Hypoxic preconditioning with cobalt of bone marrow mesenchymal stem cells improves cell migration and enhances therapy for treatment of ischemic acute kidney injury

Hypoxia-preconditioned mesenchymal stem cells attenuate bleomycin-induced pulmonary fibrosis

INTRODUCTION

Idiopathic pulmonary fibrosis is a progressive diffuse parenchymal lung disorder of unknown etiology. Mesenchymal stem cell (MSC)-based therapy is a novel approach with great therapeutic potential for the treatment of lung diseases. Despite demonstration of MSC grafting, the populations of engrafted MSCs have been shown to decrease dramatically 24 hours post-transplantation due to exposure to harsh microenvironments. Hypoxia is known to induce expression of cytoprotective genes and also secretion of anti-inflammatory, anti-apoptotic and anti-fibrotic factors. Hypoxic preconditioning is thought to enhance the therapeutic potency and duration of survival of engrafted MSCs. In this work, we aimed to prolong the duration of survival of engrafted MSCs and to enhance the effectiveness of idiopathic pulmonary fibrosis transplantation therapy by the use of hypoxia-preconditioned MSCs.

METHODS

Hypoxic preconditioning was achieved in MSCs under an optimal hypoxic environment. The expression levels of cytoprotective factors and their biological effects on damaged alveolar epithelial cells or transforming growth factor-beta 1-treated fibroblast cells were studied in co-culture experiments in vitro. Furthermore, hypoxia-preconditioned MSCs (HP-MSCs) were intratracheally instilled into bleomycin-induced pulmonary fibrosis mice at day 3, and lung functions, cellular, molecular and pathological changes were assessed at 7 and 21 days after bleomycin administration.

RESULTS

The expression of genes for pro-survival, anti-apoptotic, anti-oxidant and growth factors was upregulated in MSCs under hypoxic conditions. In transforming growth factor-beta 1-treated MRC-5 fibroblast cells, hypoxia-preconditioned MSCs attenuated extracellular matrix production through paracrine effects. The pulmonary respiratory functions significantly improved for up to 18 days of hypoxia-preconditioned MSC treatment. Expression of inflammatory factors and fibrotic factor were all downregulated in the lung tissues of the hypoxia-preconditioned MSC-treated mice. Histopathologic examination observed a significant amelioration of the lung fibrosis. Several LacZ-labeled MSCs were observed within the lungs in the hypoxia-preconditioned MSC treatment groups at day 21, but no signals were detected in the normoxic MSC group. Our data further demonstrated that upregulation of hepatocyte growth factor possibly played an important role in mediating the therapeutic effects of transplanted hypoxia-preconditioned MSCs.

CONCLUSION

Transplantation of hypoxia-preconditioned MSCs exerted better therapeutic effects in bleomycin-induced pulmonary fibrotic mice and enhanced the survival rate of engrafted MSCs, partially due to the upregulation of hepatocyte growth factor.

Short-term memory of danger signals or environmental stimuli in mesenchymal stem cells: implications for therapeutic potential

Mesenchymal stem/stromal cells (MSCs) possess some characteristics of immune cells, including a pro-inflammatory phenotype, an immunosuppressive phenotype, antibacterial properties and the expression of Toll-like receptor proteins. Here we show that, similar to immune cells, MSCs retain information from danger signals or environmental stimuli for a period of time. When treated with the pro-inflammatory factors lipopolysaccharide (LPS) or tumor necrosis factor-α (TNF-α), MSCs display increased expression of IL-6, IL-8 and MCP-1. Following re-plating and several rounds of cell division in the absence of stimulating factors, the expression of IL-6, IL-8 and MCP-1 remained higher than in untreated cells for over 7 days. A spike in cytokine secretion occurred when cells were exposed to a second round of stimulation. We primed MSCs with LPS and LPS-primed MSCs had better therapeutic efficacy at promoting skin flap survival in a diabetic rat model than did unprimed MSCs. Finally, we found that several microRNAs, including miR146a, miR150 and miR155, along with the modification of DNA by 5-hydroxymethylcytosine (5hmC), mediate the MSC response to LPS and TNF-α stimulation. Collectively, our data suggest that MSCs have a short-term memory of environmental signals, which may impact their therapeutic potential.

Hypoxia regulates the therapeutic potential of mesenchymal stem cells through enhanced autophagy

Bone marrow-derived mesenchymal stem cells (BM-MSCs)have great therapeutic potential for the repair of diabetic lower-limb ischemia because of their proangiogenic properties. However, cells transplanted into an ischemic environment have reduced cell survival rates and impaired angiogenic capacity in vivo. We explored hypoxia pretreatment as a method to promote BM-MSC survival by inducing autophagy. Our results showed that hypoxic pretreatment has no effect on the phenotype or differentiation capacity of BM-MSCs; however, hypoxia increased viability and reduced apoptosis in cells treated with lipopolysaccharide. Immunofluorescence and western blot results showed that hypoxia pretreatment enhances cell autophagy mediated by elevated expression of hypoxia inducible factor-1α (HIF-1α). The AMPK/mTOR (adenosine monophosphate-activated protein kinase/mammalian target of rapamycin) signaling pathway was also activated in BM-MSCs during hypoxia-enhanced autophagy. It is important to note that hypoxia pretreatment in BM-MSCs significantly enhanced cell survival and promoted angiogenesis in the lower limb of ischemic diabetic rats. In conclusion, hypoxia pretreatment enhances survival in BM-MSCs, promoting angiogenesis by increasing autophagy and significantly decreasing apoptosis. Therefore, modulation of autophagy with hypoxic pretreatment may provide a novel strategy to improve MSC-based therapies.

CCR7 guides migration of mesenchymal stem cell to secondary lymphoid organs: a novel approach to separate GvHD from GvL effect

Inefficient homing of systemically infused mesenchymal stem cells (MSCs) limits the efficacy of existing MSC-based clinical graft-versus-host disease (GvHD) therapies. Secondary lymphoid organs (SLOs) are the major niches for generating immune responses or tolerance. MSCs home to a wide range of organs, but rarely to SLOs after intravenous infusion. Thus, we hypothesized that targeted migration of MSCs into SLOs may significantly improve their immunomodulatory effect. Here, chemokine receptor 7 (CCR7) gene, encoding a receptor that specifically guides migration of immune cells into SLOs, was engineered into a murine MSC line C3H10T1/2 by retrovirus transfection system (MSCs/CCR7). We found that infusion of MSCs/CCR7 potently prolonged the survival of GvHD mouse model. The infused MSCs/CCR7 migrate to SLOs, relocate in proximity with T lymphocytes, therefore, potently inhibited their proliferation, activation, and cytotoxicity. Natural killer (NK) cells contribute to the early control of leukemia relapse. Although MSCs/CCR7 inhibited NK cell activity in vitro coculture, they did not impact on the proportion and cytotoxic capacities of NK cells in the peripheral blood of GvHD mice. In an EL4 leukemia cell loaded GvHD model, MSCs/CCR7 infusion preserved the graft-versus-leukemia (GvL) effect. In conclusion, this study demonstrates that CCR7 guides migration of MSCs to SLOs and thus highly intensify their in vivo immunomodulatory effect while preserving the GvL activity. This exciting therapeutic strategy may improve the clinical efficacy of MSC based therapy for immune diseases.

Superparamagnetic iron oxide promotes osteogenic differentiation of rat adipose-derived stem cells

Adult adipose tissue-derived stem cells (ADSCs) were found to hold great promise for use in bone tissue repair and regeneration. The present study aims to improve the osteogenesis of ADSCs by Superparamagnetic Iron Oxide (SPIO), which is widely used in tissue imaging. In this study, adipose-derived stem cells were harvested from 4-week-old male Sprague-Dawley (SD) rats. The proliferation rates of ADSCs labeling with or without SPIO were assessed by using trypan blue assay. The osteogenic capability was examined by employing the ALP activity detection kit. The mineralization of cells was determined by staining with Alizarin red S. Flow cytometry analysis was used to examine the cell apoptosis treated with or without SPIO. Real-time reverse transcription polymerase chain reaction (RT-PCR) analysis was utilized to detect the Runx2, Opn, Ocn and ALP genes in the cells. The results indicated that SPIO could promote rat ADSCs proliferation and reduce rat ADSCs apoptosis. Also, SPIO could significantly enhance the ALP and alizarin red staining of ADSCs in -SPIO group and +SPIO group (P < 0.01). Furthermore, we also found that the expression of Runx2, Opn, Ocn and ALP was significantly increased after SPIO treatment compared to the un-treated cells (P < 0.01). In conclusion, SPIO could promote the osteogenic differentiation of rat adipose-derived stem cells, which would also become a great potential therapeutic tool in bone tissue engineering.

Metabolic regulation of mesenchymal stem cell in expansion and therapeutic application

Human mesenchymal or stromal cells (hMSCs) isolated from various adult tissues are primary candidates in cell therapy and tissue regeneration. Despite promising results in preclinical studies, robust therapeutic responses to MSC treatment have not been reproducibly demonstrated in clinical trials. In the translation of MSC-based therapy to clinical application, studies of MSC metabolism have significant implication in optimizing bioprocessing conditions to obtain therapeutically competent hMSC population for clinical application. In addition, understanding the contribution of metabolic cues in directing hMSC fate also provides avenues to potentiate their therapeutic effects by modulating their metabolic properties. This review focuses on MSC metabolism and discusses their unique metabolic features in the context of common metabolic properties shared by stem cells. Recent advances in the fundamental understanding of MSC metabolic characteristics in relation to their in vivo origin and metabolic regulation during proliferation, lineage-specific differentiation, and exposure to in vivo ischemic conditions are summarized. Metabolic strategies in directing MSC fate to enhance their therapeutic potential in tissue engineering and regenerative medicine are discussed.

Hypoxia-controlled EphA3 marks a human endometrium-derived multipotent mesenchymal stromal cell that supports vascular growth

Eph and ephrin proteins are essential cell guidance cues that orchestrate cell navigation and control cell-cell interactions during developmental tissue patterning, organogenesis and vasculogenesis. They have been extensively studied in animal models of embryogenesis and adult tissue regeneration, but less is known about their expression and function during human tissue and organ regeneration. We discovered the hypoxia inducible factor (HIF)-1α-controlled expression of EphA3, an Eph family member with critical functions during human tumour progression, in the vascularised tissue of regenerating human endometrium and on isolated human endometrial multipotent mesenchymal stromal cells (eMSCs), but not in other highly vascularised human organs. EphA3 affinity-isolation from human biopsy tissue yielded multipotent CD29⁺/CD73⁺/CD90⁺/CD146⁺ eMSCs that can be clonally propagated and respond to EphA3 agonists with EphA3 phosphorylation, cell contraction, cell-cell segregation and directed cell migration. EphA3 silencing significantly inhibited the ability of transplanted eMSCs to support neovascularisation in immunocompromised mice. In accord with established roles of Eph receptors in mediating interactions between endothelial and perivascular stromal cells during mouse development, our findings suggest that HIF-1α-controlled expression of EphA3 on human MSCs functions during the hypoxia-initiated early stages of adult blood vessel formation.

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.

Peripheral Blood-Derived Mesenchymal Stromal Cells Promote Angiogenesis via Paracrine Stimulation of Vascular Endothelial Growth Factor Secretion in the Equine Model

Mesenchymal stromal cells (MSCs) have received much attention as a potential treatment of ischemic diseases, including ischemic tissue injury and cardiac failure. The beneficial effects of MSCs are thought to be mediated by their ability to provide proangiogenic factors, creating a favorable microenvironment that results in neovascularization and tissue regeneration. To study this in more detail and to explore the potential of the horse as a valuable translational model, the objectives of the present study were to examine the presence of angiogenic stimulating factors in the conditioned medium (CM) of peripheral blood-derived equine mesenchymal stromal cells (PB-MSCs) and to study their in vitro effect on angiogenesis-related endothelial cell (EC) behavior, including proliferation and vessel formation. Our salient findings were that CM from PB-MSCs contained significant levels of several proangiogenic factors. Furthermore, we found that CM could induce angiogenesis in equine vascular ECs and confirmed that endothelin-1, insulin growth factor binding protein 2, interleukin-8, and platelet-derived growth factor-AA, but not urokinase-type plasminogen activator, were responsible for this enhanced EC network formation by increasing the expression level of vascular endothelial growth factor-A, an important angiogenesis stimulator.

Strategies to improve homing of mesenchymal stem cells for greater efficacy in stem cell therapy

Stem/progenitor cell-based therapeutic approach in clinical practice has been an elusive dream in medical sciences, and improvement of stem cell homing is one of major challenges in cell therapy programs. Stem/progenitor cells have a homing response to injured tissues/organs, mediated by interactions of chemokine receptors expressed on the cells and chemokines secreted by the injured tissue. For improvement of directed homing of the cells, many techniques have been developed either to engineer stem/progenitor cells with higher amount of chemokine receptors (stem cell-based strategies) or to modulate the target tissues to release higher level of the corresponding chemokines (target tissue-based strategies). This review discusses both of these strategies involved in the improvement of stem cell homing focusing on mesenchymal stem cells as most frequent studied model in cellular therapies.

Therapeutic action of bone marrow-derived stem cells against acute kidney injury

Acute kidney injury (AKI) is a frequent clinical disease with a high morbidity rate and mortality rate, while the treatment options for this intractable disease are limited currently. In recent years, bone marrow-derived mesenchymal stem cells (BMSCs) have been demonstrated to hold an effect therapeutic action against AKI by scientists gradually, and the cells are capable to localize to renal compartments and contribute to kidney regeneration though differentiation or paracrine action. Especially, the advantages of BMSCs, such as low toxicity and side effect as well as autologous transplantation, endue the cell with a promising potential in clinical therapy against AKI. In this review, we mainly provide a concise overview of the application of BMSCs in the treatment of AKI, and summarize a series of published data regarding the mechanisms and optimizations of the BMSC-based therapy in renal repair after AKI. Even though some critical points about the BMSC-based therapy model still need clarification, we hope to develop more reliable pharmacological or biotechnical strategies utilizing the stem cell for the eventual treatment of humans with AKI, based on these studies and the understanding of mechanism of renal protection by BMSCs.

Design considerations of iron-based nanoclusters for noninvasive tracking of mesenchymal stem cell homing

Stem-cell-based therapies have attracted considerable interest in regenerative medicine and oncological research. However, a major limitation of systemic delivery of stem cells is the low homing efficiency to the target site. Here, we report a serendipitous finding that various iron-based magnetic nanoparticles (MNPs) actively augment chemokine receptor CXCR4 expression of bone-marrow-derived mesenchymal stem cells (MSCs). On the basis of this observation, we designed an iron-based nanocluster that can effectively label MSCs, improve cell homing efficiency, and track the fate of the cells in vivo. Using this nanocluster, the labeled MSCs were accurately monitored by magnetic resonance imaging and improved the homing to both traumatic brain injury and glioblastoma models as compared to unlabeled MSCs. Our findings provide a simple and safe method for imaging and targeted delivery of stem cells and extend the potential applications of iron-based MNPs in regenerative medicine and oncology.

Design considerations of iron-based nanoclusters for noninvasive tracking of mesenchymal stem cell homing

Stem-cell-based therapies have attracted considerable interest in regenerative medicine and oncological research. However, a major limitation of systemic delivery of stem cells is the low homing efficiency to the target site. Here, we report a serendipitous finding that various iron-based magnetic nanoparticles (MNPs) actively augment chemokine receptor CXCR4 expression of bone-marrow-derived mesenchymal stem cells (MSCs). On the basis of this observation, we designed an iron-based nanocluster that can effectively label MSCs, improve cell homing efficiency, and track the fate of the cells in vivo. Using this nanocluster, the labeled MSCs were accurately monitored by magnetic resonance imaging and improved the homing to both traumatic brain injury and glioblastoma models as compared to unlabeled MSCs. Our findings provide a simple and safe method for imaging and targeted delivery of stem cells and extend the potential applications of iron-based MNPs in regenerative medicine and oncology.

Atorvastatin improves survival of implanted stem cells in a rat model of renal ischemia-reperfusion injury

AIMS

To investigate the impacts of combinatorial atorvastatin (Ator) perioperative administration and mesenchymal stem cell (MSC) implantation on therapeutic effects in the rat experimental acute kidney injury.

METHODS

The model of renal ischemia-reperfusion (I/R) injury was induced by the release of bilateral renal pedicle clamps following 45 min of occlusion. Immediately after reperfusion, CM-Dil-labeled MSCs (1 × 10(6) cells) or vehicles only were administered through the carotid artery of the animals pretreated with or without Ator.

RESULTS

The combined treatment with Ator and MSCs (Ator+MSCs) markedly reduced the elevated levels of serum creatinine and blood urea nitrogen, as well as the severity of renal damage 24 h after I/R injury. In addition, we also observed inhibition of renal tubular cell apoptosis and promotion of proliferation in the Ator+MSCs group compared with the other groups. Consistent with the improvement in renal function and morphology, Ator pretreatment significantly ameliorated oxidative stress, inhibited inflammation response, and increased the viability of implanted MSCs. With regard to the further mechanism, we found that the expression of Toll-like receptor 4 (TLR4) and high-mobility group box 1, potential mediators of innate immunity, was significantly decreased in the Ator-treated groups.

CONCLUSION

Ator treatment may protect the kidney undergoing I/R injury through suppression of TLR4 signaling, creating a better environment for the survival of grafted MSCs. The extra benefit of the Ator+MSCs combined therapy may result from the Ator-mediated inhibition of oxidative stress and inflammation in the ischemic kidney.

Using stem and progenitor cells to recapitulate kidney development and restore renal function

PURPOSE OF REVIEW

There is considerable interest in the idea of generating stem and precursor cells that can differentiate into kidney cells and be used to treat kidney diseases. Within this field, we highlight recent research articles focussing on mesenchymal stem cells (MSCs), embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs) and kidney-derived stem/progenitor cells (KSPCs).

RECENT FINDINGS

In preclinical studies, MSCs ameliorate varied acute and chronic kidney diseases. Their efficacy depends on immunomodulatory and paracrine properties but MSCs do not differentiate into functional kidney epithelia. iPSCs can be derived from healthy individuals and from kidney patients by forced expression of precursor genes. Like ESCs, iPSCs are pluripotent and so theoretically they have the potential to form functional kidney epithelia when used therapeutically. KSPCs, existing as cell subsets within adult and developing kidneys, constitute attractive future therapeutic agents.

SUMMARY

Results from preclinical studies are encouraging but caution is required regarding potential human therapeutic applications because molecular, morphological and functional characterization of 'kidney cells' generated from ECSs, iPSCs, KSPCs have not been exhaustive. The long-term safety of renal stem and precursor cells needs more study, including potential negative effects on renal growth and their potential for tumor formation.

Females transplanted with ovaries subjected to hypoxic preconditioning show impair of ovarian function

Background

Cryopreservation of the ovarian tissue has shown promising results. However, there remain controversial issues such as the short half-life of grafts. In this aspect, there are some evidences that preconditioning the ovarian tissue before transplantation is beneficial.

Objective

To determine the effect of hypoxic preconditioning in vitro on ovarian tissue prior to transplantation.

Methods

Eighteen female adult Wistar rats, were sorted into three experimental groups. Ovaries were maintained in DMEM low glucose serum free at 37°C with 5% CO2, at atmospheric oxigen concentration (normoxia) or 1% O₂ (hypoxia) for 16 hours. Oxigen concentration was determined by injection of nitrogen in the incubator. Animals submitted to ovarian transplantation immediately after oophorectomy were the Control Group (C). After this, the ovaries were implanted in the retroperitoneum with nonabsorbable suture and animals evaluated for thirty days after transplantation. Beginning on postoperative (PO) day 11, a daily collection of vaginal smear was carried out. Analyses comprised morphological, morphometric (counting ovarian follicles and corpora lutea) and immunohistochemistry for cleaved caspase-3 (apoptosis).

Results

In normoxia and control groups all animals recovered their estrous cycles, while in the hypoxia group, two animals did not ovulate but, among those which did, resumption took longer than in the other groups (p < 0.05). The number of ovarian follicles and corpora lutea decreased significantly in the hypoxia group when compared to the other two groups (p < 0.001) and apoptosis was increased in the few ovarian follicles which remained viable (p < 0.001).

Conclusion

The hypoxic preconditioning in vitro was not beneficial to the graft and worsened their viability, compromising its functionality or delaying the return of this.

Maximum efficacy of mesenchymal stem cells in rat model of renal ischemia-reperfusion injury: renal artery administration with optimal numbers

Backgrounds

Despite the potential therapeutic benefits, cell therapy in renal ischemia-reperfusion (I/R) injury is currently limited by low rates of cell engraftment after systemic delivery. In this study, we investigate whether locally administration through renal artery can enhance the migration and therapeutic potential of mesenchymal stem cells (MSCs) in ischemic kidney.

Methods

The model of renal I/R injury was induced by 45 min occlusion of the left renal pedicle and right nephrectomy in rat. Followed by reperfusion, graded doses of CM-Dil labeled MSCs were implanted via three routes: tail vein (TV), carotid artery (CA), and renal artery (RA). Renal blood flow was evaluated by color and spectral Doppler ultrasound at 1 h and 24 h post-I/R. All the samples were collected for analysis at 24 h post-I/R.

Results

After injection of 1×10⁶ MSCs, RA group showed obviously increased renal retention of grafted MSCs compared with TV and CA group; however, the renal function was even further deteriorated. When graded doses of MSCs, the maximal therapeutic efficiency was achieved with renal artery injection of 1×10⁵ MSCs, which was significantly better than TV and CA group of 1×10⁶ MSCs. In addition, further fluorescent microscopic and ultrasonic examination confirmed that the aggravated renal dysfunction in RA group was due to renal hypoperfusion caused by cell occlusion.

Conclusion

Administration route and dosage are two critical factors determining the efficiency of cell therapy and 1×10⁵ MSCs injected through renal artery produces the most dramatic improvement in renal function and morphology in rat model of renal I/R injury.

Hypoxia enhances protective effect of placental-derived mesenchymal stem cells on damaged intestinal epithelial cells by promoting secretion of insulin-like growth factor-1

Apoptosis and necrosis of intestinal epithelial cells (IECs), induced by ischemia-reperfusion (I/R) injury, can lead to dysfunction of the intestinal barrier, which could cause multiple organ dysfunction syndromes. Mesenchymal stem cells (MSCs) have the potential of providing protective effects on damaged IECs via paracrine action. This study investigated whether hypoxia can enhance the protective effect of placental-derived MSCs (pMSCs) on H2O2-treated-caco2 cells, and explored the possible mechanism. The pMSCs isolated by tissue culture were fibroblast-like, positive for CD73, CD90 and CD105 and can differentiate into chondrocytes and endothelial cells. Five days after treatment with H2O2, the numbers of living caco2 cells significantly decreased. More live H2O2-treated-caco2 cells were observed in pMSCs hypoxia culture medium (pMSCs-HCM) than pMSCs normoxia culture medium (pMSCs-NCM), and the application of a specific antibody that blocked insulin-like growth factor-1 (IGF-1) leads to a significant decrease of the protective effect of pMSCs-HCM. Hypoxia can promote IGF-1 expression of pMSCs at mRNA and protein levels, and caco2 stably expressed IGF-1 receptor. Knocking down IGF-1 expression in pMSCs by siRNA resulted in a significant attenuation of the increase in apoptosis of H2O2-treated-caco2 cultured in pMSCs-HCM. In conclusion, hypoxia can increase the protective effect of pMSCs on H2O2-treated-caco2 cells via a promotion of their paracrine actions, and the key cytokine involved is IGF-1.

Role of mesenchymal stem cells in cell life and their signaling

Mesenchymal stem cells (MSCs) have various roles in the body and cellular environment, and the cellular phenotypes of MSCs changes in different conditions. MSCs support the maintenance of other cells, and the capacity of MSCs to differentiate into several cell types makes the cells unique and full of possibilities. The involvement of MSCs in the epithelial-mesenchymal transition is an important property of these cells. In this review, the role of MSCs in cell life, including their application in therapy, is first described, and the signaling mechanism of MSCs is investigated for a further understanding of these cells.

Ion channels in regulation of neuronal regenerative activities

The regeneration of the nervous system is achieved by the regrowth of damaged neuronal axons, the restoration of damaged nerve cells, and the generation of new neurons to replace those that have been lost. In the central nervous system, the regenerative ability is limited by various factors including damaged oligodendrocytes that are essential for neuronal axon myelination, an emerging glial scar, and secondary injury in the surrounding areas. Stem cell transplantation therapy has been shown to be a promising approach to treat neurodegenerative diseases because of the regenerative capability of the stem cells that secrete neurotrophic factors and give rise to differentiated progeny. However, some issues of stem cell transplantation, such as survival, homing, and efficiency of neural differentiation after transplantation, still need to be improved. Ion channels allow for the exchange of ions between the intra- and extracellular spaces or between the cytoplasm and organelles. These ion channels maintain the ion homeostasis in the brain and play a key role in regulating the physiological function of the nervous system and allowing the processing of neuronal signals. In seeking a potential strategy to enhance the efficacy of stem cell therapy in neurological and neurodegenerative diseases, this review briefly summarizes the roles of ion channels in cell proliferation, differentiation, migration, chemotropic axon guidance of growth cones, and axon outgrowth after injury.

Priming adult stem cells by hypoxic pretreatments for applications in regenerative medicine

The efficiency of regenerative medicine can be ameliorated by improving the biological performances of stem cells before their transplantation. Several ex-vivo protocols of non-damaging cell hypoxia have been demonstrated to significantly increase survival, proliferation and post-engraftment differentiation potential of stem cells. The best results for priming cultured stem cells against a following, otherwise lethal, ischemic stress have been obtained with brief intermittent episodes of hypoxia, or anoxia, and reoxygenation in accordance with the extraordinary protection afforded by the conventional maneuver of ischemic preconditioning in severely ischemic organs. These protocols of hypoxic preconditioning can be rather easily reproduced in a laboratory; however, more suitable pharmacological interventions inducing stem cell responses similar to those activated in hypoxia are considered among the most promising solutions for future applications in cell therapy. Here we want to offer an up-to-date review of the molecular mechanisms translating hypoxia into beneficial events for regenerative medicine. To this aim the involvement of epigenetic modifications, microRNAs, and oxidative stress, mainly activated by hypoxia inducible factors, will be discussed. Stem cell adaptation to their natural hypoxic microenvironments (niche) in healthy and neoplastic tissues will be also considered.