Telomerase activity promotes osteoblast differentiation by modulating IGF-signaling pathway

Senescence of skeletal stem cells and their contribution to age-related bone loss

Human aging is linked to bone loss, resulting in bone fragility and an increased risk of fractures. This is primarily due to an age-related decline in the function of bone-forming osteoblastic cells and accelerated cellular senescence within the bone microenvironment. Here, we provide a detailed discussion of the hypothesis that age-related defective bone formation is caused by senescence of skeletal stem cells, as they are the main source of bone forming osteoblastic cells and influence the composition of bone microenvironment. Furthermore, this review discusses potential strategies to target cellular senescence as an emerging approach to treat age-related bone loss.

Kaempferol: Paving the path for advanced treatments in aging-related diseases

Aging-related diseases (ARDs) are a major global health concern, and the development of effective therapies is urgently needed. Kaempferol, a flavonoid found in several plants, has emerged as a promising candidate for ameliorating ARDs. This comprehensive review examines Kaempferol's chemical properties, safety profile, and pharmacokinetics, and highlights its potential therapeutic utility against ARDs. Kaempferol's therapeutic potential is underpinned by its distinctive chemical structure, which confers antioxidative and anti-inflammatory properties. Kaempferol counteracts reactive oxygen species (ROS) and modulates crucial cellular pathways, thereby combating oxidative stress and inflammation, hallmarks of ARDs. Kaempferol's low toxicity and wide safety margins, as demonstrated by preclinical and clinical studies, further substantiate its therapeutic potential. Compelling evidence supports Kaempferol's substantial potential in addressing ARDs through several mechanisms, notably anti-inflammatory, antioxidant, and anti-apoptotic actions. Kaempferol exhibits a versatile neuroprotective effect by modulating various proinflammatory signaling pathways, including NF-kB, p38MAPK, AKT, and the β-catenin cascade. Additionally, it hinders the formation and aggregation of beta-amyloid protein and regulates brain-derived neurotrophic factors. In terms of its anticancer potential, kaempferol acts through diverse pathways, inducing apoptosis, arresting the cell cycle at the G2/M phase, suppressing epithelial-mesenchymal transition (EMT)-related markers, and affecting the phosphoinositide 3-kinase/protein kinase B signaling pathways. Subsequent studies should focus on refining dosage regimens, exploring innovative delivery systems, and conducting comprehensive clinical trials to translate these findings into effective therapeutic applications.

Effect of RNA-binding proteins on osteogenic differentiation of bone marrow mesenchymal stem cells

Tissue regeneration mediated by mesenchymal stem cells (MSCs) is an ideal way to repair bone defects. RNA-binding proteins (RBPs) can affect cell function through post-transcriptional regulation. Exploring the role of RBPs in the process of osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) is helpful to find a key method to promote the osteogenic efficiency of BMSCs. By reviewing the literature, we obtained a differentially expressed mRNA dataset during the osteogenic differentiation of BMSCs and a human RBP dataset. A total of 82 differentially expressed RBPs in the osteogenic differentiation of BMSCs were screened by intersection of the two datasets. Functional analysis showed that the differentially expressed RBPs were mainly involved in RNA transcription, translation and degradation through the formation of spliceosomes and ribonucleoprotein complexes. The top 15 RBPs determined by degree score were FBL, NOP58, DDX10, RPL9, SNRPD3, NCL, IFIH1, RPL18A, NAT10, EXOSC5, ALYREF, PA2G4, EIF5B, SNRPD1 and EIF6. The results of this study demonstrate that the expression of many RBPs changed during osteogenic differentiation of BMSCs.

Human Wharton's jelly-derived mesenchymal stromal cells promote bone formation in immunodeficient mice when administered into a bone microenvironment

BACKGROUND

Wharton's Jelly (WJ) Mesenchymal Stromal Cells (MSC) have emerged as an attractive allogeneic therapy for a number of indications, except for bone-related conditions requiring new tissue formation. This may be explained by the apparent recalcitrance of MSC,WJ to differentiate into the osteogenic lineage in vitro, as opposed to permissive bone marrow (BM)-derived MSCs (MSC,BM) that readily commit to bone cells. Consequently, the actual osteogenic in vivo capacity of MSC,WJ is under discussion.

METHODS

We investigated how physiological bone environments affect the osteogenic commitment of recalcitrant MSCs in vitro and in vivo. To this end, MSC of BM and WJ origin were co-cultured and induced for synchronous osteogenic differentiation in vitro using transwells. For in vivo experiments, immunodeficient mice were injected intratibially with a single dose of human MSC and bone formation was evaluated after six weeks.

RESULTS

Co-culture of MSC,BM and MSC,WJ resulted in efficient osteogenesis in both cell types after three weeks. However, MSC,WJ failed to commit to bone cells in the absence of MSC,BM's osteogenic stimuli. In vivo studies showed successful bone formation within the medullar cavity of tibias in 62.5% of mice treated with MSC, WJ. By contrast, new formed trabeculae were only observed in 25% of MSC,BM-treated mice. Immunohistochemical staining of human COXIV revealed the persistence of the infused cells at the site of injection. Additionally, cells of human origin were also identified in the brain, heart, spleen, kidney and gonads in some animals treated with engineered MSC,WJ (eMSC,WJ). Importantly, no macroscopic histopathological alterations, ectopic bone formation or any other adverse events were detected in MSC-treated mice.

CONCLUSIONS

Our findings demonstrate that in physiological bone microenvironment, osteogenic commitment of MSC,WJ is comparable to that of MSC,BM, and support the use of off-the-shelf allogeneic MSC,WJ products in bone repair and bone regeneration applications.

Insulin-like growth factor binding protein-3 induces senescence by inhibiting telomerase activity in MCF-7 breast cancer cells

Insulin-like growth factor binding protein-3 (IGFBP-3) has been known to inhibit cell proliferation and exert tumor-suppressing effects depending on the cell type. In this study, we aimed to show that IGFBP-3 induces cellular senescence via suppression of the telomerase activity, thereby inhibiting MCF-7 breast cancer cell proliferation. We found that the induction of IGFBP-3 in MCF-7 cells enhanced the loss of cell viability. Flow cytometry revealed a higher percentage of non-cycling cells among IGFBP-3-expressing cells than among controls. IGFBP-3 induction also resulted in morphological alterations, such as a flattened cytoplasm and increased granularity, suggesting that IGFBP-3 induces a senescence-like phenotype. The percentage of IGFBP-3 expressing cells with senescence-associated β-galactosidase activity was 3.4 times higher than control cells. Telomeric repeat amplification and real-time PCR showed that IGFBP-3 decreased telomerase activity by reducing the levels of the RNA component (hTR) and catalytic protein component with reverse transcriptase activity (hTERT) of telomerase in a dose-dependent manner. These results suggest that IGFBP-3 is a negative regulator of MCF-7 breast cancer cell growth by inducing senescence through telomerase suppression.

Identifying Biomarkers for Osteogenic Potency Assay Development

There has been extensive exploration of how cells may serve as advanced therapy medicinal products to treat skeletal pathologies. Osteoblast progenitors responsible for production of extracellular matrix that is subsequently mineralized during bone formation have been characterised as a rare bone marrow subpopulation of cell culture plastic adherent cells. Conveniently, they proliferate to form single-cell derived colonies of fibroblastoid cells, termed colony forming unit fibroblasts that can subsequently differentiate to aggregates resembling small areas of cartilage or bone. However, donor heterogeneity and loss of osteogenic differentiation capacity during extended cell culture have made the discovery of reliable potency assay biomarkers difficult. Nonetheless, functional osteoblast models derived from telomerised human bone marrow stromal cells have allowed extensive comparative analysis of gene expression, microRNA, morphological phenotypes and secreted proteins. This chapter highlights numerous insights into the molecular mechanisms underpinning osteogenic differentiation of multipotent stromal cells and bone formation, discussing aspects involved in the choice of useful biomarkers for functional attributes that can be quantitively measured in osteogenic potency assays.

Aging and aging-related diseases: from molecular mechanisms to interventions and treatments

Aging is a gradual and irreversible pathophysiological process. It presents with declines in tissue and cell functions and significant increases in the risks of various aging-related diseases, including neurodegenerative diseases, cardiovascular diseases, metabolic diseases, musculoskeletal diseases, and immune system diseases. Although the development of modern medicine has promoted human health and greatly extended life expectancy, with the aging of society, a variety of chronic diseases have gradually become the most important causes of disability and death in elderly individuals. Current research on aging focuses on elucidating how various endogenous and exogenous stresses (such as genomic instability, telomere dysfunction, epigenetic alterations, loss of proteostasis, compromise of autophagy, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, deregulated nutrient sensing) participate in the regulation of aging. Furthermore, thorough research on the pathogenesis of aging to identify interventions that promote health and longevity (such as caloric restriction, microbiota transplantation, and nutritional intervention) and clinical treatment methods for aging-related diseases (depletion of senescent cells, stem cell therapy, antioxidative and anti-inflammatory treatments, and hormone replacement therapy) could decrease the incidence and development of aging-related diseases and in turn promote healthy aging and longevity.

Aging of mesenchymal stem cell: machinery, markers, and strategies of fighting

Human mesenchymal stem cells (MSCs) are primary multipotent cells capable of differentiating into osteocytes, chondrocytes, and adipocytes when stimulated under appropriate conditions. The role of MSCs in tissue homeostasis, aging-related diseases, and cellular therapy is clinically suggested. As aging is a universal problem that has large socioeconomic effects, an improved understanding of the concepts of aging can direct public policies that reduce its adverse impacts on the healthcare system and humanity. Several studies of aging have been carried out over several years to understand the phenomenon and different factors affecting human aging. A reduced ability of adult stem cell populations to reproduce and regenerate is one of the main  contributors to the human aging process. In this context, MSCs senescence is a major challenge in front of cellular therapy advancement. Many factors, ranging from genetic and metabolic pathways to extrinsic factors through various cellular signaling pathways, are involved in regulating the mechanism of MSC senescence. To better understand and reverse cellular senescence, this review highlights the underlying mechanisms and signs of MSC cellular senescence, and discusses the strategies to combat aging and cellular senescence.

The Effect of Diabetes Mellitus on IGF Axis and Stem Cell Mediated Regeneration of the Periodontium

Periodontitis and diabetes mellitus (DM) are two of the most common and challenging health problems worldwide and they affect each other mutually and adversely. Current periodontal therapies have unpredictable outcome in diabetic patients. Periodontal tissue engineering is a challenging but promising approach that aims at restoring periodontal tissues using one or all of the following: stem cells, signalling molecules and scaffolds. Mesenchymal stem cells (MSCs) and insulin-like growth factor (IGF) represent ideal examples of stem cells and signalling molecules. This review outlines the most recent updates in characterizing MSCs isolated from diabetics to fully understand why diabetics are more prone to periodontitis that theoretically reflect the impaired regenerative capabilities of their native stem cells. This characterisation is of utmost importance to enhance autologous stem cells based tissue regeneration in diabetic patients using both MSCs and members of IGF axis.

HIF-1α and Pro-Inflammatory Signaling Improves the Immunomodulatory Activity of MSC-Derived Extracellular Vesicles

Despite the strong evidence for the immunomodulatory activity of mesenchymal stromal cells (MSCs), clinical trials have so far failed to clearly show benefit, likely reflecting methodological shortcomings and lack of standardization. MSC-mediated tissue repair is commonly believed to occur in a paracrine manner, and it has been stated that extracellular vesicles (EVs) secreted by MSCs (EVMSC) are able to recapitulate the immunosuppressive properties of parental cells. As a next step, clinical trials to corroborate preclinical studies should be performed. However, effective dose in large mammals, including humans, is quite high and EVs industrial production is hindered by the proliferative senescence that affects MSCs during massive cell expansion. We generated a genetically modified MSC cell line overexpressing hypoxia-inducible factor 1-alpha and telomerase to increase the therapeutic potency of EVMSC and facilitate their large-scale production. We also developed a cytokine-based preconditioning culture medium to prime the immunomodulatory response of secreted EVs (EV_MSC-T-HIF^c). We tested the efficacy of this system in vitro and in a delayed-type hypersensitivity mouse model. MSC-T with an HIF-1α-GFP lentiviral vector (MSC-T-HIF) can be effectively expanded to obtain large amounts of EVs without major changes in cell phenotype and EVs composition. EV_MSC-T-HIF^c suppressed the proliferation of activated T-cells more effectively than did EVs from unmodified MSC in vitro, and significantly blunted the ear-swelling response in vivo by inhibiting cell infiltration and improving tissue integrity. We have developed a long-lived EV source that secretes high quantities of immunosuppressive EVs, facilitating a more standard and cost-effective therapeutic product.

Insulin-like growth factor 1 of wild vertebrates in a life-history context

Broad variation in intra- and interspecific life-history traits is largely shaped by resource limitation and the ensuing allocation trade-offs that animals are forced to make. Insulin-like growth factor 1 (IGF-1), a growth-hormone-dependent peptide, may be a key player in the regulation of allocation processes. In laboratory animals, the effects of IGF-1 on growth- and development (positive), reproduction (positive), and longevity (negative) are well established. We here review the evidence on these effects in wild vertebrates, where animals are more likely to face resource limitation and other challenges. We point out the similarities and dissimilarities in patterns of IGF-1 functions obtained in these two different study settings and discuss the knowledge we need to develop a comprehensive picture of the role of IGF-1 in mediating life-history variation of wild vertebrates.

Cycloastragenol protects against glucocorticoid-induced osteogenic differentiation inhibition by activating telomerase

Glucocorticoid-induced osteoporosis (GIOP) that is mainly featured as low bone density and increased risk of fracture is prone to occur with the administration of excessive glucocorticoids. Cycloastragenol (CAG) has been verified to be a small molecule that activates telomerase. Studied showed that up-regulated telomerase was associated with promoting osteogeneic differentiation, so we explored whether CAG could promote osteogenic differentiation to protect against GIOP and telomerase would be the target that CAG exerted its function. Our results demonstrated that CAG prominently increased the ALP activity, mineralization, mRNA of runt-related transcription factor 2, osteocalcin, osteopontin, collagen type I in both MC3T3-E1 cells and dexamethasone (DEX)-treated MC3T3-E1 cells. CAG up-regulated telomerase reverse transcriptase and the protective effect of CAG was blocked by telomerase inhibitor TMPyP4. Moreover, CAG improved bone mineralization in DEX-induced bone damage in a zebrafish larvea model. Therefore, the study showed that CAG could alleviate the osteogenic differentiation inhibition induced by DEX in vitro and in vivo, and CAG might be considered as a candidate drug for the treatment of GIOP.

Mesenchymal Stem/Progenitor Cells: The Prospect of Human Clinical Translation

Mesenchymal stem/progenitor cells (MSCs) are key players in regenerative medicine, relying principally on their differentiation/regeneration potential, immunomodulatory properties, paracrine effects, and potent homing ability with minimal if any ethical concerns. Even though multiple preclinical and clinical studies have demonstrated remarkable properties for MSCs, the clinical applicability of MSC-based therapies is still questionable. Several challenges exist that critically hinder a successful clinical translation of MSC-based therapies, including but not limited to heterogeneity of their populations, variability in their quality and quantity, donor-related factors, discrepancies in protocols for isolation, in vitro expansion and premodification, and variability in methods of cell delivery, dosing, and cell homing. Alterations of MSC viability, proliferation, properties, and/or function are also affected by various drugs and chemicals. Moreover, significant safety concerns exist due to possible teratogenic/neoplastic potential and transmission of infectious diseases. Through the current review, we aim to highlight the major challenges facing MSCs' human clinical translation and shed light on the undergoing strategies to overcome them.

Improved therapeutics of modified mesenchymal stem cells: an update

Background

Mesenchymal stromal cells (MSCs) have attracted intense interest due to their powerful intrinsic properties of self-regeneration, immunomodulation and multi-potency, as well as being readily available and easy to isolate and culture. Notwithstanding, MSC based therapy suffers reduced efficacy due to several challenges which include unfavorable microenvironmental factors in vitro and in vivo.

Body

In the quest to circumvent these challenges, several modification techniques have been applied to the naïve MSC to improve its inherent therapeutic properties. These modification approaches can be broadly divided into two groups to include genetic modification and preconditioning modification (using drugs, growth factors and other molecules). This field has witnessed great progress and continues to gather interest and novelty. We review these innovative approaches in not only maintaining, but also enhancing the inherent biological activities and therapeutics of MSCs with respect to migration, homing to target site, adhesion, survival and reduced premature senescence. We discuss the application of the improved modified MSC in some selected human diseases. Possible ways of yet better enhancing the therapeutic outcome and overcoming challenges of MSC modification in the future are also elaborated.

Conclusion

The importance of prosurvival and promigratory abilities of MSCs in their therapeutic applications can never be overemphasized. These abilities are maintained and even further enhanced via MSC modifications against the inhospitable microenvironment during culture and transplantation. This is a turning point in MSC-based therapy with promising preclinical studies and higher future prospect.

Effects of chlorinated polyfluoroalkyl ether sulfonate in comparison with perfluoroalkyl acids on gene profiles and stemness in human mesenchymal stem cells

Chlorinated polyfluoroalkyl ether sulfonate (Cl-PFESA) is a novel alternative of perfluorooctane sulfonate (PFOS). While its health risks remain unknown, there is preliminary evidence of developmental toxicity. In the present study, human bone mesenchymal stem cells (hBMSCs) were used to evaluate the effects of Cl-PFESA at non-cytotoxic concentrations on molecular regulation and cellular function of stem cells compared to PFOS, perfluorohexane sulfonate (PFHxS) and perfluorooctanoic acid (PFOA). Gene profiles of hBMSCs exposed to 100 nM of Cl-PFESA and the other 3 perfluoroalkyl acids (PFAAs) correlated significantly with each other. A total of 261 genes were found to be affected by all 4 compounds. Functional annotation analysis revealed that osteoblast differentiation, ERK1/2, TGFβ and calcium signalling were interfered. Moreover, DUSP mRNA and P-SMAD protein, key factors in ERK and TGFβ/SMAD signaling, were decreased by Cl-PFESA. Furthermore, intracellular calcium image suggested that calcium transients were enhanced by Cl-PFESA with lower effective concentrations and more prolonged induction than PFOS and PFHxS. Immunofluorescence staining confirmed that the stemness marker CD44 was dose-dependently repressed by Cl-PFESA. In the osteogenic differentiation following exposure to 100 nM of Cl-PFESA, both mRNA and protein of RUNX2, a target of multiple osteogenic pathways, was depressed on differentiation day 7. Exposure to Cl-PFESA at human relevant concentrations during a vulnerable period before differentiation posed persistent effects on hBMSCs, with common or even stronger potency compared to PFAAs.

Experimental manipulation of telomere length: does it reveal a corner-stone role for telomerase in the natural variability of individual fitness?

Telomeres, the non-coding ends of linear chromosomes, are thought to be an important mechanism of individual variability in performance. Research suggests that longer telomeres are indicative of better health and increased fitness; however, many of these data are correlational and whether these effects are causal are poorly understood. Experimental tests are emerging in medical and laboratory-based studies, but these types of experiments are rare in natural populations, which precludes conclusions at an evolutionary level. At the crossroads between telomere length and fitness is telomerase, an enzyme that can lengthen telomeres. Experimental modulation of telomerase activity is a powerful tool to manipulate telomere length, and to look at the covariation of telomerase, telomeres and individual life-history traits. Here, we review studies that manipulate telomerase activity in laboratory conditions and emphasize the associated physiological and fitness consequences. We then discuss how telomerase's impact on ageing may go beyond telomere maintenance. Based on this overview, we then propose several research avenues for future studies to explore how individual variability in health, reproduction and survival may have coevolved with different patterns of telomerase activity and expression. Such knowledge is of prime importance to fully understand the role that telomere dynamics play in the evolution of animal ageing.This article is part of the theme issue 'Understanding diversity in telomere dynamics'.

Towards frailty biomarkers: Candidates from genes and pathways regulated in aging and age-related diseases

OBJECTIVE

Use of the frailty index to measure an accumulation of deficits has been proven a valuable method for identifying elderly people at risk for increased vulnerability, disease, injury, and mortality. However, complementary molecular frailty biomarkers or ideally biomarker panels have not yet been identified. We conducted a systematic search to identify biomarker candidates for a frailty biomarker panel.

METHODS

Gene expression databases were searched (http://genomics.senescence.info/genes including GenAge, AnAge, LongevityMap, CellAge, DrugAge, Digital Aging Atlas) to identify genes regulated in aging, longevity, and age-related diseases with a focus on secreted factors or molecules detectable in body fluids as potential frailty biomarkers. Factors broadly expressed, related to several "hallmark of aging" pathways as well as used or predicted as biomarkers in other disease settings, particularly age-related pathologies, were identified. This set of biomarkers was further expanded according to the expertise and experience of the authors. In the next step, biomarkers were assigned to six "hallmark of aging" pathways, namely (1) inflammation, (2) mitochondria and apoptosis, (3) calcium homeostasis, (4) fibrosis, (5) NMJ (neuromuscular junction) and neurons, (6) cytoskeleton and hormones, or (7) other principles and an extensive literature search was performed for each candidate to explore their potential and priority as frailty biomarkers.

RESULTS

A total of 44 markers were evaluated in the seven categories listed above, and 19 were awarded a high priority score, 22 identified as medium priority and three were low priority. In each category high and medium priority markers were identified.

CONCLUSION

Biomarker panels for frailty would be of high value and better than single markers. Based on our search we would propose a core panel of frailty biomarkers consisting of (1) CXCL10 (C-X-C motif chemokine ligand 10), IL-6 (interleukin 6), CX3CL1 (C-X3-C motif chemokine ligand 1), (2) GDF15 (growth differentiation factor 15), FNDC5 (fibronectin type III domain containing 5), vimentin (VIM), (3) regucalcin (RGN/SMP30), calreticulin, (4) PLAU (plasminogen activator, urokinase), AGT (angiotensinogen), (5) BDNF (brain derived neurotrophic factor), progranulin (PGRN), (6) α-klotho (KL), FGF23 (fibroblast growth factor 23), FGF21, leptin (LEP), (7) miRNA (micro Ribonucleic acid) panel (to be further defined), AHCY (adenosylhomocysteinase) and KRT18 (keratin 18). An expanded panel would also include (1) pentraxin (PTX3), sVCAM/ICAM (soluble vascular cell adhesion molecule 1/Intercellular adhesion molecule 1), defensin α, (2) APP (amyloid beta precursor protein), LDH (lactate dehydrogenase), (3) S100B (S100 calcium binding protein B), (4) TGFβ (transforming growth factor beta), PAI-1 (plasminogen activator inhibitor 1), TGM2 (transglutaminase 2), (5) sRAGE (soluble receptor for advanced glycosylation end products), HMGB1 (high mobility group box 1), C3/C1Q (complement factor 3/1Q), ST2 (Interleukin 1 receptor like 1), agrin (AGRN), (6) IGF-1 (insulin-like growth factor 1), resistin (RETN), adiponectin (ADIPOQ), ghrelin (GHRL), growth hormone (GH), (7) microparticle panel (to be further defined), GpnmB (glycoprotein nonmetastatic melanoma protein B) and lactoferrin (LTF). We believe that these predicted panels need to be experimentally explored in animal models and frail cohorts in order to ascertain their diagnostic, prognostic and therapeutic potential.

Role of lncRNAs in aging and age-related diseases

Aging is progressive physiological degeneration and consequently declined function, which is linked to senescence on both cellular and organ levels. Accumulating studies indicate that long noncoding RNAs (lncRNAs) play important roles in cellular senescence at all levels-transcriptional, post-transcriptional, translational, and post-translational. Understanding the molecular mechanism of lncRNAs underlying senescence could facilitate interpretation and intervention of aging and age-related diseases. In this review, we describe categories of known and novel lncRNAs that have been involved in the progression of senescence. We also identify the lncRNAs implicated in diseases arising from age-driven degeneration or dysfunction in some representative organs and systems (brains, liver, muscle, cardiovascular system, bone pancreatic islets, and immune system). Improved comprehension of lncRNAs in the aging process on all levels, from cell to organismal, may provide new insights into the amelioration of age-related pathologies and prolonged healthspan.

IGFBP-3 plays an important role in senescence as an aging marker

Aging study requires aging markers to measure the degree of aging process. The aging markers such as senescence associated-β-galactosidase (SA-β-gal), lipofuscin, telomere, p53 and p16 have been known in aging study until now. Therefore, we investigated the role of genes and proteins related to aging in young, senescent and H₂O₂-induced old cells to develop a novel aging marker involved in aging mechanism. After cellular aging was compared in young, senescent and H₂O₂-induced old cells using SA-β-galactosidase staining assay, the expression level of genes and proteins in senescent and H₂O₂-induced old cells were compared and analyzed with those of young cells using RT-PCR, western blot and immunofluorescence staining. First of all, the senescent cells and the cells aged by H₂O₂ showed higher level of SA-β-galactosidase staining than young cells. In particular, the expression level of IGFBP-3 was decreased in senescent and H₂O₂-induced old cells compared with young cells. Moreover, the senescent and H2O2-induced old cells showed higher expression levels of p-PI3K, Akt-1, p-mTOR, p-FoxO1 and FoxO1 than young cells. Furthermore, the expression levels of p300, Ac-p53, p53, p-p21 and p16 were significantly increased in senescent and H₂O₂-induced cells compared to young cells. However, the expression level of SIRT-1 was decreased in senescent and H₂O₂-induced old cells compared to young cells. In conclusion, IGFBP-3 up-regulates PI3K/Akt/mTOR signaling pathway and down-regulates autophagy during cell aging. These results suggest that IGFBP-3 could play a key role in aging study as an important aging marker.

MicroRNA profiles of BMSCs induced into osteoblasts with osteoinductive medium

MicroRNA (miRNA) plays an important role in cell differentiation and functions as a regulator. Therefore, miRNA is important in the process of bone marrow mesenchymal stem cells (BMSCs) being induced into osteoblasts. In this study, mouse BMSCs were induced with osteoinductive medium, the indices related to osteoblastic differentiation were assayed, including alkaline phosphatase, the deposit of calcium and protein levels of osteocalcin. Using miRNA microarray and reverse transcription-quantitative polymerase chain reaction analyses, differentially expressed miRNAs in the cells, which were induced with osteoinductive medium, were selected and identified. The target genes of the differentially expressed miRNAs were then predicted using bioinformatics analysis. The results revealed that osteoinductive medium promoted osteoblastic differentiation of BMSCs, and let-7c-5p, miR-181c-3p, miR-3092-3p and miR-5132-3p were identified as differentially expressed miRNAs in the cells treated with osteoinductive medium for 14 and 21 days. Certain target genes and signal pathways related to osteoblastic differentiation of the four miRNAs were predicted. These findings indicated the four differently expressed miRNAs may be potential regulators of osteoblastic differentiation, providing a basis for further study on the regulation of miRNAs in the osteogenic differentiation of BMSCs.

Patients with Congenital Limb Anomaly Show Short Telomere, Shutdown of Telomerase and Deregulated Expression of Various Telomere-Associated Proteins in Peripheral Blood Mononuclear Cells-A Case Series

Congenital limb anomalies are outcome of improper bone formation during embryonic development when cells divide, differentiate with high rate. So, telomerase activity is essential to maintain telomere length for such highly dividing cells. Here, we report four cases of congenital limb anomalies with detailed structures of limbs along with other clinical manifestations of age less than two years. We compared telomere length, expression of telomerase and telomere-associated genes of Peripheral Blood Mononuclear Cells (PBMC) in patient and four age-matched normal individual. Patient-1 was diagnosed with congenital limb hypogenesis ectrodactyly sequence, an autosomal dominant disorder, showing absence of digits and fibula in upper and lower limb respectively. Both mother and grandmother of Patient-1 showed similar hypogenesis of limbs. Patient-2 showed bilateral clenched hand with arthrogryposis, microcephaly and holoprosencephaly. Both Patient-3 and Patient-4 has no radius in upper limb. Additionally, Paient-3 showed right sided orbital Space Occupying Lesion (SOL) and Paranasal Sinuses (PNS) whereas Patient-4 showed fused kidney with fanconi anaemia. Furthermore, all the patients showed shorter telomere length, inactive telomerase and de-regulated expression of telomere-associated proteins in PBMC compared with age-matched control group. So, we can conclude that congenital limb anomalies may be linked with telomeropathy and a study with large number of samples is required to firmly establish such association.

A compartmentalized phosphoinositide signaling axis at cilia is regulated by INPP5E to maintain cilia and promote Sonic Hedgehog medulloblastoma

Sonic Hedgehog (SHH) signaling at primary cilia drives the proliferation and progression of a subset of medulloblastomas, the most common malignant paediatric brain tumor. Severe side effects associated with conventional treatments and resistance to targeted therapies has led to the need for new strategies. SHH signaling is dependent on primary cilia for signal transduction suggesting the potential for cilia destabilizing mechanisms as a therapeutic target. INPP5E is an inositol polyphosphate 5-phosphatase that hydrolyses PtdIns(4,5)P₂ and more potently, the phosphoinositide (PI) 3-kinase product PtdIns(3,4,5)P₃. INPP5E promotes SHH signaling during embryonic development via PtdIns(4,5)P₂ hydrolysis at cilia, that in turn regulates the cilia recruitment of the SHH suppressor GPR161. However, the role INPP5E plays in cancer is unknown and the contribution of PI3-kinase signaling to cilia function is little characterized. Here, we reveal INPP5E promotes SHH signaling in SHH medulloblastoma by negatively regulating a cilia-compartmentalized PI3-kinase signaling axis that maintains primary cilia on tumor cells. Conditional deletion of Inpp5e in a murine model of constitutively active Smoothened-driven medulloblastoma slowed tumor progression, suppressed cell proliferation, reduced SHH signaling and promoted tumor cell cilia loss. PtdIns(3,4,5)P₃, its effector pAKT and the target pGSK3β, which when non-phosphorylated promotes cilia assembly/stability, localized to tumor cell cilia. The number of PtdIns(3,4,5)P₃/pAKT/pGSK3β-positive cilia was increased in cultured Inpp5e-null tumor cells relative to controls. PI3-kinase inhibition or expression of wild-type, but not catalytically inactive HA-INPP5E partially rescued cilia loss in Inpp5e-null tumor cells in vitro. INPP5E mRNA and copy number were reduced in human SHH medulloblastoma compared to other molecular subtypes and consistent with the murine model, reduced INPP5E was associated with improved overall survival. Therefore our study identifies a compartmentalized PtdIns(3,4,5)P₃/AKT/GSK3β signaling axis at cilia in SHH-dependent medulloblastoma that is regulated by INPP5E to maintain tumor cell cilia, promote SHH signaling and thereby medulloblastoma progression.

Skeletal stem cells and their contribution to skeletal fragility: senescence and rejuvenation

Age-related osteoporotic fractures are major health care problem worldwide and are the result of impaired bone formation, decreased bone mass and bone fragility. Bone formation is accomplished by skeletal stem cells (SSC) that are recruited to bone surfaces from bone marrow microenvironment. This review discusses targeting SSC to enhance bone formation and to abolish age-related bone fragility in the context of using stem cells for treatment of age-related disorders. Recent studies are presented that have demonstrated that SSC exhibit impaired functions during aging due to intrinsic senescence-related changes as well as the presence of senescent microenvironment. Also, a number of approaches aiming at increasing bone formation through targeting SSC and that include systemic SSC transplantation, systemic SSC targeting using aptamers or antibodies, use of therapeutic screteome and tissue engineering approaches will be presented and discussed.