Mesenchymal stem/progenitor cells developed in cultures from UC blood

Stem Cell Therapy for Neonatal Disorders: Prospects and Challenges

Despite recent advances in neonatal medicine, neonatal disorders, such as bronchopulmonary dysplasia and intraventricular hemorrhage in preterm neonates and hypoxic ischemic encephalopathy in term neonates, remain major causes of mortality and morbidities. Promising preclinical research results suggest that stem cell therapies represent the next breakthrough in the treatment of currently intractable and devastating neonatal disorders with complex multifactorial etiologies. This review focuses primarily on the potential role of stem cell therapy in the above mentioned neonatal disorders, highlighting the results of human clinical trials and the challenges that remain to be addressed for their safe and successful translation into clinical care of newborn infants.

Restoration of a large osteochondral defect of the knee using a composite of umbilical cord blood-derived mesenchymal stem cells and hyaluronic acid hydrogel: a case report with a 5-year follow-up

Background

The treatment of articular cartilage defects is a therapeutic challenge for orthopaedic surgeons. Furthermore, large osteochondral defects needs restoration of the underlying bone for sufficient biomechanical characteristics as well as the overlying cartilage.

Case presentation

A symptomatic large osteochondral defect in the knee joint was restored using a composite of umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) 0.5 x 10⁷/ml and 4% hyaluronic acid (HA) hydrogel. Significant improvements in pain and function of the knee joint were identified by the evaluation at 12 months after surgery. A hyaline-like cartilage completely filled the defect and was congruent with the surrounding normal cartilage as revealed by magnetic resonance imaging (MRI), a second-look arthroscopy and histological assessment. The improved clinical outcomes maintained until 5.5 years. MRI also showed the maintenance of the restored bony and cartilaginous tissues.

Conclusion

This case report suggests that the composite of allogeneic UCB-MSCs and HA hydrogel can be considered a safe and effective treatment option for large osteochondral defects of the knee.

Magnetic Resonance Imaging of Ferumoxytol-Labeled Human Mesenchymal Stem Cells in the Mouse Brain

The success of stem cell therapy is highly dependent on accurate delivery of stem cells to the target site of interest. Possible ways to track the distribution of MSCs in vivo include the use of reporter genes or nanoparticles. The U.S. Food and Drug Administration (FDA) has approved ferumoxytol (Feraheme® [USA], Rienso® [UK]) as a treatment for iron deficiency anemia. Ferumoxytol is an ultrasmall superparamagnetic iron oxide nanoparticle (USPIO) that has recently been used to track the fate of transplanted cells using magnetic resonance imaging (MRI). The major objectives of this study were to demonstrate the feasibility of labeling hUCB-MSCs with ferumoxytol and to observe, through MRI, the engraftment of ferumoxytol-labeled human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) delivered via stereotactic injection into the hippocampi of a transgenic mouse model of familial Alzheimer's disease (5XFAD). Ferumoxytol had no toxic effects on the viability or stemness of hUCB-MSCs when assessed in vitro. Through MRI, hypointense signals were discernible at the site where ferumoxytol-labeled human MSCs were injected. Iron-positive areas were also observed in the engrafted hippocampi. The results from this study support the use of nanoparticle labeling to monitor transplanted MSCs in real time as a follow-up for AD stem cell therapy in the clinical field.

Umbilical cord blood-derived non-hematopoietic stem cells retrieved and expanded on bone marrow-derived extracellular matrix display pluripotent characteristics

BACKGROUND

Umbilical cord blood (UCB) not only contains hematopoietic stem cells (HSCs), but also non-hematopoietic stem cells (NHSCs) that are able to differentiate into a number of distinct cell types. Based on studies published to date, the frequency of NHSCs in UCB is believed to be very low. However, the isolation of these cells is primarily based on their adhesion to tissue culture plastic surfaces.

METHODS AND RESULTS

In the current study, we demonstrate that this approach overlooks some of the extremely immature NHSCs because they lack the ability to adhere to plastic. Using a native extracellular matrix (ECM), produced by bone marrow (BM) stromal cells, the majority of the UCB-NHSCs attached within 4 h. The colony-forming unit fibroblast frequency of these cells was 1.5 × 10⁴/10⁸ mononuclear cells, which is at least 4000-fold greater than previously reported for UCB-NHSCs. The phenotype of these cells was fibroblast-like and different from those obtained by plastic adhesion; they formed embryonic body-like clusters that were OCT4-positive and expressed other human embryonic stem cell-related markers. Importantly, when implanted subcutaneously for 8 weeks into immunocompromised mice, these ECM-adherent and expanded NHSCs generated three germ layer-derived human tissues including muscle, fat, blood vessel, bone, gland, and nerve. Moreover, injection of these cells into muscle damaged by cryoinjury significantly accelerated muscle regeneration.

CONCLUSIONS

These results indicate that UCB may be a virtually unlimited source of NHSCs when combined with isolation and expansion on ECM. NHSCs may be a practical alternative to embryonic stem cells for a number of therapeutic applications.

Mesenchymal Stem Cells: The Magic Cure for Intraventricular Hemorrhage?

Severe intraventricular hemorrhage (IVH) remains a major cause of mortality and long-term neurologic morbidities in premature infants, despite recent advances in neonatal intensive care medicine. Several preclinical studies have demonstrated the beneficial effects of mesenchymal stem cell (MSC) transplantation in attenuating brain injuries resulting from severe IVH. Because there currently exists no effective intervention for severe IVH, the therapeutic potential of MSC transplantation in this intractable and devastating disease is creating excitement in this field. This review summarizes recent progress in stem cell research for treating neonatal brain injury due to severe IVH, with a particular focus on preclinical data concerning important issues, such as mechanism of protective action and determining optimal source, route, timing, and dose of MSC transplantation, and on the translation of these preclinical study results to a clinical trial.

Netrin-1-Induced Stem Cell Bioactivity Contributes to the Regeneration of Injured Tissues via the Lipid Raft-Dependent Integrin α6β4 Signaling Pathway

Netrin-1 (Ntn-1) is a multifunctional neuronal signaling molecule; however, its physiological significance, which improves the tissue-regeneration capacity of stem cells, has not been characterized. In the present study, we investigate the mechanism by which Ntn-1 promotes the proliferation of hUCB-MSCs with regard to the regeneration of injured tissues. We found that Ntn-1 induces the proliferation of hUCB-MSCs mainly via Inα6β4 coupled with c-Src. Ntn-1 induced the recruitment of NADPH oxidases and Rac1 into membrane lipid rafts to facilitate ROS production. The Inα6β4 signaling of Ntn-1 through ROS production is uniquely mediated by the activation of SP1 for cell cycle progression and the transcriptional occupancy of SP1 on the VEGF promoter. Moreover, Ntn-1 has the ability to induce the F-actin reorganization of hUCB-MSCs via the Inα6β4 signaling pathway. In an in vivo model, transplantation of hUCB-MSCs pre-treated with Ntn-1 enhanced the skin wound healing process, where relatively more angiogenesis was detected. The potential effect of Ntn-1 on angiogenesis is further verified by the mouse hindlimb ischemia model, where the pre-activation of hUCB-MSCs with Ntn-1 significantly improved vascular regeneration. These results demonstrate that Ntn-1 plays an important role in the tissue regeneration process of hUCB-MSC via the lipid raft-mediated Inα6β4 signaling pathway.

Effect of Transplanting Various Concentrations of a Composite of Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells and Hyaluronic Acid Hydrogel on Articular Cartilage Repair in a Rabbit Model

Background

Mesenchymal stem cells (MSCs) are known to have therapeutic potential for cartilage repair. However, the optimal concentration of MSCs for cartilage repair remains unclear. Therefore, we aimed to explore the feasibility of cartilage repair by human umbilical cord blood-derived MSCs (hUCB-MSCs) and to determine the optimal concentrations of the MSCs in a rabbit model.

Methods

Osteochondral defects were created in the trochlear groove of femur in 55 rabbits. Four experimental groups (11 rabbits/group) were treated by transplanting the composite of hUCB-MSCs and HA with various MSCs concentrations (0.1, 0.5, 1.0, and 1.5 x 10⁷ cells/ml). One control group was left untreated. At 4, 8, and 16 weeks post-transplantation, the degree of cartilage repair was evaluated grossly and histologically.

Findings

Overall, transplanting hUCB-MSCs and HA hydrogel resulted in cartilage repair tissue with better quality than the control without transplantation (P = 0.015 in 0.1, P = 0.004 in 0.5, P = 0.004 in 1.0, P = 0.132 in 1.5 x 10⁷ cells/ml). Interestingly, high cell concentration of hUCB-MSCs (1.5×10⁷ cells/ml) was inferior to low cell concentrations (0.1, 0.5, and 1.0 x 10⁷ cells/ml) in cartilage repair (P = 0.394,P = 0.041, P = 0.699, respectively). The 0.5 x 10⁷ cells/ml group showed the highest cartilage repair score at 4, 8 and 16 weeks post transplantation, and followed by 0.1x10⁷ cells/ml group or 1.0 x 10⁷ cell/ml group.

Conclusions

The results of this study suggest that transplantation of the composite of hUCB-MSCs and HA is beneficial for cartilage repair. In addition, this study shows that optimal MSC concentration needs to be determined for better cartilage repair.

Cartilage Regeneration in Osteoarthritic Patients by a Composite of Allogeneic Umbilical Cord Blood-Derived Mesenchymal Stem Cells and Hyaluronate Hydrogel: Results from a Clinical Trial for Safety and Proof-of-Concept with 7 Years of Extended Follow-Up

Few methods are available to regenerate articular cartilage defects in patients with osteoarthritis. We aimed to assess the safety and efficacy of articular cartilage regeneration by a novel medicinal product composed of allogeneic human umbilical cord blood‐derived mesenchymal stem cells (hUCB‐MSCs). Patients with Kellgren‐Lawrence grade 3 osteoarthritis and International Cartilage Repair Society (ICRS) grade 4 cartilage defects were enrolled in this clinical trial. The stem cell‐based medicinal product (a composite of culture‐expanded allogeneic hUCB‐MSCs and hyaluronic acid hydrogel [Cartistem]) was applied to the lesion site. Safety was assessed by the World Health Organization common toxicity criteria. The primary efficacy outcome was ICRS cartilage repair assessed by arthroscopy at 12 weeks. The secondary efficacy outcome was visual analog scale (VAS) score for pain on walking. During a 7‐year extended follow‐up, we evaluated safety, VAS score, International Knee Documentation Committee (IKDC) subjective score, magnetic resonance imaging (MRI) findings, and histological evaluations. Seven participants were enrolled. Maturing repair tissue was observed at the 12‐week arthroscopic evaluation. The VAS and IKDC scores were improved at 24 weeks. The improved clinical outcomes were stable over 7 years of follow‐up. The histological findings at 1 year showed hyaline‐like cartilage. MRI at 3 years showed persistence of the regenerated cartilage. Only five mild to moderate treatment‐emergent adverse events were observed. There were no cases of osteogenesis or tumorigenesis over 7 years. The application of this novel stem cell‐based medicinal product appears to be safe and effective for the regeneration of durable articular cartilage in osteoarthritic knees. Stem Cells Translational Medicine2017;6:613–621

Distribution of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) in canines after intracerebroventricular injection

In this study, we investigated the distribution of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) administered via intracerebroventricular (ICV) injection in a canine model. Ten beagles (11-13 kg per beagle) each received an injection of 1 × 10⁶ cells into the right lateral ventricle and were sacrificed 7 days after administration. Based on immunohistochemical analysis, hUCB-MSCs were observed in the brain parenchyma, especially along the lateral ventricular walls. Detected as far as 3.5 mm from the cortical surface, these cells migrated from the lateral ventricle toward the cortex. We also observed hUCB-MSCs in the hippocampus and the cervical spinal cord. According to real-time polymerase chain reaction results, most of the hUCB-MSCs were found distributed in the brain and the cervical spinal cord but not in the lungs, heart, kidneys, spleen, and liver. ICV administered hUCB-MSCs also enhanced the endogenous neural stem cell population in the subventricular zone. These results highlighted the ICV delivery route as an optimal route to be performed in stem cell-based clinical therapies for neurodegenerative diseases.

Intra-Arterially Delivered Mesenchymal Stem Cells Are Not Detected in the Brain Parenchyma in an Alzheimer's Disease Mouse Model

Mesenchymal stem cells (MSCs) have a promising role as a therapeutic agent for neurodegenerative diseases such as Alzheimer’s disease (AD). Prior studies suggested that intra-arterially administered MSCs are engrafted into the brain in stroke or traumatic brain injury (TBI) animal models. However, a controversial standpoint exists in terms of the integrity of the blood brain barrier (BBB) in transgenic AD mice. The primary goal of this study was to explore the feasibility of delivering human umbilical cord-blood derived mesenchymal stem cells (hUCB-MSCs) into the brains of non-transgenic WT (C3H/C57) and transgenic AD (APP/PS1) mice through the intra-arterial (IA) route. Through two experiments, mice were infused with hUCB-MSCs via the right internal carotid artery and were sacrificed at two different time points: 6 hours (experiment 1) or 5 minutes (experiment 2) after infusion. In both experiments, no cells were detected in the brain parenchyma while MSCs were detected in the cerebrovasculature in experiment 2. The results from this study highlight that intra-arterial delivery of MSCs is not the most favorable route to be implemented as a potential therapeutic approach for AD.

Senescence-Associated MCP-1 Secretion Is Dependent on a Decline in BMI1 in Human Mesenchymal Stromal Cells

AIMS

Cellular senescence and its secretory phenotype (senescence-associated secretory phenotype [SASP]) develop after long-term expansion of mesenchymal stromal cells (MSCs). Further investigation of this phenotype is required to improve the therapeutic efficacy of MSC-based cell therapies. In this study, we show that positive feedback between SASP and inherent senescence processes plays a crucial role in the senescence of umbilical cord blood-derived MSCs (UCB-MSCs).

RESULTS

We found that monocyte chemoattractant protein-1 (MCP-1) was secreted as a dominant component of the SASP during expansion of UCB-MSCs and reinforced senescence via its cognate receptor chemokine (c-c motif) receptor 2 (CCR2) by activating the ROS-p38-MAPK-p53/p21 signaling cascade in both an autocrine and paracrine manner. The activated p53 in turn increased MCP-1 secretion, completing a feed-forward loop that triggered the senescence program in UCB-MSCs. Accordingly, knockdown of CCR2 in UCB-MSCs significantly improved their therapeutic ability to alleviate airway inflammation in an experimental allergic asthma model. Moreover, BMI1, a polycomb protein, repressed the expression of MCP-1 by binding to its regulatory elements. The reduction in BMI1 levels during UCB-MSC senescence altered the epigenetic status of MCP-1, including the loss of H2AK119Ub, and resulted in derepression of MCP-1.

INNOVATION

Our results provide the first evidence supporting the existence of the SASP as a causative contributor to UCB-MSC senescence and reveal a so far unappreciated link between epigenetic regulation and SASP for maintaining a stable senescent phenotype.

CONCLUSION

Senescence of UCB-MSCs is orchestrated by MCP-1, which is secreted as a major component of the SASP and is epigenetically regulated by BMI1.

Downregulation of Melanoma Cell Adhesion Molecule (MCAM/CD146) Accelerates Cellular Senescence in Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells

Therapeutic applications of mesenchymal stem cells (MSCs) for treating various diseases have increased in recent years. To ensure that treatment is effective, an adequate MSC dosage should be determined before these cells are used for therapeutic purposes. To obtain a sufficient number of cells for therapeutic applications, MSCs must be expanded in long-term cell culture, which inevitably triggers cellular senescence. In this study, we investigated the surface markers of human umbilical cord blood-derived MSCs (hUCB-MSCs) associated with cellular senescence using fluorescence-activated cell sorting analysis and 242 cell surface-marker antibodies. Among these surface proteins, we selected the melanoma cell adhesion molecule (MCAM/CD146) for further study with the aim of validating observed expression differences and investigating the associated implications in hUCB-MSCs during cellular senescence. We observed that CD146 expression markedly decreased in hUCB-MSCs following prolonged in vitro expansion. Using preparative sorting, we found that hUCB-MSCs with high CD146 expression displayed high growth rates, multilineage differentiation, expression of stemness markers, and telomerase activity, as well as significantly lower expression of the senescence markers p16, p21, p53, and senescence-associated β-galactosidase, compared with that observed in hUCB-MSCs with low-level CD146 expression. In contrast, CD146 downregulation with small interfering RNAs enhanced the senescence phenotype. In addition, CD146 suppression in hUCB-MSCs caused downregulation of other cellular senescence regulators, including Bmi-1, Id1, and Twist1. Collectively, our results suggest that CD146 regulates cellular senescence; thus, it could be used as a therapeutic marker to identify senescent hUCB-MSCs.

SIGNIFICANCE

One of the fundamental requirements for mesenchymal stem cell (MSC)-based therapies is the expansion of MSCs during long-term culture because a sufficient number of functional cells is required. However, long-term growth inevitably induces cellular senescence, which potentially causes poor clinical outcomes by inducing growth arrest and the loss of stem cell properties. Thus, the identification of markers for evaluating the status of MSC senescence during long-term culture may enhance the success of MSC-based therapy. This study provides strong evidence that CD146 is a novel and useful marker for predicting senescence in human umbilical cord blood-derived MSCs (hUCB-MSCs), and CD146 can potentially be applied in quality-control assessments of hUCB-MSC-based therapy.

Stem Cells for Neonatal Brain Disorders

Despite recent advances in neonatal intensive care medicine, neonatal brain injury resulting from intraventricular hemorrhage or hypoxic-ischemic encephalopathy remains a major cause of neonatal mortality and neurologic morbidities in survivors. Several studies have indicated that stem cell therapy is a promising novel therapy for neonatal brain injury resulting from these disorders. This review summarizes recent advances in stem cell research for treating neonatal brain injury due to intraventricular hemorrhage or hypoxic-ischemic encephalopathy with a particular focus on preclinical data, covering important issues for clinical translation such as optimal cell type, route, dose and timing of stem cell therapy, and translation of these preclinical results into a clinical trial.

Cartilage repair by human umbilical cord blood-derived mesenchymal stem cells with different hydrogels in a rat model

This study was carried out to assess the feasibility of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) in articular cartilage repair and to further determine a suitable delivering hydrogel in a rat model. Critical sized full thickness cartilage defects were created. The hUCB-MSCs and three different hydrogel composites (hydrogel A; 4% hyaluronic acid/30% pluronic (1:1, v/v), hydrogel B; 4% hyaluronic acid, and hydrogel C; 4% hyaluronic acid/30% pluronic/chitosan (1:1:2, v/v)) were implanted into the experimental knee (right knee) and hydrogels without hUCB-MSCs were implanted into the control knee (left knee). Defects were evaluated after 8 weeks. The hUCB-MSCs with hydrogels composites resulted in a better repair as seen by gross and histological evaluation compared with hydrogels without hUCB-MSCs. Among the three different hydrogels, the 4% hyaluronic acid hydrogel composite (hydrogel B) showed the best result in cartilage repair as seen by the histological evaluation compared with the other hydrogel composites (hydrogel A and C). The results of this study suggest that hUCB-MSCs may be a promising cell source in combination with 4% hyaluronic acid hydrogels in the in vivo repair of cartilage defects.

Antibacterial effect of mesenchymal stem cells against Escherichia coli is mediated by secretion of beta- defensin- 2 via toll- like receptor 4 signalling

Recently, we demonstrated that intratracheal transplantation of human umbilical cord blood‐ derived mesenchymal stem cells (MSCs) attenuates Escherichia (E) coli‐ induced acute lung injury primarily by down‐ modulating inflammation and enhancing bacterial clearance iQn mice. This study was performed to elucidate the mechanism underlying the antibacterial effects of MSCs. The growth of E. coli in vitro was significantly inhibited only by MSCs or their conditioned medium with bacterial preconditioning, but not by fibroblasts or their conditioned medium. Microarray analysis identified significant up‐ regulation of toll‐ like receptors (TLR)‐ 2 and TLR‐ 4, and β‐ defensin 2 (BD2) in MSCs compared with fibroblasts after E. coli exposure. The increased BD2 level and the in vitro antibacterial effects of MSCs were abolished by specific antagonist or by siRNA‐ mediated knockdown of TLR‐ 4, but not TLR‐ 2, and restored by BD2 supplementation. The in vivo down‐ modulation of the inflammatory response and enhanced bacterial clearance, increased BD2 secretion and the resultant protection against E. coli‐ induced pneumonia observed only with MSCs, but not fibroblasts, transplantation in mice, were abolished by knockdown of TLR‐ 4 with siRNA transfection. Our data indicate that BD2 secreted by the MSCs via the TLR‐ 4 signalling pathway is one of the critical paracrine factors mediating their microbicidal effects against E. coli, both in vitro and in vivo. Furthermore, TLR‐ 4 from the transplanted MSCs plays a seminal role in attenuating in vivo E. coli‐ induced pneumonia and the ensuing acute lung injury through both its anti‐ inflammatory and antibacterial effects.

Optimal Timing of Mesenchymal Stem Cell Therapy for Neonatal Intraventricular Hemorrhage

We recently showed that intraventricular transplantation of human umbilical cord blood (UCB)-derived mesenchymal stem cells (MSCs) significantly attenuated posthemorrhagic hydrocephalus (PHH) and brain injury after severe intraventricular hemorrhage (IVH) in newborn rat pups. The purpose of this study was to optimize the timing of MSC transplantation for severe IVH. Severe IVH was induced by injecting 100 µl of blood into each ventricle of Sprague-Dawley rats on postnatal day 4 (P4). Human UCB-derived MSCs (1 × 10(5) cells in 10 µl of normal saline) were transplanted intraventricularly under stereotaxic guidance either early at P6 or late at P11. Serial brain MRIs and behavioral function tests, such as negative geotaxis and rotarod tests, were performed. At P32, brain tissue samples were obtained for histological and biochemical analyses. Intracerebroventricular transplantation of MSCs significantly attenuated the development of PHH, behavioral impairment, increased apoptosis and astrogliosis, reduced corpus callosum thickness and brain myelination, and upregulated inflammatory cytokines including interleukin (IL)-1α, IL-1β, IL-6, and tumor necrosis factor-α (TNF-α) at P6 but not at P11 after induction of severe IVH. Intracerebroventricular transplantation of human UCB-derived MSCs attenuated PHH and brain injury after severe IVH in newborn rats in a time-dependent manner. Significant neuroprotection was only demonstrated when administered early at 2 days after induction but not late at 7 days after induction of severe IVH.

Regeneration of Full-Thickness Rotator Cuff Tendon Tear After Ultrasound-Guided Injection With Umbilical Cord Blood-Derived Mesenchymal Stem Cells in a Rabbit Model

Rotator cuff tendon tear is one of the most common causes of chronic shoulder pain and disability. In this study, we investigated the therapeutic effects of ultrasound-guided human umbilical cord blood (UCB)-derived mesenchymal stem cell (MSC) injection to regenerate a full-thickness subscapularis tendon tear in a rabbit model by evaluating the gross morphology and histology of the injected tendon and motion analysis of the rabbit's activity. At 4 weeks after ultrasound-guided UCB-derived MSC injection, 7 of the 10 full-thickness subscapularis tendon tears were only partial-thickness tears, and 3 remained full-thickness tendon tears. The tendon tear size and walking capacity at 4 weeks after UCB-derived MSC injection under ultrasound guidance were significantly improved compared with the same parameters immediately after tendon tear. UCB-derived MSC injection under ultrasound guidance without surgical repair or bioscaffold resulted in the partial healing of full-thickness rotator cuff tendon tears in a rabbit model. Histology revealed that UCB-derived MSCs induced regeneration of rotator cuff tendon tear and that the regenerated tissue was predominantly composed of type I collagens. In this study, ultrasound-guided injection of human UCB-derived MSCs contributed to regeneration of the full-thickness rotator cuff tendon tear without surgical repair. The results demonstrate the effectiveness of local injection of MSCs into the rotator cuff tendon.

SIGNIFICANCE

The results of this study suggest that ultrasound-guided umbilical cord blood-derived mesenchymal stem cell injection may be a useful conservative treatment for full-thickness rotator cuff tendon tear repair.

Human umbilical cord blood-derived mesenchymal stem cells improve functional recovery through thrombospondin1, pantraxin3, and vascular endothelial growth factor in the ischemic rat brain

Cell therapy is a potential therapeutic method for cerebral ischemia, which remains a serious problem. In the search for more effective therapeutic methods, many kinds of stem cells from various tissues have been developed and tested as candidate therapeutic agents. Among them, human umbilical cord blood (hUCB)-derived mesenchymal stem cells (MSCs) are widely used for cell therapy because of their genetic flexibility. To confirm that they are effective and understand how they affect ischemic neural cells, hUCB-MSCs were directly administered ipsilaterally into an ischemic zone induced by middle cerebral artery occlusion (MCAO). We found that the neurobehavioral performance of the hUCB-MSC group was significantly improved compared with that of the vehicle-injected control group. The infarct was also remarkably smaller in the hUCB-MSC group. Additionally, hUCB-MSC transplantation resulted in a greater number of newly generated cells and angiogenic and tissue repair factors and a lower number of inflammatory events in the penumbra zone. To determine why these events occurred, hUCB-MSCs were assayed under hypoxic and normoxic conditions in vitro. The results showed that hUCB-MSCs exhibit higher expression levels of thrombospondin1, pantraxin3, and vascular endothelial growth factor under hypoxic conditions than under normoxic conditions. These results were found to be correlated with our in vivo immunofluorescent staining results. On the basis of these findings, we suggest that hUCB-MSCs may have a beneficial effect on cerebral ischemia, especially through angiogenesis, neurogenesis, and anti-inflammatory effects, and thus could be used as a therapeutic agent to treat neurological disorders such as cerebral ischemia.

Optimal Route for Human Umbilical Cord Blood-Derived Mesenchymal Stem Cell Transplantation to Protect Against Neonatal Hyperoxic Lung Injury: Gene Expression Profiles and Histopathology

The aim of this study was to determine the optimal route of mesenchymal stem cell (MSC) transplantation. To this end, gene expression profiling was performed to compare the effects of intratracheal (IT) versus intravenous (IV) MSC administration. Furthermore, the therapeutic efficacy of each route to protect against neonatal hyperoxic lung injury was also determined. Newborn Sprague-Dawley rats were exposed to hyperoxia (90% oxygen) from birth for 14 days. Human umbilical cord blood-derived MSCs labeling with PKH26 were transplanted through either the IT (5×10⁵) or IV (2×10⁶) route at postnatal day (P) 5. At P14, lungs were harvested for histological, biochemical and microarray analyses. Hyperoxic conditions induced an increase in the mean linear intercept and mean alveolar volume (MAV), indicative of impaired alveolarization. The number of ED-1 positive cells was significantly decreased by both IT and IV transplantations. However, IT administration of MSCs resulted in a greater decrease in MAV and ED-1 positive cells compared to IV administration. Moreover, the number of TUNEL-positive cells was significantly decreased in the IT group, but not in the IV group. Although the IT group received only one fourth of the number of MSCs that the IV group did, a significantly higher number of donor cell-derived red PKH 26 positivity were recovered in the IT group. Hyperoxic conditions induced the up regulation of genes associated with the inflammatory response, such as macrophage inflammatory protein-1 α, tumor necrosis factor-α and inter leukin-6; genes associated with cell death, such as p53 and caspases; and genes associated with fibrosis, such as connective tissue growth factor. In contrast, hyperoxic conditions induced the dwon-regulation of vascular endothelial growth factor and hepatocyte growth factor. These hyperoxia-induced changes in gene expression were decreased in the IT group, but not in the IV group. Thus, local IT MSC transplantation was more effective than systemic IV MSC administration in protecting against neonatal hyperoxic lung injury.

Differentiation of Bone Marrow: Derived Mesenchymal Stem Cells into Hepatocyte-like Cells

Cirrhosis is the end-stage liver fibrosis, whereby normal liver architecture is disrupted by fibrotic bands, parenchymal nodules and vascular distortion. Portal hypertension and hepatocyte dysfunction are the end results and give rise to major systemic complications and premature death. Mesenchymal stem cells (MSC) have the capacity of self-renew and to give rise to cells of various lineages, so MSC can be isolated from bone marrow (BM) and induced to differentiate into hepatocyte-like cells. MSC were induced to differentiate into hepatocyte-like cells by hepatotic growth factor (HGF) and fibroblast growth factor-4 (FGF-4). Differentiated cells were examined for the expression of hepatocyte-specific markers and hepatocyte functions. MSC were isolated. Flow cytometry analysis showed that they expressed the MSC-specific markers, reverse transcriptase-polymerase chain reaction (RT-PCR) demonstrated that MSC expressed the hepatocyte-specific marker cytokeratin 18 (CK-18) following hepatocyte induction. This study demonstrates that BM-derived-MSC can differentiate into functional hepatocyte-like cells following the induction of HGF and FGF-4. MSC can serve as a favorable cell source for tissue engineering in the treatment of liver disease.

GDF-15 secreted from human umbilical cord blood mesenchymal stem cells delivered through the cerebrospinal fluid promotes hippocampal neurogenesis and synaptic activity in an Alzheimer's disease model

Our previous studies demonstrated that transplantation of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) into the hippocampus of a transgenic mouse model of Alzheimer's disease (AD) reduced amyloid-β (Aβ) plaques and enhanced cognitive function through paracrine action. Due to the limited life span of hUCB-MSCs after their transplantation, the extension of hUCB-MSC efficacy was essential for AD treatment. In this study, we show that repeated cisterna magna injections of hUCB-MSCs activated endogenous hippocampal neurogenesis and significantly reduced Aβ42 levels. To identify the paracrine factors released from the hUCB-MSCs that stimulated endogenous hippocampal neurogenesis in the dentate gyrus, we cocultured adult mouse neural stem cells (NSCs) with hUCB-MSCs and analyzed the cocultured media with cytokine arrays. Growth differentiation factor-15 (GDF-15) levels were significantly increased in the media. GDF-15 suppression in hUCB-MSCs with GDF-15 small interfering RNA reduced the proliferation of NSCs in cocultures. Conversely, recombinant GDF-15 treatment in both in vitro and in vivo enhanced hippocampal NSC proliferation and neuronal differentiation. Repeated administration of hUBC-MSCs markedly promoted the expression of synaptic vesicle markers, including synaptophysin, which are downregulated in patients with AD. In addition, in vitro synaptic activity through GDF-15 was promoted. Taken together, these results indicated that repeated cisterna magna administration of hUCB-MSCs enhanced endogenous adult hippocampal neurogenesis and synaptic activity through a paracrine factor of GDF-15, suggesting a possible role of hUCB-MSCs in future treatment strategies for AD.

Cartilage Repair Using Composites of Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells and Hyaluronic Acid Hydrogel in a Minipig Model

The cartilage regeneration potential of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) with a hyaluronic acid (HA) hydrogel composite has shown remarkable results in rat and rabbit models. The purpose of the present study was to confirm the consistent regenerative potential in a pig model using three different cell lines. A full-thickness chondral injury was intentionally created in the trochlear groove of each knee in 6 minipigs. Three weeks later, an osteochondral defect, 5 mm wide by 10 mm deep, was created, followed by an 8-mm-wide and 5-mm-deep reaming. A mixture (1.5 ml) of hUCB-MSCs (0.5×10(7) cells per milliliter) and 4% HA hydrogel composite was then transplanted into the defect on the right knee. Each cell line was used in two minipigs. The osteochondral defect created in the same manner on the left knee was untreated to act as the control. At 12 weeks postoperatively, the pigs were sacrificed, and the degree of subsequent cartilage regeneration was evaluated by gross and histological analysis. The transplanted knee resulted in superior and more complete hyaline cartilage regeneration compared with the control knee. The cellular characteristics (e.g., cellular proliferation and chondrogenic differentiation capacity) of the hUCB-MSCs influenced the degree of cartilage regeneration potential. This evidence of consistent cartilage regeneration using composites of hUCB-MSCs and HA hydrogel in a large animal model could be a stepping stone to a human clinical trial in the future.

SIGNIFICANCE

To date, several studies have investigated the chondrogenic potential of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs); however, the preclinical studies are still limited in numbers with various results. In parallel, in the past several years, the cartilage regeneration potential of hUCB-MSCs with a hyaluronic acid (HA) hydrogel composite have been investigated and remarkable results in rat and rabbit models have been attained. (These experimental results are currently in preparation for publication.) Before applying the cartilage regeneration technique in a human clinical trial, it seemed necessary to confirm the consistent result in a larger animal model. At 12 weeks postoperatively, the minipigs were sacrificed, and the degree of subsequent cartilage regeneration was evaluated by gross and histological analysis. The transplanted knee resulted in superior and more complete hyaline cartilage regeneration compared with the control knee. This evidence of consistent cartilage regeneration with composites of hUCB-MSCs and HA hydrogel in a large animal model could be a stepping stone to a human clinical trial in the future.

Efficacy and Safety of Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells in Anterior Cruciate Ligament Reconstruction of a Rabbit Model: New Strategy to Enhance Tendon Graft Healing

PURPOSE

To investigate whether non-autologous transplantation of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) could be integrated safely at the bone-tendon junction without immune rejection and could enhance bone-tendon healing effectively during anterior cruciate ligament (ACL) reconstruction in an animal model.

METHODS

ACL reconstructions using hamstring tendons were performed in 30 adult rabbits. The bone tunnels were treated with hUCB-MSCs or were untreated. The specimens were harvested at 4, 8, and 12 weeks. We performed a gross examination of the knee joint; a histologic assessment using H&E staining, as well as immunohistochemical staining, for type II collagen; and an evaluation of bone tunnel widening using micro-computed tomography.

RESULTS

No evidence of immune rejection was detected. Tendon-bone healing through Sharpey-like fibers was noticed around tendon grafts at 12 weeks in the control group. A smooth transition from bone to tendon through broad fibrocartilage formation was identified in the treatment group, and the interface zone showed abundant type II collagen production on immunohistochemical staining. Histologic scores for bone-tendon healing were significantly higher in the treatment group at all time points (P < .001). Micro-computed tomography at 12 weeks showed a significantly smaller tibial (P = .029) and femoral (P = .033) bone tunnel enlargement in the treated group than in the control group.

CONCLUSIONS

Non-autologous transplantation of hUCB-MSCs was applied in ACL reconstruction without early immune rejection. There was enhanced tendon-bone healing through broad fibrocartilage formation with higher histologic scores and decreased femoral and tibial tunnel widening compared with the control group (79.2% and 80%, respectively, of the control group tunnel area at 12 weeks).

CLINICAL RELEVANCE

Non-autologous transplantation of hUCB-MSCs has therapeutic potential in promoting tendon-to-bone healing after ACL reconstruction. Further study in the human model is warranted.

Optimal Route for Mesenchymal Stem Cells Transplantation after Severe Intraventricular Hemorrhage in Newborn Rats

Recently, we showed that intracerebroventricular (IC) transplantation of human umbilical cord blood (UCB)-derived mesenchymal stem cells (MSCs) significantly attenuates posthemorrhagic hydrocephalus (PHH) and brain damage after severe IVH in newborn rats. This study was performed to determine the optimal route for transplanting MSCs for severe IVH by comparing IC transplantation, intravenous (IV) transplantation, and IV transplantation plus mannitol infusion. Severe IVH was induced by injecting 100 uL of blood into each ventricle of Sprague-Dawley rats on postnatal day 4 (P4). After confirming severe IVH with brain magnetic resonance imaging (MRI) at P5, human UCB-derived MSCs were transplanted at P6 by an IC route (1×10⁵), an IV route (5×10⁵), or an IV route with mannitol infused. Follow-up brain MRIs and rotarod tests were performed. At P32, brain tissue samples were obtained for biochemical and histological analyses. Although more MSCs localized to the brain after IC than after IV delivery, both methods were equally effective in preventing PHH; attenuating impaired rotarod test; increasing the number of TUNEL-positive cells, inflammatory cytokines, and astrogliosis; and reducing corpus callosal thickness and myelin basic protein expression after severe IVH regardless of mannitol co-infusion. Despite the superior delivery efficacy with IC than with the IV route, both IC and IV transplantation of MSCs had equal therapeutic efficacy in protecting against severe IVH. These findings suggest that the less invasive IV route might be a good alternative for clinically unstable, very preterm infants that cannot tolerate a more invasive IC delivery of MSCs.

Wound-healing potential of human umbilical cord blood-derived mesenchymal stromal cells in vitro--a pilot study

BACKGROUND AIMS

Our previous studies demonstrated that human bone marrow-derived mesenchymal stromal cells have great potential for wound healing. However, it is difficult to clinically utilize cultured stem cells. Recently, human umbilical cord blood-derived mesenchymal stromal cells (hUCB-MSCs) have been commercialized for cartilage repair as a first cell therapy product that uses allogeneic stem cells. Should hUCB-MSCs have a superior effect on wound healing as compared with fibroblasts, which are the main cell source in current cell therapy products for wound healing, they may possibly replace fibroblasts. The purpose of this in vitro study was to compare the wound-healing activity of hUCB-MSCs with that of fibroblasts.

METHODS

This study was particularly designed to compare the effect of hUCB-MSCs on diabetic wound healing with those of allogeneic and autologous fibroblasts. Healthy (n = 5) and diabetic (n = 5) fibroblasts were used as the representatives of allogeneic and autologous fibroblasts for diabetic patients in the control group. Human UCB-MSCs (n = 5) were used in the experimental group. Cell proliferation, collagen synthesis and growth factor (basic fibroblast growth factor, vascular endothelial growth factor and transforming growth factor-β) production were compared among the three cell groups.

RESULTS

Human UCB-MSCs produced significantly higher amounts of vascular endothelial growth factor and basic fibroblast growth factor when compared with both fibroblast groups. Human UCB-MSCs were superior to diabetic fibroblasts but not to healthy fibroblasts in collagen synthesis. There were no significant differences in cell proliferation and transforming growth factor-β production.

CONCLUSIONS

Human UCB-MSCs may have greater capacity for diabetic wound healing than allogeneic or autologous fibroblasts, especially in angiogenesis.

Oleic acid enhances the motility of umbilical cord blood derived mesenchymal stem cells through EphB2-dependent F-actin formation

The role of unsaturated fatty acids (UFAs) is essential for determining stem cell functions. Eph/Ephrin interactions are important for regulation of stem cell fate and localization within their niche, which is significant for a wide range of stem cell behavior. Although oleic acid (OA) and Ephrin receptors (Ephs) have critical roles in the maintenance of stem cell functions, interrelation between Ephs and OA has not been explored. Therefore, the present study investigated the effect of OA-pretreated UCB-MSCs in skin wound-healing and underlying mechanism of Eph expression. OA promoted the motility of UCB-MSCs via EphB2 expression. OA-mediated GPR40 activation leads to Gαq-dependent PKCα phosphorylation. In addition, OA-induced phosphorylation of GSK3β was followed by β-catenin nuclear translocation in UCB-MSCs. Activation of β-catenin was blocked by PKC inhibitors, and OA-induced EphB2 expression was suppressed by β-cateninsiRNA transfection. Of those Rho-GTPases, Rac1 was activated in an EphB2-dependent manner. Accordingly, knocking down EphB2 suppressed F-actin expression. In vivo skin wound-healing assay revealed that OA-treated UCB-MSCs enhanced skin wound repair compared to UCB-MSCs pretreated with EphB2siRNA and OA. In conclusion, we showed that OA enhances UCB-MSC motility through EphB2-dependent F-actin formation involving PKCα/GSK3β/β-catenin and Rac1 signaling pathways.

Stem cell therapy for bronchopulmonary dysplasia: bench to bedside translation

Bronchopulmonary dysplasia (BPD), a chronic lung disease affecting very premature infants, is a major cause of mortality and long-term morbidities despite of current progress in neonatal intensive care medicine. Though there has not been any effective treatment or preventive strategy for BPD, recent stem cell research seems to support the assumption that stem cell therapy could be a promising and novel therapeutic modality for attenuating BPD severity. This review summarizes the recent advances in stem cell research for treating BPD. In particular, we focused on the preclinical data about stem cell transplantation to improve the lung injury using animal models of neonatal BPD. These translational research provided the data related with the safety issue, optimal type of stem cells, optimal timing, route, and dose of cell transplantation, and potency marker of cells as a therapeutic agent. Those are essential subjects for the approval and clinical translation. In addition, the successful phase I clinical trial results of stem cell therapies for BPD are also discussed.

The Effect of Umbilical Cord Blood Derived Mesenchymal Stem Cells in Monocrotaline-induced Pulmonary Artery Hypertension Rats

Pulmonary arterial hypertension (PAH) causes right ventricular failure due to a gradual increase in pulmonary vascular resistance. The purposes of this study were to confirm the engraftment of human umbilical cord blood-mesenchymal stem cells (hUCB-MSCs) placed in the correct place in the lung and research on changes of hemodynamics, pulmonary pathology, immunomodulation and several gene expressions in monocrotaline (MCT)-induced PAH rat models after hUCB-MSCs transfusion. The rats were grouped as follows: the control (C) group; the M group (MCT 60 mg/kg); the U group (hUCB-MSCs transfusion). They received transfusions via the external jugular vein a week after MCT injection. The mean right ventricular pressure (RVP) was significantly reduced in the U group after the 2 week. The indicators of RV hypertrophy were significantly reduced in the U group at week 4. Reduced medial wall thickness in the pulmonary arteriole was noted in the U group at week 4. Reduced number of intra-acinar muscular pulmonary arteries was observed in the U group after 2 week. Protein expressions such as endothelin (ET)-1, endothelin receptor A (ERA), endothelial nitric oxide synthase (eNOS) and matrix metalloproteinase (MMP)-2 significantly decreased at week 4. The decreased levels of ERA, eNOS and MMP-2 immunoreactivity were noted by immnohistochemical staining. After hUCB-MSCs were administered, there were the improvement of RVH and mean RVP. Reductions in several protein expressions and immunomodulation were also detected. It is suggested that hUCB-MSCs may be a promising therapeutic option for PAH.

Cell type-dependent variation in paracrine potency determines therapeutic efficacy against neonatal hyperoxic lung injury

BACKGROUND AIMS

The aim of this study was to determine the optimal cell type for transplantation to protect against neonatal hyperoxic lung injury. To this end, the in vitro and in vivo therapeutic efficacies and paracrine potencies of human umbilical cord blood-derived mesenchymal stromal cells (HUMs), human adipose tissue-derived mesenchymal stromal cells (HAMs) and human umbilical cord blood mononuclear cells (HMNs) were compared.

METHODS

Hyperoxic injury was induced in vitro in A549 cells by challenge with H2O2. Alternatively, hyperoxic injury was induced in newborn Sprague-Dawley rats in vivo by exposure to hyperoxia (90% oxygen) for 14 days. HUMs, HAMs or HMNs (5 × 10(5) cells) were given intratracheally at postnatal day 5.

RESULTS

Hyperoxia-induced increases in in vitro cell death and in vivo impaired alveolarization were significantly attenuated in both the HUM and HAM groups but not in the HMN group. Hyperoxia impaired angiogenesis, increased the cell death and pulmonary macrophages and elevated inflammatory cytokine levels. These effects were significantly decreased in the HUM group but not in the HAM or HMN groups. The levels of human vascular endothelial growth factor and hepatocyte growth factor produced by donor cells were highest in HUM group, followed by HAM group and then HMN group.

CONCLUSIONS

HUMs exhibited the best therapeutic efficacy and paracrine potency than HAMs or HMNs in protecting against neonatal hyperoxic lung injury. These cell type-dependent variations in therapeutic efficacy might be associated or mediated with the paracrine potency of the transplanted donor cells.

Hypothermia augments neuroprotective activity of mesenchymal stem cells for neonatal hypoxic-ischemic encephalopathy

Though hypothermia is the only clinically available treatment for neonatal hypoxic-ischemic encephalopathy (HIE), it is not completely effective in severe cases. We hypothesized that combined treatment with hypothermia and transplantation of human umbilical cord blood (UCB)-derived mesenchymal stem cells (MSCs) would synergistically attenuate severe HIE compared to stand-alone therapy. To induce hypoxia-ischemia (HI), male Sprague-Dawley rats were subjected to 8% oxygen for 120 min after unilateral carotid artery ligation on postnatal day (P) 7. After confirmation of severe HIE involving >50% of the ipsilateral hemisphere volume as determined by diffusion-weighted brain magnetic resonance imaging (MRI) within 2 h after HI, intraventricular MSC transplantation (1 × 105 cells) and/or hypothermia with target temperature at 32°C for 24 h were administered 6 h after induction of HI. Follow-up brain MRI at P12 and P42, sensorimotor function tests at P40–42, evaluation of cytokines in the cerebrospinal fluid (CSF) at P42, and histologic analysis of peri-infarct tissues at P42 were performed. Severe HI resulted in progressively increased brain infarction over time as assessed by serial MRI, increased number of cells positive for terminal deoxynucleotidyl transferase nick-end labeling, microgliosis and astrocytosis, increased CSF cytokine levels, and impaired function in behavioral tests such as rotarod and cylinder tests. All of the abnormalities observed in severe HIE showed greater improvement after combined treatment with hypothermia and MSC transplantation than with either therapy alone. Overall, these findings suggest that combined treatment with hypothermia and human UCB-derived MSC transplantation might be a novel therapeutic modality to improve the prognosis of severe HIE, an intractable disease that currently has no effective treatment.

The state of cartilage regeneration: current and future technologies

It is clear that mature human articular cartilage does not have the innate ability to regenerate. Due to this, much effort has been put forth to work on bestowing this ability. While early data focused on more basic outcomes such as percentage of defect fill, the tissue formed was a "cartilage scar" or "hyaline-like" tissue. Even with more advanced technologies, it is clear that no current procedure is able to reconstitute the native structure and function of true hyaline cartilage. As research advancement has somewhat plateaued in this regard, it is crucial that future work focuses on a multifactorial approach, treating the joint as an organ system. The purpose of this review is to update readers on the most recent literature and controversies surrounding articular cartilage regeneration. Specific focus will be placed on current technologies available in the USA and the basic science to support them.

Reactive oxygen species induce MMP12-dependent degradation of collagen 5 and fibronectin to promote the motility of human umbilical cord-derived mesenchymal stem cells

BACKGROUND AND PURPOSE

Reactive oxygen species (ROS) are potent regulators of stem cell behaviour; however, their physiological significance as regards MMP-mediated regulation of the motility of human umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) has not been characterized. In the present study, we investigated the role of hydrogen peroxide (H2O2 ) and associated signalling pathways in promoting UCB-MSCs motility.

EXPERIMENTAL APPROACH

The regulatory effects of H2O2 on the activation of PKC, MAPKs, NF-κB and β-catenin were determined. The expressions of MMP and extracellular matrix proteins were examined. Pharmacological inhibitors and gene-specific siRNA were used to identify the signalling pathways of H2O2 that affect UCB-MSCs motility. An experimental skin wound-healing model was used to confirm the functional role of UCB-MSCs treated with H2O2 in ICR mice.

KEY RESULTS

H2O2 increased the motility of UCB-MSCs by activating PKCα via a calcium influx mechanism. H2O2 activated ERK and p38 MAPK, which are responsible for the distinct activation of transcription factors NF-κB and β-catenin. UCB-MSCs expressed eight MMP genes, but only MMP12 expression was uniquely regulated by NF-κB and β-catenin activation. H2O2 increased the MMP12-dependent degradation of collagen 5 (COL-5) and fibronectin (FN) associated with UCB-MSCs motility. Finally, topical transplantation of UCB-MSCs treated with H2O2 enhanced skin wound healing in mice.

CONCLUSIONS AND IMPLICATIONS

H2O2 stimulated UCB-MSCs motility by increasing MMP12-dependent degradation of COL-5 and FN through the activation of NF-κB and glycogen synthase kinase-3β/β-catenin, which is critical for providing a suitable microenvironment for MSCs transplantation and re-epithelialization of skin wounds in mice.

Creatine inhibits adipogenesis by downregulating insulin-induced activation of the phosphatidylinositol 3-kinase signaling pathway

Creatine is a nitrogenous organic acid known to function in adenosine triphosphate (ATP) metabolism. Recent evidence indicates that creatine regulates the differentiation of mesenchymal stem cells (MSCs) in processes such as osteogenesis and myogenesis. In this study, we show that creatine also has a negative regulatory effect on fat cell formation. Creatine inhibits the accumulation of cytoplasmic triglycerides in a dose-dependent manner irrespective of the adipogenic cell models used, including a C3H10T1/2 MSC line, 3T3-L1 preadipocytes, and primary human MSCs. Consistently, a dramatic reduction in mRNA expression of adipogenic transcription factors, peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα), glucose transporters, 1 and 4 (Glut1, Glut4), and adipocyte markers, aP2 and adipsin, was observed in the presence of creatine. Creatine appears to exert its inhibitory effects on adipogenesis during early differentiation, but not late differentiation, or proliferation stages through inhibition of the PI3K-Akt-PPARγ signaling pathway. In an in vivo model, administration of creatine into mice resulted in body mass increase without fat accumulation. In summary, our results indicate that creatine downregulates adipogenesis through inhibition of phosphatidylinositol 3-kinase (PI3K) activation and imply the potent therapeutic value of creatine in treating obesity and obesity-related metabolic disorders.

Optimizing isolation culture and freezing methods to preserve Wharton's jelly's mesenchymal stem cell (MSC) properties: an MSC banking protocol validation for the Hellenic Cord Blood Bank

BACKGROUND

Mesenchymal stem or stromal cells (MSCs) are a heterogeneous population that can be isolated from many tissues including umbilical cord Wharton's jelly (UC-WJ). Although initially limited in studies such as a hematopoietic stem cell transplantation adjuvant, an increasing number of clinical trials consider MSCs as a potential anti-inflammatory or a regenerative medicine agent. It has been proposed that creating a repository of MSCs would increase their availability for clinical applications. The aim of this study was to assess the optimal isolation and cryopreservation procedures to facilitate WJ MSC banking.

STUDY DESIGN AND METHODS

Cells were isolated from UC-WJ using enzymatic digestion or plastic adhesion methods. Their isolation efficacy, growth kinetics, immunophenotype, and differentiation potential were studied, as well as the effects of freezing. Flow cytometry for common MSC markers was performed on all cases and differentiation was shown with histocytochemical staining. Finally, the isolation efficacy on cryopreserved WJ tissue fragments was tested.

RESULTS

MSC isolation was successful using both isolation methods on fresh UC-WJ tissue. However, UC-WJ MSC isolation from frozen tissue fragments was impossible. Flow cytometry analysis revealed that only MSC markers were expressed on the surface of the isolated cells while differentiation assays showed that they were capable of trilinear differentiation. All the above characteristics were also preserved in isolated UC-WJ MSCs over the cryopreservation study period.

CONCLUSION

These data showed that viable MSCs can only be isolated from fresh UC-WJ tissue, setting the foundation for clinical-grade banking.

Melatonin enhances the human mesenchymal stem cells motility via melatonin receptor 2 coupling with Gαq in skin wound healing

Melatonin, a circadian rhythm-promoting molecule, has a variety of biological functions, but the functional role of melatonin in the motility of mesenchymal stem cells (MSCs) has yet to be studied. In a mouse skin excisional wound model, we found that transplantation of umbilical cord blood (UCB)-MSCs pretreated with melatonin enhanced wound closure, granulation, and re-epithelialization at mouse skin wound sites, where relatively more UCB-MSCs which were engrafted onto the wound site were detected. Thus, we identified the signaling pathway of melatonin, which affects the motility of UCB-MSCs. Melatonin (1 μm) significantly increased the motility of UCB-MSCs, which had been inhibited by the knockdown of melatonin receptor 2 (MT2). We found that Gαq coupled with MT2 and that the binding of Gαq to MT2 uniquely stimulated an atypical PKC isoform, PKCζ. Melatonin induced the phosphorylation of FAK and paxillin, which were concurrently downregulated by blocking of the PKC activity. Melatonin increased the levels of active Cdc42 and Arp2/3, and it has the ability to stimulate cytoskeletal reorganization-related proteins such as profilin-1, cofilin-1, and F-actin in UCB-MSCs. Finally, a lack of MT2 expression in UCB-MSCs during a mouse skin transplantation experiment resulted in impaired wound healing and less engraftment of stem cells at the wound site. These results demonstrate that melatonin signaling via MT2 triggers FAK/paxillin phosphorylation to stimulate reorganization of the actin cytoskeleton, which is responsible for Cdc42/Arp2/3 activation to promote UCB-MSCs motility.

Critical role of vascular endothelial growth factor secreted by mesenchymal stem cells in hyperoxic lung injury

Intratracheal transplantation of human umbilical cord blood (UCB)-derived mesenchymal stem cells (MSCs) protects against neonatal hyperoxic lung injury by a paracrine rather than a regenerative mechanism. However, the role of paracrine factors produced by the MSCs, such as vascular endothelial growth factor (VEGF), has not been delineated. This study examined whether VEGF secreted by MSCs plays a pivotal role in protecting against neonatal hyperoxic lung injury. VEGF was knocked down in human UCB-derived MSCs by transfection with small interfering RNA specific for human VEGF. The in vitro effects of MSCs with or without VEGF knockdown or neutralizing antibody were evaluated in a rat lung epithelial (L2) cell line challenged with H2O2. To confirm these results in vivo, newborn Sprague-Dawley rats were exposed to hyperoxia (90% O2) for 14 days. MSCs (1 × 10(5) cells) with or without VEGF knockdown were administered intratracheally at postnatal Day 5. Lungs were serially harvested for biochemical and histologic analyses. VEGF knockdown and antibody abolished the in vitro benefits of MSCs on H2O2-induced cell death and the up-regulation of inflammatory cytokines in L2 cells. VEGF knockdown also abolished the in vivo protective effects of MSCs in hyperoxic lung injury, such as the attenuation of impaired alveolarization and angiogenesis, reduction in the number of terminal deoxynucleotidyl transferase dUTP nick end labeling-positive and ED-1-positive cells, and down-regulation of proinflammatory cytokine levels. Our data indicate that VEGF secreted by transplanted MSCs is one of the critical paracrine factors that play seminal roles in attenuating hyperoxic lung injuries in neonatal rats.

Netrin-1 induces MMP-12-dependent E-cadherin degradation via the distinct activation of PKCα and FAK/Fyn in promoting mesenchymal stem cell motility

Netrin-1 (Ntn-1) is a potent inducer of neuronal cell migration; however, its molecular mechanism that guides the migratory behavior of stem cells has not been characterized. In this study, we investigate the role of Ntn-1 in promoting the motility of human umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) and its related signaling pathways. Ntn-1 (50 ng/mL) significantly increased motility of UCB-MSCs, which was inhibited by blocking antibodies for deleted in colorectal cancer (DCC) and integrin (IN) α6β4. Ntn-1 in DCC stimulated protein kinase Cα (PKCα) activation, but not PKCɛ, PKCθ, and PKCζ, while Ntn-1 in INα6β4 induced the phosphorylation of focal adhesion kinase (FAK) and Fyn. Notably, Ntn-1 induced phosphorylation of extracellular signal-regulated kinases (ERK), c-Jun N-terminal kinases (JNK), and nuclear factor kappa-B (NF-κB), but they were concurrently downregulated by blocking the activities of PKCα, FAK, and Fyn. Ntn-1 uniquely increased the MMP-12 expression of all the matrix metalloproteinase (MMP) isoforms present in UCB-MSCs, though this was significantly blocked by an NF-κB inhibitor. Finally, Ntn-1 induced the MMP-12-dependent degradation of E-cadherin (E-cad), while Ntn-1 abrogated the interaction between E-cad and p120-catenin. In addition, Ntn-1 has the ability to stimulate cytoskeletal reorganization-related proteins, such as Cdc42, Rac1, Profilin-1, Cofilin-1, α-Actinin-4, and filamentous actin (F-actin) in UCB-MSCs. These results demonstrate that Ntn-1 induces MMP-12-dependent E-cad degradation via the distinct activation of PKCα and FAK/Fyn, which is necessary to govern the activation of ERK, JNK, and NF-κB in promoting motility of UCB-MSCs.

Human umbilical cord blood-derived mesenchymal stem cells producing IL15 eradicate established pancreatic tumor in syngeneic mice

Mesenchymal stem cells (MSC) represent a new tool for delivery of therapeutic agents to cancer sites because of their strong tropism toward tumors. IL15 has demonstrated a potent antitumor activity in various animal models as well as clinical trials. However, because of its short half-life, effective therapeutic effects usually require a high dose, which often results in undesired side effects; thus, new strategies for overcoming this disadvantage are needed. In this study, human MSCs were isolated from umbilical cord blood as delivery vehicles and transduced with lentivirus vector expressing murine IL15 (MSC-IL15). In vitro assays of lymphocyte activation and proliferation demonstrated that IL15 produced by MSCs was biofunctional. In syngeneic mice bearing Pan02 pancreatic tumors, systemic administration of MSC-IL15 significantly inhibited tumor growth and prolonged the survival of tumor-bearing mice, which were associated with tumor cell apoptosis, and natural killer (NK)- and T-cell accumulation. Furthermore, we confirmed that MSC-IL15 could migrate toward tumor and secreted IL15 in tumor-specific sites. Depletion of NK and CD8(+) T cells abolished the antitumor activity of MSC-IL15, suggesting that NK and CD8(+) T cells play a key role for MSC-IL15-mediated effect. Interestingly, cured mice after MSC-IL15 treatment were resistant to Pan02 pancreatic tumor rechallenge, and adoptive transfer of lymphocytes from cured mice also could cause rejection of Pan02 tumor inoculation in naïve mice, indicating that MSC-IL15 induced tumor-specific T-cell immune memory response. Overall, these data support that MSCs producing IL15 might represent an innovative strategy for therapy of pancreatic tumor.

Mesenchymal stem cells for bronchopulmonary dysplasia: phase 1 dose-escalation clinical trial

OBJECTIVE

To assess the safety and feasibility of allogeneic human umbilical cord blood (hUCB)-derived mesenchymal stem cell (MSC) transplantation in preterm infants.

STUDY DESIGN

In a phase I dose-escalation trial, we assessed the safety and feasibility of a single, intratracheal transplantation of hUCB-derived MSCs in preterm infants at high risk for bronchopulmonary dysplasia (BPD). The first 3 patients were given a low dose (1 × 10(7) cells/kg) of cells, and the next 6 patients were given a high dose (2 × 10(7) cells/kg). We compared their adverse outcomes, including BPD severity, with those of historical case-matched comparison group.

RESULTS

Intratracheal MSC transplantation was performed in 9 preterm infants, with a mean gestational age of 25.3 ± 0.9 weeks and a mean birth weight of 793 ± 127 g, at a mean of 10.4 ± 2.6 days after birth. The treatments were well tolerated, without serious adverse effects or dose-limiting toxicity attributable to the transplantation. Levels of interleukin-6, interleukin-8, matrix metalloproteinase-9, tumor necrosis factor α, and transforming growth factor β1 in tracheal aspirates at day 7 were significantly reduced compared with those at baseline or at day 3 posttransplantation. BPD severity was lower in the transplant recipients, and rates of other adverse outcomes did not differ between the comparison group and transplant recipients.

CONCLUSION

Intratracheal transplantation of allogeneic hUCB-derived MSCs in preterm infants is safe and feasible, and warrants a larger and controlled phase II study.

Human umbilical cord blood mesenchymal stem cell transplantation suppresses inflammatory responses and neuronal apoptosis during early stage of focal cerebral ischemia in rabbits

AIM

Human umbilical cord blood mesenchymal stem cells (hUCB-MSCs) have been shown to ameliorate cerebral ischemia in animal models. In this study we investigated the effects of hUCB-MSCs on inflammatory responses and neuronal apoptosis during the early stage of focal cerebral ischemia in rabbits.

METHODS

Focal cerebral ischemia was induced in male New Zealand rabbits by occlusion of MCA for 2 h. The blood samples were collected at different time points prior and during MCAO-reperfusion. The animals were euthanized 3 d after MCAO, and the protein levels of IL-1β, IL-6, IL-10 and TNF-α in the serum and peri-ischemic brain tissues were detected using Western blot and ELISA, respectively. Inflammatory cell infiltration, neuronal apoptosis and neuronal density were measured morphologically. hUCB-MSCs (5 × 10(6)) were iv injected a few minutes after MCAO.

RESULTS

The serum levels of IL-1β, IL-6 and TNF-α were rapidly increased, and peaked at 2 h after the start of MCAO. hUCB-MSC transplantation markedly and progressively suppressed the ischemia-induced increases of serum IL-1β, IL-6 and TNF-α levels within 6 h MCAO-reperfusion. Focal cerebral ischemia decreased the serum level of IL-10, which was prevented by hUCB-MSC transplantation. The expression of IL-1β, IL-6, IL-10 and TNF-α in the peri-ischemic brain tissues showed similar changes as in the serum. hUCB-MSC transplantation markedly suppressed the infiltration of inflammatory cells, and increased the neuronal density around the ischemic region. Furthermore, hUCB-MSC transplantation significantly decreased the percentage of apoptosis around the ischemic region.

CONCLUSION

hUCB-MSCs transplantation suppresses inflammatory responses and neuronal apoptosis during the early stage focal cerebral ischemia in rabbits.

Comparison of articular cartilage repair with different hydrogel-human umbilical cord blood-derived mesenchymal stem cell composites in a rat model

Introduction

The present work was designed to explore the feasibility and efficacy of articular cartilage repair using composites of human umbilical cord blood derived mesenchymal stem cells (hUCB-MSCs) and four different hydrogels in a rat model.

Methods

Full-thickness articular cartilage defects were created at the trochlear groove of femur in both knees of rats. Composites of hUCB-MSCs and four different hydrogels (group A, 4% hyaluronic acid; group B, 3% alginate:30% pluronic (1:1, v/v); group C, 4% hyaluronic acid: 3% alginate: 20% pluronic (2:1:1, v/v}; and group D, 4% hyaluronic acid:3% alginate:20% pluronic;chitosan (4:1:1:2, v/v).) were then transplanted into right knee defect in each study group (five rats/group). Left knees were transplanted with corresponding hydrogels without hUCB-MSCs as controls. At 16 weeks post-transplantation, degrees of cartilage repair were evaluated macroscopically and histologically using Masson’s Trichrome, safranin-O, Sirius red staining, and type-II collagen immunostaining.

Results

Overall, group A with 4% hyaluronic acid hydrogel resulted in superior cartilage repair grossly and histologically and achieved a cellular arrangement and collagen organization pattern mimicking adjacent uninjured articular cartilage. Immunostaining and safranin-O staining also revealed that group A displayed the largest areas of type II collagen staining. Sirius red staining revealed that the organization pattern of collagen bundles was more similar to normal cartilage in group A. No evidence of rejection was found.

Conclusions

The results of this study suggest that hUCB-MSCs could be used to repair articular cartilage defects in vivo and that hyaluronic acid is an attractive hydrogel candidate for use in combination with hUCB-MSCs.

Effect of human umbilical cord blood mesenchymal stem cell transplantation on neuronal metabolites in ischemic rabbits

Background

Because there is little research on the effects of transplanted stem cells on neuronal metabolites in infarct areas, we transplanted human umbilical cord blood mesenchymal stem cells (hUCB-MSCs) into cerebral ischemic rabbits and examined the neuronal metabolites.

Results

Rabbits (n = 40) were equally divided into sham, middle cerebral artery occlusion (MCAO), hUCB-MSC, and saline groups. The rabbit ischemic model was established by MCAO. The effects of hUCB-MSC transplantation were assessed by proton magnetic resonance spectroscopy (¹H-MRS), neurological severity scores (NSSs), infarct area volume, neuronal density, and optical density (OD) of microtubule-associated protein 2 (MAP2)-positive cells. We also evaluated complete blood cell counts(CBCs) and serum biochemical parameters. NSSs in the hUCB-MSC group at 7 and 14 days after reperfusion were lower than in MCAO and saline groups (p < 0.05). Compared with MCAO and saline groups at 2 weeks after MCAO, the infarction volume in the hUCB-MSC group had decreased remarkably (p < 0.05). Significant neuronal metabolic changes occurred in the infarct area at 24 h and 2 weeks after MCAO. ¹H-MRS revealed an elevation in the lactate (Lac)/creatine including phosphocreatine (Cr) ratio and a decrease in the N-acetylaspartate (NAA)/Cr and choline-containing phospholipids (Cho)/Cr ratios at 24 h after MCAO in the MCAO group (p < 0.01). Compared with saline and MCAO groups at 24 h and 2 weeks after MCAO, NAA/Cr and Cho/Cr ratios had increased significantly, whereas the Lac/Cr ratio had decreased significantly in the hUCB-MSC group (p < 0.01). Neuronal density and OD of MAP2-positive cells in the MCAO group were significantly lower than those in the sham group, whereas the neuronal density and OD of MAP2-positive cells in the hUCB-MSC group were higher than those in MCAO and saline groups (p < 0.05). CBCs and biochemical parameters were unchanged in the MCAO group at 24 h and 2 weeks after hUCB-MSC transplantation.

Conclusions

Transplanted hUCB-MSCs might ameliorate ischemic damage by influencing neuronal metabolites in the infarct area, providing additional evidence for neuroprotection by stem cells. No significant changes were observed in CBCs or serum biochemical parameters, suggesting that intravenous infusion of hUCB-MSCs is safe for rabbits in the short-term.

Optimization of the therapeutic efficacy of human umbilical cord blood-mesenchymal stromal cells in an NSG mouse xenograft model of graft-versus-host disease

BACKGROUND AIMS

Although in vitro studies have demonstrated the immunosuppressive capacity of mesenchymal stromal cells (MSCs), most in vivo studies on graft-versus-host disease (GVHD) have focused on prevention, and the therapeutic effect of MSCs is controversial. Moreover, optimal time intervals for infusing MSCs have not been established.

METHODS

We attempted to evaluate whether human umbilical cord blood-MSCs (hUCB-MSCs) could either prevent or treat GVHD in an NSG mouse xenograft model by injection of MSCs before or after in vivo clearance. Mice were infused with either a single dose or multiple doses of 5 × 10(5) hUCB-MSCs (3- or 7-day intervals) before or after GVHD onset.

RESULTS

Before onset, hUCB-MSCs significantly improved the survival rate only when repeatedly injected at 3-day intervals. In contrast, single or repeated injections after GVHD onset significantly increased the survival rate and effectively attenuated tissue damage and inflammation. Furthermore, the levels of prostaglandin E2 and transforming growth factor-β1 increased significantly, whereas the level of interferon-γ decreased significantly in all MSC treatment groups.

CONCLUSIONS

These data establish the optimal time intervals for preventing GVHD and show that hUCB-MSCs effectively attenuated symptoms and improved survival rate when administered after the onset of GVDH.

Human umbilical cord blood-derived stromal cells: A new source of stromal cells in hematopoietic stem cell transplantation

The hematopoietic inductive microenvironment (HIM), which is composed of stromal cells, extracellular matrix and cytokines, plays a vital role in hematopoietic stem cell transplantation (HSCT). Bone marrow stromal cells (BMSCs), as the main component of HIM, have been well studied. However, the highly invasive procedure of bone marrow (BM) collection limits the clinical application of BMSCs. Human umbilical cord blood-derived stromal cells (hUCBDSCs) isolated and cultured in our laboratory have attracted much attention for their ease collection and low probability of pathophoresis. Previous research demonstrated that hUCBDSCs have numerous functions that are identical to those of BMSCs, for example, hUCBDSCs can support the growth of hematopoietic stem and progenitor cells, especially during the expansion of megakaryocyte colony-forming units (CFU-Mk), promote engraftment after hematopoietic stem cell transplantation (HSCT), exert immunosuppressive effects on xenogenic T cells in vitro and suppress acute graft-versus-host disease (aGVHD) in vivo. Although hUCBDSCs, as new stromal cells, have not been used in clinical practice, they have great practical significance because of their superiority in hematopoiesis and the regulation of immunity.