Gebremeskel, S. | bioRxiv Science

bioRxiv2025

A Rapid and Scalable Subcutaneously Administered Murine Thymus Micro-organoid for Generating Functional T cells

Thymic function can decline due to age-related involution, congenital disorders, acute infections, or chemo/radiation therapy. Decline in thymic function leads to decreased T cell production and weakened immunity. To address these thymic insufficiencies, we aimed to develop a transplantable and scalable micro-organoid system utilizing fibroblasts and thymic cells. We have developed a reliable and rapid method to generate thymic micro-organoids using selectively screened fibroblasts and murine thymic cells. The thymic micro-organoids are cryo-preservable, injectable, and give rise to T cells both in vitro and in vivo. Thymic organoids expressed key genes required to sustain T cell development and maturation: ccl25, dll-1, dll-4, foxn-1, il-7, scf. When injected into T cell-deficient Prkdcscid mice, the organoids gave rise to functional {beta}, {psi}8, natural killer T (NKT) cells, and FoxP3+ regulatory T cells. Organoid-derived T cells expressed a diverse T cell receptor (TCR) repertoire in vivo and responded to stimulation with anti-CD3/28, Concanavalin-A, or Phytohemagglutinin. Thymic organoids derived from pmel-1 thymocytes gave rise to V{beta}13+ T cells that delayed the growth of B16 melanoma and enhanced activation of T and NK cells. This approach presents a valuable tool for mechanistic studies and addressing current therapeutic gaps in diseases associated with thymic decline and insufficiencies.

immunology↗

bioRxiv2025

Human Dermal Fibroblast-derived Spheroids Demonstrate Efficacious Immune Modulation in a Psoriasis Mouse Model

BackgroundPsoriasis is a chronic inflammatory disease associated with high morbidity and few cases of sustained remission. Innovative immunomodulatory therapies, including fibroblast-based cell therapies, offer promising alternatives. This study investigates the therapeutic potential of human dermal fibroblasts (HDFs) organized into three-dimensional (3D) spheroids in a mouse model of imiquimod (IMQ)-induced psoriasis. MethodsHDF spheroids were cultured using Elplasia(R) microcavity plates, and their size, viability, and phenotype were compared with single cells in 2D monolayer cultures. Cellular responses in whole blood and acute inflammatory responses were evaluated at various time points following intravenous injection of HDFs. The therapeutic efficacy of HDF spheroids was assessed using an IMQ-induced psoriasis mouse model, with disease severity scored using the Psoriasis Area and Severity Index (PASI). Optimized HDF spheroids ([~]150 {micro}m, 1x106 cells/mouse) were administered intravenously in a single dose for mild psoriasis or multiple doses for moderate-to-severe psoriasis. The efficacy of HDF spheroids was compared to a pre-clinical monoclonal antibody targeting interleukin 23 (anti-IL-23). ResultsSpheroid cultures of HDFs showed reduced cell size, enhanced viability, and distinct phenotypic changes compared to monolayer cultures. Intravenous injection of HDF spheroids resulted in less thrombocytopenia and reduced acute inflammatory responses compared to single-cell injection. A single dose of HDF spheroids reduced the severity of mild psoriasis by 35%, while repeated doses resulted in a 36% reduction in moderate-to-severe psoriasis. Single-dose administration normalized blood cell counts, alleviated spleen enlargement, and improved cytokine dysregulation. Although HDF spheroids and anti-IL-23 reduced epidermal thickening and immune cell infiltration, HDF spheroids uniquely inhibited monocyte production and infiltration, a benefit not observed with anti-IL-23. No acute or chronic toxicity was observed. ConclusionsHDF spheroids offer comparable therapeutic efficacy to anti-IL-23 in treating psoriasis, with a distinct mechanism involving inhibiting monocyte production and infiltration. Their safety profile and broader immunomodulatory potential support their development as a novel therapeutic strategy for psoriasis and other inflammatory diseases.

immunology↗