Glucose Transporters in Human Renal Proximal Tubular Cells Isolated From the Urine of Patients With Non–Insulin-Dependent Diabetes

TLDR

Glucose reabsorption in the proximal tubule is mediated by transporters, but studying this in type 2 diabetes has been limited by the lack of primary renal cells from patients without biopsy. This study presents an immunomagnetic technique to isolate and culture human exfoliated proximal tubular epithelial cells from fresh urine. The method yields highly enriched, differentiated cells that retain proximal markers (CD13, SGLT2, alkaline phosphatase) through at least six subcultures, comparable to biopsy‑derived cells. In a hyperglycemic setting, cells from type 2 diabetic patients exhibit elevated SGLT2 and GLUT2 expression and increased glucose uptake, demonstrating for the first time that heightened transporter activity is linked to diabetes in a human cellular model.

Abstract

The bulk of glucose that is filtered by the renal glomerulus is reabsorbed by the glucose transporters of the proximal convoluted tubular epithelium. However, it has been difficult to investigate this in diseases such as type 2 diabetes because of the inability to isolate primary renal cells from patients without a renal biopsy. We report here a method for the immunomagnetic isolation and novel primary culture of human exfoliated proximal tubular epithelial cells (HEPTECs) from fresh urine. The primary isolates are highly enriched and differentiated and express characteristic proximal tubular phenotypic markers. They continue to express the proximal tubular markers CD13/aminopeptidase-N, sodium glucose cotransporter (SGLT) 2, and alkaline phosphatase through up to six subsequent subcultures in a similar way to human proximal cells isolated from renal biopsies. In a hyperglycemic environment, HEPTECs isolated from patients with type 2 diabetes expressed significantly more SGLT2 and the facilitative glucose transporter GLUT2 than cells from healthy individuals. We also demonstrated a markedly increased renal glucose uptake in HEPTECs isolated from patients with type 2 diabetes compared with healthy control subjects. Our findings indicate for the first time in a human cellular model that increased renal glucose transporter expression and activity is associated with type 2 diabetes.