Last update:
19-Nov-2012

OBJECTIVE In vitro nephrogenesis using the own tissues is an ideal substitute for allogeneic whole-kidney transplantation.

METHOD Adult Lewis rats were transplanted syngeneic liver structure grafts, from which hepatocytes had been removed, into an excision site in the left kidney. Either transforming growth factor (TGF)-β1 or epidermal growth factor (EGF) was then injected into the hosts.

RESULTS Good nephrogenesis was observed in the 7 rats that received a total of 60 μg of TGF-β1 each. Among these, the 4 (53%) rats with the best nephrogenesis showed a high percentage of Thy-1 (CD90)-positive bone marrow (BM) cells (60±5%), measured using a flow cytometer (FCM). In their mesenteric lymph nodes (MLN), the 7 TGF-β1 rats showed reduced percentages of CD3-positive cells (76±1%), calcineurin-regulated nuclear factor of activated T cell c1 (NFATc1)-positive cells (51±19%), and signal transducers and activators of transcription 3 (STAT3)-positive cells (39±14%). On transmission electron microscope (TEM) analyses, endothelial to mesenchymal transition (EndMT) could be observed in liver graft blood vessels, which showed massive proliferation of mesenchymal cells around a destroyed vessel to form a new nephron. On TEM analysis of specimens with pre-fixing staining with NFATc1 antibody-gold, NFATc1 expression was shown in newly generated mesangial cells, podocytes, and tubular cells. Mesenchymal cells had small granules of NFATc1. Aggregated NFATc1 in a large lysosome appeared in well-developed proximal convoluted tubular cells.

CONCLUSIONS Increased TGF-β1 signaling of EndMT trigger was very important for nephrogenesis, together with high expression of BM Thy-1. EGF injection was associated with less uniform results.

Key words: Endothelial to mesenchymal transition, Epidermal growth factor, Nephrogenesis, Rat, Transforming growth factor β1.