End stage renal failure is a devastating disease which involves multiple organs in affected individuals. Although dialysis can prolong survival for many patients with end stage renal disease, only renal transplantation can currently restore normal function. However, renal transplantation is severely limited by a critical donor shortage. In addition, renal transplantation is associated with a significant percentage of immunosuppressive complications and graft failure. Augmentation of either isolated or total renal function with kidney cell expansion in vitro and subsequent autologous transplantation may be a feasible solution. We explored the possibility of harvesting and expanding renal cells in vitro and implanting them in vivo in a three dimensional organization in order to achieve a functional artificial renal unit wherein urine production could be achieved. Kidneys from one week old C57 black mouse kidneys were digested with collagenase/dispase, plated and expanded in culture for 10 days. The cells were then harvested and seeded onto a tubular device constructed from polycarbonate (4 micron pore size), connected at both ends with silastic catheters. The device was then implanted in the subcutaneous space of athymic mice. Animals were sacrificed at 2, 4 and 8 weeks after implantation and the retrieved specimens were examined histologically. Immunohistochemical stains for osteopontin, fibronectin and alkaline phosphatase were performed to determine the cell types and their architecture in vivo. Yellow fluid was collected from inside the implant and uric acid levels were determined. Histological examination of the implanted device revealed extensive vascularization, formation of glomeruli and highly organized tubule-like structures. Immunocytochemical staining with anti-osteopontin antibody which is secreted primarily by proximal and distal tubule cells, stained the tubular sections. Immunohistochemical staining for alkaline phosphatase stained proximal tubule like structures. Furthermore, uniform staining for fibronettin in the extracellular matrix of newly formed tubes was observed. The yellow fluid collected from the newly formed renal unit contained 66mg/dl uric acid (as compared to 2mg/dl in plasma) suggesting that these tubules are capable of unidirectional secretion and concentration of uric acid. These results demonstrate that renal cells can be successfully harvested, expanded in culture and transplanted in vivo where the single suspended cells form and organize into functional renal structures which are able to excrete high levels of uric acid through a yellow urine-like fluid. These findings suggest that this system may be able to replace transplantation.
|Original language||English (US)|
|Number of pages||1|
|Journal||British Journal of Urology|
|Issue number||SUPPL. 2|
|State||Published - Dec 1 1997|
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