Browsing by Subject "fluid flow shear stress"

Diabetes mellitus (DM) is a metabolic disorder, which in 2021 alone affected approximately 537 million adults. DM is a multi-organ disease with several comorbidities, one of which is chronic kidney disease (CKD), which often leads to renal impairment and kidney damage. While current treatment strategies have improved, they fail to protect the kidneys efficiently, which is why further understanding and renoprotective strategies are required. Podocytes are terminally differentiated cells central to the proper function of the glomerular filtration barrier (GFB) in the kidneys, and their injury can lead to the leakage of protein into the primary urine, which is a hallmark of CKD. One of the potential causes of podocyte injury in DM is hyperfiltration induced increase in fluid flow shear stress (FFSS). Podocyte responses to FFSS are still, however, relatively unknown. We exposed cultured human podocytes in vitro to FFSS at 2 dyne/cm2 for 2 hours via a novel flow chamber system. From the FFSS experiments, we studied podocyte motility from live cell imaging, protein expression levels by Western blotting and finally did immunofluorescent labelling to identify protein localizations in the cells. We discovered that podocytes express different modes of motility upon FFSS exposure, notably bleb-like motility previously only described in tumor and embryonic cells. In addition, we observed that podocytes significantly increased the phosphorylation of both AMPK and Ezrin, indicating the activation of pro-survival signalling as well as formation of bleb-like protrusions in response to FFSS stimuli. However, we did not observe significant podocyte loss, indicating that podocytes are capable of withstanding increased FFSS for short exposures such as 60 minutes. We believe that upon FFSS exposure, podocytes activate pro-survival mechanisms such as increased phosphorylation of AMPK and changes in motility in order to better withstand the increased shear stress. However, increased FFSS in for example DM patients is persistent, making it potentially a key factor in the development of podocyte injury and ultimately kidney damage.