SUMMARY The canonical Wnt/β-catenin signaling pathway governs diverse developmental, homeostatic and pathologic processes. Palmitoylated Wnt ligands engage cell surface Frizzled (Fzd) receptors and Lrp5/6 co-receptors enabling β-catenin nuclear translocation and Tcf/Lef-dependent gene transactivation1–3. Mutations in Wnt downstream signaling components have revealed diverse functions presumptively attributed to Wnt ligands themselves, although direct attribution remains elusive, as complicated by redundancy between 19 mammalian Wnts and 10 Fzds1 and Wnt hydrophobicity2,3. For example, individual Wnt ligand mutations have not revealed homeostatic phenotypes in the intestinal epithelium4, an archetypal canonical Wnt pathway-dependent rapidly self-renewing tissue whose regeneration is fueled by proliferative crypt Lgr5+ intestinal stem cells (ISCs)5–9. R-spondin ligands (Rspo1–4) engage distinct Lgr4-6 and Rnf43/Znrf3 receptor classes10–13, markedly potentiate canonical Wnt/β-catenin signaling and induce intestinal organoid growth in vitro and Lgr5+ ISCs in vivo8,14–17. However, the interchangeability, functional cooperation and relative contributions of Wnt versus Rspo ligands to in vivo canonical Wnt signaling and ISC biology remain unknown. Here, we deconstructed functional roles of Wnt versus Rspo ligands in the intestinal crypt stem cell niche. We demonstrate that the default fate of Lgr5+ ISCs is lineage commitment, escape from which requires both Rspo and Wnt ligands. However, gain-of-function studies using Rspo versus a novel non-lipidated Wnt analog reveal qualitatively distinct, non-interchangeable roles for these ligands in ISCs. Wnts are insufficient to induce Lgr5+ ISC self-renewal, but rather confer a basal competency by maintaining Rspo receptor expression that enables Rspo to actively drive and specify the extent of stem cell expansion. This functionally non-equivalent yet cooperative interplay between Wnt and Rspo ligands establishes a molecular precedent for regulation of mammalian stem cells by distinct priming and self-renewal factors, with broad implications for precision control of tissue regeneration.

Mesenchymal stem cell (MSC)-derived exosomes have diverse functions in regulating wound healing and inflammation; however, the molecular mechanism of human umbilical cord MSC (hUCMSC)-derived exosomes in regulating burn-induced inflammation is not well understood. We found that burn injury significantly increased the inflammatory reaction of rats or macrophages exposed to lipopolysaccharide (LPS), increased tumor necrosis factor α (TNF-α) and interleukin-1β (IL-1β) levels and decreased IL-10 levels. hUCMSC-exosome administration successfully reversed this reaction. Further studies showed that miR-181c in the exosomes played a pivotal role in regulating inflammation. Compared to control hUCMSC-exosomes, hUCMSC-exosomes overexpressing miR-181c more effectively suppressed the TLR4 signaling pathway and alleviated inflammation in burned rats. Administration of miR-181c-expressing hUCMSC-exosomes or TLR4 knockdown significantly reduced LPS-induced TLR4 expression by macrophages and the inflammatory reaction. In summary, miR-181c expression in hUCMSC-exosomes reduces burn-induced inflammation by downregulating the TLR4 signaling pathway.

Pancreatic cancer (PaCa) has a dismal prognosis and adjuvant immunotherapy frequently is of low efficacy due to immunosuppressive features of PaCa and PaCa-stroma. We here explored, whether the efficacy of vaccination with tumor-exosome (TEX)-loaded dendritic cells (DC) can be improved by combining with drugs affecting myeloid-derived suppressor cells (MDSC). Experiments were performed with the UNKC6141 PaCa line. UNKC6141 TEX-loaded DC were weekly intravenously injected, mice additionally receiving Gemcitabine (GEM) and/or ATRA and/or Sunitinib (Sun). UNKC6141 grow aggressively after subcutaneous and orthotopic application and are consistently recovered in peripheral blood, bone marrow, lung and frequently liver. Vaccination with DC-TEX significantly prolonged the survival time, the efficacy of DC-TEX exceeding that of the cytotoxic drugs. However, ATRA, Sun and most efficiently GEM, sufficed for a pronounced reduction of MDSC including tumor-infiltrating MDSC, which was accompanied by a decrease in migrating and metastasizing tumor cells. When combined with DC-TEX vaccination, a higher number of activated T cells was recovered in the tumor and the survival time was prolonged compared with only DC-TEX vaccinated mice. As ATRA, GEM and Sun affect MDSC at distinct maturation and activation stages, a stronger support for DC-TEX vaccination was expected by the drug combination. Intrapancreatic tumor growth was prevented beyond the death of control mice. However, tumors developed after a partial breakdown of the immune system by the persisting drug application. Nonetheless, in combination with optimized drug tuning to prevent MDSC maturation and activation, vaccination with TEX-loaded DC appears a most promising option in PaCa therapy.

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Increasing evidence has demonstrated that hypoxia was an aggressive feature in endometrial cancer (EC), which is significantly associated with the tumor grade, lymph node metastasis, and tumor resistance to chemotherapy. However, the relationship between hypoxia and the immune microenvironment in EC is not very clear. Exosomes are small membrane vesicles secreted from a variety of cell types which mediate cell-to-cell communication through transported biomolecules. Here, we investigated whether exosomes can play an immunomodulatory role in intercellular communication between EC cells and macrophages. EC KEL cells were cultured under hypoxia or normoxic condition to collect exosomes. After identification, the exosomes derived from hypoxic or normoxic KEL cells were cultured with the monocyte cell line THP-1 to study the immunoregulation function of KEL cells. The results showed that the total number of exosomes produced by hypoxic KEL cells was significantly higher than that in normoxic condition. In addition, hypoxia markedly stimulated the increase in miRNA-21 expression in the exosomes. After coculture, we found that exosomal miRNA-21 could be horizontally transferred into THP-1 cells. And then, the notably enhanced mRNA expression levels of IL-10 and CD206 in THP-1 cells were observed, suggestive of M2 polarization. To further study the effect of miRNA-21-containing exosomes, we transfected miRNA-21 mimics or inhibitor into THP-1 cells. The results showed that miRNA-21 mimics promoted IL-10 and CD206 mRNA expression levels, and the miRNA-21 inhibitor significantly prevented the alteration induced by intake of hypoxic KEL cell-derived exosomes. In summary, we found that endometrial cancer KEL cells in hypoxic condition promoted monocyte THP-1 cell transformation to M2-like polarization macrophages through delivering exosomal miRNA-21, which may be a potential mechanism of the formation of the immune microenvironment in EC progression.

In patients with axial myopic astigmatism, CTR can effectively increase the rotational stability of a toric IOL, achieving improvement in corneal astigmatism and visual acuity.

Coronavirus disease 2019 (COVID‐19) patients with impact on skin and hair loss are reported. Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is detected in the skin of some patients; however, the detailed pathological features of skin tissues from patients infected with SARS‐CoV‐2 at a molecular level are limited. Especially, the ability of SARS‐CoV‐2 to infect skin cells and impact their function is not well understood. A proteome map of COVID‐19 skin is established here and the susceptibility of human‐induced pluripotent stem cell (hiPSC)‐derived skin organoids with hair follicles and nervous system is investigated, to SARS‐CoV‐2 infection. It is shown that KRT17+ hair follicles can be infected by SARS‐CoV‐2 and are associated with the impaired development of hair follicles and epidermis. Different types of nervous system cells are also found to be infected, which can lead to neuron death. Findings from the present work provide evidence for the association between COVID‐19 and hair loss. hiPSC‐derived skin organoids are also presented as an experimental model which can be used to investigate the susceptibility of skin cells to SARS‐CoV‐2 infection and can help identify various pathological mechanisms and drug screening strategies.

Highlights d Scalable suspension system is established to generate hepatic lineages from hEnSCs d scRNA-seq is used to delineate hEnSC-derived hepatic cells and their counterparts d E-heps and E-chos are transcriptomically and functionally comparable with adult cells d Encapsulated E-heps are able to rescue rats with acute liver failure