Selected renal cells harbor nephrogenic potential

Abstract

Selected renal cells (SRCs), a renal epithelial cell-enriched platform, are being advanced as an autologous cell-based therapy for the treatment of chronic kidney disease. However, the mechanism underlying its renal reparative and restorative effects remains to be fully elucidated. In this study, we coupled knowledgebase data with empirical findings to demonstrate that genes differentially expressed by SRCs form interactomes within tubules and glomeruli and mediate a suite of renal developmental activities including epithelial cell differentiation, renal vasculature development, and glomerular and nephron development. In culture, SRCs form organoids which self-assemble into tubules in the presence of a scaffold. Implanted into the kidneys of subtotally nephrectomized rats, SRCs are associated with comma- and S-shaped body cell formation and glomerular development, and improvement in renal filtration indices and renal microarchitecture. These data suggest that SRCs harbor nephrogenic potential, which may explain, at least in part, their therapeutic activity.

Keywords: cell; disease; glomeruli; kidney; nephrogenic; organoids; therapy; tubules.

FIGURE 1

Renal expression of selected renal cell (SRC) genes and their interactomes. Each of the SRC mRNA is expressed by the kidney with an average confidence of 0.51 (A). Interactomes are formed by these mRNA together with other mRNA in the kidney (B), tubules (C), glomeruli (D), and podocytes (E). Interaction strength confidence for these networks is kidney < tubule < glomerus < podocyte (F).

FIGURE 2

Compartmentalization of selected renal cell (SRC) gene products. Antibody imaging data housed in the human tissue atlas indicate compartmentalization (black arrows) of SRC gene products. Staining for CDH1 antibody is punctate and prominent in the collecting ducts and distal tubules (A). Staining for the EPO (B) and CUBN (C) antibodies is localized to the tubules whereas PECAM1 (D), NPHS1 (E), and KDR (F) antibodies exhibit punctate glomerular staining.

FIGURE 3

Selected renal cell (SRC) genes are also expressed by renal progenitors. Human Fetal Kidney Atlas heat map showing cells involved in fetal kidney development that also expresses SRC genes.

FIGURE 4

Selected renal cells (SRCs) form organoids and tubules. Representative image obtained using phase contrast microscopy showing formation of organoids (black arrows) (A) by SRCs in culture. SRC-derived organoids express the tubular marker chemokine receptor 4 (CXCR4) (white arrows) (B). Representative image showing tubule formation by SRCs in culture (black arrow) (C).

FIGURE 5

Activity of selected renal cells (SRCs) in vivo. Representative day 5 renal sections from rats submitted to Nx and administered SRC exhibiting the different stages of glomerulogenesis (yellow outline or black arrow) can be seen, including commashaped body cell (A), S-shaped body cell (B), the capillary loop phase (C), and the maturing glomerulus (D,E). Nx was associated with an increased BUN (F) at weeks 2, 4, 6, and 8 following randomization (*p < 0.01 vs. sham control). Compared to the Nx cohort, treatment with SRCs was associated with reduced BUN levels at weeks 2 (#p < 0.05 vs. Nx; *p < 0.01 vs. sham control), 4 (!p < 0.01 vs. Nx; *p < 0.01 vs. sham control) and 6 (#p < 0.05 vs. Nx; $p < 0.05 vs. sham control) following randomization. At 8 weeks following randomization, BUN levels were not significantly different vs. Nx (p = 0.057; *p < 0.01 vs. sham control). Nx was associated with increased SCr (G) at weeks 2, 4, 6, and 8 following randomization (*p < 0.01 vs. sham control). Compared to the Nx cohort, treatment with SRCs was associated with reduced SCr levels at weeks 2 (#p < 0.05 vs. Nx; *p < 0.01 vs. sham control), 4 (!p < 0.01 vs. Nx; *p < 0.01 vs. sham control), 6 (#p < 0.05 vs. Nx; p > 0.05 vs. sham control) and 8 (#p < 0.05 vs. Nx; p > 0.05 vs. sham control). Representative month 6 renal sections (H) from sham control, Nx and Nx + SRC cohorts. The Nx cohort exhibits severe focal segmental glomerulosclerosis, glomerular atrophy, adhesions of sclerotic segment to Bowman’s capsule (arrows), and shrinkage of capillary tufts (*), accompanied by tubular dilatation (“TD”) and tubular casts (“TC”). By contrast, the Nx + SRC treated kidney exhibits reduced glomerular changes, consisting predominantly of compensatory glomerular hypertrophy (“GH”), characterized by enlargement of glomeruli without appreciable injury. In addition, SRC treatment is associated reduced tubular and glomerular injury vs. the Nx cohort (I).

FIGURE 6

Selected renal cells (SRCs). Rat renal cortical cells are expanded and subjected to buoyancy separation. Two bands differentially expressing nphs1, kdr, hes1, epo, pecam1, cdh1, and cubn are selected and combined to produce rat SRCs. Culturing of SRCs results in the formation of organoids and implanted into the diseased kidney, SRCs are associated with nephron development and improvement in renal function and tissue microarchitecture.