Elucidation of the biological functions of extracellular vesicles (EVs) and their potential roles in physiological and pathological processes is an expanding field of research. In this study, we characterized USC–derived EVs and studied their capacity to modulate the human immune response in vitro. We found that the USC–derived EVs are a heterogeneous population, ranging in size from that of micro–vesicles (150 nm–1 μm) down to that of exosomes (60–150 nm). Regarding their immunomodulatory functions, we found that upon isolation, the EVs (60–150 nm) induced B cell proliferation and IgM antibody secretion. Analysis of the EV contents unexpectedly revealed the presence of BAFF, APRIL, IL–6, and CD40L, all known to play a central role in B cell stimulation, differentiation, and humoral immunity. In regard to their effect on T cell functions, they resembled the function of mesenchymal stem cell (MSC)–derived EVs previously described, suppressing T cell response to activation. The finding that USC–derived EVs transport a potent bioactive cargo opens the door to a novel therapeutic avenue for boosting B cell responses in immunodeficiency or cancer.

The interplay between mesenchymal stem cells (MSCs) and immune cells has been studied for MSCs isolated from different tissues. However, the immunomodulatory capacity of urine stem cells (USCs) has not been adequately researched. The present study reports on the effect of USCs on peripheral blood lymphocytes. USCs were isolated and characterized before coculture with resting and with anti-CD3/CD28 bead stimulated lymphocytes. Similarly to bone marrow mesenchymal stem cells (BM-MSCs), USCs inhibited the proliferation of activated T lymphocytes and induced their apoptosis. However, they also induced strong activation, proliferation, and cytokine and antibody production by B lymphocytes. Molecular phenotype and supernatant analysis revealed that USCs secrete a range of cytokines and effector molecules, known to play a central role in B cell biology. These included B cell-activating factor (BAFF), interleukin 6 (IL-6) and CD40L. These findings raise the possibility of an unrecognized active role for kidney stem cells in modulating local immune cells.

The emergence of vaccine-evading SARS-CoV-2 variants urges the need for vaccines that elicit broadly neutralizing antibodies (bnAbs). Here, we assess covalently circularized nanodiscs decorated with recombinant SARS-CoV-2 spike glycoproteins from several variants for eliciting bnAbs with vaccination. Cobalt porphyrin–phospholipid (CoPoP) was incorporated into the nanodisc to allow for anchoring and functional orientation of spike trimers on the nanodisc surface through their His-tag. Monophosphoryl-lipid (MPLA) and QS-21 were incorporated as immunostimulatory adjuvants to enhance vaccine responses. Following optimization of nanodisc assembly, spike proteins were effectively displayed on the surface of the nanodiscs and maintained their conformational capacity for binding with human angiotensin-converting enzyme 2 (hACE2) as verified using electron microscopy and slot blot assay, respectively. Six different formulations were prepared where they contained mono antigens; four from the year 2020 (WT, Beta, Lambda, and Delta) and two from the year 2021 (Omicron BA.1 and BA.2). Additionally, we prepared a mosaic nanodisc displaying the four spike proteins from year 2020. Intramuscular vaccination of CD-1 female mice with the mosaic nanodisc induced antibody responses that not only neutralized matched pseudo-typed viruses, but also neutralized mismatched pseudo-typed viruses corresponding to later variants from year 2021 (Omicron BA.1 and BA.2). Interestingly, sera from mosaic-immunized mice did not effectively inhibit Omicron spike binding to human ACE-2, suggesting that some of the elicited antibodies were directed towards conserved neutralizing epitopes outside the receptor binding domain. Our results show that mosaic nanodisc vaccine displaying spike proteins from 2020 can elicit broadly neutralizing antibodies that can neutralize mismatched viruses from a following year, thus decreasing immune evasion of new emerging variants and enhancing healthcare preparedness.

Alkali burn is a vision-threatening ocular emergency with no targeted acute therapy. We previously identified tissue hypoxia as a key driver and developed a perfluorodecalin-based supersaturated oxygen emulsion (SSOE) that delivers high levels of oxygen topically. In this study, we aim to investigate the role of hypoxia-inducible factor signaling in postburn sequalae and evaluate the therapeutic efficacy and timing of SSOE in treating ocular alkali burn. Experimental animal study. A total of 207 BALB/c mice were used in this study. Subjects were assigned to 6 experimental groups: naïve (n = 31), untreated or vehicle-treated controls (n = 75), and treatment groups receiving SSOE either immediately postinjury (n = 33), or with delayed initiation at 1 day (n = 26), 2 days (n = 21), or 5 days (n = 21) after alkali burn. Where possible, mice were used for multiple outcome assessments to reduce total animal use in accordance with ethical and institutional guidelines. Alkali burn was induced by applying 1M sodium hydroxide solution to the central cornea of BALB/c mice, followed by immediate or delayed (by 1, 2, or 5 days) topical application of SSOE or vehicle control daily for 14 days. Corneal opacity, neovascularization (NV), and cataract formation were assessed, and hypoxia-inducible factor 1-alpha (HIF-1α) and VEGF expression were measured. Corneal NV, anterior chamber (AC) inflammation, cataract formation, and HIF-1α or VEGF expression. Alkali burn led to persistent HIF-1α activation in the cornea up to day 14 postinjury, which was strongly correlated with corneal NV. Immediate SSOE treatment significantly reduced corneal NV, edema, AC inflammation, cataract formation, and expression of HIF-1α and VEGF at days 14 and 28. Delayed SSOE application (up to 5 days postinjury) also improved corneal NV, edema, inflammation, and fibrosis but did not prevent cataract formation. Daily SSOE treatment mitigates hypoxia-driven corneal NV by inhibiting HIF-1α and VEGF signaling. Early administration offers the greatest benefit, though delayed treatment remains effective in reducing corneal damage. These findings support the potential of SSOE as a novel topical therapy for chemical eye injuries. Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.