Human Amnion-Derived Mesenchymal Stem Cells Protect Human Bone Marrow Mesenchymal Stem Cells against Oxidative Stress-Mediated Dysfunction via ERK1/2 MAPK Signaling

Tiron Has Negative Effects on Osteogenic Differentiation via Mitochondrial Dysfunction in Human Periosteum-Derived Cells

Tiron is a potent antioxidant that counters the pathological effects of reactive oxygen species (ROS) production due to oxidative stress in various cell types. We examined the effects of tiron on mitochondrial function and osteoblastic differentiation in human periosteum-derived cells (hPDCs). Tiron increased mitochondrial activity and decreased senescence-associated β-galactosidase activity in hPDCs; however, it had a detrimental effect on osteoblastic differentiation by reducing alkaline phosphatase (ALP) activity and alizarin red-positive mineralization, regardless of H₂O₂ treatment. Osteoblast-differentiating hPDCs displayed increased ROS production compared with non-differentiating hPDCs, and treatment with tiron reduced ROS production in the differentiating cells. Antioxidants decreased the rates of oxygen consumption and ATP production, which are increased in hPDCs during osteoblastic differentiation. In addition, treatment with tiron reduced the levels of most mitochondrial proteins, which are increased in hPDCs during culture in osteogenic induction medium. These results suggest that tiron exerts negative effects on the osteoblastic differentiation of hPDCs by causing mitochondrial dysfunction.

Human mesenchymal stem cell treatment of premature ovarian failure: new challenges and opportunities

Premature ovarian failure (POF) is one of the common disorders found in women leading to 1% female infertility. Clinical features of POF are hypoestrogenism or estrogen deficiency, increased gonadotropin level, and, most importantly, amenorrhea. With the development of regenerative medicine, human mesenchymal stem cell (hMSC) therapy brings new prospects for POF. This study aimed to describe the types of MSCs currently available for POF therapy, their biological characteristics, and their mechanism of action. It reviewed the latest findings on POF to provide the theoretical basis for further investigation and clinical therapy.

Comparison of Anti-Oxidative Effect of Human Adipose- and Amniotic Membrane-Derived Mesenchymal Stem Cell Conditioned Medium on Mouse Preimplantation Embryo Development

Oxidative stress is a major cause of damage to the quantity and quality of embryos produced in vitro. Antioxidants are usually supplemented to protect embryos from the suboptimal in vitro culture (IVC) environment. Amniotic membrane-derived mesenchymal stem cells (AMSC) have emerged as a promising regenerative therapy, and their paracrine factors with anti-oxidative effects are present in AMSC conditioned medium (CM). We examined the anti-oxidative potential of human AMSC-CM treatment during IVC on mouse preimplantation embryo development and antioxidant gene expression in the forkhead box O (FoxO) pathway. AMSC-CM (10%) was optimal for overall preimplantation embryo developmental processes and upregulated the expression of FoxOs and their downstream antioxidants in blastocysts (BL). Subsequently, compared to adipose-derived mesenchymal stem cell (ASC)-CM, AMSC-CM enhanced antioxidant gene expression and intracellular GSH levels in the BL. Total antioxidant capacity and SOD activity were greater in AMSC-CM than in ASC-CM. Furthermore, SOD and catalase were more active in culture medium supplemented with AMSC-CM than in ASC-CM. Lastly, the anti-apoptotic effect of AMSC-CM was observed with the regulation of apoptosis-related genes and mitochondrial membrane potential in BL. In conclusion, the present study established AMSC-CM treatment at an optimal concentration as a novel antioxidant intervention for assisted reproduction.

Human amnion-derived mesenchymal stem cells promote osteogenic differentiation of lipopolysaccharide-induced human bone marrow mesenchymal stem cells via ANRIL/miR-125a/APC axis

BACKGROUND AND AIM

Periodontitis is a chronic inflammatory disease inducing the absorption of alveolar bone and leading to tooth loss. Human amnion-derived mesenchymal stem cells (HAMSCs) have been used for studying inflammatory processes. This study aimed to explore the role of long noncoding RNA (lncRNA) antisense noncoding RNA in the INK4 locus (ANRIL) in HAMSC-driven osteogenesis in lipopolysaccharide (LPS)-induced human bone marrow mesenchymal stem cells (HBMSCs).

METHODS

The cells were incubated with a co-culture system. Reactive oxygen species (ROS) level and superoxide dismutase (SOD) activity were used to detect the oxidative stress level. Flow cytometry was performed to determine cell proliferation. The alkaline phosphatase (ALP) activity, Alizarin red assay, cell transfection, and rat mandibular defect model were used to evaluate the osteogenic differentiation. Quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR), Western blot analysis, dual-luciferase reporter assay, and immunofluorescence staining were used to evaluate the molecular mechanisms.

RESULTS

This study showed that HAMSCs promoted the osteogenesis of LPS-induced HBMSCs, while the ANRIL level in HBMSCs decreased during co-culture. ANRIL had no significant influence on the proliferation of LPS-induced HBMSCs. However, its overexpression inhibited the HAMSC-driven osteogenesis in vivo and in vitro, whereas its knockdown reversed these effects. Mechanistically, this study found that downregulating ANRIL led to the overexpression of microRNA-125a (miR-125a), and further contributed to the competitive binding of miR-125a and adenomatous polyposis coli (APC), thus significantly activating the Wnt/β-catenin pathway.

CONCLUSION

The study indicated that HAMSCs promoted the osteogenic differentiation of LPS-induced HBMSCs via the ANRIL/miR-125a/APC axis, and offered a novel approach for periodontitis therapy.

Mesenchymal Stem Cell Transplantation for the Treatment of Cognitive Frailty

As life expectancy increases, frailty and cognitive impairment have become major factors influencing healthy aging in elderly individuals. Frailty is a complicated clinical condition characterized by decreased physiological reserve and multisystem abnormalities. Cognitive frailty is a subtype of frailty that has aroused widespread concern among the scientific community and public health organizations. We herein review the pathogenesis of cognitive frailty, such as chronic inflammatory response, immunological hypofunction, imbalanced oxidative stress, reduced regenerative function, endocrine dysfunction, and energy metabolism disorder. Although existing interventions show some therapeutic effects, they do not meet the current clinical needs. To date, studies using stem cell technology for treating age-related diseases have achieved remarkable success. This suggests the possibility of applying stem cell treatment to cognitive frailty. We analyzed stem cell-based strategies for targeting anti-inflammation, antioxidation, regeneration, and immunoregulation using mesenchymal stem cells, as well as potential therapeutic targets for cognitive frailty. Based on this investigation, we propose a highly effective and low-cost stem cell-based replacement strategy. However, there is a lack of comprehensive research on the prospect of stem cell transplantation for improving cognitive frailty. In this review, we aim to provide the scientific background and a theoretical basis for testing cell therapy in future research.

Ganoderic Acid D Protects Human Amniotic Mesenchymal Stem Cells against Oxidative Stress-Induced Senescence through the PERK/NRF2 Signaling Pathway

Aging is an important risk factor in the occurrence of many chronic diseases. Senescence and exhaustion of adult stem cells are considered as a hallmark of aging in organisms. In this study, a senescent human amniotic mesenchymal stem cell (hAMSC) model subjected to oxidative stress was established in vitro using hydrogen peroxide. We investigated the effects of ganoderic acid D (GA-D), a natural triterpenoid compound produced from Ganoderma lucidum, on hAMSC senescence. GA-D significantly inhibited β-galactosidase (a senescence-associated marker) formation, in a dose-dependent manner, with doses ranging from 0.1 μM to 10 μM, without inducing cytotoxic side-effects. Furthermore, GA-D markedly inhibited the generation of reactive oxygen species (ROS) and the expression of p21 and p16 proteins, relieved the cell cycle arrest, and enhanced telomerase activity in senescent hAMSCs. Furthermore, GA-D upregulated the expression of phosphorylated protein kinase R- (PKR-) like endoplasmic reticulum kinase (PERK), peroxidase III (PRDX3), and nuclear factor-erythroid 2-related factor (NRF2) and promoted intranuclear transfer of NRF2 in senescent cells. The PERK inhibitor GSK2656157 and/or the NRF2 inhibitor ML385 suppressed the PERK/NRF2 signaling, which was activated by GA-D. They induced a rebound for the generation of ROS and β-galactosidase-positive cells and attenuated the differentiation capacity. These findings suggest that GA-D retards hAMSC senescence through activation of the PERK/NRF2 signaling pathway and may be a promising candidate for the discovery of antiaging agents.

Human amnion mesenchymal stem cells restore spermatogenesis in mice with busulfan-induced testis toxicity by inhibiting apoptosis and oxidative stress

Background

Before starting gonadotoxic therapies, cryopreservation of mature sperm has been proposed worldwide as a method for male fertility preservation and for enabling the conception of a healthy baby with assisted reproductive technology (ART); however, these technologies are not feasible for prepubertal boys and men with spermatogenic failure. Transplantation of mesenchymal stem cells has exhibited successful therapeutic benefits in restoring spermatogenesis via gonadal graft angiogenesis, transplanted cell clonogenesis, and disordered somatic compartment recovery. This study aimed to elucidate the fertility protective effects and the underlying mechanisms of human amnion mesenchymal stem cells (hAMSCs) against busulfan-induced testis toxicity.

Methods

An in vivo busulfan-induced testis toxicity mouse model and an in vitro busulfan-administered mouse Sertoli cell line were employed to evaluate the efficacy and mechanisms of hAMSC transplantation on male fertility preservation. The process of spermatogenesis was evaluated histologically, and the percentage of seminiferous tubules with vacuoles was evaluated by HE staining. Semen parameters were calculated by computer-assisted semen analysis. ELISA was employed to test the testosterone concentration and the levels of oxidative- and antioxidative-associated substances LDH, MDA, GR, SOD, GPx, and CAT. The rates of proliferation (Ki67), apoptosis (Annexin V), and ROS were measured by FACS. The fluorescence intensity of a marker of apoptosis (TUNEL) and a meiosis gene in spermatogenesis (SCP3) were detected by immunofluorescence assay. The expression of mRNA in germ cell-specific (GCS) genes (Dazl, Ddx4, and Miwi) and meiosis genes (Scp3, Cyclin A1, and Stra8) was tested by qPCR. The expression of antiapoptotic proteins (SURVIVIN and BCL2), apoptotic proteins (CASPASE3 and CASPASE9), GCS proteins (Dazl, Ddx4, and Miwi), and meiosis proteins (Scp3, Cyclin A1, and Stra8) was tested by western blotting.

Results

hAMSC transplantation following disruption by busulfan-induced testis toxicity restored spermatogenesis, elevating testosterone levels and enhancing testicular weight, size, and semen parameters in vivo. In addition, hAMSCs clearly ameliorated cell apoptosis, enhanced cell proliferation, repressed oxidative damage, and augmented oxidative defense in vivo and in vitro. Moreover, hAMSCs distinctly increased the expression of the GCS genes Dazl, Ddx4, and Miwi and the meiosis genes Scp3, Cyclin A1, and Stra8 in vivo.

Conclusions

hAMSCs might represent a promising tool for the use in regenerative medicine, as these cells can restore spermatogenesis in a busulfan-induced testis toxicity mouse model and facilitate activity in a busulfan-administered mouse Sertoli cell line by resisting apoptosis and oxidative stress.

LOXL2 from human amniotic mesenchymal stem cells accelerates wound epithelialization by promoting differentiation and migration of keratinocytes

In this study, we identified wound healing-related proteins secreted by human amniotic epithelial cells (hAECs) and human amniotic mesenchymal stem cells (hAMSCs). We observed increased migration and reduced proliferation and differentiation when keratinocytes were co-cultured in media conditioned by hAECs (hAECs-CM) and hAMSCs (hAMSCs-CM). Label-free mass spectrometry and bioinformatic analyses of the hAECs-CM and hAMSCs-CM proteome revealed several proteins associated with wound healing, angiogenesis, cellular differentiation, immune response and cell motility. The levels of the proteins related to wound healing, including CTHRC1, LOXL2 and LGALS1, were significantly higher in hAMSCs-CM than hAECs-CM. LOXL2 significantly enhanced in vitro keratinocyte migration and differentiation compared to CTHRC1 and LGALS1. Moreover, LOXL2 enhanced keratinocyte migration and differentiation by activating the JNK signaling pathway. We observed significant reduction in the in vitro migration and differentiation of keratinocytes when co-cultured with medium conditioned by LOXL2-silenced hAMSCs and when treated with 10 μM SP600125, a specific JNK inhibitor. Treatment with hAMSCs-CM and LOXL2 significantly accelerated wound healing in the murine skin wound model. These findings show that LOXL2 promotes wound healing by inducing keratinocyte migration and differentiation via a JNK signaling pathway.

Human amnion-derived mesenchymal stem cells promote osteogenic differentiation of human bone marrow mesenchymal stem cells via H19/miR-675/APC axis

Bone volume inadequacy is an emerging clinical problem impairing the feasibility and longevity of dental implants. Human bone marrow mesenchymal stem cells (HBMSCs) have been widely used in bone remodeling and regeneration. This study examined the effect of long noncoding RNAs (lncRNAs)-H19 on the human amnion-derived mesenchymal stem cells (HAMSCs)-droved osteogenesis in HBMSCs. HAMSCs and HBMSCs were isolated from abandoned amniotic membrane samples and bone marrow. The coculture system was conducted using transwells, and H19 level was measured by quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR). The mechanism was further verified. We here discovered that osteogenesis of HBMSCs was induced by HAMSCs, while H19 level in HAMSCs was increased during coculturing. H19 had no significant effect on the proliferative behaviors of HBMSCs, while its overexpression of H19 in HAMSCs led to the upregulated osteogenesis of HBMSCs in vivo and in vitro; whereas its knockdown reversed these effects. Mechanistically, H19 promoted miR-675 expression and contributed to the competitively bounding of miR-675 and Adenomatous polyposis coli (APC), thus significantly activating the Wnt/β-catenin pathway. The results suggested that HAMSCs promote osteogenic differentiation of HBMSCs via H19/miR-675/APC pathway, and supply a potential target for the therapeutic treatment of bone-destructive diseases.

Antioxidant Properties of Tonsil-Derived Mesenchymal Stem Cells on Human Vocal Fold Fibroblast Exposed to Oxidative Stress

The therapeutic potential of tonsil-derived mesenchymal stem cells (TMSCs) has been proved in several in vitro and in vivo models based on their antioxidative capacity. Oxidative stress is involved in the formation of vocal fold scars and the aging of vocal folds. However, few studies have examined the direct correlation between oxidative damage and reconstitution of extracellular matrix (ECM) in the vocal fold fibrosis. We, therefore, sought to investigate the impact of oxidative stress on cell survival and ECM production of human vocal fibroblasts (hVFFs) and the protective effects elicited by TMSCs against oxidative damages in hVFFs. hVFFs were exposed to different concentrations of tert-butyl hydroperoxide in the presence or absence of TMSCs. Cell viability and reactive oxygen species (ROS) production were assessed to examine the progression of oxidative stress in vitro. In addition, expression patterns of ECM-associated factors including various collagens were examined by real-time PCR and immunocytochemical analysis. We found that both cell viability and proliferation capacity of hVFFs were decreased following the exposure to tBHP in a dose-dependent manner. Furthermore, tBHP treatment induced the generation of ROS and reactive aldehydes, while it decreased endogenous activity of antioxidant enzymes in hVFF. Importantly, TMSCs could rescue these oxidative stress-associated damages of hVFFs. TMSCs also downregulated tBHP-mediated production of proinflammatory cytokines in hVFFs. In addition, coculture with TMSC could restore the endogenous matrix metalloproteinase (MMP) activity of hVFFs upon tBHP treatment and, in turn, reduce the oxidative stress-induced ECM accumulation in hVFFs. We have, therefore, shown that the changes in hVFF proliferative capacity and ECM gene expression induced by oxidative stress are consistent with in vivo phenotypes observed in aging vocal folds and vocal fold scarring and that TMSCs may function to reduce oxidative stress in aging vocal folds.

Human Amniotic Mesenchymal Stem Cells Promote Endogenous Bone Regeneration

Bone regeneration has become a research hotspot and therapeutic target in the field of bone and joint medicine. Stem cell-based therapy aims to promote endogenous regeneration and improves therapeutic effects and side-effects of traditional reconstruction of significant bone defects and disorders. Human amniotic mesenchymal stem cells (hAMSCs) are seed cells with superior paracrine functions on immune-regulation, anti-inflammation, and vascularized tissue regeneration. The present review summarized the source and characteristics of hAMSCs and analyzed their roles in tissue regeneration. Next, the therapeutic effects and mechanisms of hAMSCs in promoting bone regeneration of joint diseases and bone defects. Finally, the clinical application of hAMSCs from current clinical trials was analyzed. Although more studies are needed to confirm that hAMSC-based therapy to treat bone diseases, the clinical application prospect of the approach is worth investigating.

KR-12-a5 Reverses Adverse Effects of Lipopolysaccharides on HBMSC Osteogenic Differentiation by Influencing BMP/Smad and P38 MAPK Signaling Pathways

KR-12-a5 is an analogue of the antimicrobial peptide KR-12. Both of these two agents can play key effects in the treatment of infections such as osteomyelitis. Our previous work demonstrated that the osteogenic differentiation of human bone marrow mesenchymal stem cells (HBMSCs) can be enhanced by KR-12. The present study investigated if KR-12-a5 could reverse the adverse effects of lipopolysaccharides (LPS) on HBMSC osteogenesis and the involved molecular mechanisms. We observed the proliferation, cell cycle, and apoptosis of HBMSCs in the presence of KR-12-a5 by a cell counting kit-8 assay and flow cytometry. The osteogenic differentiation of HBMSCs was studied by alkaline phosphatase, Alizarin Red staining, and quantitative assays. Osteogenic differentiation marker levels were detected using real-time quantitative PCR analysis, which demonstrated that KR-12-a5 treatment reversed the inhibition of osteogenesis. Western blot analysis indicated that LPS-activated P38 mitogen-activated protein kinase (MAPK) signaling was inhibited and BMP/Smad pathway was reactivated after KR-12-a5 treatment under induced osteogenic conditions. Furthermore, flow cytometry results demonstrated that KR-12-a5 relieved LPS-induced oxidative stress. Combining the LPS-treated mouse model results, we proved that KR-12-a5 reversed the adverse effects of LPS on HBMSC osteogenic differentiation by influencing the BMP/Smad and P38 MAPK signaling pathways.

A comparative study of HAMSCs/HBMSCs transwell and mixed coculture systems

Our previous studies indicated that a coculture system containing human amnion-derived mesenchymal stem cells (HAMSCs) and human bone marrow mesenchymal stem cells (HBMSCs) has the potential of application for bone regeneration. However, there is currently no enough comparative investigation between HAMSCs/HBMSCs transwell and mixed coculture systems. This study aimed to assess the phenotype and mechanisms regulated by indirect and direct coculture systems, respectively. Two in vitro models were employed with HAMSCs and HBMSCs at a ratio of 3:1, and then were analyzed by a series of processes, including flow cytometry, alkaline phosphatase (ALP) substrate assays, Alizarin red S staining, quantitative reverse transcription polymerase chain reaction (RT-qPCR), and Western blot analysis. We found that cell proliferation, ALP activity, mineralized matrix formation, and osteoblast-related mRNA expression were accelerated in transwell coculture system compared with mixed coculture system. Conditioned medium from transwell coculture system achieved an elevated level of vascular endothelial growth factor and induced more vascular structures in human umbilical vein endothelial cells than those of mixed coculture system. Moreover, we observed that transwell coculture system, promoted osteogenesis and angiogenesis by maintaining stemness through extracellular regulated protein kinases 1/2 (ERK1/2) mitogen-activated protein kinase (MAPK) signaling pathway. U0126, a selective inhibitor of ERK1/2 MAPK signaling, significantly suppressed maintaining of the stemness-based effects on transwell coculture system. Taken together, our results compared the merits of two different models and clarified the role of HAMSCs/HBMSCs transwell coculture system in the development of bone tissue engineering. © 2019 IUBMB Life, 2019.

Differential response of immortalized human amnion mesenchymal and epithelial cells against oxidative stress

Cells are equipped with various antioxidant defense factors to antagonize insults from reactive oxygen species (ROS), thus the antioxidant capacity has been characterized by a variety of cellular responses during the pathophysiological processes. Amniotic cells have been extensively applied in clinical practice for burn treatment, corneal repair, and tissue regeneration. However, the antioxidative properties of amniotic cells have not yet been fully understood. Therefore, the current study was aimed to observe the response of amniotic cells against ROS stimuli, and to investigate the underlying molecular mechanisms. The immortalized human amniotic mesenchymal cells (iHAMs) and immortalized human amniotic epithelial cells (iHAEs) were used. The human skin fibroblast (HSF) was used as a control cell line. Changes in intracellular ROS generation, cell viability, and cellular morphology were investigated to reveal the response of amniotic cells against oxidative stresses induced by x-rays and hydrogen peroxide. In addition, expression of apoptosis-related proteins and response to antioxidative stress was also examined. The intracellular ROS level and cell apoptosis in iHAMs was remarkably increased. iHAEs showed relatively high resistance to ROS stimulation, which can be attributed to the high SOD2 expression and up-regulation of Nrf2, HO-1 after x-rays exposure. In contrast, iHAMs were found sensitive to oxidative damage. Expression of caspase-3, caspase-8 and BAX was increased, whereas down-regulation of Bcl-xL, Nrf2, HO-1, and TrxR-1. Taken together, findings have highlighted the characterization of response of amniotic derived epithelial and mesenchymal cells to oxidative stress. In physiological processes, iHAMs may play an important role to maintain the homeostasis of the pregnancy environment. However, under oxidative stimulations, iHAEs provides protection against oxidative damage in amnion tissue.

Human amnion-derived mesenchymal stem cells promote osteogenesis of human bone marrow mesenchymal stem cells against glucolipotoxicity

Epidemiological evidence suggests that diabetes mellitus (DM) is an important factor in promoting periodontitis. It not only affects the attachment of connective tissue but also causes loss of alveolar bone. Hence, there is an urgent need to find an effective treatment for DM‐induced bone deficiency. This study aimed to investigate the effects of human amniotic mesenchymal stem cells (HAMSCs) on the proliferation and osteogenic differentiation of DM‐induced human bone marrow mesenchymal stem cells (HBMSCs). High glucose and palmitic acid (GP) were used to mimic DM‐induced glucolipotoxicity. The proliferation levels were measured using flow cytometry. Alkaline phosphatase activity substrate assays, Alizarin red S staining, and western blotting were used to investigate osteogenic differentiation. Oxidative stress was measured by assaying the levels of reactive oxygen species. This study found that glucolipotoxicity caused by GP remarkably inhibited cell proliferation and osteogenesis, and upregulated the oxidative stress level in HBMSCs. However, HAMSCs attenuated HBMSC dysfunction through antioxidant activity by influencing p38 mitogen‐activated protein kinase and vascular endothelial growth factor secretion. In conclusion, our findings indicate that HAMSCs might be suitable for treating DM‐mediated bone deficiency.

Human amnion-derived mesenchymal stem cells induced osteogenesis and angiogenesis in human adipose-derived stem cells via ERK1/2 MAPK signaling pathway

Mesenchymal stem cells (MSCs) have shown great potential in treating bone deficiency. Human adipose-derived stem cells (HASCs) are multipotent progenitor cells with multi-lineage differentiation potential. Human amnion-derived mesenchymal stem cells (HAMSCs) are capable of promoting osteogenic differentiation of MSCs. In this study, we investigated the effect of HAMSCs on HASCs by a transwell co-culture system. HAMSCs promoted proliferation, osteogenic differentiation, angiogenic potential and adiponectin (APN) secretion of HASCs. Moreover, the positive effect of HAMSCs was significantly inhibited by U0126, a highly selective inhibitor of extracellular signaling-regulated kinase 1/2 (ERK1/2) mitogen-activated protein kinase (MAPK) signaling pathway. These observations suggested that HAMSCs induced bone regeneration in HASCs via ERK1/2 MAPK signaling pathway.

HAMSCs/HBMSCs coculture system ameliorates osteogenesis and angiogenesis against glucolipotoxicity

Osteoporosis and vascular lesions induced by glucolipotoxicity are common complications of diabetes mellitus (DM). In order to deal with these complications, we designed a new therapeutic strategy, i.e. coculture system containing human amnion-derived mesenchymal stem cells (HAMSCs) and human bone marrow mesenchymal stem cells (HBMSCs). Two in vitro coculture models, transwell and mixed cocultures, were proposed for 7 days with variable HAMSCs: HBMSCs ratios. Then, supernatant from each coculture was used to reverse the deficiency of HBMSCs and human umbilical vein endothelial cells (HUVECs) impaired by high glucose and palmitic acid (GP). We found that glucolipotoxicity caused by GP remarkably inhibited cell proliferation, osteogenic differentiation and superoxide dismutase (SOD) activity, as well as induced the reactive oxygen species (ROS) level in HBMSCs. Meanwhile, glucolipotoxicity suppressed cell proliferation, tube formation capacity and angiogenic potential of HUVECs. Though, HAMSCs/HBMSCs coculture system reduced HBMSCs dysfunction by antioxidant properties and promoted angiogenesis in HUVECs. The mixed HAMSCs/HBMSCs coculture at the optimal ratio of 3/1 showed significantly greater cell proliferation, antioxidant properties, osteogenic and angiogenic differentiation than HBMSCs or HUVECs alone. In conclusion, the current coculture system of HAMSCs/HBMSCs can be a potential therapeutic material for advancing bone and vascular regeneration against DM-induced glucolipotoxicity.

Erythropoietin induces the osteogenesis of periodontal mesenchymal stem cells from healthy and periodontitis sources via activation of the p38 MAPK pathway

Erythropoietin (Epo), a hematopoietic hormone, has multiple biological functions. Recently, the positively osteogenic effects of Epo on mesenchymal stem cells (MSCs) have attracted broad interest. However, the effects of Epo on the osteogenesis of human periodontal ligament tissue‑derived mesenchymal stem cells (hPDLSCs) and periodontitis mesenchymal stem cells (pPDLSCs) from patients with periodontitis remain unknown. In the present study, osteogenic effects of Epo on hPDLSCs and pPDLSCs were investigated, and the results suggested that the effects were mediated by promoting the expression of runt related transcription factor 2, alkaline phosphatase (ALP) and osteocalcin. Using Alizarin Red and ALP staining, it was demonstrated that Epo exerted positive osteogenic effects on hPDLSCs and pPDLSCs. Additionally, Epo upregulated the proliferation of hPDLSCs and pPDLSCs, based on flow cytometric analyses of the cell cycle. To determine the underlying mechanism, the role of the p38 mitogen‑activated protein kinase (MAPK) pathway, which is associated with the osteogenesis of hPDLSCs and pPDLSCs, was investigated further. Epo increases p38 phosphorylation (the target of the MAPK pathway) in hPDLSCs and pPDLSCs. Furthermore, when the cells were treated with SB203580, an inhibitor of the p38 MAPK pathway, the osteogenic effects of Epo on hPDLSCs and pPDLSCs were attenuated. In conclusion, Epo may upregulate the bone formation ability of hPDLSCs and pPDLSCs via the p38 MAPK pathways.

Human amniotic epithelial cells regulate osteoblast differentiation through the secretion of TGFβ1 and microRNA-34a-5p

Since the beginning of the use of stem cells in tissue regenerative medicine, there has been a search for optimal sources of stem cells. Human amniotic epithelial cells (hAECs) are derived from human amnions, which are typically discarded as medical waste, but were recently found to include cells with trilineage differentiation potential in vitro. Previous study has focused on the osteogenic differentiation ability of hAECs as seed cells in bone regeneration; however, their paracrine effects on osteoblasts (OBs) are yet to be elucidated. In the present study, conditioned medium (CM) derived from hAECs was used to determine their paracrine effects on the human fetal OB cell line (hFOB1.19), and the potential bioactive factors involved in this process were investigated. The results suggested that hAEC-CM markedly promoted the proliferation, migration and osteogenic differentiation of hFOB1.19 cells. Expression of transforming growth factor β₁ (TGFβ₁) and microRNA 34a-5p (miR-34a-5p) were detected in hAECs. Furthermore, it was demonstrated that TGFβ₁ and miR-34a-5p stimulated the differentiation of hFOB1.19 cells, and that TGFβ₁ promoted cell migration. Moreover, the effects of hAEC-CM were downregulated following the depletion of either TGFβ₁ or miR-34a-5p. These results demonstrated that hAECs promote OB differentiation through the secretion of TGFβ₁ and miR-34a-5p, and that hAECs may be an optimal cell source in bone regenerative medicine.

Human amnion-derived mesenchymal stem cells promote osteogenic and angiogenic differentiation of human adipose-derived stem cells

Tissue engineering using suitable mesenchymal stem cells (MSCs) shows great potential to regenerate bone defects. Our previous studies have indicated that human amnion-derived mesenchymal stem cells (HAMSCs) could promote the osteogenic differentiation of human bone marrow mesenchymal stem cells (HBMSCs). Human adipose-derived stem cells (HASCs), obtained from adipose tissue in abundance, are capable of multi-lineage differentiation. In this study, the effects of HAMSCs on osteogenic and angiogenic differentiation of HASCs were systematically investigated. Proliferation levels were measured by flow cytometry. Osteoblastic differentiation and mineralization were investigated using chromogenic alkaline phosphatase activity (ALP) activity substrate assays, Alizarin red S staining, real-time polymerase chain reaction (real-time PCR) analysis of osteogenic marker expression, and Western blotting. We found that HAMSCs increased the proliferation and osteoblastic differentiation of HASCs. Moreover, enzyme-linked immunosorbent assay (ELISA) and human umbilical vein endothelial cells (HUVECs) tube formation suggested HAMSCs enhanced angiogenic potential of HASCs via secretion of increased vascular endothelial growth factor (VEGF). Thus, we conclude that HAMSC might be a valuable therapeutic approach to promote HASCs-involved bone regeneration.

Hydrogen sulfide promotes osteogenic differentiation of human periodontal ligament cells via p38-MAPK signaling pathway under proper tension stimulation

OBJECTIVE

Hydrogen sulfide (H₂S), one of endogenous gaseous signalling molecules, can be induced by mechanical force stimulation on human periodontal ligament cells (hPDLCs). Little is known about the mechanism of H₂S on the osteogenic differentiation although previous studies have demonstrated that H₂S stimulated or inhibited osteoclastic differentiation. The present study was to investigate whether H₂S played a regulatory role in osteogenic differentiation of the periodontal tissue remodeling and the involvement of mitogen-activated protein kinase (MAPK) signaling in this process.

DESIGN

hPDLCs were applied with cycle tension force for 6h, 12h, 24h or 48h to select the optimal time for force application. Then the effects of H₂S on hPDLCs osteogenic differentiation were investigated. Signal-regulated kinases p38-MAPK and ERK activities with H₂S treatment were measured. Finally, specific MAPK inhibitors SB203580 and U0126 were employed to investigate the involvement of the two kinases in hPDLCs osteogenic differentiation with H₂S pre-treatment.

RESULTS

Tension stimulation promoted mRNA and protein expression of ALP, OCN and Runx2 in hPDLCs. The expression of ALP, OCN and Runx2 increased in a concentration-dependent manner with H₂S pre-treatment. Importantly, p38-MAPK and ERK were activated in different ways upon induction by H₂S. Furthermore, expression of Runx2, ALP and OCN, the osteogenic regulators, was reversed by SB203580 and U0126.

CONCLUSIONS

H₂S could promote osteogenic differentiation of hPDLCs by activating p38-MAPK and ERK signaling pathways.