TGFß4 alleviates the phenotype of Charcot-Marie-Tooth disease type 1A.

The duplication of the peripheral myelin protein 22 (PMP22) gene causes a demyelinating type of neuropathy, commonly known as Charcot-Marie-Tooth disease type 1A (CMT1A). Development of effective drugs for CMT1A still remains as an unmet medical need. In the present study, we assessed the role of the transforming growth factor beta 4 (TGFß4)/Nodal axis in the pathogenesis of CMT1A. First, we identified PMP22 overexpression-induced Nodal expression in Schwann cells, which might be one of the downstream effectors in CMT1A. Administration of Nodal protein at the developmental stage of peripheral nerves induced the demyelinating phenotype in vivo. Second, we further isolated TGFß4 as an antagonist that could abolish Nodal-induced demyelination. Finally, we developed a recombinant TGFß4-fragment crystallizable (Fc) fusion protein, CX201, and demonstrated that its application had promyelinating efficacy in Schwann cells. CX201 administration improved the demyelinating phenotypes of CMT1A mouse models at both pre-symptomatic and post-symptomatic stages. These results suggest that the TGFß4/Nodal axis plays a crucial role in the pathogenesis of CMT1A and might be a potential therapeutic target for CMT1A.

Iron Oxide Nanoparticle-Incorporated Mesenchymal Stem Cells for Alzheimer's Disease Treatment.

Alzheimer's disease (AD) is a neurodegenerative disease with multifactorial pathogenesis. However, most current therapeutic approaches for AD target a single pathophysiological mechanism, generally resulting in unsatisfactory therapeutic outcomes. Recently, mesenchymal stem cell (MSC) therapy, which targets multiple pathological mechanisms of AD, has been explored as a novel treatment. However, the low brain retention efficiency of administered MSCs limits their therapeutic efficacy. In addition, autologous MSCs from AD patients may have poor therapeutic abilities. Here, we overcome these limitations by developing iron oxide nanoparticle (IONP)-incorporated human Wharton's jelly-derived MSCs (MSC-IONPs). IONPs promote therapeutic molecule expression in MSCs. Following intracerebroventricular injection, MSC-IONPs showed a higher brain retention efficiency under magnetic guidance. This potentiates the therapeutic efficacy of MSCs in murine models of AD. Furthermore, human Wharton's jelly-derived allogeneic MSCs may exhibit higher therapeutic abilities than those of autologous MSCs in aged AD patients. This strategy may pave the way for developing MSC therapies for AD.

A New Method of Myostatin Inhibition in Mice via Oral Administration of Lactobacillus casei Expressing Modified Myostatin Protein, BLS-M22.

Myostatin is a member of the transforming growth factor-beta superfamily and is an endogenous negative regulator of muscle growth. This study aimed to determine whether an oral administration of Lactobacillus casei expressing modified human myostatin (BLS-M22) could elicit sufficient levels of myostatin-specific antibody and improve the dystrophic features of an animal model of Duchenne muscular dystrophy (DMD; mdx mouse). BLS-M22 is a recombinant L. casei engineered to harbor the pKV vector and poly-gamma-glutamic acid gene linked to a modified human myostatin gene. Serological analysis showed that anti-myostatin IgG titers were significantly increased, and serum creatine kinase was significantly reduced in the BLS-M22-treated mdx mice compared to the control mice. In addition, treatment of BLS-M22 resulted in a significant increase in body weight and motor function (Rotarod behavior test). Histological analysis showed an improvement in the dystrophic features (fibrosis and muscle hypertrophy) of the mdx mice with the administration of BLS-M22. The circulating antibodies generated after BLS-M22 oral administration successfully lowered serum myostatin concentration. Myostatin blockade resulted in serological, histological, and functional improvements in mdx mice. Overall, the findings suggest the potential of BLS-M22 to treat DMD; however, further clinical trials are essential to ascertain its efficacy and safety in humans.

Fibulin 5, a human Wharton's jelly-derived mesenchymal stem cells-secreted paracrine factor, attenuates peripheral nervous system myelination defects through the Integrin-RAC1 signaling axis.

In the peripheral nervous system (PNS), proper development of Schwann cells (SCs) contributing to axonal myelination is critical for neuronal function. Impairments of SCs or neuronal axons give rise to several myelin-related disorders, including dysmyelinating and demyelinating diseases. Pathological mechanisms, however, have been understood at the elementary level and targeted therapeutics has remained undeveloped. Here, we identify Fibulin 5 (FBLN5), an extracellular matrix (ECM) protein, as a key paracrine factor of human Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) to control the development of SCs. We show that co-culture with WJ-MSCs or treatment of recombinant FBLN5 promotes the proliferation of SCs through ERK activation, whereas FBLN5-depleted WJ-MSCs do not. We further reveal that during myelination of SCs, FBLN5 binds to Integrin and modulates actin remodeling, such as the formation of lamellipodia and filopodia, through RAC1 activity. Finally, we show that FBLN5 effectively restores the myelination defects of SCs in the zebrafish model of Charcot-Marie-Tooth (CMT) type 1, a representative demyelinating disease. Overall, our data propose human WJ-MSCs or FBLN5 protein as a potential treatment for myelin-related diseases, including CMT.

Comparative Proteomic Analysis of the Mesenchymal Stem Cells Secretome from Adipose, Bone Marrow, Placenta and Wharton's Jelly.

Mesenchymal stem cells (MSCs) have the potential to be a viable therapy against various diseases due to their paracrine effects, such as secretion of immunomodulatory, trophic and protective factors. These cells are known to be distributed within various organs and tissues. Although they possess the same characteristics, MSCs from different sources are believed to have different secretion potentials and patterns, which may influence their therapeutic effects in disease environments. We characterized the protein secretome of adipose (AD), bone marrow (BM), placenta (PL), and Wharton's jelly (WJ)-derived human MSCs by using conditioned media and analyzing the secretome by mass spectrometry and follow-up bioinformatics. Each MSC secretome profile had distinct characteristics depending on the source. However, the functional analyses of the secretome from different sources showed that they share similar characteristics, such as cell migration and negative regulation of programmed cell death, even though differences in the composition of the secretome exist. This study shows that the secretome of fetal-derived MSCs, such as PL and WJ, had a more diverse composition than that of AD and BM-derived MSCs, and it was assumed that their therapeutic potential was greater because of these properties.

Recovery of Tendon Characteristics by Inhibition of Aberrant Differentiation of Tendon-Derived Stem Cells from Degenerative Tendinopathy.

The inhibition of the aberrant differentiation of tendon-derived stem cells (TDSCs) is a major target for the regeneration of damaged tendon tissues, as tendinopathy can be caused by the aberrant differentiation of TDSCs. We investigated whether the possible aberrant differentiation of TDSCs can be prevented by using adequate inhibitors. TDSCs extracted from chemically induced tendinopathy and injury-with-overuse tendinopathy models were cultured with 18α-glycyrrhetinic acid (AGA) and T0070907 to block osteogenic differentiation and adipogenic differentiation, respectively. The optimal dose of AGA decreased the osteogenic-specific marker Runx2 (Runt-related transcription factor 2), and T0070907 blocked the adipogenic-specific marker peroxisome proliferator-activated receptor gamma (PPARγ) in mRNA levels. We also found that AGA induced tenogenic differentiation in mRNA levels. However, T0070907 did not affect the tenogenic differentiation and regenerative capacity of TDSCs. We expect that optimal doses of AGA and T0070907 can prevent tendinopathy by inhibiting osteogenic and adipogenic differentiation, respectively. In addition, AGA and T0070907 may play important roles in the treatment of tendinopathy.

A Comparison of Immune Responses Exerted Following Syngeneic, Allogeneic, and Xenogeneic Transplantation of Mesenchymal Stem Cells into the Mouse Brain.

Due to their multifactorial aspects, mesenchymal stem cells (MSCs) have been widely established as an attractive and potential candidate for the treatment of a multitude of diseases. A substantial number of studies advocate that MSCs are poorly immunogenic. In several studies, however, immune responses were observed following injections of xenogeneic donor MSCs. In this study, the aim was to examine differences in immune responses exerted based on transplantations of xenogeneic, syngeneic, and allogeneic MSCs in the wild-type mouse brain. Xenogeneic, allogeneic, and syngeneic MSCs were intracerebrally injected into C57BL/6 mice. Mice were sacrificed one week following transplantation. Based on immunohistochemical (IHC) analysis, leukocytes and neutrophils were expressed at the injection sites in the following order (highest to lowest) xenogeneic, allogeneic, and syngeneic. In contrast, microglia and macrophages were expressed in the following order (highest to lowest): syngeneic, allogeneic, and xenogeneic. Residual human MSCs in the mouse brain were barely detected after seven days. Although the discrepancy between leukocytes versus macrophages/microglia infiltration should be resolved, our results overall argue against the previous notions that MSCs are poorly immunogenic and that modulation of immune responses is a prerequisite for preclinical and clinical studies in MSC therapy of central nervous system diseases.

Ethionamide Preconditioning Enhances the Proliferation and Migration of Human Wharton's Jelly-Derived Mesenchymal Stem Cells.

Mesenchymal stem cells (MSCs) are a useful source for cell-based therapy of a variety of immune-mediated diseases, including neurodegenerative disorders. However, poor migration ability and survival rate of MSCs after brain transplantation hinder the therapeutic effects in the disease microenvironment. Therefore, we attempted to use a preconditioning strategy with pharmacological agents to improve the cell proliferation and migration of MSCs. In this study, we identified ethionamide via the screening of a drug library, which enhanced the proliferation of MSCs. Preconditioning with ethionamide promoted the proliferation of Wharton's jelly-derived MSCs (WJ-MSCs) by activating phosphatidylinositol 3-kinase (PI3K)/Akt and mitogen-activated protein kinase/extracellular signal-regulated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK)1/2 signaling. Preconditioning with ethionamide also enhanced the migration ability of MSCs by upregulating expression of genes associated with migration, such as C-X-C motif chemokine receptor 4 (CXCR4) and C-X-C motif chemokine ligand 12 (CXCL12). Furthermore, preconditioning with ethionamide stimulated the secretion of paracrine factors, including neurotrophic and growth factors in MSCs. Compared to naïve MSCs, ethionamide-preconditioned MSCs (ETH-MSCs) were found to survive longer in the brain after transplantation. These results suggested that enhancing the biological process of MSCs induced by ethionamide preconditioning presents itself as a promising strategy for enhancing the effectiveness of MSCs-based therapies.

Anti-Fibrotic Effect of Human Wharton's Jelly-Derived Mesenchymal Stem Cells on Skeletal Muscle Cells, Mediated by Secretion of MMP-1.

Extracellular matrix (ECM) components play an important role in maintaining skeletal muscle function, but excessive accumulation of ECM components interferes with skeletal muscle regeneration after injury, eventually inducing fibrosis. Increased oxidative stress level caused by dystrophin deficiency is a key factor in fibrosis in Duchenne muscular dystrophy (DMD) patients. Mesenchymal stem cells (MSCs) are considered a promising therapeutic agent for various diseases involving fibrosis. In particular, the paracrine factors secreted by MSCs play an important role in the therapeutic effects of MSCs. In this study, we investigated the effects of MSCs on skeletal muscle fibrosis. In 2-5-month-old mdx mice intravenously injected with 1 × 105 Wharton's jelly (WJ)-derived MSCs (WJ-MSCs), fibrosis intensity and accumulation of calcium/necrotic fibers were significantly decreased. To elucidate the mechanism of this effect, we verified the effect of WJ-MSCs in a hydrogen peroxide-induced fibrosis myotubes model. In addition, we demonstrated that matrix metalloproteinase-1 (MMP-1), a paracrine factor, is critical for this anti-fibrotic effect of WJ-MSCs. These findings demonstrate that WJ-MSCs exert anti-fibrotic effects against skeletal muscle fibrosis, primarily via MMP-1, indicating a novel target for the treatment of muscle diseases, such as DMD.

Pressure Stimuli Improve the Proliferation of Wharton's Jelly-Derived Mesenchymal Stem Cells under Hypoxic Culture Conditions.

Mesenchymal stem cells (MSCs) are safe, and they have good therapeutic efficacy through their paracrine action. However, long-term culture to produce sufficient MSCs for clinical use can result in side-effects, such as an inevitable senescence and the reduction of the therapeutic efficacy of the MSCs. In order to overcome this, the primary culture conditions of the MSCs can be modified to simulate the stem cells' niche environment, resulting in accelerated proliferation, the achievement of the target production yield at earlier passages, and the improvement of the therapeutic efficacy. We exposed Wharton's jelly-derived MSCs (WJ-MSCs) to pressure stimuli during the primary culture step. In order to evaluate the proliferation, stemness, and therapeutic efficacy of WJ-MSCs, image, genetic, and Western blot analyses were carried out. Compared with standard incubation culture conditions, the cell proliferation was significantly improved when the WJ-MSCs were exposed to pressure stimuli. However, the therapeutic efficacy (the promotion of cell proliferation and anti-apoptotic effects) and the stemness of the WJ-MSCs was maintained, regardless of the culture conditions. Exposure to pressure stimuli is a simple and efficient way to improve WJ-MSC proliferation without causing changes in stemness and therapeutic efficacy. In this way, clinical-grade WJ-MSCs can be produced rapidly and used for therapeutic applications.

Exploring the Potential of Mesenchymal Stem Cell-Based Therapy in Mouse Models of Vascular Cognitive Impairment.

Closely linked to Alzheimer's disease (AD), the pathological spectrum of vascular cognitive impairment (VCI) is known to be wide and complex. Considering that multiple instead of a single targeting approach is considered a treatment option for such complicated diseases, the multifaceted aspects of mesenchymal stem cells (MSCs) make them a suitable candidate to tackle the heterogeneity of VCI. MSCs were delivered via the intracerebroventricular (ICV) route in mice that were subjected to VCI by carotid artery stenosis. VCI was induced in C57BL6/J mice wild type (C57VCI) mice by applying a combination of ameroid constrictors and microcoils, while ameroid constrictors alone were bilaterally applied to 5xFAD (transgenic AD mouse model) mice (5xVCI). Compared to the controls (minimal essential medium (MEM)-injected C57VCI mice), changes in spatial working memory were not noted in the MSC-injected C57VCI mice, and unexpectedly, the mortality rate was higher. In contrast, compared to the MEM-injected 5xVCI mice, mortality was not observed, and the spatial working memory was also improved in MSC-injected 5xVCI mice. Disease progression of the VCI-induced mice seems to be affected by the method of carotid artery stenosis and due to this heterogeneity, various factors must be considered to maximize the therapeutic benefits exerted by MSCs. Factors, such as the optimal MSC injection time point, cell concentration, sacrifice time point, and immunogenicity of the transplanted cells, must all be adequately addressed so that MSCs can be appropriately and effectively used as a treatment option for VCI.

TCTP regulates spindle microtubule dynamics by stabilizing polar microtubules during mouse oocyte meiosis.

Dynamic changes in spindle structure and function are essential for maintaining genomic integrity during the cell cycle. Spindle dynamics are highly dependent on several microtubule-associated proteins that coordinate the dynamic behavior of microtubules, including microtubule assembly, stability and organization. Here, we show that translationally controlled tumor protein (TCTP) is a novel microtubule-associated protein that regulates spindle dynamics during meiotic maturation. TCTP was expressed and widely distributed in the cytoplasm with strong enrichment at the spindle microtubules during meiosis. TCTP was found to be phosphorylated during meiotic maturation, and was exclusively localized to the spindle poles. Knockdown of TCTP impaired spindle organization without affecting chromosome alignment. These spindle defects were mostly due to the destabilization of the polar microtubules. However, the stability of kinetochore microtubules attached to chromosomes was not affected by TCTP knockdown. Overexpression of a nonphosphorylable mutant of TCTP disturbed meiotic maturation, stabilizing the spindle microtubules. In addition, Plk1 was decreased by TCTP knockdown. Taken together, our results demonstrate that TCTP is a microtubule-associating protein required to regulate spindle microtubule dynamics during meiotic maturation in mouse oocytes.

Lowering the concentration affects the migration and viability of intracerebroventricular-delivered human mesenchymal stem cells.

Due to their widely known therapeutic benefits, mesenchymal stem cells have been proposed as a novel treatment option for a wide range of diseases including Alzheimer's disease. To maximize these benefits, critical factors such as delivery route, cell viability, and cell migration must be accounted for. Out of the various delivery routes to the brain, the intracerebroventricular (ICV) route stands out due to the widespread distribution that can occur via cerebrospinal fluid flow. The major objective of this present study was to observe how altering cell concentration influences the migration and viability of human umbilical cord blood derived-mesenchymal stem cells (hUCB-MSCs), delivered via ICV injection, in the brains of wild-type (WT) mice. C3H/C57 WT mice were divided into three groups and were injected with 1 × 105 hUCB-MSCs suspended in varying volumes: high (3 µl), middle (5 µl), and low (7 µl) concentrations, respectively. Lowering the concentration increased the migratory capabilities and elevated the viability of hUCB-MSCs. These results suggest that cell concentration can affect the physiological state of hUCB-MSCs, and thus the extent of therapeutic efficacy that can be achieved.

Anti-apoptotic Effects of Human Wharton's Jelly-derived Mesenchymal Stem Cells on Skeletal Muscle Cells Mediated via Secretion of XCL1.

The role of Wharton's jelly-derived human mesenchymal stem cells (WJ-MSCs) in inhibiting muscle cell death has been elucidated in this study. Apoptosis induced by serum deprivation in mouse skeletal myoblast cell lines (C2C12) was significantly reduced when the cell lines were cocultured with WJ-MSCs. Antibody arrays indicated high levels of chemokine (C motif) ligand (XCL1) secretion by cocultured WJ-MSCs and XCL1 protein treatment resulted in complete inhibition of apoptosis in serum-starved C2C12 cells. Apoptosis of C2C12 cells and loss of differentiated C2C12 myotubes induced by lovastatin, another muscle cell death inducer, was also inhibited by XCL1 treatment. However, XCL1 treatment did not inhibit apoptosis of cell lines other than C2C12. When XCL1-siRNA pretreated WJ-MSCs were cocultured with serum-starved C2C12 cells, apoptosis was not inhibited, thus confirming that XCL1 is a key factor in preventing C2C12 cell apoptosis. We demonstrated the therapeutic effect of XCL1 on the zebrafish myopathy model, generated by knock down of a causative gene ADSSL1. Furthermore, the treatment of XCL1 resulted in significant recovery of the zebrafish skeletal muscle defects. These results suggest that human WJ-MSCs and XCL1 protein may act as promising and novel therapeutic agents for treatment of myopathies and other skeletal muscle diseases.

Pexophagy is induced by increasing peroxisomal reactive oxygen species in 1'10-phenanthroline-treated cells.

Although autophagy regulates the quality and quantity of cellular organelles, the regulatory mechanisms of peroxisomal autophagy remain largely unknown. In this study, we developed a cell-based image screening assay, and identified 1,10-phenanthroline (Phen) as a novel pexophagy inducer from chemical library screening. Treatment with Phen induces selective loss of peroxisomes but not endoplasmic reticulum and Golgi apparatus in hepatocytes. In addition, Phen increases autophagic engulfment of peroxisomes in an ATG5 dependent manner. Interestingly, treatment of Phen excessively produces peroxisomal reactive oxygen species (ROS), and inhibition of the ROS suppresses loss of peroxisome in Phen-treated cells. Taken together, these results suggest that Phen triggers pexophagy by enhancing peroxisomal ROS.

BIX-01294-induced autophagy regulates elongation of primary cilia.

Previously, we showed that BIX-01294 treatment strongly activates autophagy. Although, the interplay between autophagy and ciliogenesis has been suggested, the role of autophagy in ciliogenesis is controversial and largely unknown. In this study, we investigated the effects of autophagy induced by BIX-01294 on the formation of primary cilia in human retinal pigmented epithelial (RPE) cells. Treatment of RPE cells with BIX-01294 caused strong elongation of the primary cilium and increased the number of ciliated cells, as well as autophagy activation. The elongated cilia in serum starved cultured cells were gradually decreased by re-feeding the cells with normal growth medium. However, the disassembly of cilia was blocked in the BIX-01294-treated cells. In addition, both genetic and chemical inhibition of autophagy suppressed BIX-01294-mediated ciliogenesis in RPE cells. Taken together, these results suggest that autophagy induced by BIX-01294 positively regulates the elongation of primary cilium.

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.

Low immunogenicity of allogeneic human umbilical cord blood-derived mesenchymal stem cells in vitro and in vivo.

Evaluation of the immunogenicity of human mesenchymal stem cells (MSCs) in an allogeneic setting during therapy has been hampered by lack of suitable models due to technical and ethical limitations. Here, we show that allogeneic human umbilical cord blood derived-MSCs (hUCB-MSCs) maintained low immunogenicity even after immune challenge in vitro. To confirm these properties in vivo, a humanized mouse model was established by injecting isolated hUCB-derived CD34+ cells intravenously into immunocompromised NOD/SCID IL2γnull (NSG) mice. After repeated intravenous injection of human peripheral blood mononuclear cells (hPBMCs) or MRC5 cells into these mice, immunological alterations including T cell proliferation and increased IFN-γ, TNF-α, and human IgG levels, were observed. In contrast, hUCB-MSC injection did not elicit these responses. While lymphocyte infiltration in the lung and small intestine and reduced survival rates were observed after hPBMC or MRC5 transplantation, no adverse events were observed following hUCB-MSC introduction. In conclusion, our data suggest that allogeneic hUCB-MSCs have low immunogenicity in vitro and in vivo, and are therefore "immunologically safe" for use in allogeneic clinical applications.

Thrombospondin-2 secreted by human umbilical cord blood-derived mesenchymal stem cells promotes chondrogenic differentiation.

Increasing evidence indicates that the secretome of mesenchymal stem cells (MSCs) has therapeutic potential for the treatment of various diseases, including cartilage disorders. However, the paracrine mechanisms underlying cartilage repair by MSCs are poorly understood. Here, we show that human umbilical cord blood-derived MSCs (hUCB-MSCs) promoted differentiation of chondroprogenitor cells by paracrine action. This paracrine effect of hUCB-MSCs on chondroprogenitor cells was increased by treatment with synovial fluid (SF) obtained from osteoarthritis (OA) patients but was decreased by SF of fracture patients, compared to that of an untreated group. To identify paracrine factors underlying the chondrogenic effect of hUCB-MSCs, the secretomes of hUCB-MSCs stimulated by OA SF or fracture SF were analyzed using a biotin label-based antibody array. Among the proteins increased in response to these two kinds of SF, thrombospondin-2 (TSP-2) was specifically increased in only OA SF-treated hUCB-MSCs. In order to determine the role of TSP-2, exogenous TSP-2 was added to a micromass culture of chondroprogenitor cells. We found that TSP-2 had chondrogenic effects on chondroprogenitor cells via PKCα, ERK, p38/MAPK, and Notch signaling pathways. Knockdown of TSP-2 expression on hUCB-MSCs using small interfering RNA abolished the chondrogenic effects of hUCB-MSCs on chondroprogenitor cells. In parallel with in vitro analysis, the cartilage regenerating effect of hUCB-MSCs and TSP-2 was also demonstrated using a rabbit full-thickness osteochondral-defect model. Our findings suggested that hUCB-MSCs can stimulate the differentiation of locally presented endogenous chondroprogenitor cells by TSP-2, which finally leads to cartilage regeneration.

Autophagy induced by resveratrol suppresses α-MSH-induced melanogenesis.

Autophagy degrades cellular components and organelles through a cooperative process involving autophagosomes and lysosomes. Although autophagy is known to mainly regulate the turnover of cellular components, the role of autophagy in melanogenesis has not been well addressed. Here, we show that inhibition of autophagy suppresses the antimelanogenesis activity of resveratrol (RSV), a well-known antimelanogenic agent. RSV strongly increased autophagy in melanocytes. However, the depletion of ATG5 significantly suppressed RSV-mediated antimelanogenesis as well as RSV-induced autophagy in melanocytes. Moreover, suppression of ATG5 retrieved the RSV-mediated downregulation of tyrosinase and TRP1 in α-MSH-treated cells. Most importantly, electron microscopy analysis revealed that autophagosomes engulfed melanin or melanosomes after combined treatment of α-MSH and RSV. Taken together, these results suggest that RSV-mediated autophagy regulates melanogenesis.