Differentiated kidney tubular cell-derived extracellular vesicles enhance maturation of tubuloids

Abstract

Advanced kidney in vitro models such as organoids or tubuloids still lack the intrinsic expression of various transport proteins needed for active secretory function. Extracellular vesicles (EVs), cell-derived structures that constitute the organ's microenvironment, are known to regulate various cellular processes, including kidney development and regeneration across the nephron. In this study, we propose a new application of renal tubular epithelial cell EVs as modulators for tubuloid functional maturation by increasing the levels of various differentiation markers such as organic anion transport 1 (OAT1), a protein involved in endogenous waste excretion. First, we show that EVs from engineered proximal tubule cells increased the expression of several transcription factors and epithelial transporters in tubuloids that resulted in improved cellular transport capacity. Next, a more in-depth proteomic data analysis demonstrated that EVs can trigger various biological pathways, including mesenchymal-to-epithelial transition, which is crucial in the tubular epithelial maturation process. Moreover, we demonstrated that EV-treated tubuloid-derived cells in a 3D tubular conformation as part of a bioartificial kidney can generate a tight polarized epithelial monolayer with formation of dense cilia structures. In conclusion, EVs from renal tubular epithelial cells can phenotypically improve tubuloid maturation, thereby enhancing their potential as preclinical models and functional units in regenerative therapies.

Extracellular Vesicles in Kidney Diseases: Moving Forward

“…In vitro studies have demonstrated that proximal tubular EVs modify the activity of the epithelial sodium channel (ENaC) in the distal nephron [95], [96]. Similarly, EVs isolated from engineered proximal tubule cells were shown to improve the functional maturation of "tubuloids" (organoids showing a predominant tubular phenotype) including enhanced transport capacity of organic anion transporter 1 (OAT1) [97]. This raises the possibility that EVs mediate proximal-to-distal cross-talk to modify transport function (see Figure 4) [98].…”

“…110,111 Similarly, EVs isolated from engineered proximal tubule cells were shown to improve the functional maturation of “tubuloids” (organoids showing a predominant tubular phenotype) including enhanced transport capacity of organic anion transporter 1. 112 This raises the possibility that EVs mediate proximal-to-distal cross-talk to modify transport function (see Figure 5). 113 If confirmed in vivo , this would represent a novel layer of regulation in addition to other signaling systems.…”