Characteristics of multilineage‐differentiating stress‐enduring cell clusters in different culture conditions

OBJECTIVE: To observe the morphological characteristics of clusters of Muse cells from normal human dermal fibroblasts (NHDFs) under different culture conditions. METHODS: Muse cells were sorted by magnetic activated cell sorting (MACS) from NHDFs, and were evaluated by flow cytometry. Muse cells were cultured in suspension and in adherent conditions to obtain Muse cell clusters (M‐clusters), which were further characterized by alkaline phosphatase (AP) staining, immunofluorescence (IF) staining and transmission electron microscopy (TEM). The M‐clusters were further cultured on Lando artificial dermal regeneration matrix (LADRM) for analysis by scanning electron microscopy (SEM) and IF staining of frozen sections. RESULTS: The proportion of SSEA3 and CD105 double‐positive cells obtained by MACS was 87.4%. The sorted cells rapidly formed M‐clusters after suspension culture, and showed internal characteristics of stem cells under TEM. After adherent culture, M‐clusters stained positively for AP, SSEA‐3 and OCT‐4. Each M‐cluster on the surface of the LADRM displayed an outer membrane of amorphous materials under SEM. Frozen sections and fluorescence staining of LADRM loaded with M‐clusters showed an uneven fluorescence intensity of SSEA‐3 within the clusters. CONCLUSIONS: Muse cells sorted by MACS from NHDFs could generate M‐clusters, which included cells of different stemness and are wrapped in membrane‐like structures.