Fig. 7

Implantation of aggregates in a subrenal capsule assay formed SG-like organoid structures in vivo. SMG-ECM-treated aggregates or BM-MSCs mixed with Matrigel (MSCs/Matrigel) were implanted under the kidney capsule in immunocompromised mice to study organoid development. The in vivo experiment was repeated 2 times, and there were 4 replicates of each treatment. Kidneys, containing the implants, were harvested after 14 and 30 days for histological analysis. A The shadow of a 14-day implant (i.e., transplantation of SMG-ECM-treated aggregates) is outlined by a white square in the figure, while a 30-day implant is indicated by a white arrow. BM-MSCs mixed with Matrigel (negative control) did not form any visible structures following implantation for 30 days. B Paraffin sections of the implants were stained with H&E, PAS, and Trichrome. In the H&E and Trichrome images of day 14 specimens, a dotted yellow line identifies the junction of the implant (Imp) with kidney tissue; in day 30 specimens, a black square outlines representative secretory acini-like units. In the PAS images, arrows identify positive-staining cells. Bar: 50 µm. C Immunofluorescence staining of specimens harvested from day 14 and 30 implants identified the presence of amylase, Krt14, Aqp5, and Cldn10. BM-MSCs mixed with Matrigel (MSCs/Matrigel) were implanted for 30 days as controls and processed in an identical fashion. Staining with nonspecific isotype antibody was used as a negative control (not shown). Bar: 50 µm (images of MSC/Matrigel implants); 20 µm (images of day 14 and 30 Agg/SM-ECM implants). D TEM images of the 30 day implants (Agg/SMG-ECM) reveal the ultrastructural organization of the forming SG organoids. Note: scale bar distances are shown in each panel. N: cell nucleus; SG: secretory granule; and CF: collagen fibers