Constructing Kidney-like Tissues from Cells Based on Programs for Organ Development: Toward a Method ofIn VitroTissue Engineering of the Kidney

Abstract

The plausibility of constructing vascularized three-dimensional (3D) kidney tissue from cells was investigated. The kidney develops from mutual inductive interactions between cells of the ureteric bud (UB), derived from the Wolffian duct (WD), and the metanephric mesenchyme (MM). We found that isolated MMs were capable of inducing branching morphogenesis of the WD (an epithelial tube) in recombination cultures; suggesting that the isolated MM retains inductive capacity for WD-derived epithelial tubule cells other than those from the UB. Hanging drop aggregates of embryonic and adult renal epithelial cells from UB and mouse inner medullary collecting duct cell (IMCD) lines, which are ultimately of WD origin, were capable of inducing MM epithelialization and tubulogenesis with apparent connections (UB cells) and collecting duct-like tubules with lumens (IMCD). This supports the view that the collecting system can be constructed from certain epithelial cells (those ultimately of WD origin) when stimulated by MM. Although the functions of the MM could not be replaced by cultured mesenchymal cells, primary MM cells and one MM-derived cell line (BSN) produced factors that stimulate UB branching morphogenesis, whereas another, rat inducible metanephric mesenchyme (RIMM-18), supported WD budding as a feeder layer. This indicates that some MM functions can be recapitulated by cells. Although engineering of a kidney-like tissue from cultured cells alone remains to be achieved, these results suggest the feasibility of such an approach following the normal developmental progression of the UB and MM. Consistent with this notion, implants of kidney-like tissues constructed in vitro from recombinations of the UB and MM survived for over 5 weeks and achieved an apparently host-derived glomerular vasculature. Lastly, we addressed the issue of optimal macro-and micro-patterning of kidney-like tissue, which might be necessary for function of an organ assembled using a tissue engineering approach. To identify suitable conditions, 3D reconstructions of HoxB7-green fluorescent protein mouse rudiments (E12) cultured on a filter or suspended in a collagen gel (type I or type IV) revealed that type IV collagen 3D culture supports the deepest tissue growth (600 AE 8 mm) and the largest kidney volume (0.22 AE 0.02 mm 3 ), and enabled the development of an umbrella-shaped collecting system such as occurs in vivo. Taken together with prior work Steer et al., 2002), 1,2 these results support the plausibility of a developmental strategy for constructing and propagating vascularized 3D kidney-like tissues from recombinations of cultured renal progenitor cells and/or primordial tissue.

Antibiotics and renal branching morphogenesis: comparison of toxicities

“…Our study shows no correlation between the surface expansion and a more direct kidney developmental marker such as ureteric bud count. This lack of correlation may be explained by flattening of the metanephros in organ culture and its partial loss of three dimensional structure as has been reported previously (15). However, the impact on actual measurements had not been studied.…”

Functional Genetic Targeting of Embryonic Kidney Progenitor Cells Ex Vivo

“…12,14,46 A significant limitation of this approach is that the nephrogenesis has to be induced before the dissociation step of the MM to prevent concurrent apoptosis of the uninduced MM cells. 15 The kidney dissociation approach was also recently applied by others [16][17][18][19][20] but with respect to the MM, the means to conduct critical gene function studies before or during the tubule induction process 17,19 are lacking. A further problem is the impossibility of targeting gene functions in the ex vivo setups, so that long-term cultures and inducible functional studies would be possible.…”

“…3,15 Dissociation strategies were again recently applied. [16][17][18][19][20] However, it is currently still impossible to target the cellular and molecular genetic details before or during the transmission and transduction of the inductive signals. [21][22][23][24] We show here that the dissociated and reaggregated kidney mesenchyme (drMM) survives and remains competent at least for 24 hours in the presence of human recombinant bone morphogenetic protein 7 (hrBMP7) and human recombinant fibroblast growth factor 2 (hrFGF2), and can assemble segmented nephrons when induced ex vivo.…”

Cellular and Developmental Strategies Aimed at Kidney Tissue Engineering

“…Furthermore, even an uninduced WD tubule was found to behave as the UB when recombined with MM [13]. Thus, the required starting materials for the collecting system of the kidney have been reduced to a tubular structure with a WD-like identity, presumably more attainable than the heterogeneous UB structure - which has a tip and stalk domain.…”