Migration of CXCR4 gene-modified bone marrow-derived mesenchymal stem cells to the acute injured kidney

Combination Therapy of Bone Marrow Mesenchymal Stem Cell Transplantation and Electroacupuncture for the Repair of Intrauterine Adhesions in Rats: Mechanisms and Functional Recovery

Transplantation of bone marrow mesenchymal stem cells (BMSCs) has demonstrated promising clinical utility in the treatment of endometrial injury and the restoration of fertility. However, since the efficacy of BMSCs after transplantation is not stable, it is very important to find effective ways to enhance the utilisation of BMSCs. Electroacupuncture (EA) has some positive effects on the chemotaxis of stem cells and diseases related to uterine injury. In this study, we established the intrauterine adhesion (IUA) model of the Sprague-Dawley rat using lipopolysaccharide infection and mechanical scratching. Phosphate-buffered saline, BMSCs alone, and BMSCs combined with EA were randomly administered to the rats. Fluorescent cell labelling showed the migration of transplanted BMSCs. H&E staining, Masson staining, Western blot, immunohistochemistry, ELISA, and qRT-PCR were utilised to detect changes in endometrial morphology and expressions of endometrial receptivity-related factors, endometrial pro-inflammatory factors, and fibrosis factors. Finally, we conducted a fertility test to measure the recovery of uterine function. The results showed that EA promoted transplanted BMSCs to migrate into the injured uterus by activating the SDF-1/CXCR4 axis. Endometrial morphology showed the most significant improvement in the BMSC + EA group. The expressions of endometrial pro-inflammatory factors and fibrosis indexes in the BMSC + EA group were lower than those in the model and BMSC groups. Further studies revealed that the expression of endometrial receptivity-related factors and the number of embryos implanted on day 8 of gestation increased in the BMSC + EA group compared with the model group and the BMSC group.

ISL1-overexpressing BMSCs attenuate renal ischemia-reperfusion injury by suppressing apoptosis and oxidative stress through the paracrine action

Ischemia-reperfusion injury (IRI) is a major event in renal transplantation, leading to adverse outcomes. Bone marrow mesenchymal stem cells (BMSCs) are novel promising therapeutics for repairing kidney injuries. The therapeutic efficacy of BMSCs with ISL1 overexpression in renal IRI and its underlying mechanism need to be investigated. The unilateral renal IRI rat model was established to mimic clinical acute kidney injury. Rats were injected with PBS, BMSCs-Scrambled or BMSCs-ISL1 via the tail vein at the timepoint of reperfusion, and then sacrificed after 24 h of reperfusion. The administration of BMSCs-ISL1 significantly improved renal function, inhibited tubular cells apoptosis, inflammation, oxidative stress in rats. In vitro, HKC cells subjected to H2O2 stimulation were pretreated with the conditioned medium (CM) of BMSCs-Scrambled or BMSCs-ISL1. The pretreatment of ISL1-CM attenuated apoptosis and oxidative stress induced by H2O2 in HKC cells. Our proteomic data suggested that haptoglobin (Hp) was one of the secretory proteins in ISL1-CM. Subsequent experiments confirmed that Hp was the important paracrine factor from BMSCs-ISL1 that exerted anti-apoptotic and antioxidant functions. Mechanistically, Hp played a cytoprotective role via the inhibition of ERK signaling pathway, which could be abrogated by Ro 67-7476, the ERK phosphorylation agonist. The results suggested that paracrine action may be the main mechanism for BMSCs-ISL1 to exert protective effects. As an important anti-apoptotic and antioxidant factor in ISL1-CM, Hp may serve as a new therapeutic agent for treating IRI, providing new insights for overcoming the long-term adverse effects of stem cell therapy.

The Beneficial Effects of Mesenchymal Stem Cells in Acute Kidney Injury: A Narrative Review

BACKGROUND

Acute kidney injury (AKI) is a multifaced disease characterized by a rapid decline in renal function. However, with growing insight into the pathophysiologic mechanisms of AKI, currently available interventions for AKI are merely supportive. Thus, novel therapies are urgently needed to improve the outcomes of patients with AKI. This narrative review aims to explore enhancing the beneficial effects of Mesenchymal Stem Cells(MSCs) in AKI.

METHODS

The authors examined all studies regarding the role of MSCs in AKI. And the authors undertook a structured search of bibliographic databases for peer-reviewed research literature using a focused review question. The most relevant and up-to-date research was included.

RESULTS AND DISCUSSION

Based on encouraging preclinical results, stem cell therapy has been widely explored over the last decade. Among the various stem cell types investigated, mesenchymal stem cells are being intensely investigated by virtue of their numerous strengths, such as easy derivation, undemanding cell culture conditions, anti-apoptosis, immunomodulation, and anti-inflammation effects. Mounting evidence suggests that MSCs hold great potential in accelerating kidney repair following AKI in various preclinical models. Unfortunately, low engrafting efficiency and poor survival rate of injected MSCs in the injured renal tissue are major obstacles MSCs clinical application faces.

CONCLUSION

Various strategies, including genetic manipulation, mimicking the cellular microenvironment with different culture conditions, optimizing MSCs preparation and administration schedule, and screening patients who may more like benefit from MSCs therapy, have been developed to enhance the therapeutic potential of MSCs in AKI.

Advances in the Treatment of Kidney Disorders using Mesenchymal Stem Cells

Renal disease is a medical condition that poses a potential threat to the life of an individual and is related to substantial morbidity and mortality rates in clinical environments. The aetiology of this condition is influenced by multiple factors, and its incidence tends to increase with progressive aging. Although supportive therapy and kidney transplantation have potential advantages, they also have limitations in terms of mitigating the progression of KD. Despite significant advancements in the domain of supportive therapy, mortality rates in patients continue to increase. Due to their ability to self-renew and multidirectionally differentiate, stem cell therapy has been shown to have tremendous potential in the repair of the diseased kidney. MSCs (Mesenchymal stem cells) are a cell population that is extensively distributed and can be located in various niches throughout an individual's lifespan. The cells in question are characterised by their potential for indefinite replication and their aptitude for undergoing differentiation into fully developed cells of mesodermal origin under laboratory conditions. It is essential to emphasize that MSCs have demonstrated a favorable safety profile and efficacy as a therapeutic intervention for renal diseases in both preclinical as well as clinical investigations. MSCs have been found to slow the advancement of kidney disease, and this impact is thought to be due to their control over a number of physiological processes, including immunological response, tubular epithelial- mesenchymal transition, oxidative stress, renal tubular cell death, and angiogenesis. In addition, MSCs demonstrate recognised effectiveness in managing both acute and chronic kidney diseases via paracrine pathways. The proposal to utilise a therapy that is based on stem-cells as an effective treatment has been put forward in search of discovering novel therapies to promote renal regeneration. Preclinical researchers have demonstrated that various types of stem cells can provide advantages in acute and chronic kidney disease. Moreover, preliminary results from clinical trials have suggested that these interventions are both safe and well-tolerated. This manuscript provides a brief overview of the potential renoprotective effects of stem cell-based treatments in acute as well as chronic renal dysfunction. Furthermore, the mechanisms that govern the process of kidney regeneration induced by stem cells are investigated. This article will examine the therapeutic approaches that make use of stem cells for the treatment of kidney disorders. The analysis will cover various cellular sources that have been utilised, potential mechanisms involved, and the outcomes that have been achieved so far.

Recent advances in pre-conditioned mesenchymal stem/stromal cell (MSCs) therapy in organ failure; a comprehensive review of preclinical studies

Mesenchymal stem/stromal cells (MSCs)-based therapy brings the reassuring capability to regenerative medicine through their self-renewal and multilineage potency. Also, they secret a diversity of mediators, which are complicated in moderation of deregulated immune responses, and yielding angiogenesis in vivo. Nonetheless, MSCs may lose biological performance after procurement and prolonged expansion in vitro. Also, following transplantation and migration to target tissue, they encounter a harsh milieu accompanied by death signals because of the lack of proper tensegrity structure between the cells and matrix. Accordingly, pre-conditioning of MSCs is strongly suggested to upgrade their performances in vivo, leading to more favored transplantation efficacy in regenerative medicine. Indeed, MSCs ex vivo pre-conditioning by hypoxia, inflammatory stimulus, or other factors/conditions may stimulate their survival, proliferation, migration, exosome secretion, and pro-angiogenic and anti-inflammatory characteristics in vivo. In this review, we deliver an overview of the pre-conditioning methods that are considered a strategy for improving the therapeutic efficacy of MSCs in organ failures, in particular, renal, heart, lung, and liver.

Study on the Promotion of hADSCs Migration and Chemotaxis by SDF-1

PURPOSE

The purpose of this study was to investigate the chemotaxis effect of stromal cell-derived factor-1 (SDF-1) on human adipose-derived stem cells (hADSCs).

METHODS

A lentivirus vector with the enhanced green fluorescent protein gene was constructed and transfected to hADSCs. A control group and an SDF-1 induction group were set to estimate the efficacy of SDF-1 in promoting hADSCs chemotaxis and migration.

RESULTS

After 7 days of infection with hADSCs by enhanced green fluorescent protein lentivirus, the positive rate of fluorescence expression detected by flow cytometry was 100%. After the addition of SDF-1 induction, the invasion ability of hADSCs was enhanced.

CONCLUSIONS

SDF-1 can promote hADSCs migration and chemotaxis, which may play a role in stem cell transplantation.

Chemokine C-X-C receptor 4 mediates recruitment of bone marrow-derived nonhematopoietic and immune cells to the pregnant uterus†

Bone marrow-derived progenitor cells (BMDPCs) are mobilized to the circulation in pregnancy and get recruited to the pregnant decidua where they contribute functionally to decidualization and successful implantation. However, the molecular mechanisms underlying BMDPCs recruitment to the decidua are unknown. CXCL12 ligand and its CXCR4 receptor play crucial roles in the mobilization and homing of stem/progenitor cells to various tissues. To investigate the role of CXCL12-CXCR4 axis in BMDPCs recruitment to decidua, we created transgenic GFP mice harboring CXCR4 gene susceptible to tamoxifen-inducible Cre-mediated ablation. These mice served as BM donors into wild-type C57BL/6 J female recipients using a 5-fluorouracil-based nongonadotoxic submyeloablation to achieve BM-specific CXCR4 knockout (CXCR4KO). Successful CXCR4 ablation was confirmed by RT-PCR and in vitro cell migration assays. Flow cytometry and immunohistochemistry showed a significant increase in GFP+ BM-derived cells (BMDCs) in the implantation site as compared to the nonpregnant uterus of control (2.7-fold) and CXCR4KO (1.8-fold) mice. This increase was uterus-specific and was not observed in other organs. This pregnancy-induced increase occurred in both hematopoietic (CD45+) and nonhematopoietic (CD45-) uterine BMDCs in control mice. In contrast, in CXCR4KO mice there was no increase in nonhematopoietic BMDCs in the pregnant uterus. Moreover, decidual recruitment of myeloid cells but not NK cells was diminished by BM CXCR4 deletion. Immunofluorescence showed the presence of nonhematopoietic GFP+ cells that were negative for CD45 (panleukocyte) and DBA (NK) markers in control but not CXCR4KO decidua. In conclusion, we report that CXCR4 expression in nonhematopoietic BMDPCs is essential for their recruitment to the pregnant decidua.

Rapamycin Improves Adipose-Derived Mesenchymal Stem Cells (ADMSCs) Renoprotective Effect against Cisplatin-Induced Acute Nephrotoxicity in Rats by Inhibiting the mTOR/AKT Signaling Pathway

Objective: Because the poor survival of transplanted cells in a hostile microenvironment limits stem cell therapy, in the current study, we investigated the effect of rapamycin (Rapa)-preactivated autophagy on the survival and homing of transplanted adipose mesenchymal stem cells (ADMSCs) in a rat model of cisplatin (Cis)-induced nephrotoxicity, as well as the possible role of the mTOR/AKT signaling pathway. Materials and methods: In vitro, ADMSCs isolated from rats were treated with 50 nmol/L rapamycin for 2 h, after which the cytoprotective and autophagy-inducing effects of Rapa were investigated. The cis-induced acute nephrotoxicity rat model was constructed in vivo. ADMSCs and Rapa-ADMSCs were administered into the tail vein before Cis therapy. At 3, 7, and 10 days after Cis injection, all animals were euthanized. The renal functions and morphology as well as autophagy response were assessed. Results: The pretreatment of cultured ADMSCs with Rapa caused a significant increase in autophagic activities and lysosome production of the cells, with a significant increase in the secretion of SDF-1, IL-10 and autophagy promoter LC3 and Beclin from these cells, while mTOR/AKT pathways were inhibited. In addition, the transplantation of Rapa-pretreated ADMSCs restored the kidney functions and morphology dramatically. Renal expression of SDF-1 and HIF1 was upregulated, while expression of IL-6, NF-kB and TGF-β1 was downregulated. Conclusions: We concluded that the preactivation of autophagy with Rapa improves the survival and differentiation of the transplanted ADMSCs by inhibiting the mTOR/AKT signaling pathway, which in turn could significantly attenuate the Cis-induced acute renal injury.

Targeted Therapy for Inflammatory Diseases with Mesenchymal Stem Cells and Their Derived Exosomes: From Basic to Clinics

Inflammation is a beneficial and physiological process, but there are a number of inflammatory diseases which have detrimental effects on the body. In addition, the drugs used to treat inflammation have toxic side effects when used over a long period of time. Mesenchymal stem cells (MSCs) are pluripotent stem cells that can be isolated from a variety of tissues and can be differentiate into diverse cell types under appropriate conditions. They also exhibit noteworthy anti-inflammatory properties, providing new options for the treatment of inflammatory diseases. The therapeutic potential of MSCs is currently being investigated for various inflammatory diseases, such as kidney injury, lung injury, osteoarthritis (OA), rheumatoid arthritis (RA), and inflammatory bowel disease (IBD). MSCs can perform multiple functions, including immunomodulation, homing, and differentiation, to enable damaged tissues to form a balanced inflammatory and regenerative microenvironment under severe inflammatory conditions. In addition, accumulated evidence indicates that exosomes from extracellular vesicles of MSCs (MSC-Exos) play an extraordinary role, mainly by transferring their components to recipient cells. In this review, we summarize the mechanism and clinical trials of MSCs and MSC-Exos in various inflammatory diseases in detail, with a view to contributing to the treatment of MSCs and MSC-Exos in inflammatory diseases.

Klotho and Mesenchymal Stem Cells: A Review on Cell and Gene Therapy for Chronic Kidney Disease and Acute Kidney Disease

Chronic kidney disease (CKD) and acute kidney injury (AKI) are public health problems, and their prevalence rates have increased with the aging of the population. They are associated with the presence of comorbidities, in particular diabetes mellitus and hypertension, resulting in a high financial burden for the health system. Studies have indicated Klotho as a promising therapeutic approach for these conditions. Klotho reduces inflammation, oxidative stress and fibrosis and counter-regulates the renin-angiotensin-aldosterone system. In CKD and AKI, Klotho expression is downregulated from early stages and correlates with disease progression. Therefore, the restoration of its levels, through exogenous or endogenous pathways, has renoprotective effects. An important strategy for administering Klotho is through mesenchymal stem cells (MSCs). In summary, this review comprises in vitro and in vivo studies on the therapeutic potential of Klotho for the treatment of CKD and AKI through the administration of MSCs.

Endometriosis stem cell sources and potential therapeutic targets: literature review and bioinformatics analysis

The stem cell origin theory of endometriosis (EMS) is a significant area of new research but the sources of this have yet to be adequately summarized. Existing treatments for EMS are commonly associated with a high recurrence rate; consequently, there is an urgent need to develop new therapeutic measures for the future treatment of this disease from the view of stem cells and gene therapy. Recently, we described the evidence for the potential sources of EMS stem cells and other key molecules participating in the establishment of lesions, and predict the miRNAs that target these key genes via bioinformatics analysis for further research. This review highlights the origin of EMS stem cells and potential therapy targets.

Stromal Cell-Derived Factor (SDF)-1-Pretreated Bone Marrow Mesenchymal Stem Cells (BMSCs) Ameliorates Acute Kidney Injury in Mice

To explore the effects of stromal cell-derived factor (SDF-1) pretreatment of bone marrow mesenchymal stem cells (BMSCs) on acute kidney injury (AKI) in mice. BMSCs were cultured and treated with SDF-1 to detect osteogenic and adipogenic ability. Cisplatin (20 mg/kg) was used to establish AKI model and then divided into blank group, control group 2 (BMSCs injection), and experimental group (intraperitoneal injection of BMSCs treated with SDF-1 (80 ng/ml)) followed by analysis of serum cytokines (Toll like receptor 4 (TLR4), tumor necrosis factor-α (TNF-α), and interleukine-6 (IL-6)) by enzyme linked immunosorbent assay (ELISA). In cultured BMSCs, positive rates of CD29, CD44, CD45, and CD11b were 98.2%, 97.6%, 2.5% and 2.1%, respectively. When the concentration of SDF-1 was within 80 ng/mL, the chemotaxis and proliferation ability was dose-dependent (p < 0.05). SDF-1 pretreatment did not affect BMSCs adipogenic and osteogenic abilities. The creatinine and serum cytokines (TLR4, TNF-α, and IL-6) level in experimental group showed statistical significance (p < 0.05). At 24 h, thrombosis and tubular dilatation in the mesangial region of control group 2 and experimental group under light microscope were similar without difference of inflammatory cell infiltration and fibrosis. At 72 h, the glomerular mesangium widened in control group 2 with focal segmental sclerosis, renal tubules dilated, and protein casts and inflammatory cell infiltration and fibrosis. Experimental group showed a small amount of cell proliferation in the glomerular mesangium with few inflammatory cell infiltration and fibrosis. SDF-1 can enhance the migration and proliferation activity of BMSCs, reduce extracellular matrix precipitation, improve renal fibrosis, and alleviate AKI.

FGF23 ameliorates ischemia-reperfusion induced acute kidney injury via modulation of endothelial progenitor cells: targeting SDF-1/CXCR4 signaling

The levels of fibroblast growth factor 23 (FGF23) rapidly increases after acute kidney injury (AKI). However, the role of FGF23 in AKI is still unclear. Here, we observe that pretreatment with FGF23 protein into ischemia-reperfusion induced AKI mice ameliorates kidney injury by promoting renal tubular regeneration, proliferation, vascular repair, and attenuating tubular damage. In vitro assays demonstrate that SDF-1 induces upregulation of its receptor CXCR4 in endothelial progenitor cells (EPCs) via a non-canonical NF-κB signaling pathway. FGF23 crosstalks with the SDF-1/CXCR4 signaling and abrogates SDF-1-induced EPC senescence and migration, but not angiogenesis, in a Klotho-independent manner. The downregulated pro-angiogenic IL-6, IL-8, and VEGF-A expressions after SDF-1 infusion are rescued after adding FGF23. Diminished therapeutic ability of SDF-1-treated EPCs is counteracted by FGF23 in a SCID mouse in vivo AKI model. Together, these data highlight a revolutionary and important role that FGF23 plays in the nephroprotection of IR-AKI.

Stem/progenitor cell in kidney: characteristics, homing, coordination, and maintenance

Renal failure has a high prevalence and is becoming a public health problem worldwide. However, the renal replacement therapies such as dialysis are not yet satisfactory for its multiple complications. While stem/progenitor cell-mediated tissue repair and regenerative medicine show there is light at the end of tunnel. Hence, a better understanding of the characteristics of stem/progenitor cells in kidney and their homing capacity would greatly promote the development of stem cell research and therapy in the kidney field and open a new route to explore new strategies of kidney protection. In this review, we generally summarize the main stem/progenitor cells derived from kidney in situ or originating from the circulation, especially bone marrow. We also elaborate on the kidney-specific microenvironment that allows stem/progenitor cell growth and chemotaxis, and comment on their interaction. Finally, we highlight potential strategies for improving the therapeutic effects of stem/progenitor cell-based therapy. Our review provides important clues to better understand and control the growth of stem cells in kidneys and develop new therapeutic strategies.

Low-Intensity Pulsed Ultrasound Promotes Autophagy-Mediated Migration of Mesenchymal Stem Cells and Cartilage Repair

Mesenchymal stem cell (MSC) migration is promoted by low-intensity pulsed ultrasound (LIPUS), but its mechanism is unclear. Since autophagy is known to regulate cell migration, our study aimed to investigate if LIPUS promotes the migration of MSCs via autophagy regulation. We also aimed to investigate the effects of intra-articular injection of MSCs following LIPUS stimulation on osteoarthritis (OA) cartilage. For the in vitro study, rat bone marrow-derived MSCs were treated with an autophagy inhibitor or agonist, and then they were stimulated by LIPUS. Migration of MSCs was detected by transwell migration assays, and stromal cell-derived factor-1 (SDF-1) and C-X-C chemokine receptor type 4 (CXCR4) protein levels were quantified. For the in vivo study, a rat knee OA model was generated and treated with LIPUS after an intra-articular injection of MSCs with autophagy inhibitor added. The cartilage repair was assessed by histopathological analysis and extracellular matrix protein expression. The in vitro results suggest that LIPUS increased the expression of SDF-1 and CXCR4, and it promoted MSC migration. These effects were inhibited and enhanced by autophagy inhibitor and agonist, respectively. The in vivo results demonstrate that LIPUS significantly enhanced the cartilage repair effects of MSCs on OA, but these effects were blocked by autophagy inhibitor. Our results suggest that the migration of MSCs was enhanced by LIPUS through the activation autophagy, and LIPUS improved the protective effect of MSCs on OA cartilage via autophagy regulation.

Mesenchymal Stem Cell Therapy for Diabetic Kidney Disease: A Review of the Studies Using Syngeneic, Autologous, Allogeneic, and Xenogeneic Cells

Diabetic kidney disease (DKD) is a microvascular complication of diabetes mellitus (DM) and comprises multifactorial pathophysiologic mechanisms. Despite current treatment, around 30-40% of individuals with type 1 and type 2 DM (DM1 and DM2) have progressive DKD, which is the most common cause of end-stage chronic kidney disease worldwide. Mesenchymal stem cell- (MSC-) based therapy has important biological and therapeutic implications for curtailing DKD progression. As a chronic disease, DM may impair MSC microenvironment, but there is compelling evidence that MSC derived from DM1 individuals maintain their cardinal properties, such as potency, secretion of trophic factors, and modulation of immune cells, so that both autologous and allogeneic MSCs are safe and effective. Conversely, MSCs derived from DM2 individuals are usually dysfunctional, exhibiting higher rates of senescence and apoptosis and a decrease in clonogenicity, proliferation, and angiogenesis potential. Therefore, more studies in humans are needed to reach a conclusion if autologous MSCs from DM2 individuals are effective for treatment of DM-related complications. Importantly, the bench to bedside pathway has been constructed in the last decade for assessing the therapeutic potential of MSCs in the DM setting. Laboratory research set the basis for establishing further translation research including preclinical development and proof of concept in model systems. Phase I clinical trials have evaluated the safety profile of MSC-based therapy in humans, and phase II clinical trials (proof of concept in trial participants) still need to answer important questions for treating DKD, yet metabolic control has already been documented. Therefore, randomized and controlled trials considering the source, optimal cell number, and route of delivery in DM patients are further required to advance MSC-based therapy. Future directions include strategies to reduce MSC heterogeneity, standardized protocols for isolation and expansion of those cells, and the development of well-designed large-scale trials to show significant efficacy during a long follow-up, mainly in individuals with DKD.

Enhanced recruitment and hematopoietic reconstitution of bone marrow-derived mesenchymal stem cells in bone marrow failure by the SDF-1/CXCR4

Aplastic anemia (AA) is a bone marrow failure disease. It is difficult to treat AA, and in addition, relapses are common because of its complex disease pathogenesis. Allogeneic bone marrow-derived mesenchymal stem cells (BMSCs) infusion is an effective and safe treatment option for the AA patients. However, it found that BMSCs infusion in AA patients is less than 30% effective. Therefore, the key to improve the efficacy of BMSCs treatment in these patients is to enhance their homing efficiency to the target sites. Studies have shown that stromal cell-derived factor-1 (SDF-1)/CXC chemokine receptor 4 (CXCR4) axis plays an important role in promoting BMSCs homing. In this study, human BMSCs were transduced with lentivirus stably expressing CXCR4-BMSCs. Transduced BMSCs resemble normal BMSCs in many ways. Migration ability of CXCR4-BMSCs toward SDF-1 was increased because of the overexpression of CXCR4. In the mice with bone marrow failure, the migration and colonization ability of CXCR4-BMSCs to the bone marrow was significantly improved as seen by IVIS imaging and FACS. The SDF-1 level in the bone marrow failure mice was significantly higher than in the normal mice. Thus, from our study, it is clear that after CXCR4-BMSCs were infused into mice with bone marrow failure, SDF-1 interacted with CXCR4 receptor, leading cells to migrate and colonize to bone marrow. Because of the high SDF-1 expression in mouse bone marrow and CXCR4 receptor expression in cells, BMSCs homing was increased.

Local SDF-1α application enhances the therapeutic efficacy of BMSCs transplantation in osteoporotic bone healing

Bone defect healing is markedly impaired in osteoporotic patient due to poor bone regeneration ability. Stromal cell derived factor-1α (SDF-1α) plays a pivotal role in the repair of various injured tissues including bone. Here, we definite that SDF-1α hydrogels potentiates in vivo osteogenesis of bone marrow-derived stromal stem cells (BMSCs) in osteoporosis. The characteristics of rat primary BMSCs including superficial markers by flow cytometry and multi-lineage differentiation by induction were determined. At different time intervals, the release media from the SDF-1α-releasing hydrogels were collected to identificate SDF-1α exhibited a sustained release profile and maintained its bioactivity after release from the hydrogels to stimulate chemotaxis of BMSCs in a time dependent manner. Bilateral alveolar defects were operated in ovariectomized (OVX) rats and repaired with systemic BMSCs transplantation with or without the hydrogels. Local administration of SDF-1α significantly enhanced BMSCs recruitment and promoted more bone regeneration as well as the expression of OCN and Runx2 compared with the effect of BMSCs transplantation alone. Moreover, after BMSCs transplantation with SDF-1α delivery, macrophage polarization was promoted toward the M2 phenotype, that is identified as an important symbol in tissue regeneration process. Taken together, local SDF-1α application enhances the efficacy of BMSCs transplantation therapy in osteoporotic bone healing, suggesting clinical potential of SDF-1α to serve as a therapeutic drug target for osteoporosis treatment.

Stem cells: a potential treatment option for kidney diseases

The prevalence of kidney diseases is emerging as a public health problem. Stem cells (SCs), currently considered as a promising tool for therapeutic application, have aroused considerable interest and expectations. With self-renewal capabilities and great potential for proliferation and differentiation, stem cell therapy opens new avenues for the development of renal function and structural repair in kidney diseases. Mounting evidence suggests that stem cells exert a therapeutic effect mainly by replacing damaged tissues and paracrine pathways. The benefits of various types of SCs in acute kidney disease and chronic kidney disease have been demonstrated in preclinical studies, and preliminary results of clinical trials present its safety and tolerability. This review will focus on the stem cell-based therapy approaches for the treatment of kidney diseases, including various cell sources used, possible mechanisms involved, and outcomes that are generated so far, along with prospects and challenges in clinical application.

Enhancer of zeste homolog 2 enhances the migration and chemotaxis of dental mesenchymal stem cells

Objective

To investigate the function of enhancer of zeste homolog 2 (EZH2) in the migration and chemotaxis of human dental tissue-derived mesenchymal stem cells.

Methods

The expression of EZH2, C-X-C motif chemokine ligand 11 (CXCL11), CXCL16, and CXCR1 in stem cells from the apical papilla (SCAPs) was determined by real-time reverse transcription PCR and western blotting. The effects of EZH2 on the homing of SCAPs and the effects of EZH2-overexpressing SCAP culture supernatant on periodontal ligament stem cells (PDLSCs) were tested by scratch migration assays and transwell chemotaxis assays.

Results

EZH2 overexpression significantly enhanced the migration and chemotaxis of SCAPs and upregulated the expression of CXCL11, CXCL16, and CXCR1 in SCAPs. EZH2 depletion had the opposite effect, impairing the migration and chemotaxis of SCAPs and downregulating the expression of CXCL11, CXCL16, and CXCR1. The culture supernatant of EZH2-overexpressing SCAPs advanced the migration and chemotaxis of PDLSCs.

Conclusions

EZH2 evidently promoted the migration and chemotaxis of SCAPs by upregulating the expression of CXCL11, CXCL16, and CXCR1. Moreover, EZH2-overexpressing SCAPs enhanced the homing, migration, and chemotaxis of PDLSCs via paracrine signaling.

Surface Pre-Reacted Glass Filler Contributes to Tertiary Dentin Formation through a Mechanism Different Than That of Hydraulic Calcium-Silicate Cement

The induction of tissue mineralization and the mechanism by which surface pre-reacted glass-ionomer (S-PRG) cement influences pulpal healing remain unclear. We evaluated S-PRG cement-induced tertiary dentin formation in vivo, and its effect on the pulp cell healing process in vitro. Induced tertiary dentin formation was evaluated with micro-computed tomography (μCT) and scanning electron microscopy (SEM). The distribution of elements from the S-PRG cement in pulpal tissue was confirmed by micro-X-ray fluorescence (μXRF). The effects of S-PRG cement on cytotoxicity, proliferation, formation of mineralized nodules, and gene expression in human dental pulp stem cells (hDPSCs) were assessed in vitro. μCT and SEM revealed that S-PRG induced tertiary dentin formation with similar characteristics to that induced by hydraulic calcium-silicate cement (ProRoot mineral trioxide aggregate (MTA)). μXRF showed Sr and Si ion transfer into pulpal tissue from S-PRG cement. Notably, S-PRG cement and MTA showed similar biocompatibility. A co-culture of hDPSCs and S-PRG discs promoted mineralized nodule formation on surrounding cells. Additionally, S-PRG cement regulated the expression of genes related to osteo/dentinogenic differentiation. MTA and S-PRG regulated gene expression in hDPSCs, but the patterns of regulation differed. S-PRG cement upregulated CXCL-12 and TGF-β1 gene expression. These findings showed that S-PRG and MTA exhibit similar effects on dental pulp through different mechanisms.

The synergistic effect of electroacupuncture and bone mesenchymal stem cell transplantation on repairing thin endometrial injury in rats

BACKGROUND

Tissue regeneration disorder after endometrial injury is an important cause of intrauterine adhesions, amenorrhea, and infertility in women. Both bone marrow mesenchymal stem cell (BMSC) transplantation and electroacupuncture (EA) are promising therapeutic applications for endometrial injury. This study examined their combined effects on thin endometrium in rats and the possible mechanisms underlying these effects.

METHODS

A thin endometrial model was established in Sprague-Dawley (SD) rats by perfusing 95% ethanol into the right side of the uterus. The wounds were randomly treated with PBS (model group), BMSCs only (BMSC group), EA only (EA group), and BMSCs combined with EA (BMSC + EA group). Endometrial morphological alterations were observed by hematoxylin and eosin (H&E) staining. Changes in markers of epithelial and stromal endometrium cells, endometrial receptivity-related chemokines, and paracrine factors were detected using immunohistochemistry, western blotting, and quantitative reverse-transcription polymerase chain reaction (qRT-PCR). Finally, the functional recovery of the uterus was evaluated by determining the rate of embryo implantation.

RESULTS

As shown by endometrial morphology, the damaged uteri in all the treatment groups recovered to some extent, with the best effects observed in the BMSC + EA group. Further studies showed that EA promoted the migration of transplanted BMSCs to damaged uteri by activating the stromal cell-derived factor-1/C-X-C chemokine receptor type 4 (SDF-1/CXCR4) axis. As compared with the other groups, upregulated expression of endometrial cytokeratin and vimentin, increased secretion of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in endometrial lesions, and improved embryo implantation rates on the 8th day of pregnancy were found in the BMSC + EA group.

CONCLUSIONS

EA plays an important role in supporting BMSCs in the repair of thin endometrium, most likely by promoting the migration of BMSCs and enhancing the paracrine effect of BMSCs.

[Experimental study on the effect of desferrioxamine on targeted homing and angiogenesis of bone marrow mesenchymal stem cells]

Objective

To investigate whether desferrioxamine (DFO) can enhance the homing of bone marrow mesenchymal stem cells (BMSCs) and improve neovascularization in random flaps of rats.

Methods

BMSCs and fibroblasts (FB) of luciferase transgenic Lewis rats were isolated and cultured. Forty 4-week-old Lewis male rats were used to form a 10 cm×3 cm rectangular flap on their back. The experimental animals were randomly divided into 4 groups with 10 rats in each group: in group A, 200 μL PBS were injected through retrobulbar venous plexus; in group B, 200 μL FB with a concentration of 1×10 ⁶ cells/mL were injected; in group C, 200 μL BMSCs with a concentration of 1×10 ⁶ cells/mL were injected; in group D, cells transplantation was the same as that in group C, after cells transplantation, DFO [100 mg/(kg·d)] were injected intraperitoneally for 7 days. On the 7th day after operation, the survival rate of flaps in each group was observed and calculated; the blood perfusion was observed by laser speckle imaging. Bioluminescence imaging was used to detect the distribution of transplanted cells in rats at 30 minutes and 1, 4, 7, and 14 days after operation. Immunofluorescence staining was performed at 7 days after operation to observe CD31 staining and count capillary density under 200-fold visual field and to detect the expressions of stromal cell derived factor 1 (SDF-1), epidermal growth factor (EGF), fibroblast growth factor (FGF), and Ki67. Transplanted BMSCs were labeled with luciferase antibody and observed by immunofluorescence staining whether they participated in the repair of injured tissues.

Results

The necrosis boundary of ischemic flaps in each group was clear at 7 days after operation. The survival rate of flaps in groups C and D was significantly higher than that in groups A and B, and in group D than in group C ( P<0.05). Laser speckle imaging showed that the blood perfusion units of flaps in groups C and D was significantly higher than that in groups A and B, and in group D than in group C ( P<0.05). Bioluminescence imaging showed that BMSCs gradually migrated to the ischemia and hypoxia area and eventually distributed to the ischemic tissues. The photon signal of group D was significantly stronger than that of other groups at 14 days after operation ( P<0.05). CD31 immunofluorescence staining showed that capillary density in groups C and D was significantly higher than that in groups A and B, and in group D than in group C ( P<0.05). The expressions of SDF-1, EGF, FGF, and Ki67 in groups C and D were significantly stronger than those in groups A and B, and in group D than in group C. Luciferase-labeled BMSCs were expressed in the elastic layer of arteries, capillaries, and hair follicles at 7 days after transplantation.

Conclusion

DFO can enhance the migration and homing of BMSCs to the hypoxic area of random flap, accelerate the differentiation of BMSCs in ischemic tissue, and improve the neovascularization of ischemic tissue.

Preconditioning of umbilical cord-derived mesenchymal stem cells by rapamycin increases cell migration and ameliorates liver ischaemia/reperfusion injury in mice via the CXCR4/CXCL12 axis

Objectives

Transfusion of umbilical cord‐derived mesenchymal stem cells (UC‐MSCs) is a novel strategy for treatment of various liver diseases. However, the therapeutic effect of UC‐MSCs is limited because only a few UC‐MSCs migrate towards the damaged regions. In this study, we observed the effects of autophagy on the migration of UC‐MSCs in vitro and in a model of liver ischaemia/reperfusion (I/R) injury.

Materials and Methods

We investigated the effects of autophagy on the status of the cell, release of anti‐inflammatory factors and migration of UC‐MSCs in vitro. The therapeutic effects and in vivo migration of rapamycin‐preconditioned UC‐MSCs were observed in a C57/B6 mouse model of liver I/R injury.

Results

Induction of autophagy by rapamycin enhanced the ability of UC‐MSCs to migrate and release anti‐inflammatory cytokines as well as increased expression of CXCR4 without affecting cell viability. Inhibition of CXCR4 activation markedly decreased migration of these cells. In a mouse model of liver I/R injury, we found significantly upregulated expression of CXCR12 in the damaged liver. More rapamycin‐preconditioned UC‐MSCs migrated towards the ischaemic regions than 3‐methyladenine‐preconditioned or non‐preconditioned UC‐MSCs, leading to improvement in hepatic performance, pathological changes and levels of inflammatory cytokines. These effects were abolished by AMD3100.

Conclusions

Preconditioning of UC‐MSCs by rapamycin afforded increased protection against liver I/R injury by enhancing immunosuppression and strengthening the homing and migratory capacity of these cells via the CXCR4/CXCL12 axis.

Enhanced proliferation and differentiation of HO-1 gene-modified bone marrow-derived mesenchymal stem cells in the acute injured kidney

The aim of the present study was to investigate the effect of heme oxygenase-1 (HO-1) overexpression on the survival and differentiation ability of bone marrow‑derived mesenchymal stem cells (BMSCs) in the acute kidney injury (AKI) microenvironment. HO-1-BMSCs and enhanced green fluorescent protein (eGFP)-BMSCs were constructed. Rat ischemia/reperfusion (I/R)‑AKI-kidney homogenate supernatant was prep-ared to treat the BMSCs, eGFP-BMSCs and HO-1-BMSCs in vitro. In the AKI microenvironment, the HO-1-BMSCs exhibited a smaller proportion of cells at the G0/G1 phase, and a larger proportion of cells expressing proliferating cell nuclear antigen (PCNA) and cytokeratin 18 (CK18). Phosphorylated protein kinase B (Akt) and extracellular signal‑regulated kinase (ERK) protein levels were observed to be increased in the HO-1-BMSCs compared with the BMSCs. LY294002 and PD98059 each inhibited the above effects. BMSCs, eGFP-BMSCs and HO-1-BMSCs were implanted into an I/R-AKI rat model. The proportions of PCNA+ BMSCs and CK18+ BMSCs were higher in the HO-1-BMSCs group compared with the BMSCs group, which resulted in a decreased acute tubular necrosis score and improved renal function for the AKI rats. In conclusion, the enhanced proliferation and differentiation of HO-1-BMSCs suggest the beneficial effects of such cells in the BMSC-based therapy of AKI. The mechanism underlying these effects may involve the stimulation of Akt and ERK signaling.

The Donor Major Histocompatibility Complex Class I Chain-Related Molecule A Allele rs2596538 G Predicts Cytomegalovirus Viremia in Kidney Transplant Recipients

The interaction of major histocompatibility complex class I chain-related protein A (MICA) and its cognate activating receptor natural killer (NK) group 2 member D (NKG2D) receptor plays a significant role in viral immune control. In the context of kidney transplantation (KTx), cytomegalovirus (CMV) frequently causes severe complications. Hypothesizing that functional polymorphisms of the MICA/NKG2D axis might affect antiviral NK and T cell responses to CMV, we explored the association of the MICA-129 Met/Val single nucleotide polymorphism (SNP) (affecting the binding affinity of MICA with the NKG2D receptor), the MICA rs2596538 G/A SNP (influencing MICA transcription), and the NKG2D rs1049174 G/C SNP (determining the cytotoxic potential of effector cells) with the clinical outcome of CMV during the first year after KTx in a cohort of 181 kidney donor-recipients pairs. Univariate analyses identified the donor MICA rs2596538 G allele status as a protective prognostic determinant for CMV disease. In addition to the well-known prognostic factors CMV high-risk sero-status of patients and the application of lymphocyte-depleting drugs, the donor MICA rs2596538 G allele carrier status was confirmed by multivariate analyses as novel-independent factor predicting the development of CMV infection/disease during the first year after KTx. The results of our study emphasize the clinical importance of the MICA/NKG2D axis in CMV control in KTx and point out that the potential MICA transcription in the donor allograft is of clinically relevant importance for CMV immune control in this allogeneic situation. Furthermore, they provide substantial evidence that the donor MICA rs2596538 G allele carrier status is a promising genetic marker predicting CMV viremia after KTx. Thus, in the kidney transplant setting, donor MICA rs2596538 G may help to allow the future development of personal CMV approaches within a genetically predisposed patient cohort.

Quercetin inhibits NTHi-triggered CXCR4 activation through suppressing IKKα/NF-κB and MAPK signaling pathways in otitis media

Otitis media is one of the most common bacterial infections in children, contributing to hearing loss. A vital bacterial pathogen leading to otitis media development is the nontypeable Haemophilus influenzae (NTHi). Inflammation response is reported as an important characristic for otitis media. Chemokine CXC receptor 4 (CXCR4) is a 352-amino acid seven-span transmembrane G-protein coupled receptor, essential for inflammatory response. However, the possible molecular mechanism indicating the alteration of CXCR4 modulated by NTHi is poorly known. In the present study, NTHi enhanced CXCR4 expression through phosphorylation of IKKα and p38, which relied on nuclear factor-κB (NF-κB) translocation in vitro as well as in the middle ear of mice in vivo. Previously, quercetin, a natural production mainly isolated from rutin, has shown anti-inflammatory effects. Here, we report that quercetin suppressed NTHi-induced CXCR4 expression levels in vitro and in vivo. Quercetin blocked CXCR4 activation through direct IKKβ phosphorylation inhibition, as well as of p38 MAPK restraining. Hence, identification of quercetin may be a potential therapeutic strategy for treating otitis media induced by NTHi through inflammation suppression.

Alteration of renal excretion pathways in gentamicin-induced renal injury in rats

The kidney plays a major part in the elimination of many drugs and their metabolites, and drug-induced kidney injury commonly alters either glomerular filtration or tubular transport, or both. However, the renal excretion pathway of drugs has not been fully elucidated at different stages of renal injury. This study aimed to evaluate the alteration of renal excretion pathways in gentamicin (GEN)-induced renal injury in rats. Results showed that serum cystatin C, creatinine and urea nitrogen levels were greatly increased by the exposure of GEN (100 mg kg^-1 ), and creatinine concentration was increased by 39.7% by GEN (50 mg kg^-1 ). GEN dose-dependently upregulated the protein expression of rOCT1, downregulated rOCT2 and rOAT1, but not affected rOAT2. Efflux transporters, rMRP2, rMRP4 and rBCRP expressions were significantly increased by GEN(100), and the rMATE1 level was markedly increased by GEN(50) but decreased by GEN(100). GEN(50) did not alter the urinary excretion of inulin, but increased metformin and furosemide excretion. However, GEN(100) resulted in a significant decrease of the urinary excretion of inulin, metformin and p-aminohippurate. In addition, urinary metformin excretions in vivo were significantly decreased by GEN(100), but slightly increased by GEN(50). These results suggested that GEN(50) resulted in the induction of rOCTs-rMATE1 and rOAT3-rMRPs pathway, but not changed the glomerular filtration rate, and GEN(100)-induced acute kidney injury caused the downregulated function of glomerular filtration -rOCTs-rMATE1 and -rOAT1-rMRPs pathway.

Ischemia-Reperfusion Injury Reduces Long Term Renal Graft Survival: Mechanism and Beyond

Ischemia-reperfusion injury (IRI) during renal transplantation often initiates non-specific inflammatory responses that can result in the loss of kidney graft viability. However, the long-term consequence of IRI on renal grafts survival is uncertain. Here we review clinical evidence and laboratory studies, and elucidate the association between early IRI and later graft loss. Our critical analysis of previous publications indicates that early IRI does contribute to later graft loss through reduction of renal functional mass, graft vascular injury, and chronic hypoxia, as well as subsequent fibrosis. IRI is also known to induce kidney allograft dysfunction and acute rejection, reducing graft survival. Therefore, attempts have been made to substitute traditional preserving solutions with novel agents, yielding promising results.

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Ischaemia reperfusion injury (IRI) potentiates delayed renal graft function and causes reduction in renal graft survival

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IRI causes innate immune system activation, hypoxic injury, inflammation and graft vascular disease

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Reducing prolonged cold ischaemic time improves graft survival

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Novel protective strategies include mesenchymal stem cells, machine perfusion, and ex vivo preservation solution saturated with gas.

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Further studies are needed to investigate the long-term effects of novel ex vivo preservation agents

Deferoxamine promotes mesenchymal stem cell homing in noise-induced injured cochlea through PI3K/AKT pathway

OBJECTIVE

Over 5% of the world's population suffers from disabling hearing loss. Stem cell homing in target tissue is an important aspect of cell-based therapy, which its augmentation increases cell therapy efficiency. Deferoxamine (DFO) can induce the Akt activation, and phosphorylation status of AKT (p-AKT) upregulates CXC chemokine receptor-4 (CXCR4) expression. We examined whether DFO can enhance mesenchymal stem cells (MSCs) homing in noise-induced damaged cochlea by PI3K/AKT dependent mechanism.

MATERIALS AND METHODS

Mesenchymal stem cells were treated with DFO. AKT, p-AKT protein and hypoxia inducible factor 1- α (HIF-1α) and CXCR4 gene and protein expression was evaluated by RT- PCR and Western blot analysis. For in vivo assay, rats were assigned to control, sham, noise exposure groups without any treatment or receiving normal, DFO-treated and DFO +LY294002 (The PI3K inhibitor)-treated MSCs. Following chronic exposure to 115 dB white noise, MSCs were injected into the rat cochlea through the round window. Number of Hoechst- labelled cells was determined in the endolymph after 24 hours.

RESULTS

Deferoxamine increased P-AKT, HIF-1α and CXCR4 expression in MSCs compared to non-treated cells. DFO pre-conditioning significantly increased the homing ability of MSCs into injured ear compared to normal MSCs. These effects of DFO were blocked by LY294002.

CONCLUSIONS

Pre-conditioning of MSCs by DFO before transplantation can improve stem cell homing in the damaged cochlea through PI3K/AKT pathway activation.

The different dosages of estrogen affect endometrial fibrosis and receptivity, but not SDF-1/CXCR4 axis in the treatment of intrauterine adhesions

OBJECTIVE

The study was to evaluate whether fibrotic markers, endometrial receptivity markers and SDF-1/CXCR4 had been changed in the treatment of intrauterine adhesions (IUAs) by different dosages of estrogen.

STUDY DESIGN

A total of 39 patients with IUAs were treated with EV 4 mg or 9 mg randomly post-surgery. TGF-β1/MMP-9, VEGF/αvβ3 and SDF-1/CXCR4 were detected in endometrial tissue before and after treatment by real-time PCR and Western blot.

RESULTS

TGF-β1 and MMP-9 expression significantly decreased after treatment for 3 months than before (p < .05), the falling range was larger with EV 4 mg than 9 mg in the mild-moderate degree IUAs (p < .05); Integrin avβ3 expression significantly increased after treatment for 3 months than before (p < .05), the variation range was larger with EV 4 mg than 9 mg (p < .05); CXCR4 expression had no significant change after treatment 3 months compared to that before treatment (p > .05). SDF-1 presented an upward tendency at early phase, and it came back to the level of pre-surgery. But there were no significant difference between treatment with 4 mg and 9 mg in the rate of menstrual restoration and pregnancy follow-up 3 months after the treatment.

CONCLUSIONS

Endometrium fibrosis may be inhibited and endometrium receptivity may be improved by estrogen with moderate dosage therapy. Compared to the large one, it seems to be advantageous.

Critical role of SDF-1/CXCR4 signaling pathway in stem cell homing in the deafened rat cochlea after acoustic trauma

Previous animal studies have shown that stromal cell-derived factor-1 (SDF-1)/CXC chemokine receptor-4 (CXCR4) signaling pathway plays an important role in the targeted migration of bone marrow-derived mesenchymal stem cells (BMSCs) to the injured area. In the present study, we aimed to investigate the potential role of chemotactic SDF-1/CXCR4 signaling pathway in the homing of transplanted BMSCs to the injured cochlea after noise-induced hearing loss (NIHL) in a rat model. White noise exposure (110 dB) paradigm was used for hearing loss induction in male rats for 6 hours in 5 days. Distortion-product otoacoustic emission (DPOAE) responses were recorded before the experiment and post noise exposure. Hoechst 33342-labeled BMSCs and CXCR4 antagonist (AMD3100)-treated BMSCs were injected into the rat cochlea through the round window. SDF-1 protein expression in the cochlear tissue was assayed using western blot assay. The number of labeled BMSCs reaching the endolymph was determined after 24 hours. SDF-1 was significantly increased in the cochlear tissue of rats in the noise exposure group than in the control group. The number of Hoechst 33342-labeled BMSCs reaching the endolymph of the cochlea was significantly smaller in the AMD3100-treated BMSCs group than in the normal BMSCs group. Our present findings suggest that the SDF-1/CXCR4 signaling pathway has a critical role in BMSCs migration to the injured cochlea in a rat model of noise-induced hearing loss.

In vitro cell behaviors of bone mesenchymal stem cells derived from normal and postmenopausal osteoporotic rats

Postmenopausal osteoporosis (PMO) increases bone fragility and the risk of fractures, and impairs the healing procedure of bone defects in aged women. The stromal cell-derived factor-1α (SDF-1α)/CXC chemokine receptor type 4 (CXCR4) axis helps to maintain the biological and physiological functions of bone marrow mesenchymal stem cells (BMSCs) and increase the homing efficiency of BMSCs. The present study aimed to provide insights into the possible association between migration and osteogenic ability and the SDF-1α/CXCR4 axis in BMSCs derived from a rat model of PMO. In order to do this, the general and SDF-1α/CXCR4-associated biological characteristics as well as associated molecular mechanisms in BMSCs isolated from a PMO rat model (OVX-BMSCs) and normal rats (Sham-BMSCs) were investigated and compared. In comparison with Sham-BMSCs, OVX-BMSCs exhibited an impaired osteogenic ability, but a stronger adipogenic activity as well as a higher proliferative ability. In addition, OVX-BMSCs presented a lower chemotactic activity towards SDF-1α, lower expression levels of CXCR4 and reduced levels of phosphorylated AKT (p-AKT). Therefore, the lower expression levels of CXCR4 and p-AKT may be responsible for the impaired osteogenic ability and lower chemotactic activity towards SDF-1α of OVX-BMSCs.

Mesenchymal Stem Cell-based Therapy as a New Horizon for Kidney Injuries

Today, the prevalence of kidney diseases is increasing around the world, but there has still been no effective medical treatment. The therapeutic choices are confined to supportive cares and preventive strategies. Currently, mesenchymal stem cells (MSCs)-based cell therapy was proposed for the treatment of kidney injuries. However, after the transplantation of MSCs, they are exposed to masses of cytotoxic factors involving an inflammatory cytokine storm, a nutritionally-poor hypoxic environment and oxidative stresses that finally lead to minimize the efficacy of MSCs based cell therapy. Therefore, several innovative strategies were developed in order to potentiate MSCs to withstand the unfavorable microenvironments of the injured kidney tissues and improve their therapeutic potentials. This review aims to introduce MSCs as a new modality in the treatment of renal failure. Here, we discuss the clinical trials of MSCs-based therapy in kidney diseases as well as the in vivo studies dealing with MSCs application in kidney injuries mainly from the proliferation, differentiation, migration and survival points of view. The obstacles and challenges of this new modality in kidney injuries are also discussed.

Interleukin-3 enhances the migration of human mesenchymal stem cells by regulating expression of CXCR4

BACKGROUND

Mesenchymal stem cells (MSCs) represent an important source for cell therapy in regenerative medicine. MSCs have shown promising results for repair of damaged tissues in various degenerative diseases in animal models and also in human clinical trials. However, little is known about the factors that could enhance the migration and tissue-specific engraftment of exogenously infused MSCs for successful regenerative cell therapy. Previously, we have reported that interleukin-3 (IL-3) prevents bone and cartilage damage in animal models of rheumatoid arthritis and osteoarthritis. Also, IL-3 promotes the differentiation of human MSCs into functional osteoblasts and increases their in-vivo bone regenerative potential in immunocompromised mice. However, the role of IL-3 in migration of MSCs is not yet known. In the present study, we investigated the role of IL-3 in migration of human MSCs under both in-vitro and in-vivo conditions.

METHODS

MSCs isolated from human bone marrow, adipose and gingival tissues were used for in-vitro cell migration, motility and wound healing assays in the presence or absence of IL-3. The effect of IL-3 preconditioning on expression of chemokine receptors and integrins was examined by flow cytometry and real-time PCR. The in-vivo migration of IL-3-preconditioned MSCs was investigated using a subcutaneous matrigel-releasing stromal cell-derived factor-1 alpha (SDF-1α) model in immunocompromised mice.

RESULTS

We observed that human MSCs isolated from all three sources express IL-3 receptor-α (IL-3Rα) both at gene and protein levels. IL-3 significantly enhances in-vitro migration, motility and wound healing abilities of MSCs. Moreover, IL-3 preconditioning upregulates expression of chemokine (C-X-C motif) receptor 4 (CXCR4) on MSCs, which leads to increased migration of cells towards SDF-1α. Furthermore, CXCR4 antagonist AMD3100 decreases the migration of IL-3-treated MSCs towards SDF-1α. Importantly, IL-3 also induces in-vivo migration of MSCs towards subcutaneously implanted matrigel-releasing-SDF-1α in immunocompromised mice.

CONCLUSIONS

The present study demonstrates for the first time that IL-3 has an important role in enhancing the migration of human MSCs through regulation of the CXCR4/SDF-1α axis. These findings suggest a potential role of IL-3 in improving the efficacy of MSCs in regenerative cell therapy.

Effects of SDF-1/CXCR4 on the Repair of Traumatic Brain Injury in Rats by Mediating Bone Marrow Derived Mesenchymal Stem Cells

Our study aims to investigate the effects of the SDF-1/CXCR4 axis on the repair of traumatic brain injury (TBI) in rats by mediating bone marrow derived from mesenchymal stem cells (BMSCs). Healthy male SD rats were collected, their tibiofibulars were removed, cultured, and BMSCs were collected. The expression of cell-surface molecular proteins was examined using flow cytometry. The mRNA and protein expression of CXCR4 in cells were tested using qRT-PCR and western blotting analysis. An electronic brain injury instrument was utilized to build TBI rat models and each rat was assigned into the experiment, positive control and control groups (10 rats in each group). The morris water maze was used to calculate the escape latency and number of times rats in each group crossed the platform. Neurological severity scores (NSS) was calculated to evaluate the recovery of neurological functioning. The distribution of neuronal nuclear antigens was detected using double-labeling immunohistochemistry. The morphological changes in the hippocampal neuronal and the number of BrdU-positive cells were observed through Nissl's staining and high magnification. The mRNA and protein expressions of CXCR4 were gradually increased as SDF-1 concentration increased. NGF and BDNF positive cells were expressed in each group. The distribution of neuronal nuclear antigens in the experiment group was elevated compared to the control and positive control groups. Among the three groups, the experimental group had the shortest escape latency and the highest number platform crossings. The difference in NSS among the three groups was significant. The experimental group had better cell morphology and a higher number of BrdU-positive cells than the other groups. The present study demonstrates that transplanting BMSCs with SDF-1-induced CXCR4 expression can promote the repair of TBI. This is expected to become a new treatment regimen for TBI.

Niche matters: The comparison between bone marrow stem cells and endometrial stem cells and stromal fibroblasts reveal distinct migration and cytokine profiles in response to inflammatory stimulus

Objective

Intrinsic inflammatory characteristics play a pivotal role in stem cell recruitment and homing through migration where the subsequent change in niche has been shown to alter these characteristics. The bone marrow mesenchymal stem cells (bmMSCs) have been demonstrated to migrate to the endometrium contributing to the stem cell reservoir and regeneration of endometrial tissue. Thus, the aim of the present study was to compare the inflammation-driven migration and cytokine secretion profile of human bmMSCs to endometrial mesenchymal stem cells (eMSCs) and endometrial fibroblasts (eSFs).

Materials and methods

The bmMSCs were isolated from bone marrow aspirates through culturing, whereas eMSCs and eSFs were FACS-isolated. All cell types were tested for their surface marker, proliferation profiles and migration properties towards serum and inflammatory attractants. The cytokine/chemokine secretion profile of 35 targets was analysed in each cell type at basal level along with lipopolysaccharide (LPS)-induced state.

Results

Both stem cell types, bmMSCs and eMSCs, presented with similar stem cell surface marker profiles as well as possessed high proliferation and migration potential compared to eSFs. In multiplex assays, the secretion of 16 cytokine targets was detected and LPS stimulation expanded the cytokine secretion pattern by triggering the secretion of several targets. The bmMSCs exhibited higher cytokine secretion of vascular endothelial growth factor (VEGF)-A, stromal cell-derived factor-1 alpha (SDF)-1α, interleukin-1 receptor antagonist (IL-1RA), IL-6, interferon-gamma inducible protein (IP)-10, monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)1α and RANTES compared to eMSCs and/or eSFs after stimulation with LPS. The basal IL-8 secretion was higher in both endometrial cell types compared to bmMSCs.

Conclusion

Our results highlight that similar to bmMSCs, the eMSCs possess high migration activity while the differentiation process towards stromal fibroblasts seemed to result in loss of stem cell surface markers, minimal migration activity and a subtler cytokine profile likely contributing to normal endometrial function.

SDF-1/CXCR4 axis induces human dental pulp stem cell migration through FAK/PI3K/Akt and GSK3β/β-catenin pathways

SDF-1 (stromal cell derived factor-1) has been found to be widely expressed during dental pulp inflammation, while hDPSCs (human dental pulp stem cells) contribute to the repair of dental pulp. We showed that the migration of hDPSCs was induced by SDF-1 in a concentration-dependent manner and could be inhibited with siCXCR4 (C-X-C chemokine receptor type 4) and siCDC42 (cell division control protein 42), as well as drug inhibitors such as AMD3100 (antagonist of CXCR4), LY294002 (inhibitor of PI3K) and PF573228 (inhibitor of FAK). It was also confirmed that SDF-1 regulated the phosphorylation of FAK (focal adhesion kinases) on cell membranes and the translocation of β-catenin into the cell nucleus. Subsequent experiments confirmed that the expression of CXCR4 and β-catenin and the phosphorylation of FAK, PI3K (phosphoinositide 3-kinase), Akt and GSK3β (glycogen synthase kinase-3β) were altered significantly with SDF-1 stimulation. FAK and PI3K worked in coordination during this process. Our findings provide direct evidence that SDF-1/CXCR4 axis induces hDPSCs migration through FAK/PI3K/Akt and GSK3β/β-catenin pathways, implicating a novel mechanism of dental pulp repair and a possible application of SDF-1 for the treatment of pulpitis.

Comprehensive Screening of Cell Surface Markers Expressed by Adult-Derived Human Liver Stem/Progenitor Cells Harvested at Passage 5: Potential Implications for Engraftment

Mesenchymal stromal cells (MSCs) are known to have potential therapeutic benefits for a number of diseases. However, many studies report low engraftment levels, regardless of the target organ. One possible explanation could be that MSCs do not express the necessary receptors for engraftment. Indeed, MSCs appear to use a similar mechanism to leukocytes to engraft into injured organs, relying on various receptors for rolling, firm adhesion, and transmigration. In this study, we conducted an extensive surface molecule screening of adult-derived human liver stem/progenitor cells (ADHLSC) in an attempt to shed some light on this subject. We observed that ADHLSCs lack expression of most of the costimulatory molecules tested. Furthermore, study of the adhesion molecule profile of ADHLSCs revealed that they do not express selectin ligands or LFA-1 which are, respectively, involved in the rolling process and the firm adhesion. In addition, ADHLSCs slightly express VLA-4 and lose expression of CXCR4 altogether on their surface during culture expansion. However, ADHLSCs express all the integrin couples and matrix metalloproteinases needed to bind and integrate the extracellular matrix once the endothelial barrier is crossed. Collectively, these results suggest that binding to the endothelium may be the critical weak point in the engraftment process.

Mesenchymal Stem Cell-Based Therapy for Kidney Disease: A Review of Clinical Evidence

Mesenchymal stem cells form a population of self-renewing, multipotent cells that can be isolated from several tissues. Multiple preclinical studies have demonstrated that the administration of exogenous MSC could prevent renal injury and could promote renal recovery through a series of complex mechanisms, in particular via immunomodulation of the immune system and release of paracrine factors and microvesicles. Due to their therapeutic potentials, MSC are being evaluated as a possible player in treatment of human kidney disease, and an increasing number of clinical trials to assess the safety, feasibility, and efficacy of MSC-based therapy in various kidney diseases have been proposed. In the present review, we will summarize the current knowledge on MSC infusion to treat acute kidney injury, chronic kidney disease, diabetic nephropathy, focal segmental glomerulosclerosis, systemic lupus erythematosus, and kidney transplantation. The data obtained from these clinical trials will provide further insight into safety, feasibility, and efficacy of MSC-based therapy in renal pathologies and allow the design of consensus protocol for clinical purpose.

Genetic Engineering of Mesenchymal Stem Cells to Induce Their Migration and Survival

Mesenchymal stem cells (MSCs) are very attractive for regenerative medicine due to their relatively easy derivation and broad range of differentiation capabilities, either naturally or induced through cell engineering. However, efficient methods of delivery to diseased tissues and the long-term survival of grafted cells still need improvement. Here, we review genetic engineering approaches designed to enhance the migratory capacities of MSCs, as well as extend their survival after transplantation by the modulation of prosurvival approaches, including prevention of senescence and apoptosis. We highlight some of the latest examples that explore these pivotal points, which have great relevance in cell-based therapies.

Injectable hydrogel delivery plus preconditioning of mesenchymal stem cells: exploitation of SDF-1/CXCR4 axis toward enhancing the efficacy of stem cells' homing

Clinical applications of mesenchymal stem cells (MSCs) rely on their capacity to home and engraft in the appropriate target injury tissues for the long term. However, their homing efficiency has been observed to be very poor because of the lack or modifications of homing factors SDF-1α and CXCR4 receptors. Hence, this study was designed to investigate the homing and retention of pretreated human adipose tissue-derived MSCs (hASCs) from three different delivery routes in response to SDF-1α, released from chitosan-based injectable hydrogels. After stimulation of ASCs with a hypoxia mimicking agent, the expression level and functionality of CXCR4 were analyzed by flowcytometric analysis (FACS), transwell migration assay and qPCR. Then, the homing/retention of pretreated DiI-labeled hASCs were compared through three different in vivo delivery routes, 2 weeks after transplantation in Wistar rats. The cells were tracked histologically by fluorescent microscope and by PCR for human-specific CXCR4 gene. Results showed CXCR4 has dynamic expression pattern and pretreatment of hASCs significantly up-regulates CXCR4, leading to an increase in migration capacity toward 100 ng/mL SDF-1α in vitro and homing into the subcutaneously implanted hydrogel releasing SDF-1α in vivo. Furthermore, it seems that SDF-1α is particularly important in the retention of ASCs, in addition to its chemoattraction role. In summary, the delivery route in which the ASCs were mixed with the hydrogel rather than systemic delivery and local injection and preconditioning undertaken to increase CXCR4 expression concomitant with SDF-1α delivery by the injectable hydrogel, allowed for further homing/retention of ASCs. This might be a promising way to get better therapeutic outcomes in stem cell therapy.

Enhanced renoprotective effect of IGF-1 modified human umbilical cord-derived mesenchymal stem cells on gentamicin-induced acute kidney injury

The therapeutic action of umbilical cord-derived mesenchymal stem cells (UC-MSCs) against acute kidney injury (AKI) has been demonstrated by several groups. However, how to further enhance the renoprotective effect of UC-MSCs and improve the therapy effect, are still unclear. In this study, we mainly investigated whether insulin-like growth factor-1 (IGF-1)-modified UC-MSCs hold an enhanced protective effect on gentamicin-induced AKI in vivo. Our results indicated that the IGF-1 overexpression could enhance the therapeutic action of human UC-MSCs, and the AKI rats treated with IGF-1-overexpressed UC-MSCs (UC-MSCs-IGF-1) showed better recovery of biochemical variables in serum or urine associated with renal function, histological injury and renal apoptosis, compared with AKI rats treated with normal UC-MSCs. RNA microarray analysis indicated that some key genes in the signal pathways associated with anti-oxidation, anti-inflammatory, and cell migratory capacity were up-regulated in UC-MSCs-IGF-1, and the results were further confirmed with qPCR. Furthermore, a series of detection in vitro and in vivo indicated that the UC-MSCs-IGF-1 hold better anti-oxidation, anti-inflammatory, and cell migratory capacity for IGF-1 overexpression. Thus, our study indicated that enhancement of UC-MSCs bioactivities with IGF-1 overexpression could increase the UC-MSCs therapeutic potential and further developed a new therapeutic strategy for the treatment of AKI.

Enhanced Homing of CXCR-4 Modified Bone Marrow-Derived Mesenchymal Stem Cells to Acute Kidney Injury Tissues by Micro-Bubble-Mediated Ultrasound Exposure

Although the curative effects of bone marrow stromal cells (BMSCs) for acute kidney injury (AKI) have been recognized, their in vivo reparative capability is limited by the low levels of targeted homing and retention of intravenous injected cells. Stromal cell-derived factor-1 (SDF-1) plays an important role in stem cell homing and retention through interaction with its specific functional receptor, CXCR4, which is presumably related to the poor homing in AKI therapy. However, most of the functional CXCR4 chemokine receptors are lost upon in vitro culturing. Ultrasound-targeted micro-bubble destruction (UTMD) has become one of the most promising strategies for the targeted delivery of drugs and genes. To improve BMSC homing to AKI kidneys, we isolated and cultured rat BMSCs to third passage and enhanced CXCR-4 transfection efficiency in vitro by applying UTMD and polyethylenimine. Transwell migration assay showed that the migration ability of CXCR4-modified BMSCs was nine-fold higher than controls. Then, mercuric chloride-induced AKI rats were injected with transfected BMSCs through their tail veins. We showed that enhanced homing and retention of BMSCs were observed in the CXCR-4 modified group compared with other groups at 1, 2 and 3 d post-treatment. Collectively, our data indicated that UTMD was an effective method to increase BMSCs' engraftment to AKI kidney tissues by increasing CXCR-4 expression.

Chronic exposure of low dose salinomycin inhibits MSC migration capability in vitro

Salinomycin is a polyether antiprotozoal antibiotic that is used as a food additive, particularly in poultry farming. By consuming animal products, there may be a chronic human exposure to salinomycin. Salinomycin inhibits the differentiation of preadipocytes into adipocytes. As human mesenchymal stem cells (MSC) may differentiate into different mesenchymal cells, it thus appeared worthwhile to investigate whether chronic salinomycin exposure impairs the functional properties of MSC and induces genotoxic effects. Bone marrow MSC were treated with low-dose salinomycin (100 nM) (MSC-Sal) for 4 weeks, while the medium containing salinomycin was changed every other day. Functional changes were evaluated and compared to MSC without salinomycin treatment (MSC-control). MSC-Sal and MSC-control were positive for cluster of differentiation 90 (CD90), CD73 and CD44, and negative for CD34. There were no differences observed in cell morphology or cytoskeletal structures following salinomycin exposure. The differentiation into adipocytes and osteocytes was not counteracted by salinomycin, and proliferation capability was not inhibited following salinomycin exposure. The migration of MSC-Sal was attenuated significantly as compared to the MSC-control. There were no genotoxic effects after 4 weeks of salinomycin exposure. The present study shows an altered migration capacity as a sign of functional impairment of MSC induced by chronic salinomycin exposure. Further in vitro toxicological investigations, particularly with primary human cells, are required to understand the impact of chronic salinomycin consumption on human cell systems.

Effects of SOX2 on Proliferation, Migration and Adhesion of Human Dental Pulp Stem Cells

As a key factor for cell pluripotent and self-renewing phenotypes, SOX2 has attracted scientists’ attention gradually in recent years. However, its exact effects in dental pulp stem cells (DPSCs) are still unclear. In this study, we mainly investigated whether SOX2 could affect some biological functions of DPSCs. DPSCs were isolated from the dental pulp of human impacted third molar. SOX2 overexpressing DPSCs (DPSCs-SOX2) were established through retroviral infection. The effect of SOX2 on cell proliferation, migration and adhesion ability was evaluated with CCK-8, trans-well system and fibronectin-induced cell attachment experiment respectively. Whole genome expression of DPSCs-SOX2 was analyzed with RNA microarray. Furthermore, a rescue experiment was performed with SOX2-siRNA in DPSC-SOX2 to confirm the effect of SOX2 overexpression in DPSCs. We found that SOX2 overexpression could result in the enhancement of cell proliferation, migration, and adhesion in DPSCs obviously. RNA microarray analysis indicated that some key genes in the signal pathways associated with cell cycle, migration and adhesion were upregulated in different degree, and the results were further confirmed with qPCR and western-blot. Finally, DPSC-SOX2 transfected with SOX2-siRNA showed a decrease of cell proliferation, migration and adhesion ability, which further confirmed the biological effect of SOX2 in human DPSCs. This study indicated that SOX2 could improve the cell proliferation, migration and adhesion ability of DPSCs through regulating gene expression about cell cycle, migration and adhesion, and provided a novel strategy to develop seed cells with strong proliferation, migration and adhesion ability for tissue engineering.

Mesenchymal stromal cells derived from various tissues: Biological, clinical and cryopreservation aspects

Originally isolated from bone marrow, mesenchymal stromal cells (MSCs) have since been obtained from various fetal and post-natal tissues and are the focus of an increasing number of clinical trials. Because of their tremendous potential for cellular therapy, regenerative medicine and tissue engineering, it is desirable to cryopreserve and bank MSCs to increase their access and availability. A remarkable amount of research and resources have been expended towards optimizing the protocols, freezing media composition, cooling devices and storage containers, as well as developing good manufacturing practices in order to ensure that MSCs retain their therapeutic characteristics following cryopreservation and that they are safe for clinical use. Here, we first present an overview of the identification of MSCs, their tissue sources and the properties that render them suitable as a cellular therapeutic. Next, we discuss the responses of cells during freezing and focus on the traditional and novel approaches used to cryopreserve MSCs. We conclude that viable MSCs from diverse tissues can be recovered after cryopreservation using a variety of freezing protocols, cryoprotectants, storage periods and temperatures. However, alterations in certain functions of MSCs following cryopreservation warrant future investigations on the recovery of cells post-thaw followed by expansion of functional cells in order to achieve their full therapeutic potential.

Chemoattraction of bone marrow-derived stem cells towards human endometrial stromal cells is mediated by estradiol regulated CXCL12 and CXCR4 expression

Bone marrow derived cells engraft to the uterine endometrium and contribute to endometriosis. The mechanism by which these cells are mobilized and directed to the endometrium has not been previously characterized. We demonstrate that human endometrial stromal cells (hESCs) produce the chemokine CXCL12 and that bone marrow cells (BMCs) express the CXCL12 receptor, CXCR4. Treatment with physiological levels of estradiol (E2) induced both CXCL12 and CXCR4 expression in hESCs and BMCs, respectively. BMCs migrated towards hESCs conditioned media; a CXCR4 antagonist blocked migration indicating that CXCL12 acting through its receptor, CXCR4, is necessary for chemoattraction of BM cells to human endometrial cells. E2 increased both CXCL12 expression in endometrial cells and CXCR4 expression in BM cells, further enhancing chemoattraction. E2 induced CXCL12/CXCR4 expression in endometrium and BM, respectively, drives migration of stem cells to the endometrium. The E2-CXCL12/CXCR4 signaling pathway may be useful in determining treatments for endometrial disorders, and may be antagonized to block stem cell migration to endometriosis.

Pericytes, mesenchymal stem cells and their contributions to tissue repair

Regenerative medicine using mesenchymal stem cells for the purposes of tissue repair has garnered considerable public attention due to the potential of returning tissues and organs to a normal, healthy state after injury or damage has occurred. To achieve this, progenitor cells such as pericytes and bone marrow-derived mesenchymal stem cells can be delivered exogenously, mobilised and recruited from within the body or transplanted in the form organs and tissues grown in the laboratory from stem cells. In this review, we summarise the recent evidence supporting the use of endogenously mobilised stem cell populations to enhance tissue repair along with the use of mesenchymal stem cells and pericytes in the development of engineered tissues. Finally, we conclude with an overview of currently available therapeutic options to manipulate endogenous stem cells to promote tissue repair.