Congratulations to Cathelijne W. van den Berg, on the publication of her paper “In Vivo Assessment of Size-Selective Glomerular Sieving in Transplanted Human Induced Pluripotent Stem Cell–Derived Kidney Organoids” in JASN magazine. Cathelijne is one of the researchers at Leiden University Medical Center working in the Kidney Moonshot, whose main goal is the creation of a functioning bioengineered kidney.
For her publication, Cathelijne worked with induced pluripotent stem cells that have the unique ability to specialize to any cell type of the human body. In the laboratory Cathelijne developed miniature kidneys of 0.5 cm in diameter that contained all cells that are also present in the adult kidney, however they were still immature and did not fully develop. Upon transplantation in mice, the miniature kidneys developed further and became more adult-like. In this paper, Cathelijne investigated the functionality of these miniature kidneys. One of the most important functions of the kidney is filtration of the blood by the glomerulus that sieves molecules on the basis of size. Smaller molecules are filtrated and excreted in urine, whereas larger molecules such as albumin should be retained in the blood and are not filtrated. Cathelijne and her colleagues observed that the glomerular structures in the miniature kidneys develop an appropriate barrier function upon transplantation and that the glomerular structures discriminate molecules of varying size, similar as in the adult kidney. The smaller sized molecules passage the membrane into Bowman’s space and were detected in the tubular structures suggesting a functional connection was present between those parts of the nephron. The results published in JASN provide clear evidence of functional filtration in these kidney organoids and this approach holds promise for the development of a bioengineered kidney from stem cells.