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

The prevalence of end-stage kidney disease (ESKD) is rapidly increasing with the need for regenerative therapies. Adult stem cell derived kidney tubuloids have the potential to functionally mimic the adult kidney tubule, but still lack the expression of important transport proteins needed for waste removal. Here, we investigated the potential of extracellular vesicles (EVs) obtained from matured kidney tubular epithelial cells to modulate in vitro tubuloids functional maturation. We focused on organic anion transporter 1 (OAT1), one of the most important proteins 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, resulting in improved OAT1 transport capacity. Next, a more in-depth proteomic data analysis showed that EVs can trigger various biological pathways, including mesenchymal-to-epithelial transition, which is crucial in the tubular epithelial maturation. Moreover, we demonstrated that the combination of EVs and tubuloid-derived cells can be used as part of a bioartificial kidney to generate a tight polarized epithelial monolayer with formation of dense cilia structures. In conclusion, EVs from kidney tubular epithelial cells can phenotypically improve in vitro tubuloid maturation, thereby enhancing their potential as functional units in regenerative or renal replacement therapies. Graphical Abstract: [Figure not available: see fulltext.]

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

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

Tubuloid differentiation to model the human distal nephron and collecting duct in health and disease

Summary: Organoid technology is rapidly gaining ground for studies on organ (patho)physiology. Tubuloids are long-term expanding organoids grown from adult kidney tissue or urine. The progenitor state of expanding tubuloids comes at the expense of differentiation. Here, we differentiate tubuloids to model the distal nephron and collecting ducts, essential functional parts of the kidney. Differentiation suppresses progenitor traits and upregulates genes required for function. A single-cell atlas reveals that differentiation predominantly generates thick ascending limb and principal cells. Differentiated human tubuloids express luminal NKCC2 and ENaC capable of diuretic-inhibitable electrolyte uptake and enable disease modeling as demonstrated by a lithium-induced tubulopathy model. Lithium causes hallmark AQP2 loss, induces proliferation, and upregulates inflammatory mediators, as seen in vivo. Lithium also suppresses electrolyte transport in multiple segments. In conclusion, this tubuloid model enables modeling of the human distal nephron and collecting duct in health and disease and provides opportunities to develop improved therapies

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

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

Cysteamine–bicalutamide combination therapy corrects proximal tubule phenotype in cystinosis

Nephropathic cystinosis is a severe monogenic kidney disorder caused by mutations in CTNS, encoding the lysosomal transporter cystinosin, resulting in lysosomal cystine accumulation. The sole treatment, cysteamine, slows down the disease progression, but does not correct the established renal proximal tubulopathy. Here, we developed a new therapeutic strategy by applying omics to expand our knowledge on the complexity of the disease and prioritize drug targets in cystinosis. We identified alpha-ketoglutarate as a potential metabolite to bridge cystinosin loss to autophagy, apoptosis and kidney proximal tubule impairment in cystinosis. This insight combined with a drug screen revealed a bicalutamide–cysteamine combination treatment as a novel dual-target pharmacological approach for the phenotypical correction of cystinotic kidney proximal tubule cells, patient-derived kidney tubuloids and cystinotic zebrafish

Cysteamine–bicalutamide combination therapy corrects proximal tubule phenotype in cystinosis

Nephropathic cystinosis is a severe monogenic kidney disorder caused by mutations in CTNS, encoding the lysosomal transporter cystinosin, resulting in lysosomal cystine accumulation. The sole treatment, cysteamine, slows down the disease progression, but does not correct the established renal proximal tubulopathy. Here, we developed a new therapeutic strategy by applying omics to expand our knowledge on the complexity of the disease and prioritize drug targets in cystinosis. We identified alpha-ketoglutarate as a potential metabolite to bridge cystinosin loss to autophagy, apoptosis and kidney proximal tubule impairment in cystinosis. This insight combined with a drug screen revealed a bicalutamide–cysteamine combination treatment as a novel dual-target pharmacological approach for the phenotypical correction of cystinotic kidney proximal tubule cells, patient-derived kidney tubuloids and cystinotic zebrafish