcium content analysis, Real-time RT-PCR assay, and all tests of differentiation staining have shown that 17-β estradiol and progesterone cannot induce hEnSCs' osteogenic differentiation. In conclusion, it is indicated that 17-β estradiol and progesterone do not have positive effects on hEnSCs' osteogenic differentiation in vitro.

Altered expression of some miRNAs and their target genes following mesenchymal stem cell treatment in busulfan-induced azoospermic rats

Studies have recently demonstrated that mesenchymal stem cells (MSCs) have therapeutic capabilities on many diseases and this effect is mainly mediated by miRNAs. However, the actual mechanism of MSCs paracrine effect on testis to improve male fertility is still elusive. Herein, we evaluated the altered expression of some spermatogenesis-related miRNAs and their target genes following transplantation of bone marrow (BM)-derived MSCs into testes of busulfan-induced azoospermic rats using real time PCR. Transplantation of MSCs improved fertility of azoospermic rats as revealed by enhanced serum levels of testosterone and estradiol, and upregulated expression of germ cell‑specific genes. Azo rats injected with MSCs also exhibited a significant downregulated expression of miRNA-19b, miRNA-100, miRNA-141, miRNA‑146a, miRNA-429, and let‑7a and a significant upregulated expression of miRNA-21, miRNA-34b, miRNA-34c, miRNA-122, miRNA-449a, miRNA-449b, and miRNA-449c in the testis as compared to Azo rats injected with phosphate buffer saline. Transplantation of MSCs was also accompanied with restoration of the disrupted expression of Ccnd1, E2F1, Myc, and PLCXD3 (target genes for miRNA-34 and miRNA‑449 clusters) and ERα and AKT1 (target genes for miRNA-100 and let‑7a) to level comparable to that of the fertile group. Upon these data, we infer that BM-MSCs can improve fertility of azoospermic rats and this effect was followed by altered expression of some spermatogenesis-related miRNAs and their target genes. These findings provide MSCs as a promising and effective cell-based therapeutic method for azoospermic patients, but further investigations are required before clinical application.

Retinoic acid and 17β-estradiol improve male germ cell differentiation from mouse-induced pluripotent stem cells

This research aimed to explore the impacts of retinoic acid (RA)/17β-estradiol (E) induction and embryoid body formation to enhance differentiation of mouse-induced pluripotent stem cells (miPSCs) into male germ cells in vitro. Flow cytometry and qPCR were conducted to describe miPSCs differentiation process. Various temporal expression profiles of germ cell-related genes were traced. Stra8 gene expression increased in the RA group on the 4th day compared to other groups. The RA group experienced a more significant increase than E group. The expression of Sycp3 increased in RA + E group on 4th day compared with other groups. Expression of AKAP3 enhanced in the RA + E group than other groups on day 4. Moreover, miPSCs showed that this gene expression in the RA + E group was increased in comparison to RA and E groups on day 7. AKAP3 gene expression on day 7 of miPSCs decreased in RA and E groups. Flow cytometry data indicated that 3%-8% of the cells in sub-G1 stage were haploid after RA and E induction compared to other groups on day 4. This study showed that miPSCs possess the power for differentiating into male germ cells in vitro via formation of embryoid body by RA with/or E induction.

Alterations in IL-6/STAT3 Signaling by Korean Mistletoe Lectin Regulate the Self-Renewal Activity of Placenta-Derived Mesenchymal Stem Cells

Korean mistletoe (Viscum album L. var. coloratum) lectin (VCA) is known as an anticancer drug. However, it is not clear whether VCA affects the self-renewal activity of mesenchymal stem cells (MSCs). Therefore, the objectives of this study were to analyze the effect of VCA on the proliferation of MSCs and expression of stemness markers. We also evaluated the usefulness of placenta-derived MSCs (PD-MSCs) as a screening tool. VCA was stably administered to MSCs, and analyzed self-renewal activities. The effect of IL-6 signaling on MSC proliferation was explored by quantitative methylation-specific PCR (qMSP) and western blot analysis. Compared with the control condition, low concentrations of VCA (10 pg/mL) induced an increase in the self-renewal activity of MSCs. Interestingly, a low concentration of VCA promoted IL-6 signaling in PD-MSCs through altered IL-6/STAT3 gene methylation. Furthermore, inhibition of IL-6 expression in PD-MSCs using an anti-IL-6 antibody caused a decrease in their self-renewal activity through IL-6/STAT3 signaling by altering IL-6/STAT3 gene methylation. These findings provide helpful data for understanding the mechanism of MSC self-renewal via VCA and show that VCA may be useful as a functional natural product for developing efficient therapies using placenta-derived stem cells.

Dihydrotestosterone and 17-Estradiol Enhancement of in vitro Osteogenic Differentiation of Castrated Male Rat Bone Marrow Mesenchymal Stem Cells (rBMMSCs)

Background: In vitro impact of dihydrotestosterone (DHT) and 17-estradiol (E2) in osteogenic differentiation of castrated rat bone marrow mesenchymal stem cells (rBMMSC) still need to be clarified. Materials and Methods: The viability, proliferation and density of cultured rBMMSC isolated from sham operated (Sham) and castrated (Cast) male rats were evaluated. rBMMSC were cultured with osteogenic differentiating medium (ODM) in the presence of DHT (5,10 nM) and E2 (10,100 nM). Osteogenesis was evaluated by alizarin red staining and measurement of calcium deposition and bone alkaline phosphatase (B-ALP) activity. Results: Population doubling (PD) of rBMMSC isolated from Cast rats was significantly lower (P<0.05) compared to that isolated from Sham rats. rBMMSC from Cast rats showed low scattered calcified nodule after culturing in ODM and did not cause a significant increase in calcium deposition and B-ALP activity compared to rBMMSCs from Sham rats. Exposure of rBMMSC isolated from Cast rats to DHT (5 nM) or E2 (10 nM) in ODM showed medium scattered calcified nodules with significantly higher (P<0.05) calcium deposition and B-ALP activity. Moreover, exposure of rBMMSC to DHT (10 nM) or E2 (100 nM) showed high scattered calcified nodules with higher (P<0.01) calcium deposition and B-ALP activity Conclusion: These results indicated that the presence of testes might participate in controlling the in vitro proliferation and osteogenic differentiation capacity of rBMMSCs. DHT and E2 can enhance the osteogenic capacity of rBMMSCs in a dose-dependent manner. Based on these observations, optimum usage of DHT and E2 can overcome the limitations of MSCs and advance the therapeutic bone regeneration potential in the future.

The effects of transplanted mesenchymal stem cells treated with 17-b estradiol on experimental autoimmune encephalomyelitis

The present study was conducted aimed at exploring the modulatory effects of 17-b estradiol (17-bED) on mesenchymal stem cells (MSCs) in the EAE (experimental autoimmune encephalomyelitis) animal model of multiple sclerosis (MS). Following the isolation of bone marrow-derived MSCs from the bilateral femurs and tibias of the male Wistar rats, the cells were harvested and cultured in the presence of 100 nM 17-bED for 24 h. EAE was induced in male Wistar rats (8-12 weeks old) using guinea pig spinal cord homogenate, in combination with the complete Freund's adjuvant. The MSC therapy was triggered when all of the animals obtained a disability score. The symptoms were monitored on a daily basis throughout the study until the rats were euthanized. The mRNA expression of cytokines, including IL-17, IFN-γ, TNF-α, IL-10, IL-4, and TGF-β together with MMP8 and MMP9 as the family members of matrix metalloproteinases (MMPs) in the brain and spinal cord tissues were examined using real-time PCR. The levels of splenocytes-originated IL-10 and IFN-γ cytokines were also measured by ELISA. The MTT-based research findings showed that the infiltration of lymphocytes into the spleen decreased considerably. It was also observed that the mRNA expression of proinflammatory cytokines decreased significantly, while the mRNA levels of anti-inflammatory cytokines increased remarkably. It was also found that the mRNA levels of the examined matrix metalloproteinases (MMP8 and MMP9) were downregulated significantly. The findings of the present study indicated that the administration of 17-bED enhanced the efficacy of MSCs transplantation and modulated immune responses relatively in the EAE model, via the regulation of either pro- or anti-inflammatory cytokines and matrix metalloproteinases.

Influence of Donor and Recipient Gender on Telomere Maintenance after Umbilical Cord Blood Cell Transplantation: A Study by the Gruppo Italiano Trapianto Di Midollo Osseo

Physiologic loss of telomerase activity in adult life determines progressive telomere length (TL) shortening. Inflammation and oxidative damage are established causes of TL loss; moreover, males have shorter telomeres compared with females. Despite these notions, mechanisms regulating TL maintenance are poorly defined. Because umbilical cord blood (UCB) cells harbor very long telomeres, not yet exposed to environmental damages, UCB transplantation (UCBT) provides a unique experimental setting to study determinants of TL in humans. TL dynamics were analyzed on peripheral blood mononuclear cells (MNCs) from 36 patients (median age, 42 years) undergoing UCBT. TL was studied at a median of 20 months after UCBT. A significantly longer TL (mean, 8698 bp; range, 6521 to 11,960) was documented in UCBT recipients compared with age-matched healthy control subjects (mean, 7396 bp; range, 4375 to 11,108; P < .01). Among variables potentially influencing TL maintenance, including recipient features, graft type, transplant procedure, and engraftment kinetics, only donor-recipient gender combination was associated with TL, with the longest TL in women receiving male UCB (mean, 10,063 bp; range, 8381 to 11,960). To further investigate this trend, telomerase activation was assessed in vitro. Experiments showed that telomerase subunits were preferentially upregulated in male-derived bone marrow MNCs exposed ex vivo to estradiol as compared with female MNCs. This implies an increased sensitivity of male-derived MNCs to telomerase activation induced by estradiol. The results suggest that extrinsic and modifiable factors such as hormonal status and female milieu could be major determinants of TL in humans, providing the rationale for investigating hormonal-based approaches to counteract telomere erosion and aging-related diseases.

Influence of diet and metabolism on hematopoietic stem cells and leukemia development following ionizing radiation exposure

PURPOSE

The review aims to discuss the prominence of dietary and metabolic regulators in maintaining hematopoietic stem cell (HSC) function, long-term self-renewal, and differentiation.

RESULTS

Most adult stem cells are preserved in a quiescent, nonmotile state in vivo which acts as a "protective state" for stem cells to reduce endogenous stress provoked by DNA replication and cellular respiration as well as exogenous environmental stress. The dynamic balance between quiescence, self-renewal and differentiation is critical for supporting a functional blood system throughout life of an organism. Stress-conditions, for example ionizing radiation exposure can trigger the blood forming HSCs to proliferate and migrate through extramedullary tissues to expand the number of HSCs and increase hematopoiesis. In addition, a wealth of investigation validated that deregulation of this balance plays a critical pathogenic role in various different hematopoietic diseases including the leukemia development.

CONCLUSION

The review summarizes the current knowledge on how alterations in dietary and metabolic factors could alter the risk of leukemia development following ionizing radiation exposure by inhibiting or even reversing the leukemic progression. Understanding the influence of diet, metabolism, and epigenetics on radiation-induced leukemogenesis may lead to the development of practical interventions to reduce the risk in exposed populations.

Serum-mediated Activation of Bone Marrow-derived Mesenchymal Stem Cells in Ischemic Stroke Patients: A Novel Preconditioning Method

Stroke induces complex and dynamic, local and systemic changes including inflammatory reactions, immune responses, and repair and recovery processes. Mesenchymal stem cells (MSCs) have been shown to enhance neurological recovery after stroke. We hypothesized that serum factors play a critical role in the activation of bone marrow (BM) MSCs after stroke such as by increasing proliferation, paracrine effects, and rejuvenation. Human MSCs (hMSCs) were grown in fetal bovine serum (FBS), normal healthy control serum (NS), or stroke patient serum (SS). MSCs cultured in growth medium with 10% SS or NS exhibited higher proliferation indices than those cultured with FBS (P < 0.01). FBS-, NS-, and SS-hMSCs showed differences in the expression of trophic factors; vascular endothelial growth factor, glial cell–derived neurotrophic factor, and fibroblast growth factor were densely expressed in samples cultured with SS (P < 0.01). In addition, SS-MSCs revealed different cell cycle– or aging-associated messenger RNA expression in a later passage, and β-galactosidase staining showed the senescence of MSCs observed during culture expansion was lower in MSCs cultured with SS than those cultured with NS or FBS (P < 0.01). Several proteins related to the activity of receptors, growth factors, and cytokines were more prevalent in the serum of stroke patients than in that of normal subjects. Neurogenesis and angiogenesis were markedly increased in rats that had received SS-MSCs (P < 0.05), and these rats showed significant behavioral improvements (P < 0.01). Our results indicate that stroke induces a process of recovery via the activation of MSCs. Culture methods for MSCs using SS obtained during the acute phase of a stroke could constitute a novel MSC activation method that is feasible and efficient for the neurorestoration of stroke.

Reproductive stage and sex steroid hormone levels influence the expression of mesenchymal stromal cell (MSC) markers in the equine endometrium

Mesenchymal stem or stromal cells (MSCs) play key roles in tissue homeostasis. In the cyclic equine endometrium, this may be regulated by changes in serum concentrations of sex steroid hormones. This study was designed to investigate the changes in endometrial expression of MSC markers during reproductive cycles in mares and the influence of sex steroid hormones on endometrial MSC proliferation in vitro. Endometrial biopsies were collected from pony mares at different reproductive stages (estrus; day 5 and 13 after ovulation; seasonal anestrus; 20 h and 7days post-partum; n = 5 per stage) and were analyzed by RT-qPCR. MSC (CD29, CD44, CD73, CD90, CD105) and perivascular (CD146, NG2) markers were present in all samples irrespective of reproductive stage. Transcript levels of most markers were present at lowest levels on day 5 after ovulation and at 20 h post-partum. MSCs isolated from endometrial tissue (n = 6 mares) were cultured in the presence of progesterone (0.01-100 μM) and estradiol 17β (0.1-1 μM), and cell proliferation was analyzed using alamarBlue^® assay. Relative to cells incubated in steroid-depleted media, both progesterone and estradiol 17β moderately increased cell proliferation (1.1- and 1.2-fold, respectively) independently of the concentration used. In conclusion, our results suggest that levels of MSC markers in equine endometrium dynamically change across reproductive cycles and that MSC populations are in part regulated by sex steroids.

STAT-3 regulation of CXCR4 is necessary for the prenylflavonoid Icaritin to enhance mesenchymal stem cell proliferation, migration and osteogenic differentiation

Mesenchymal stem cell (MSC) dysfunction has been implicated in the pathogenesis of osteoporosis. MSCs derived from osteoporotic subjects demonstrate significant impairment in proliferation, adhesion and chemotaxis, and osteogenic differentiation, leading to reduced functional bone-forming osteoblasts and ultimately nett bone loss and osteoporosis. Epimedium herbs and its active compound Icaritin (ICT) have been used in Chinese ethnopharmacology for the treatment of metabolic bone diseases. Using an in-vitro cell culture model, we investigated the benefits of ICT treatment in enhancing MSC proliferation, migration and osteogenic differentiation, and provide novel data to describe its mechanism of action. ICT enhances MSC proliferation, chemotaxis to stromal cell-derived factor-1 (SDF-1) and osteogenic differentiation through the activation of signal transduction activator transcription factor 3 (STAT-3), with a consequential up-regulation in the expression and activity of cysteine (C)-X-C motif chemokine receptor 4 (CXCR4). These findings provide a strong basis for future clinical studies to confirm the therapeutic potential of ICT for the prevention and treatment of osteoporosis and fragility fractures.

17β-estradiol improves the efficacy of exploited autologous bone marrow-derived mesenchymal stem cells in non-union radial defect healing: A rabbit model

Exploiting mesenchymal stem cells (MSCs) appears to be an appealing alternative to the traditional clinical approach in the treatment of non-union bone defects. It has been shown that 17β-estradiol improves the osteogenesis and proliferation potential of the MSCs via estrogen receptors. We investigated the effect of 17β-estradiol on exploiting autologous BMSCs (bone marrow-derived MSCs) for the purpose of healing of radial non-union segmental defect in rabbit. Twenty rabbits were divided into 4 experimental groups: 1. Control group; 2. MSC treatment group; 3. 17β-estradiol (E2) treatment group; and 4. E2+MSC treatment group. Isolated BMSCs were seeded in a critical-sized defect on radial mid-diaphysis that was filled with autologous fibrin clot differently in 4 groups: 1. intact fibrin clot (control); 2. Fibrin clot containing MSCs; 3. Estradiol; and 4. E₂ and MSCs. Defect healing was assessed by radiological (week 0, 2, 4, 6, 8 and 10) and histopathological evaluation (week 10). Radiological evaluation data demonstrated that quantities for the E2+MSC group were significantly the greatest in comparison with the other groups at week 4 to 10 inclusive. Moreover, Histopathological evaluation indicated that the E2+MSC group had the highest score which was significantly greater than the E2 group and the control group (P<0.05). In-vivo application of in situ 17β-estradiol provides the seeded BMSCs with improved osteogenic capacity in tandem with an accelerated rate of bone healing. This obviously more qualified approach that yields in a shorter time appears to be promising for the future cell-based clinical treatments of the non-union bone fractures. Exploiting mesenchymal stem cells (MSCs) appears to be an appealing alternative to the traditional clinical approach in the treatment of non-union bone defects. It has been shown that 17β-estradiol improves the osteogenesis and proliferation potential of the MSCs via estrogen receptors. We investigated the effect of 17β-estradiol on exploiting autologous BMSCs (bone marrow-derived MSCs) for the purpose of healing of radial non-union segmental defect in rabbit. Twenty rabbits were divided into 4 experimental groups: 1. Control group; 2. MSC treatment group; 3. 17β-estradiol (E2) treatment group; and 4. E2+MSC treatment group. Isolated BMSCs were seeded in a critical-sized defect on the radial mid-diaphysis that was filled with autologous fibrin clot differently in 4 groups: 1. intact fibrin clot (control); 2. Fibrin clot containing MSCs; 3. Estradiol; and 4. E₂ and MSCs. Defect healing was assessed by radiological (week 0, 2, 4, 6, 8 and 10) and histopathological evaluation (week 10). Radiological evaluation data demonstrated that quantities for the E2+MSC group were significantly the greatest in comparison with the other groups at week 4 to 10 inclusive. Moreover, Histopathological evaluation indicated that the E2+MSC group had the highest score which was significantly greater than the E2 group and the control group (P<0.05). In-vivo application of in situ 17β-estradiol provides the seeded BMSCs with improved osteogenic capacity in tandem with an accelerated rate of bone healing. This obviously more efficient approach that yields in a shorter time appears to be promising for future cell-based clinical treatments of the non-union bone fractures.

Oestrogen retains human periodontal ligament stem cells stemness in long-term culture

Objectives

During long‐term culture, loss of stemness is observed which greatly restricts the application of human periodontal ligament stem cells (hPDLSCs) in tissue regeneration. Oestrogen (E2) was found to significantly enhance the proliferation and osteogenic differentiation capacity in mesenchymal stem cells. Therefore, in this study, we investigated effects of E2 on hPDLSCs stemness in long‐term culture.

Materials and methods

Effects of E2 on hPDLSCs stemness were systematically evaluated. To characterize underlying the mechanisms, its effects on PI3K/AKT signalling pathway were determined.

Results

Our results showed that E2 was able to enhance the proliferation, modify cell cycle, up‐regulate stemness‐related genes expression, promote osteogenic differentiation and elevate the positive rate of CD146 and STRO‐1 over 10 passages in hPDLSCs. Importantly, PI3K/AKT signing pathway might play a role in these effects.

Conclusions

These findings suggest that E2 retains hPDLSCs stemness in long‐term culture, which might enhance its application in tissue engineering.

Mesenchymal stem cell differentiation: Control by calcium-activated potassium channels

Mesenchymal stem cells (MSCs) are widely used in modern medicine for which understanding the mechanisms controlling their differentiation is fundamental. Ion channels offer novel insights to this process because of their role in modulating membrane potential and intracellular milieu. Here, we evaluate the contribution of calcium-activated potassium (K_Ca ) channels to the three main components of MSC differentiation: initiation, proliferation, and migration. First, we demonstrate the importance of the membrane potential (V_m ) and the apparent association of hyperpolarization with differentiation. Of K_Ca subtypes, most evidence points to activity of big-conductance channels in inducing initiation. On the other hand, intermediate-conductance currents have been shown to promote progression through the cell cycle. While there is no information on the role of K_Ca channels in migration of MSCs, work from other stem cells and cancer cells suggest that intermediate-conductance and to a lesser extent big-conductance channels drive migration. In all cases, these effects depend on species, tissue origin and lineage. Finally, we present a conceptual model that demonstrates how K_Ca activity could influence differentiation by regulating V_m and intracellular Ca²⁺ oscillations. We conclude that K_Ca channels have significant involvement in MSC differentiation and could potentially enable novel tissue engineering approaches and therapies.

17β-Oestradiol promotes differentiation of human embryonic stem cells into dopamine neurons via cross-talk between insulin-like growth factors-1 and oestrogen receptor β

Human embryonic stem cells (hESCs) can self‐renew and differentiate into all cell lineages. E2 is known to exhibit positive effects on embryo development. Although the importance of E2 in many physiological processes has been reported, to date few researchers have investigated the effects of E2 on hESCs differentiation. We studied the effects of E2 on dopamine (DA) neuron induction of hESCs and its related signalling pathways using the three‐stage protocol. In our study, 0.1 μM E2 were applied to hESCs‐derived human embryoid bodies (hEBs) and effects of E2 on neural cells differentiation were investigated. Protein and mRNA level assay indicated that E2 up‐regulated the expression of insulin‐like growth factors (IGF)‐1, ectoderm, neural precursor cells (NPC) and DA neuron markers, respectively. The population of hESC‐derived NPCs and DA neurons was increased to 92% and 93% to that of DMSO group, respectively. Furthermore, yield of DA neuron‐secreted tyrosine hydroxylase (TH) and dopamine was also increased. E2‐caused promotion was relieved in single inhibitor (ICI or JB1) group partly, and E2 effects were repressed more stronger in inhibitors combination (ICI plus JB1) group than in single inhibitor group at hEBs, hNPCs and hDA neurons stages. Owing to oestrogen receptors regulate multiple brain functions, when single or two inhibitors were used to treat neural differentiation stage, we found that oestrogen receptor (ER)β but not ERα is strongly repressed at the hNPCs and hDA neurons stage. These findings, for the first time, demonstrate the molecular cascade and related cell biology events involved in E2‐improved hNPC and hDA neuron differentiation through cross‐talk between IGF‐1 and ERβ in vitro.

Promising Therapeutic Strategies for Mesenchymal Stem Cell-Based Cardiovascular Regeneration: From Cell Priming to Tissue Engineering

The primary cause of death among chronic diseases worldwide is ischemic cardiovascular diseases, such as stroke and myocardial infarction. Recent evidence indicates that adult stem cell therapies involving cardiovascular regeneration represent promising strategies to treat cardiovascular diseases. Owing to their immunomodulatory properties and vascular repair capabilities, mesenchymal stem cells (MSCs) are strong candidate therapeutic stem cells for use in cardiovascular regeneration. However, major limitations must be overcome, including their very low survival rate in ischemic lesion. Various attempts have been made to improve the poor survival and longevity of engrafted MSCs. In order to develop novel therapeutic strategies, it is necessary to first identify stem cell modulators for intracellular signal triggering or niche activation. One promising therapeutic strategy is the priming of therapeutic MSCs with stem cell modulators before transplantation. Another is a tissue engineering-based therapeutic strategy involving a cell scaffold, a cell-protein-scaffold architecture made of biomaterials such as ECM or hydrogel, and cell patch- and 3D printing-based tissue engineering. This review focuses on the current clinical applications of MSCs for treating cardiovascular diseases and highlights several therapeutic strategies for promoting the therapeutic efficacy of MSCs in vitro or in vivo from cell priming to tissue engineering strategies, for use in cardiovascular regeneration.

Mechanisms of marrow adiposity and its implications for skeletal health

The bone marrow niche is composed of cells from hematopoietic and mesenchymal origin. Both require energy to power differentiation and these processes are intimately connected to systemic metabolic homeostasis. Glycolysis is the preferred substrate for mesenchymal stromal cells in the niche, although fatty acid oxidation and glutaminolysis are important during stage specific differentiation. Autophagy and lipophagy, in part triggered by adenosine monophosphate-activated protein kinase (AMPK), may also play an important but temporal specific role in osteoblast differentiation. Enhanced marrow adiposity is caused by clinical factors that are genetically, environmentally, and hormonally mediated. These determinants mediate a switch from the osteogenic to the adipogenic lineage. Preliminary evidence supports an important role for fuel utilization in those cell fate decisions. Although both the origin and function of the marrow adipocyte remain to be determined, and in some genetic mouse models high marrow adiposity may co-exist with greater bone mass, in humans changes in marrow adiposity are closely linked to adverse changes in skeletal metabolism. This supports an intimate relationship between bone and fat in the marrow. Future studies will likely shed more light on the relationship of cellular as well as whole body metabolism on the ultimate fate of bone marrow stromal cells.

Association of 17-β Estradiol with Adipose-Derived Stem Cells: New Strategy to Produce Functional Myogenic Differentiated Cells with a Nano-Scaffold for Tissue Engineering

The increased incidence of stress urinary incontinence (SUI) in postmenopausal women has been proposed to be associated with a reduction in the level of 17-β estradiol (E2). E2 has also been shown to enhance the multi-differentiation ability of adipose-derived stem cells (ASCs) in vitro. However, studies on the potential value of E2 for tissue engineering in SUI treatment are rare. In the present study, we successfully fabricated myogenically differentiated ASCs (MD-ASCs), which were seeded onto a Poly(l-lactide)/Poly(e-caprolactone) electrospinning nano-scaffold, and incorporated E2 into the system, with the aim of improving the proliferation and myogenic differentiation of ASCs. ASCs were collected from the inguinal subcutaneous fat of rats. The proliferation and myogenic differentiation of ASCs, as well as the nano-scaffold biocompatibility of MD-ASCs, with or without E2 supplementation, were investigated. We demonstrated that E2 incorporation enhanced the proliferation of ASCs in vitro, and the most optimal concentration was 10-9 M. E2 also led to modulation of the MD-ASCs phenotype toward a concentrated type with smooth muscle-inductive medium. The expression of early (alpha-smooth muscle actin), mid (calponin), and late-stage (myosin heavy chain) contractile markers in MD-ASCs was enhanced by E2 during the different differentiation stages. Furthermore, the nano-scaffold was biocompatible with MD-ASCs, and cell proliferation was significantly enhanced by E2. Taken together, these results demonstrate that E2 can enhance the proliferation and myogenic differentiation of ASCs and can be used to construct a biocompatible cell/nano-scaffold. These scaffolds with desirable differentiation cells show promising applications for tissue engineering.

Panax notoginseng saponins mitigate ovariectomy-induced bone loss and inhibit marrow adiposity in rats

OBJECTIVE

Previous data have suggested that Panax notoginseng saponins (PNS) can prevent estrogen deficiency-induced bone loss by dual action: stimulation of new bone formation and inhibition of bone resorption. Marrow adipogenesis has been identified as a negative indicator of skeletal strength and integrity. This study assessed the effects of early PNS supplementation on bone microarchitecture preservation and marrow fat content in an ovariectomized rat model.

METHODS

Forty adult female Sprague-Dawley rats were randomly assigned to four equal groups for 12 weeks of treatment: (1) sham operation (SHAM) + vehicle; (2) ovariectomy (OVX) + vehicle; (3) OVX + 17β-estradiol (25 μg/kg); (4) OVX + PNS (300 mg/kg/d, PO). Marrow fat content of the femur was determined, using fat/water magnetic resonance imaging (MRI), at baseline and 6 and 12 weeks after operation. At the end of the experiment, bone turnover, trabecular microarchitecture, and marrow adipocytes were assessed by serum biomarkers, micro-computed tomography (micro-CT), and histopathology, respectively. The effects of PNS on adipocytic differentiation were reflected by expression levels of the adipogenic genes PPARγ2 and C/EBPα, as determined by reverse transcription-polymerase chain reaction.

RESULTS

Ovariectomized rats experienced remarkable increases in marrow fat content across time points, which were accompanied by elevated rate of bone turnover, global volumetric bone density, and trabecular microarchitecture deterioration. These OVX-induced pathological changes are reversible in that most of them could be mostly corrected upon 17β-estradiol treatment. PNS treatment significantly reduced marrow adipogenesis (adipocyte density, -27.2%; size, -22.7%; adipocyte volume-to-tissue volume ratio, -53.3%; all P < 0.01) and adipocyte marker gene expression, and prevented bone mass loss and microarchitecture deterioration. Moreover, PNS enhanced osteoblast activity but suppressed osteoclast turnover, as evidenced by decreased levels of serum C-terminal telopeptides of type I collagen and elevated levels of alkaline phosphatase.

CONCLUSIONS

PNS mitigates estrogen deficiency-induced deterioration of trabecular microarchitecture and suppresses marrow adipogenesis.

Effect of estrodiol on leptin receptors expression in regulating fat distribution and adipocyte genesis

OBJECTIVE

To examine how estradiol influence fat distribution and adipocyte genesis through regulating leptin function.

DESIGN AND METHODS

We randomized female SD rats into ovariectomy and sham group. After 14 weeks, we examined leptin receptor expression in perigenital, mesenteric and subcutaneous adipose tissues and leptin in serum. We further introduced mesenchymal stem cells (MSCs) to figure out the effect of 17-β estradiol on expression of leptin receptors (OBRb and OBRa), leptin and PPARγ2.

RESULTS

Weight and Lee's index was both significantly higher in ovariectomized group than sham group (p < 0.001). The interaction of serum E2 and leptin was negatively correlated with body weight. Expression of leptin receptor protein was extremely upregulated in ovariectomized group in perigenital and mesenteric fat. Both estradiol and leptin upregulated mRNA expression of OBRb, and created a dose-dependent decreasing manner in MSCs. Higher doses of estradiol (10(-7)-10(-5) M) inhibited adipogenic markers mRNA expression of leptin and PPARγ2, but low doses promoted leptin expression.

CONCLUSIONS

In ovariectomized rats, low level of serum estradiol may change body composition and promote adipocyte genesis through affecting leptin function.

17β-estradiol differently affects osteogenic differentiation of mesenchymal stem/stromal cells from adipose tissue and bone marrow

Adipose-derived and bone marrow stem/stromal cells (ASCs and BMSCs) have been often compared for their application in regenerative medicine, and several factors sustaining their differentiation and efficacy have been investigated. 17 β-estradiol (E2) has been reported to influence some functions of progenitor cells. Here we studied the effects of 10 and 100nM E2 on ASC and BMSC vitality, proliferation and differentiation towards osteogenic and adipogenic lineages. E2 did not modulate ASC and BMSC vitality and growth rate, while the hormone produced a pro-adipogenic effect on both mesenchymal stem/stromal cells (MSCs). In particular, the synergy between 7-day pre-treatment and 100nM E2 led to the most evident result, increasing lipid vacuoles formation in ASCs and BMSCs of +44% and +82%, respectively. Despite the fact that E2 did not alter collagen deposition of osteo-induced MSCs, we observed a different modulation of ASC and BMSC alkaline phosphatase (ALP) activity. Indeed, this osteogenic marker was always enhanced by 17 β-estradiol in BMSCs, and 7-day pre-treatment with 100nM E2 increased it of about 70%. In contrast, E2 weakened ASC osteogenic potential, reducing their ALP activity of about 20%, with the most evident effect on ASCs isolated from pre-menopausal women (-30%). Finally, we identified an estrogen receptor α (ERα) variant of about 37kDa expressed in both MSCs. Interestingly, adipogenic stimuli drastically reduced its expression, while osteogenic ones mildly increased this isoform in BMSCs only. In conclusion, E2 positively affected the adipogenic process of both MSCs while it favored osteogenic induction in BMSCs only, and both mesenchymal progenitors expressed a novel 37kDa ER-α variant whose expression was modulated during differentiation.

miR-26b-3p Regulates Human Umbilical Cord-Derived Mesenchymal Stem Cell Proliferation by Targeting Estrogen Receptor

Human umbilical cord-derived mesenchymal stem cells (hUC-MSC) have been considered as promising candidates for cell-based regeneration medicine. However, the application was limited to its poor in vitro proliferation ability against the huge demand of cells. MicroRNA plays important roles in the regulation of cell proliferation, apoptosis, and differentiation. The objective of this study is to explore the roles of miRNAs in regulating the in vitro proliferation of hUC-MSC and unveil their possible mechanism. In this study, we found that miR-26b-3p was significantly upregulated during serial in vitro passage of hUC-MSC and was correlated with cellular senescence and cell cycle genes. The overexpression of miR-26b-3p greatly inhibited the proliferation of hUC-MSC in vitro, which is indicated by 5-ethynyl-2'-deoxyuridine (EdU) incorporation assay, cell cycle, and cell growth curve analyses. miR-26b-3p suppression partly rescued this phenotype by maintaining its proliferation ability in vitro. For mechanism studies, we predicted and validated that miR-26b-3p suppresses estrogen receptor 1 (ESR1) expression by directly binding to the coding sequence (CDS) region of its message RNA (mRNA), thus subsequently changing the expression of its downstream effector Cyclin D1. In conclusion, we found that miR-26b-3p played an important role in the regulation of hUC-MSC proliferation in vitro by targeting the ESR-CCND1 pathway.

Ovariectomized Rats with Established Osteopenia have Diminished Mesenchymal Stem Cells in the Bone Marrow and Impaired Homing, Osteoinduction and Bone Regeneration at the Fracture Site

We investigated deleterious changes that take place in mesenchymal stem cells (MSC) and its fracture healing competence in ovariectomy (Ovx)-induced osteopenia. MSC from bone marrow (BM) of ovary intact (control) and Ovx rats was isolated. (99m)Tc-HMPAO (Technitium hexamethylpropylene amine oxime) labeled MSC was systemically transplanted to rats and fracture tropism assessed by SPECT/CT. PKH26 labeled MSC (PKH26-MSC) was bound in scaffold and applied to fracture site (drill-hole in femur metaphysis). Osteoinduction was quantified by calcein binding and microcomputed tomography. Estrogen receptor (ER) antagonist, fulvestrant was used to determine ER dependence of osteo-induction by MSC. BM-MSC number was strikingly reduced and doubling time increased in Ovx rats compared to control. SPECT/CT showed reduced localization of (99m)Tc-HMPAO labeled MSC to the fracture site, 3 h post-transplantation in Ovx rats as compared with controls. Post-transplantation, Ovx MSC labeled with PKH26 (Ovx PKH26-MSC) localized less to fracture site than control PKH26-MSC. Transplantation of either control or Ovx MSC enhanced calcein binding and bone volume at the callus of control rats over placebo group however Ovx MSC had lower efficacy than control MSC. Fulvestrant blocked osteoinduction by control MSC. When scaffold bound MSC was applied to fracture, osteoinduction by Ovx PKH26-MSC was less than control PKH26-MSC. In Ovx rats, control MSC/E2 treatment but not Ovx MSC showed osteoinduction. Regenerated bone was irregularly deposited in Ovx MSC group. In conclusion, Ovx is associated with diminished BM-MSC number and its growth, and Ovx MSC displays impaired engraftment to fracture and osteoinduction besides disordered bone regeneration.

Hormonal regulation of hematopoietic stem cells and their niche: a focus on estrogen

Self-renewal and differentiation are hallmarks of stem cells and controlled by various intrinsic and extrinsic factors. Increasing evidence indicates that estrogen (E2), the primary female sex hormone, is involved in regulating the proliferation and lineage commitment of adult and pluripotent stem cells as well as modulating the stem cell niche. Thus, a detailed understanding of the role of E2 in behavior of stem cells may help to improve their therapeutic potential. Recently, it has been reported that E2 promotes cell cycle activity of hematopoietic stem and progenitor cells and induces them to megakaryocyte-erythroid progenitors during pregnancy. This study paves the way towards a previously unexplored endocrine mechanism that controls stem cell behavior. In this review, we will focus on the scientific findings regarding the regulatory effects of E2 on the hematopoietic system including its microenvironment.

Protective effect of 17β-estradiol on serum deprivation-induced apoptosis and oxidative stress in bone marrow-derived mesenchymal stem cells

Stem cell transplantation has indicated great promise for cell therapy in a wide range of diseases, but poor and insufficient viability of cells within damaged tissues has limited its potential therapeutic effects. 17 β-Estradiol (E2) is a steroid hormone that plays an important role in expression of many genes and regulating proliferation, viability, and intracellular redox status in different cell types. In this study, we aimed to assess the effect of E2 on bone marrow-derived mesenchymal stem cells (BM-MSCs). Apoptosis was induced by serum deprivation (SD), and cells were exposed to E2 in the presence or absence of serum for varying periods of time, after which cell viability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Expression of proapoptotic and antiapoptotic proteins after exposure to E2 was examined by Western blotting. The ability of E2 to prevent reactive oxygen species (ROS) production was also measured. The results indicated that E2 significantly enhanced the viability of the cells and protected BM-MSCs against SD-induced overproduction of ROS. It could reduce lipid peroxidation, total antioxidant power, and also Bax/Bcl-2 ratio as well as expression of caspase-3. Taken together, our data support that E2 treatment protects BM-MSCs against SD-induced damage by regulating ROS production and upregulation of antiapoptotic/proapoptotic proteins ratio.

Icariin prevents ovariectomy-induced bone loss and lowers marrow adipogenesis

OBJECTIVE

Icariin prevents bone loss by stimulating new bone formation and by inhibiting bone resorption. However, less is known about how icariin affects marrow adiposity. This lack of information is a vital problem, as the degree of marrow adipogenesis may be an alternative indicator of the severity of osteoporosis in relation to the degree of osteogenesis and osteoblastogenesis. To explore this question, we tested the effects of icariin on bone mineral density (BMD) and marrow fat content in a rat model of postmenopausal osteoporosis.

METHODS

Thirty-six 3-month-old female Sprague-Dawley rats were randomly assigned to one of the following treatment groups: sham operation, ovariectomized controls, and ovariectomized rats treated orally with either 17β-estradiol or icariin for 12 weeks. BMD and marrow fat fraction were dynamically measured on weeks 0, 6, and 12. After 12 weeks of treatment, serum 17β-estradiol and bone biomarker levels were measured, and marrow adipocytes were quantitatively evaluated by histopathology.

RESULTS

Ovariectomized controls experienced a marked increase in fat fraction over time, with increases of 40% between weeks 0 and 6 and 69.4% between weeks 6 and 12 (P < 0.001). Marrow adiposity in ovariectomized controls was dramatically higher than that in sham rats on week 6; however, a reduction in BMD was detected in ovariectomized rats on week 12 (P < 0.001). Ovariectomized rats had levels of serum alkaline phosphatase and serum C-terminal telopeptide of type I collagen that were 49.4% and 67.2% higher, respectively, than those of sham rats (P < 0.001). The density, size, and volume of marrow adipocytes in ovariectomized controls were 57.3%, 29.5%, and 163% higher, respectively, than those in sham rats. Early icariin treatment decreased bone biomarker levels, inhibited bone degeneration, and restored marrow fat infiltration and adipocyte parameters to the levels observed in sham rats. Overall, the osteoprotective effect of icariin was comparable with that of 17β-estradiol; however, icariin did not produce uterine estrogenicity.

CONCLUSIONS

Early icariin treatment restores marrow adiposity in the estrogen-deficient rat model.

Effects of the endocrine-disrupting chemical DDT on self-renewal and differentiation of human mesenchymal stem cells

BACKGROUND

Although the global use of the endocrine-disrupting chemical DDT has decreased, its persistence in the environment has resulted in continued human exposure. Accumulating evidence suggests that DDT exposure has long-term adverse effects on development, yet the impact on growth and differentiation of adult stem cells remains unclear.

OBJECTIVES

Human mesenchymal stem cells (MSCs) exposed to DDT were used to evaluate the impact on stem cell biology.

METHODS

We assessed DDT-treated MSCs for self-renewal, proliferation, and differentiation potential. Whole genome RNA sequencing was performed to assess gene expression in DDT-treated MSCs.

RESULTS

MSCs exposed to DDT formed fewer colonies, suggesting a reduction in self-renewal potential. DDT enhanced both adipogenic and osteogenic differentiation, which was confirmed by increased mRNA expression of glucose transporter type 4 (GLUT4), lipoprotein lipase (LpL), peroxisome proliferator-activated receptor gamma (PPARγ), leptin, osteonectin, core binding factor 1 (CBFA1), and FBJ murine osteosarcoma viral oncogene homolog (c-Fos). Expression of factors in DDT-treated cells was similar to that in estrogen-treated MSCs, suggesting that DDT may function via the estrogen receptor (ER)-mediated pathway. The coadministration of ICI 182,780 blocked the effects of DDT. RNA sequencing revealed 121 genes and noncoding RNAs to be differentially expressed in DDT-treated MSCs compared with controls cells.

CONCLUSION

Human MSCs provide a powerful biological system to investigate and identify the molecular mechanisms underlying the effects of environmental agents on stem cells and human health. MSCs exposed to DDT demonstrated profound alterations in self-renewal, proliferation, differentiation, and gene expression, which may partially explain the homeostatic imbalance and increased cancer incidence among those exposed to long-term EDCs.

Effect of 17β-estradiol on mediators involved in mesenchymal stromal cell trafficking in cell therapy of diabetes

BACKGROUND AIMS

Mesenchymal stromal cells (MSCs) have shown great promise for cell therapy of a wide range of diseases such as diabetes. However, insufficient viability of transplanted cells reaching to damaged tissues has limited their potential therapeutic effects. Expression of estrogen receptors on stem cells may suggest a role for 17β-estradiol (E2) in regulating some functions in these cells. There is evidence that E2 enhances homing of stem cells. Induction of hypoxia-inducible factor-1α (HIF-1α) by E2 and the profound effect of HIF-1α on migration of cells have previously been demonstrated. We investigated the effect of E2 on major mediators involved in trafficking and subsequent homing of MSCs both in vitro and in vivo in diabetic rats.

METHODS

E2 has been selected to improve the poor migration capacity of MSCs toward sites of injury. MSCs were incubated with different concentrations of E2 for varying periods of time to investigate whether estradiol treatment could be effective to enhance the efficiency of MSC transplantation.

RESULTS

E2 significantly enhanced the viability of the cells that were blocked by ICI 182,780 (estrogen receptor antagonist). E2 also increased HIF-1α, CXC chemokine receptor 4 and C-C chemokine receptor 2 protein and messenger RNA levels measured by Western blot and reverse transcription-polymerase chain reaction. The enzymatic activity of matrix metalloproteinase 2 and metalloproteinase 9 was elevated in E2-treated cells through the use of gelatin zymography. Finally, the improved migration capacity of E2-treated MSCs was evaluated with the use of a Boyden chamber and in vivo migration assays.

CONCLUSIONS

Our data support that conditioning of MSCs with E2 promotes migration of cells in cultured MSCs in vitro and in a diabetic rat model in vivo through regulation of major mediators of cell trafficking.

Age influence on stromal vascular fraction cell yield obtained from human lipoaspirates

BACKGROUND AIMS

The adipose stromal vascular fraction (SVF) is a heterogeneous population of mononuclear cells that includes approximately 1-10% mesenchymal stromal cells. These SVF cells can be freshly obtained from human lipo-aspirates and represent and ideal candidate for regenerative medicine applications. In the present study, we analyzed the SVF yield as a function of the patient's age.

METHODS

Adipose tissue samples from 52 informed subjects (all women) were processed by means of an innovative point-of-care technology for SVF isolation (GID platform). After enzymatic dissociation of adipose tissue and SVF pellet resuspension, we measured the concentration of mononucleated cells as well as other cell quality analyses on the cell suspension obtained. We then calculated the cell yield as total nucleated cells per milliliter of dry adipose processed.

RESULTS

The mean SVF yield obtained was 7.19 × 10(5) ± 2.11 × 10(5) total nucleated cells per milliliter of adipose tissue. Our results show that there is a clear statistically significant decline in SVF cell yield with increasing age.

CONCLUSIONS

Because all samples were obtained from the same donor area and the isolation technique used was the same in all cases, we conclude that the SVF cell yield in women is affected by patient age. Specific age-related factors should be analyzed in the future to explain these results.

10(-7) m 17β-oestradiol enhances odonto/osteogenic potency of human dental pulp stem cells by activation of the NF-κB pathway

OBJECTIVES

Oestrogen has been proven to significantly enhance osteogenic potency, while oestrogen deficiency usually leads to impaired osteogenic differentiation of mesenchymal stem cells. However, little is known concerning direct effects of oestrogen on differentiation of human dental pulp stem cells (DPSCs).

MATERIALS AND METHODS

In this study, human DPSCs were isolated and treated with 10(-7)  m 17β-oestradiol (E2). Alkaline phosphatase (ALP) assay and alizarin red staining were performed.

RESULTS

Alkaline phosphatase and alizarin red showed that E2 treatment significantly enhanced ALP activity and mineralization ability of DPSCs, but had no effect on cell proliferation. Real-time RT-PCR and western blot assay demonstrated that odonto/osteogenic markers (ALP, RUNX2/RUNX2, OSX/OSX, OCN/OCN and DSPP/DSP) were significantly upregulated in the cells after E2 treatment. Moreover, phosphorylation of cytoplasmic IκBα/P65 and expression of nuclear P65 were enhanced in a time-dependent manner following E2 treatment, suggesting activation of NF-κB signaling. Conversely, inhibition of the NF-κB pathway suppressed E2-mediated upregulation of odonto/osteogenic markers, indicating that the NF-κB pathway was pivotal for E2-mediated differentiation.

CONCLUSION

These findings provide evidence that 10(-7)  m 17β-oestradiol promoted odonto/osteogenic differentiation of human DPSCs via activation of the NF-κB signaling pathway.

Estrogen receptor α mediates proliferation of osteoblastic cells stimulated by estrogen and mechanical strain, but their acute down-regulation of the Wnt antagonist Sost is mediated by estrogen receptor β

Mechanical strain and estrogens both stimulate osteoblast proliferation through estrogen receptor (ER)-mediated effects, and both down-regulate the Wnt antagonist Sost/sclerostin. Here, we investigate the differential effects of ERα and -β in these processes in mouse long bone-derived osteoblastic cells and human Saos-2 cells. Recruitment to the cell cycle following strain or 17β-estradiol occurs within 30 min, as determined by Ki-67 staining, and is prevented by the ERα antagonist 1,3-bis(4-hydroxyphenyl)-4-methyl-5-[4-(2-piperidinylethoxy)phenol]-1H-pyrazole dihydrochloride. ERβ inhibition with 4-[2-phenyl-5,7-bis(trifluoromethyl)pyrazolo[1,5-β]pyrimidin-3-yl] phenol (PTHPP) increases basal proliferation similarly to strain or estradiol. Both strain and estradiol down-regulate Sost expression, as does in vitro inhibition or in vivo deletion of ERα. The ERβ agonists 2,3-bis(4-hydroxyphenyl)-propionitrile and ERB041 also down-regulated Sost expression in vitro, whereas the ERα agonist 4,4′,4″-[4-propyl-(1H)-pyrazol-1,3,5-triyl]tris-phenol or the ERβ antagonist PTHPP has no effect. Tamoxifen, a nongenomic ERβ agonist, down-regulates Sost expression in vitro and in bones in vivo. Inhibition of both ERs with fulvestrant or selective antagonism of ERβ, but not ERα, prevents Sost down-regulation by strain or estradiol. Sost down-regulation by strain or ERβ activation is prevented by MEK/ERK blockade. Exogenous sclerostin has no effect on estradiol-induced proliferation but prevents that following strain. Thus, in osteoblastic cells the acute proliferative effects of both estradiol and strain are ERα-mediated. Basal Sost down-regulation follows decreased activity of ERα and increased activity of ERβ. Sost down-regulation by strain or increased estrogens is mediated by ERβ, not ERα. ER-targeting therapy may facilitate structurally appropriate bone formation by enhancing the distinct ligand-independent, strain-related contributions to proliferation of both ERα and ERβ.

Current concepts in stem cell therapy for articular cartilage repair

INTRODUCTION

Hyaline articular cartilage is the connective tissue responsible for frictionless joint movement. Its degeneration ultimately results in complete loss of joint function in the late stages of osteoarthritis. Intrinsic repair is compromised, and cartilage tissue regeneration is difficult. However, new options are available to repair cartilage tissue by applying ESCs, MSCs and CPCs.

AREAS COVERED

In this review, the authors shed light on the different concepts currently under investigation for cartilage repair.

EXPERT OPINION

So far, there is no way to derive a chondrogenic lineage from stem cells that forms functional hyaline cartilage tissue in vivo. One alternative might be to enhance the chondrogenic potential of repair cells, which are already present in diseased cartilage tissue. CPCs found in diseased cartilage tissue in situ are biologically driven toward the osteochondrogenic lineage and can be directed toward chondrogenesis at least in vitro.