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Abstract: SA-PO575

Cultured Renal Tubular Epithelia in Migration Develop 3 Forms of Filopodia Having an Inherent Short Diameter: A Scanning Electron Microscope (SEM) Study

Session Information

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms


  • Inui, Kiyoko, Showa University Fujigaoka Hospital, Yokohama, kanagawa, Japan
  • Morita, Hiroyuki, Aichi Medical University School of Medicine, Nagakute, Japan
  • Inoue, Yoshihiko, Showa University Fujigaoka Hospital, Yokohama, kanagawa, Japan
  • Sato, Yoshinori, Showa University Fujigaoka Hospital, Yokohama, kanagawa, Japan
  • Kawashima, Eri, Showa University Fujigaoka Hospital, Yokohama, kanagawa, Japan
  • Yoshimura, Ashio, Shinyokohama Daiichi Clinic, Yokohama, Japan
  • Koiwa, Fumihiko, Showa University Fujigaoka Hospital, Yokohama, kanagawa, Japan

Renal tubular epithelial regenerate themselves after severe injuries as exemplified in acute kidney injury (AKI), when cell migration plays a crucial role. Studies have demonstrated that formations of filopodia are pivotal in cell migration. However, ultrastructure of cells with filopodia in migration largely remains to be seen. In this study, we use scanning electron microscope (SEM), and report fine ultrastructural images of filopodia that tubular epithelia form in cell migration.


Rat renal epthelialia, NRK-52E, were grown to confluence, and then, scratched or subcultured. At various time points until the next 100% confluence, they were fixed and subjected to SEM analysis. Filopodia were found in the specimens almost without exceptions. 20 different areas were randomly picked up to measure the short and long diameters of filopodia.


Major findings of this study were 1) Filopodia were classified into 3 groups: having A(32±9)nm, B(108±16) nm, and C(155±21) nm short diameters. 2) Typically, the ratio of the short diameter to the long diameter in A, B, and C were 1:70, 1:150, and 1:400, respectively. 3) Group C filopodia were the major one when the cells were directionally migrating at >70% confluence. Interestingly, Group C filopodia was seen after the cells were grown to confluence (Figure). Appearances of Group A filopodia were rare.


Our ultrastructural study identified 3 forms of filopodia, although reciprocal relationship among them remained to be elucidated. Each one was associated with cell migration. We propose a hypothesis that group C filopodia play a role in learning the position of a cell in relation to adjacent ones.