Purpose The topical application of exosomes secreted by mesenchymal stem cells (MSC-Exos) on the skin is a very new and interesting topic in the medical field. In this study, we aimed to investigate whether marine sponge Haliclona sp. spicules (SHSs) could effectively enhance the skin delivery of human umbilical cord-derived MSC-Exos (hucMSC-Exos), and further evaluate the topical application of hucMSC-Exos combined with SHSs in rejuvenating photoaged mouse skin. Materials and Methods SHSs were isolated from the explants of sponge Haliclona sp. with our proprietary method, and hucMSC-Exos were prepared from the conditioned medium of hucMSCs using ultracentrifugation. The effects of SHSs on the skin penetration of fluorescently labeled hucMSC-Exos were determined using confocal microscopy in vitro (porcine skin) and in vivo (mouse skin). The therapeutic effects of hucMSC-Exos coupled with SHSs against UV-induced photoaging in mice were assessed by using microwrinkles analysis, pathohistological examination and real-time RT-PCR. We also tested the skin irritation caused by the combination of hucMSC-Exos and SHSs in guinea pigs. Results In vitro results showed that hucMSC-Exos could not readily penetrate through porcine skin by themselves. However, SHSs increased the skin absorption of exosomes by a factor of 5.87 through creating microchannels. Similar penetration enhancement of hucMSC-Exos was observed after SHSs treatment in mice. The combined use of hucMSC-Exos and SHSs showed significant anti-photoaging effects in mice, including reducing microwrinkles, alleviating histopathological changes, and promoting the expression of extracellular matrix constituents, whereas hucMSC-Exos alone produced considerably weaker effects. Skin irritation test showed that the combination of hucMSC-Exos and SHSs caused slight irritation, and the skin recovered shortly. Conclusion SHSs provide a safe and effective way to enhance the skin delivery of MSC-Exos. Moreover, the combination of MSC-Exos and SHSs may be of much use in the treatment of photoaging. View Publication

Human pluripotent stem cells including induced pluripotent stem cells (iPSCs) and embryonic stem cells hold great promise for cell-based therapies, but safety concerns that complicate consideration for routine clinical use remain. Installing a safety switch" based on the inducible caspase-9 (iCASP9) suicide gene system should offer added control over undesirable cell replication or activity. Previous studies utilized lentiviral vectors to integrate the iCASP9 system into T cells and iPSCs. This method results in random genomic insertion of the suicide switch and inefficient killing of the cells after the switch is "turned on" with a small molecule (eg AP1903). To improve the safety and efficiency of the iCASP9 system for use in iPSC-based therapy we precisely installed the system into a genomic safe harbor the AAVS1 locus in the PPP1R12C gene. We then evaluated the efficiencies of different promoters to drive iCASP9 expression in human iPSCs. We report that the commonly used EF1$\alpha$ promoter is silenced in iPSCs and that the endogenous promoter of the PPP1R12C gene is not strong enough to drive high levels of iCASP9 expression. However the CAG promoter induces strong and stable iCASP9 expression in iPSCs and activation of this system with AP1903 leads to rapid killing and complete elimination of iPSCs and their derivatives including MSCs and chondrocytes in vitro. Furthermore iPSC-derived teratomas shrank dramatically or were completely eliminated after administration of AP1903 in mice. Our data suggest significant improvements on existing iCASP9 suicide switch technologies and may serve as a guide to other groups seeking to improve the safety of stem cell-based therapies." View Publication

Adipose tissues dynamically remodel their cellular composition in response to external cues by stimulating beige adipocyte biogenesis; however, the developmental origin and pathways regulating this process remain insufficiently understood owing to adipose tissue heterogeneity. Here, we employed single-cell RNA-seq and identified a unique subset of adipocyte progenitor cells (APCs) that possessed the cell-intrinsic plasticity to give rise to beige fat. This beige APC population is proliferative and marked by cell-surface proteins, including PDGFR$\alpha$, Sca1, and CD81. Notably, CD81 is not only a beige APC marker but also required for de novo beige fat biogenesis following cold exposure. CD81 forms a complex with $\alpha$V/$\beta$1 and $\alpha$V/$\beta$5 integrins and mediates the activation of integrin-FAK signaling in response to irisin. Importantly, CD81 loss causes diet-induced obesity, insulin resistance, and adipose tissue inflammation. These results suggest that CD81 functions as a key sensor of external inputs and controls beige APC proliferation and whole-body energy homeostasis. View Publication

Glycyrrhetinic acid (GA) is one of the main components of the traditional Chinese medicine of licorice, which can coordinate and promote the effects of other medicines in the traditional prescription. We found that GA could promote the proliferation, decrease the apoptotic rate, and attenuate DFMO-elicited growth arrest and delay in restitution after wounding in IEC-6 cells via HuR. GA failed to promote proliferation and to suppress apoptosis after silencing HuR by siRNA in IEC-6 cells. Furthermore, with the model of small intestinal organoids developed from intestinal crypt stem cells, we found that GA could increase HuR and its downstream ki67 levels to promote intestinal organoid development. In the in vivo assay, GA was shown to maintain the integrity of the intestinal epithelium under the circumstance of 48 h-fasting in rats via raising HuR and its downstream genes such as EGF, EGFR, and MEK. These results suggested that via HuR modulation, GA could promote intestinal epithelium homeostasis, and therefore contribute to the absorption of constituents from other medicines co-existing in the traditional prescription with licorice in the small intestine. Our results provide a new perspective for understanding the effect of licorice on enhancing the therapeutic effect of traditional prescriptions according to the traditional Chinese medicine theory. View Publication

Juvenile myelomonocytic leukemia (JMML) is a rare aggressive myelodysplastic/myeloproliferative neoplasm of early childhood, initiated by RAS-activating mutations. Genomic analyses have recently described JMML mutational landscape; however, the nature of JMML-propagating cells (JMML-PCs) and the clonal architecture of the disease remained until now elusive. Combining genomic (exome, RNA-seq), Colony forming assay and xenograft studies, we detect the presence of JMML-PCs that faithfully reproduce JMML features including the complex/nonlinear organization of dominant/minor clones, both at diagnosis and relapse. Further integrated analysis also reveals that although the mutations are acquired in hematopoietic stem cells, JMML-PCs are not always restricted to this compartment, highlighting the heterogeneity of the disease during the initiation steps. We show that the hematopoietic stem/progenitor cell phenotype is globally maintained in JMML despite overexpression of CD90/THY-1 in a subset of patients. This study shed new lights into the ontogeny of JMML, and the identity of JMML-PCs, and provides robust models to monitor the disease and test novel therapeutic approaches. View Publication

Acute megakaryoblastic leukemia (AMKL) represents ∼10{\%} of pediatric acute myeloid leukemia cases and typically affects young children ({\textless}3 years of age). It remains plagued with extremely poor treatment outcomes ({\textless}40{\%} cure rates), mostly due to primary chemotherapy refractory disease and/or early relapse. Recurrent and mutually exclusive chimeric fusion oncogenes have been detected in 60{\%} to 70{\%} of cases and include nucleoporin 98 (NUP98) gene rearrangements, most commonly NUP98-KDM5A. Human models of NUP98-KDM5A-driven AMKL capable of faithfully recapitulating the disease have been lacking, and patient samples are rare, further limiting biomarkers and drug discovery. To overcome these impediments, we overexpressed NUP98-KDM5A in human cord blood hematopoietic stem and progenitor cells using a lentiviral-based approach to create physiopathologically relevant disease models. The NUP98-KDM5A fusion oncogene was a potent inducer of maturation arrest, sustaining long-term proliferative and progenitor capacities of engineered cells in optimized culture conditions. Adoptive transfer of NUP98-KDM5A-transformed cells into immunodeficient mice led to multiple subtypes of leukemia, including AMKL, that phenocopy human disease phenotypically and molecularly. The integrative molecular characterization of synthetic and patient NUP98-KDM5A AMKL samples revealed SELP, MPIG6B, and NEO1 as distinctive and novel disease biomarkers. Transcriptomic and proteomic analyses pointed to upregulation of the JAK-STAT signaling pathway in the model AMKL. Both synthetic models and patient-derived xenografts of NUP98-rearranged AMKL showed in vitro therapeutic vulnerability to ruxolitinib, a clinically approved JAK2 inhibitor. Overall, synthetic human AMKL models contribute to defining functional dependencies of rare genotypes of high-fatality pediatric leukemia, which lack effective and rationally designed treatments. View Publication

Rationale: Mesenchymal stem cells (MSC) hold great promise in the treatment of various diseases including autoimmune diseases, inflammatory diseases, etc., due to their pleiotropic properties. However, largely incongruent data were obtained from different MSC-based clinical trials, which may be partially due to functional heterogeneity among MSC. Here, we attempt to derive homogeneous mesenchymal stem cells with neuromesodermal origin from human pluripotent stem cells (hPSC) and evaluate their functional properties. Methods: Growth factors and/or small molecules were used for the differentiation of human pluripotent stem cells (hPSC) into neuromesodermal progenitors (NMP), which were then cultured in animal component-free and serum-free induction medium for the derivation and long-term expansion of MSC. The resulted NMP-MSC were detailed characterized by analyzing their surface marker expression, proliferation, migration, multipotency, immunomodulatory activity and global gene expression profile. Moreover, the in vivo therapeutic potential of NMP-MSC was detected in a mouse model of contact hypersensitivity (CHS). Results: We demonstrate that NMP-MSC express posterior HOX genes and exhibit characteristics similar to those of bone marrow MSC (BMSC), and NMP-MSC derived from different hPSC lines show high level of similarity in global gene expression profiles. More importantly, NMP-MSC display much stronger immunomodulatory activity than BMSC in vitro and in vivo, as revealed by decreased inflammatory cell infiltration and diminished production of pro-inflammatory cytokines in inflamed tissue of CHS models. Conclusion: Our results identify NMP as a new source of MSC and suggest that functional and homogeneous NMP-MSC could serve as a candidate for MSC-based therapies. View Publication

Background Cancer has been considered a serious global health problem and a leading cause of morbidity and mortality worldwide. Despite recent advances in cancer therapy, treatments of advance stage cancers are mostly ineffective resulting in poor survival of patients. Recent evidences suggest that multipotent human mesenchymal stem cells (hMSCs) play important roles in growth and metastasis of several cancers by enhancing their engraftment and inducing tumor neovascularization. However, the effect of hMSCs on cancer cells is still controversial because there are also evidences demonstrating that hMSCs inhibited growth and metastasis of some cancers. Methods In this study, we investigated the effects of bioactive molecules released from bone marrow and gestational tissue-derived hMSCs on the proliferation of various human cancer cells, including C3A, HT29, A549, Saos-2, and U251. We also characterized the hMSC-derived factors that inhibit cancer cell proliferation by protein fractionation and mass spectrometry analysis. Results We herein make a direct comparison and show that the effects of hMSCs on cancer cell proliferation and migration depend on both hMSC sources and cancer cell types and cancer-derived bioactive molecules did not affect the cancer suppressive capacity of hMSCs. Moreover, hMSCs use distinct combination of bioactive molecules to suppress the proliferation of human hepatoblastoma and colorectal cancer cells. Using protein fractionation and mass spectrometry analysis, we have identified several novel hMSC-derived factors that might be able to suppress cancer cell proliferation. Conclusion We believe that the procedure developed in this study could be used to discover other therapeutically useful molecules released by various hMSC sources for a future in vivo study. View Publication