Homing Of Mesenchymal Stem Cells Research Articles

Short-wave enhances mesenchymal stem cell recruitment in fracture healing by increasing HIF-1 in callus

BackgroundAs a type of high-frequency electrotherapy, a short-wave can promote the fracture healing process; yet, its underlying therapeutic mechanisms remain unclear.PurposeTo observe the effect of Short-Wave therapy on mesenchymal stem cell (MSC) homing and relative mechanisms associated with fracture healing.Materials and methodsFor in vivo study, the effect of Short-Wave therapy to fracture healing was examined in a stabilized femur fracture model of 40 SD rats. Radiography was used to analyze the morphology and microarchitecture of the callus. Additionally, fluorescence assays were used to analyze the GFP-labeled MSC homing after treatment in 20 nude mice with a femoral fracture. For in vitro study, osteoblast from newborn rats simulated fracture site was first irradiated by the Short-Wave; siRNA targeting HIF-1 was used to investigate the role of HIF-1. Osteoblast culture medium was then collected as chemotaxis content of MSC, and the migration of MSC from rats was evaluated using wound healing assay and trans-well chamber test. The expression of HIF-1 and its related factors were quantified by q RT-PCR, ELISA, and Western blot.ResultsOur in vivo experiment indicated that Short-Wave therapy could promote MSC migration, increase local and serum HIF-1 and SDF-1 levels, induce changes in callus formation, and improve callus microarchitecture and mechanical properties, thus speeding up the healing process of the fracture site. Moreover, the in vitro results further indicated that Short-Wave therapy upregulated HIF-1 and SDF-1 expression in osteoblast and its cultured medium, as well as the expression of CXCR-4, β-catenin, F-actin, and phosphorylation levels of FAK in MSC. On the other hand, the inhibition of HIF-1α was significantly restrained by the inhibition of HIF-1α in osteoblast, and it partially inhibited the migration of MSC.ConclusionsThese results suggested that Short-Wave therapy could increase HIF-1 in callus, which is one of the crucial mechanisms of chemotaxis MSC homing in fracture healing.

Inflammatory Mediators in Glioma Microenvironment Play a Dual Role in Gliomagenesis and Mesenchymal Stem Cell Homing: Implication for Cellular Therapy.

Glioblastoma is the most aggressive malignant primary brain tumor, with a dismal prognosis and a devastating overall survival. Despite aggressive surgical resection and adjuvant treatment, average survival remains approximately 14.6 months. The brain tumor microenvironment is heterogeneous, comprising multiple populations of tumor, stromal, and immune cells. Tumor cells evade the immune system by suppressing several immune functions to enable survival. Gliomas release immunosuppressive and tumor-supportive soluble factors into the microenvironment, leading to accelerated cancer proliferation, invasion, and immune escape. Mesenchymal stem cells (MSCs) isolated from bone marrow, adipose tissue, or umbilical cord are a promising tool for cell-based therapies. One crucial mechanism mediating the therapeutic outcomes often seen in MSC application is their tropism to sites of injury. Furthermore, MSCs interact with host immune cells to regulate the inflammatory response, and data points to the possibility of using MSCs to achieve immunomodulation in solid tumors. Interleukin 1β, interleukin 6, tumor necrosis factor α, transforming growth factor β, and stromal cell–derived factor 1 are notably up-regulated in glioblastoma and dually promote immune and MSC trafficking. Mesenchymal stem cells have widely been regarded as hypoimmunogenic, enabling this cell-based administration across major histocompatibility barriers. In this review, we will highlight (1) the bidirectional communication of glioma cells and tumor-associated immune cells, (2) the inflammatory mediators enabling leukocytes and transplantable MSC migration, and (3) review preclinical and human clinical trials using MSCs as delivery vehicles. Mesenchymal stem cells possess innate abilities to migrate great distances, cross the blood-brain barrier, and communicate with surrounding cells, all of which make them desirable “Trojan horses” for brain cancer therapy.

KSHV enhances mesenchymal stem cell homing and promotes KS-like pathogenesis

Kaposi's sarcoma (KS) tends to occur in injured or inflamed sites of the body, which is described as the “Koebner phenomenon”. KS is also unique in its extraordinary angio-hyperplastic inflammatory phenotype. Recently, evidence has accrued indicating that KS may derive from KSHV-infected mesenchymal stem cells (MSCs), which possess enhanced migration and homing ability. Inspired by these findings, we hypothesized that KS may arise from KSHV-infected MSCs that chemotactically migrate to preexisting inflammatory or injured sites. Here we report that KSHV infection of human MSCs significantly up-regulated expression of several chemokine receptors and enhanced cell migration ability in vitro. Furthermore, using a wound mouse model, we demonstrated that KSHV infection dramatically promotes MSCs migrating and settling in the wound sites. In addition, two mice in the KSHV-infected group showed purpura and tumors with KS-like features. Taken together, KSHV-enhanced MSC migration ability and inflammatory microenvironment play crucial roles in KS development.

Direct lineage tracing reveals Activin-a potential for improved pancreatic homing of bone marrow mesenchymal stem cells and efficient \xdf-cell regeneration in vivo

BackgroundDespite the potential, bone marrow-derived mesenchymal stem cells (BMSCs) show limitations for beta (ß)-cell replacement therapy due to inefficient methods to deliver BMSCs into pancreatic lineage. In this study, we report TGF-ß family member protein, Activin-a potential to stimulate efficient pancreatic migration, enhanced homing and accelerated ß-cell differentiation.MethodsLineage tracing of permanent green fluorescent protein (GFP)- tagged donor murine BMSCs transplanted either alone or in combination with Activin-a in diabetic mice displayed potential ß-cell regeneration and reversed diabetes.ResultsPancreatic histology of Activin-a treated recipient mice reflected high GFP+BMSC infiltration into damaged pancreas with normalized fasting blood glucose and elevated serum insulin. Whole pancreas FACS profiling of GFP+ cells displayed significant homing of GFP+BMSC with Activin-a treatment (6%) compared to BMSCs alone transplanted controls (0.5%). Within islets, approximately 5% GFP+ cells attain ß-cell signature (GFP+ Ins+) with Activin-a treatment versus controls. Further, double immunostaining for mesenchymal stem cell markers CD44+/GFP+ in infiltrated GFP+BMSC deciphers substantial endocrine reprogramming and ß-cell differentiation (6.4% Ins+/GFP+) within 15 days.ConclusionOur investigation thus presents a novel pharmacological approach for stimulating direct migration and homing of therapeutic BMSCs that re-validates BMSC potential for autologous stem cell transplantation therapy in diabetes.

The Antitumor Effect of Gene-Engineered Exosomes in the Treatment of Brain Metastasis of Breast Cancer.

Strategies for treating brain metastases of breast cancer have demonstrated limited efficacy due to the blood–brain barrier (BBB). Gene therapy could improve the efficacy of chemotherapeutic drugs. Exosomes derived from the mesenchymal stem cells (MSCs) are small membrane-based gene vectors that can pass through the BBB. CXCR4 is the most commonly found chemokine receptor in human cancer cells. Furthermore, the SDF-1/CXCR4 axis plays an important role in the homing of MSCs for tumor cell diffusion and metastasis. TRAIL can selectively induce apoptosis in transformed cells without significant toxic side effects in normal tissues. In this study, exosomes were isolated from MSCCXCR4+TRAIL transduced with CXCR4 and TRAIL using a lentiviral vector. Synergistic antitumor study showed that exosomeCXCR4+TRAIL exerted significant activity as a cooperative agent with carboplatin in an MDA-MB-231Br SCID mouse model, potentially engendering a novel strategy for advancing the treatment of brain metastases of breast cancer. Based on this study, further investigation of the effect of the vector on BBB and inducing apoptosis of brain tumors is warranted. In addition, the safety of the vector in animals during the treatment needs to be evaluated.

Study on MSCs homing and its research on osteodiseases

Mesenchymal stem cell (MSCs) has recently emerged as an appealing and potential therapeutic strategy to cure a diverse range of diseases in the orthopaedic field. Owing to its capacity of osteogenic differentiation, most of researches just focused on promoting MSC differentiation. With the in-depth study, MSCs homing is also a key issue for bone formation and bone diseases treatment, which have been described that MSCs mobilize from in situ environment (bone marrow) and migrate into injured tissues during the healing process through peripheral circulation. MSC homing is the incipient step of bone formation. MSCs need to firstly migrate to the bone surface and then differentiate into osteogenic cells to enhance bone repair. Promoting MSCs homing have been shown to improve recovery of several orthopedic diseases, such as osteoporosis, fracture, bone defect and wear-particle-related osteolysis. Therefore, further research on MSCs homing may provide a new thinking for treatment of osteoporosis.

Influence of reaming intramedullary nailing on MSC population after surgical treatment of patients with long bone fracture.

Reamed intramedullary nailing (RIN) is a surgical method of choice for treatment of diaphyseal fractures. This procedure affects the biological environment of bone tissue locally and systemically. This study investigated the influence of RIN on mesenchymal stem cells (MSCs) in patients with long bone fractures. The axis of C-X-C motif chemokine receptor 4 (CXCR4)/stromal cell-derived factor 1 (SDF-1) was selected since it is considered as major pathway for MSC homing and migration. Iliac crest bone marrow (IC-BM) samples and blood samples were collected at two different time points. One sample was collected before the RIN (BN) and the other immediately after RIN (AN). BM-MSCs were cultured and RT-qPCR was performed for CXCR4 mRNA levels and ELISA for the SDF-1 sera levels. The experimental study revealed that there was a correlation between the increase of SDF-1 levels in peripheral blood and a decrease in the levels of CXCR4 in MSCs in the IC-BM following RIN. The levels of SDF-1 showed a significant increase in the sera of patients after RIN. In conclusion, the present study is the first providing evidence of the effects of RIN on MSC population via the CXCR4/SDF-1 axis. The levels of serum SDF-1 factor were elevated after RIN while increased levels of SDF-1 in peripheral blood were inversely correlated with the mRNA levels of CXCR4 on BM-MSCs after RIN. Therefore, this study contributes to enlighten the systematic effects of RIN on the population of MSCs at a cellular level.

Recruitment of Mesenchymal Stem Cells to Damaged Sites by Plant-Derived Components.

Mesenchymal stem cells (MSCs) are capable of differentiating into a limited number of diverse cells and secrete regenerative factors that contribute to the repair of damaged tissue. In response to signals emitted by tissue damage, MSCs migrate from the bone marrow and area surrounding blood vessels within tissues into the circulating blood, and accumulate at the site of damage. Hence, MSC transplantation therapy is beginning to be applied to the treatment of various intractable human diseases. Recent medicinal plants studies have shown that plant-derived components can activate cell functions. For example, several plant-derived components activate cell signaling pathways, such as phosphatidylinositol 3-kinase and mitogen-activated protein kinase (MAPK), enhance expression of the CXCL12/CXCR4 axis, stimulate extracellular matrix remodeling, and consequently, promote cell migration of MSCs. Moreover, plant-derived components have been shown to promote recruitment of MSCs to damaged tissues and enhance healing in disease models, potentially advancing their therapeutic use. This article provides a comprehensive review of several plant-derived components that activate MSC migration and homing to damaged sites to promote tissue repair.

Progress on utilizing mesenchymal stem cells as cellular delivery system for targeting delivery of as drug/gene for anti-tumor therapy

Mesenchymal stem cells (MSCs) have the inherent tumor-homing ability with the attraction of multiple chemokines released by tumor tissues or tumor microenvironments, which can be utilized as promising cellular carriers for targeted delivery of anti-tumor drugs and genes. In most circumstances, large amount of systemicly administrated MSCs will be firstly trapped by lungs, following with re-distribution and homing to tumor tissues after lung clearance. Several approaches like enhanced interactions between chemokines and receptors on MSCs or reducing the retention of MSCs by changes of administration methods are firstly reviewed for improving the homing of MSCs towards tumor tissues. Additionally, the potentials and gains of utilizing MSCs to carry several chemotherapeutics, such as doxorubicin, paclitaxel and gemcitabine are summarized, showing the advantages of overcoming the short half-life and poor tumor targeting of these chemotherapeutics. Moreover, the applications of MSCs to protect and deliver therapeutic genes to tumor sites for selectively tumor cells eliminating or promoting immune system are highlighted. In addition, the potentials of using MSCs for tumor-targeting delivery of diagnostic and therapeutic agents are addressed. We believed that the continuous improvement and optimization of this stem cells-based cellular delivery system will provide a novel delivery strategy and option for tumor treatment.

Homing of mesenchymal stem cells after acute traumatic cervical spinal cord injury – a case report

Background & Aim Mesenchimal stem cell (MSC) therapy has been studied for years as a possible treatment strategy for traumatic spinal cord injury (tSCI), which usually results in severe permanent neurologic deficits. Here we report a case on the migration and homing ability of MSC transplanted by the intravenous and intrathecal route after tSCI. Methods, Results & Conclusion METHODS: A 33-year old male patient with complete tSCI after cervical spine dislocation at theC3 - C4 spinal level due to a diving accident underwent immediate surgical 360° decompression and instrumented fusion. Postoperative MRI showed severe spinal cord injury with minimal residual spinal cord tissue (Figure 1). Three months after injury autologous MSC were harvested from the patient`s iliac crest bone marrow and cultivated. The dose of 150 million MSC were transplanted via the intravenous route, of these one third were radiolabeled with 600MBq of 99mTc-exametazime (HMPAO). Whole-body planar and hybrid (SPECT/CT) imaging of the head and neck, to follow cell migration, were performed at 1h, 4h and 20h after transplantation. After two weeks another 150 million MSC of the same culture were transplanted directly intrathecally per lumbar puncture using the same labeling and imaging protocol and the results of the imaging between intravenous and intratechal administration were compared. RESULTS After intravenous administration, MSC were distributed in the reticuloendothelial system and in the lung parenchyma, as seen on hybrid SPECT/CT imaging and MSC retention at the site of spinal cord injury was unremarkable at any time frame. (Figure 2) After intrathecal administration, accumulation of radiolabeled MSC at the level of administration (L 3) with slow rostral progression was demonstrated on whole-body planar SPECT/CT imaging. On hybrid SPECT/CT imaging intense retention of MSC was observed at the site of spinal cord injury one hour after injection with slow gradual increase in the signal at 4h after administration. A widespread signal throughout the whole spinal canal was observed at 20h after administration due to intense background activity. (Figure 3) CONCLUSION These results suggest the existence of a homing signal that facilitates migration and engraftment of MSC at the site of spinal cord injury three months after acute tSCI and suggest that intrathecal administration is more effective than intravenous administration as the route for MSC transplantation in this respect.

Xenogeneic transplantation of human WJ-MSCs rescues mice from acute radiation syndrome via Nrf-2-dependent regeneration of damaged tissues.

There is an unmet medical need for radiation countermeasures that can be deployed for treatment of exposed individuals during ionizing radiation (IR) accidents or terrorism. Wharton's jelly mesenchymal stem cells (WJ-MSCs) from human umbilical cord have been shown to avoid allorecognition and induce a tissue-regenerating microenvironment, which makes them an attractive candidate for mitigating IR injury. We found that WJ-MSCs protected mice from a lethal dose of IR even when transplanted up to 24hours after irradiation, and a combination of WJ-MSCs and antibiotic (tetracycline) could further expand the window of protection offered by WJ-MSCs. This combinatorial approach mitigated IR-induced damage to the hematopoietic and gastrointestinal system. WJ-MSCs increased the serum concentration of the cytoprotective cytokines granulocyte colony-stimulating factor (G-CSF) and IL-6 in mice. Knockdown of G-CSF and IL-6 in WJ-MSCs before injection to lethally irradiated mice or transplantation of WJ-MSCs to lethally irradiated Nrf-2 knockout mice significantly nullified the therapeutic protective efficacy. Hence, WJ-MSCs could be a potential cell-based therapy for individuals accidentally exposed to radiation.

Quel futur pour les cellules-souches mésenchymateuses dans les affections ostéoarticulaires ?

Regenerative medicine using mesenchymal stem cells (MSC) is developped in several musculoskeletal diseases. The concentration of bone marrow or adipose tissue has been the most common therapeutic method used. The large variability of the cell-productions, however, could be a limitation. Recent biological research concerning MSC has unearthed several new aspects. Firstly, a heterogeneity of the MSC was found following the tissue origin and/or the patient's. Then, the characterisation of MSC was improved by using new combinations of cellular membrane markers. Another important step was the discovery of the paracrine activity of MSC. The MSCs are able to produce a lot of growth factors and cytokines, a production of extra cellular vesicles like exosomes arising an intercellular signaling. MSCs were found to have not only a proliferation and differentiation performance to restore the damages of time, but also immunomodulation and anti-inflammation activities. The field of cell-based therapy with MSC is enlarged with newer and more promising methods than bone marrow concentrate. Expansion culture methods of MSC have been developped, as in vitro differentiation in osteoblasts and chondrocytes or cell manipulations by transfection to produce induced pluripotent stem cells or super MSCs able to produce more growth factors or cytokines, or to modify the membrane signaling for improving MSC homing. The translation of these biological developments in human therapy is the key for the MSC future. After pre-clinical tests to verify the safety, controlled trials are needed to define the true place of this regenerative medicine.

Chemical activation of the Piezo1 channel drives mesenchymal stem cell migration via inducing ATP release and activation of P2 receptor purinergic signaling.

In this study, we examined the Ca2+‐permeable Piezo1 channel, a newly identified mechanosensing ion channel, in human dental pulp‐derived mesenchymal stem cells (MSCs) and hypothesized that activation of the Piezo1 channel regulates MSC migration via inducing ATP release and activation of the P2 receptor purinergic signaling. The Piezo1 mRNA and protein were readily detected in hDP‐MSCs from multiple donors and, consistently, brief exposure to Yoda1, the Piezo1 channel‐specific activator, elevated intracellular Ca2+ concentration. Yoda1‐induced Ca2+ response was inhibited by ruthenium red or GsMTx4, two Piezo1 channel inhibitors, and also by Piezo1‐specific siRNA. Brief exposure to Yoda1 also induced ATP release. Persistent exposure to Yoda1 stimulated MSC migration, which was suppressed by Piezo1‐specific siRNA, and also prevented by apyrase, an ATP scavenger, or PPADS, a P2 generic antagonist. Furthermore, stimulation of MSC migration induced by Yoda1 as well as ATP was suppressed by PF431396, a PYK2 kinase inhibitor, or U0126, an inhibitor of the mitogen‐activated protein kinase MEK/ERK signaling pathway. Collectively, these results suggest that activation of the Piezo1 channel stimulates MSC migration via inducing ATP release and subsequent activation of the P2 receptor purinergic signaling and downstream PYK2 and MEK/ERK signaling pathways, thus revealing novel insights into the molecular and signaling mechanisms regulating MSC migration. Such findings provide useful information for evolving a full understanding of MSC migration and homing and developing strategies to improve MSC‐based translational applications.

Novel Aptamer-Functionalized Nanoparticles Enhances Bone Defect Repair By Improving Stem Cell Recruitment.

BackgroundThe restoration and repair method in the clinic of delayed fracture healing and non-union after comminuted fractures are urgently needed to improve the prognosis of patients. The recruitment of endogenous stem cells has been considered a promising approach in bone defect repair.ProposeThe aim of this study was to generate a de novel MSCs aptamer and developed the first, feasible, economical, bio-compatible, and functional MSCs aptamer-directed nanoparticles without complex manufacture to recruit mesenchymal stem cells (MSCs) for bone defect regeneration.MethodsWhole-cell SELEX was used to generate a de novel MSCs aptamer. Flow cytometry was applied to assess the binding specificities, affinities and sorting abilities of the aptamers. Nano-Aptamer Ball (NAB) was constructed by NHS/EDC reaction. The diameter and zeta of NAB were assessed by dynamic light scattering. CCK8 assay was utilized to evaluate whether NAB could cause non-specific cytotoxicity and induce cell proliferation. To evaluate the bone repair capacity of NAB, histomorphological staining, alizarin red and micro X-ray were used to observe the repair degree of defect in vivo. ELISA was used to detect osteopontin (OPN), osteocalcin (BGP) by, and alkaline phosphatase (ALP) in peripheral blood.ResultsMSCs aptamer termed as HM69 could bind with MSCs with high specificity and Kd of 9.67 nM, while has minimal cross-reactivities to other negative cells. HM69 could capture MSCs with a purity of >89%. In vitro, NAB could bind and capture MSCs effectively, whereas did not cause obvious cytotoxicity. In vivo, serum OPN, BGP, and ALP levels in the NAB group of rats were increased at both 2 and 4 weeks, indicating the repair and osteogenesis generation. The healing of bone defects in the NAB group was significantly better than control groups, the defects became blurred, and local trabecular bone growth could be observed in X-ray. The organized hematoma and cell growth in the bone marrow of the NAB group were more vigorous in bone sections staining.ConclusionThese suggested that HM69 and HM69-functionalized nanoparticles NAB exhibited the ability to recruit MSCs both in vitro and in vivo and achieved a better outcome of bone defect repair in a rat model. The findings demonstrate a promising strategy of using aptamer-functionalized bio-nanoparticles for the restoration of bone defects via aptamer-introduced homing of MSCs.

Preclinical analysis of human mesenchymal stem cells: tumor tropism and therapeutic efficiency of local HSV-TK suicide gene therapy in glioblastoma.

Glioblastoma are highly invasive and associated with limited therapeutic options and a grim prognosis. Using stem cells to extend current therapeutic strategies by targeted drug delivery to infiltrated tumors cells is highly attractive. This study analyzes the tumor homing and therapeutic abilities of clinical grade human mesenchymal stem cells (MSCs) in an orthotopic glioblastoma mouse model. Our time course analysis demonstrated that MSCs display a rapid targeted migration to intracerebral U87 glioma xenografts growing in the contralateral hemisphere within the first 48h hours after application as assessed by histology and 7T magnetic resonance imaging. MSCs accumulated predominantly peritumorally but also infiltrated the main tumor mass and targeted distant tumor satellites while no MSCs were found in other regions of the brain. Intratumoral application of MSCs expressing herpes simplex virus thymidine kinase followed by systemic prodrug application of ganciclovir led to a significant tumor growth inhibition of 86% versus the control groups (p<0.05), which translated in a significant prolonged survival time (p<0.05). This study demonstrates that human MSCs generated according to apceth’s GMP process from healthy donors are able to target and provide a significant growth inhibition in a glioblastoma model supporting a potential clinical translation.

CCL2 But Not CCR2 Is Required for Spontaneous Articular Cartilage Regeneration Post-Injury.

The role of the inflammatory response in articular cartilage degeneration and/or repair is often debated. Chemokine networks play a critical role in directing the recruitment of immune cells to sites of injury and have been shown to regulate cell behavior. In this study, we investigated the role of the CCL2/CCR2 signaling axis in cartilage regeneration and degeneration. CCL2-/- , CCR2-/- , CCL2-/- CCR2-/- , and control (C57) mice were subjected to full-thickness cartilage defect (FTCD) injuries (n = 9/group) within the femoral groove. Cartilage regeneration at 4 and 12 weeks post-FTCD was assessed using a 14-point histological scoring scale. Mesenchymal stem cells (MSCs) (Sca-1+ , CD140a+ ), macrophages (M1:CD38+ , M2:CD206+ , and M0:F4/80+ ) and proliferating cells (Ki67+ ) were quantified within joints using immunofluorescence. The multi-lineage differentiation capacity of Sca1+ MSCs was determined for all mouse strains. ACL transection (ACL-x) was employed to determine if CCL2-/- CCR2-/- mice were protected against osteoarthritis (OA) (n = 6/group). Absence of CCR2, but not CCL2 nor both (CCL2 and CCR2), enhanced spontaneous articular cartilage regeneration by 4 weeks post-FTCD. Furthermore, increased chondrogenesis was observed in MSCs derived from CCR2-/- mice. CCL2 deficiency promoted MSC homing to the adjacent synovium and FTCD at both 4 and 12 weeks post-injury; with no MSCs present at the surface of the FTCD in the remaining strains. Lower OA scores were observed in CCL2-/- CCR2-/- mice at 12 weeks post-ACL-x compared with C57 mice. Our findings demonstrate an inhibitory role for CCR2 in cartilage regeneration after injury, while CCL2 is required for regeneration, acting through a CCR2 independent mechanism. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2561-2574, 2019.

Intercellular adhesion molecule-1 enhances the therapeutic effects of MSCs in a dextran sulfate sodium-induced colitis models by promoting MSCs homing to murine colons and spleens

BackgroundTo investigate the therapeutic effect of intercellular adhesion molecule (ICAM)-1-modified mesenchymal stem cells (MSCs) in a mouse model of inflammatory bowel disease (IBD) induced by dextran sulfate sodium.MethodsPrimary MSCs and ICAM-1-overexpressing MSCs (C3 cells) were generated in vitro. The IBD mouse model was induced with drinking water containing dextran sulfate sodium for 7 days. For stem cell therapy, mice were randomly assigned to six experimental groups: the control group, IBD group, primary MSC group, C3 group, C3-vector group, and C3-ICAM-1 group. Mice were given a single injection of 1 × 106 primary MSCs or gene-modified MSCs via the tail vein on day 3 of DDS administration. The general conditions of the mice in each group were observed. Additionally, the pathological changes in the colon were observed and scored. Primary MSCs and gene-modified MSCs were stained with the fluorescent dye CM-DIL before injection into the tail vein of mice. The distribution of infused cells in IBD mice was observed in frozen sections. Mechanistically, the polarization of Th1, Th2, Th17, and regulatory T cells (Tregs) in the spleen was determined by flow cytometry. Moreover, the mRNA expression levels of IBD-related immune factors in splenocytes were measured by quantitative PCR.ResultsA single injection of MSCs promoted general recovery and reduced pathological damage in IBD mice. Additionally, ICAM-1-overexpressing MSCs had stronger therapeutic effects than ICAM-1low MSCs. Furthermore, the in vivo distribution analysis results indicated that a higher number of ICAM-1-overexpressing MSCs homed to the colon and spleen of IBD mice. Moreover, the delivery of ICAM-1 overexpressing MSCs decreased the numbers of Th1 and Th17 cells but increased the number of Tregs in the spleen of IBD mice. The quantitative PCR analysis results revealed that an infusion of ICAM-1-overexpressing MSCs influenced the expression of spleen-derived immune factors by remarkably reducing the mRNA levels of IFN-γ and IL-17A and increasing the mRNA level of Foxp3.ConclusionsOur results demonstrate that ICAM-1-modified mesenchymal stem cells (MSCs) remarkably alleviate inflammatory damage in IBD mice by promoting MSC homing to the target and immune organs. The findings suggest that ICAM-1 is required to maintain the therapeutic effects of MSCs in IBD treatment and identified a novel role of ICAM-1 in inflammatory diseases.

Increased Bone Marrow-Specific Adipogenesis by Clofazimine Causes Impaired Fracture Healing, Osteopenia, and Osteonecrosis Without Extraskeletal Effects in Rats.

Mycobacterium leprae infection causes bone lesions and osteoporosis, however, the effect of antileprosy drugs on the bone is unknown. We, therefore, set out to address it by investigating osteogenic differentiation from bone marrow (BM)-derived mesenchymal stem cells (MSCs). Out of 7 antileprosy drugs, only clofazimine (CFZ) reduced MSCs viability (IC50 ∼ 1 μM) and their osteogenic differentiation but increased adipogenic differentiation on a par with rosiglitazone, and this effect was blocked by a peroxisome proliferator-activated receptor gamma antagonist, GW9662. CFZ also decreased osteoblast viability and resulted in impaired bone regeneration in a rat femur osteotomy model at one-third human drug dose owing to increased callus adipogenesis as GW9662 prevented this effect. CFZ treatment decreased BM MSC population and homing of MSC to osteotomy site despite drug levels in BM being much less than its in vitro IC50 value. In adult rats, CFZ caused osteopenia in long bones marked by suppressed osteoblast function due to enhanced adipogenesis and increased osteoclast functions. A robust increase in marrow adipose tissue (MAT) by CFZ did not alter the hematologic parameters but likely reduced BM vascular bed leading to osteonecrosis (ON) characterized by empty osteocyte lacunae. However, CFZ had no effect on visceral fat content and was not associated with any metabolic and hematologic changes. Levels of unsaturated fatty acids in MAT were higher than saturated fatty acids and CFZ further increased the former. From these data, we conclude that CFZ has adverse skeletal effects and could be used for creating a rodent ON model devoid of extraskeletal effects.

Possible Renal Repairing Mechanisms of Mesenchymal Stem Cells in Cyclosporine-Mediated Nephrotoxicity: Endothelial Viability and Hemodynamics

BACKGROUND: Stem cell-based therapy may represent the first realistic option for tissue repairing and regeneration. Mesenchymal stem cells (MSCs) are proved to be involved in the regeneration of many tissues which are subjected to different types of injury. Cyclosporine (CsA) in spite of its use as immune suppressive drug during kidney transplantation, it was considered as important model of nephropathy specially, during long-term administration.METHODS: Isolation and preparation of MSCs using Dulbecco's modified Eagle's medium (DMEM), in vitro differentiation through adipogenesis chondrogenesis and osteogenesis was confirmed by using Alizarin Red S stain, Oil Red O stain and Alcian Blue stain, respectively, characterization using flow cytometry technique to detect cluster of differentiation (CD)34, CD44 and CD105 surface markers and homing of MSCs using polymerase chain reaction (PCR) Sry gene assay, were executed. Serum levels of vascular endothelial growth factor (VEGF), endothelin-1 (ET-1) and endothelial nitric oxide synthase (eNOS) were quantified using enzyme-linked immunosorbent assay (ELISA) kits based on the principle of double-antibody sandwich technique. The structural organization of kidney tissue was examined using histological procedures.RESULTS: Single intravenous dose of MSCs is capable to boost kidney repairment process as indicated by the significant decrease in serum ET-1 level paralleled by significant increase in VEGF and eNOS. Moreover, histological findings revealed the improvement of focal hemorrhage in between the degenerated tubules, congestion in the cortical blood vessels, vacuolization in the endothelial cells lining the glomerular tufts and focal perivascular inflammatory cells aggregation.CONCLUSION: This study demonstrated the favorable influence of MSCs in repressing cyclosporine-induced nephropathy in rats. This could be achieved through angiogenic and anti-arteriolopathic mechanisms.KEYWORDS: angiogenesis, cyclosporine, endothelin-1, MSCs, nephropathy

Human Bone Marrow-Derived Mesenchymal Stem Cells Home via the PI3K-Akt, MAPK, and Jak/Stat Signaling Pathways in Response to Platelet-Derived Growth Factor.

Mesenchymal stem cells (MSCs) have great potential to improve clinical outcomes for many inflammatory and degenerative diseases either through intravenously delivered MSCs or through mobilization and migration of endogenous MSCs to injury sites, termed "stem cell homing." Stem cell homing involves the processes of attachment to and transmigration through endothelial cells lining the vasculature and migration through the tissue stroma to a site of injury or inflammation. Although the process of leukocyte transendothelial migration (TEM) is well understood, far less is known about stem cell homing. In this study, a transwell-based model was developed to monitor adherence and TEM of human MSCs in response to chemokine exposure. Specifically, transwell membranes lined with human synovial microvascular endothelial cells were partitioned from the tissue injury-mimetic site containing chemokine stromal cell-derived factor-1 (SDF-1). Two population subsets of MSCs were studied: migratory cells that initiated transmigration on the endothelial lining and nonmigratory cells. We hypothesized that cells would adhere to and migrate through the endothelial lining in response to SDF-1 exposure and that gene and protein expression changes would be observed between migratory and nonmigratory cells. We validated a vasculature model for MSC transmigration that showed increased expression of several genes and activation of proteins of the PI3K-Akt, MAPK, and Jak/Stat signaling pathways. These findings showed that MSC homing may be driven by activation of PDGFRA/PI3K/Akt, PDGFRA/MAPK/Grb2, and PDGFRA/Jak2/Stat signaling, as a result of SDF-1-stimulated endothelial cell production of platelet-derived growth factor. This model can be used to further investigate these key regulatory molecules toward the development of targeted therapies.