Shimmura Shigeto

Mesenchymal stem/stromal cells (MSCs) are notable for their differentiation potential and immunomodulatory properties. They share several features with macrophages as well as fibrocytes. This study aimed to investigate the relationship between MSCs, fibrocytes, and macrophages, focusing on the hypothesis of a possible direct lineage. Particularly, the focus lies on a freshly isolated murine MSC population known as PαS cells, which were transplanted into irradiated recipients, resulting in cells expressing a macrophage-like phenotype with CD45, CD68, and CSF1R (also known as CD115) expression. Further analysis showed that PαS cells cultured in macrophage differentiation media acquired characteristics of M2 macrophages (CD45, CD68, and CD206) through interaction with CSF1R. These results were confirmed in several mouse strains and human MSCs. Single-cell RNA sequencing revealed macrophage-like populations among the PαS cells, demonstrating the phenotypic plasticity of non-cultured MSCs, giving into MSC potential roles in immune regulation and tissue repair.

Abstract Retinal thickness measured using optical coherence tomography (OCT) is a major parameter to evaluate retinal diseases. However, it may be influenced by systemic factors. We retrospectively analyzed OCT images and blood sample data from 266 participants (49.1 ± 10.5 years) including 181 (68.0%) males who underwent medical checkups at Fujita Medical Innovation Center, Tokyo. Those with retinal pathological findings were excluded. Males had thicker retinas in the center and inner circles of Early Treatment Diabetic Retinopathy Study grid (P < 0.01 for all). Mean thicknesses of the superior areas were greater than those of the inferior areas in inner and outer circles (P < 0.01 for both). However, there were eyes with thicker inner inferior areas (72 eyes, 27.1%), which was observed more frequently in males (P = 0.018). Thicker retinas were associated with lower hemoglobin A1c levels in the center (P = 0.012), and inner temporal (P = 0.042) and inferior (P = 0.047) areas; lower creatinine levels in the inner temporal (P = 0.002), superior (P = 0.026), and inferior (P < 0.001) areas; and higher high-density lipoprotein cholesterol levels in the inner nasal (P = 0.029) and inferior (P = 0.029) areas after adjusting for age and sex. These results may be kept in mind in evaluating OCT data during clinical practice and future clinical trials, although further studies are warranted.

INTRODUCTION: Patients with limbal dysfunction, which occurs when corneal epithelial stem cells are depleted, require the transplantation of donor corneal epithelial stem cells or donor-independent cell sources. This study aimed to establish organoids with limbal epithelial progenitor cell function from the central cornea, where stem cells do not reside in vivo. We confirmed the regenerative capacity of organoids in a rabbit limbal deficiency model. METHODS: After treatment with collagenase, central corneal epithelial cells were scraped from corneal tissue and seeded onto Matrigel. For comparison, cells were collected from the limbus. The cells were cultured in Limbal Phenotype Maintenance Medium (LPMM). After 1 month, the organoids were observed in terms of number and size, immunohistochemistry, cell cycle, and colony-forming efficiency. Organoids were also transplanted into a rabbit model of limbal deficiency. RESULTS: Although we were able to form organoids from the central cornea, the number of organoids from the cornea was small (approximately one tenth compared to the limbus) after 1-month culture. Cornea-derived organoids were similar in shape and size to limbal-derived organoids, and expressed keratin 15 and p63, which are characteristics of the limbal epithelium, as well as collagen type IV, laminin, and tenascin-C, which are limbal basement membrane components. Cornea-derived organoids also showed colony forming efficiency, slow-cycling cells, and label-retaining cells. Transplanted corneal organoids were observed in the limbus of a rabbit limbal deficiency model, and the presence of organoid-derived cells extending into the host cornea was confirmed by immunohistochemistry using anti-human nuclei, -K12, -collagen type IV, and -laminin antibodies. CONCLUSIONS: Our data suggest that corneal organoids de-differentiated to gain a limbal phenotype and functionally supplied corneal epithelium in a rabbit limbal deficiency model for up to 1 month.