The use of fibrous, supramolecular membranes and human tubular cells for renal epithelial tissue engineering: towards a suitable membrane for a bioartificial kidney

A bioartificial kidney, which is composed of a membrane cartridge with renal epithelial cells, can substitute important kidney functions in patients with renal failure. A particular challenge is the maintenance of monolayer integrity and specialized renal epithelial cell functions ex vivo. We hypothesized that this can be improved by electro-spun, supramolecular polymer membranes which show clear benefits in ease of processability. We found that after 7¿d, in comparison to conventional microporous membranes, renal tubular cells cultured on top of our fibrous supramolecular membranes formed polarized monolayers, which is prerequisite for a well-functioning bioartificial kidney. In future, these supramolecular membranes allow for incorporation of peptides that may increase cell function even furthe

The use of fibrous, supramolecular membranes and human tubular cells for renal epithelial tissue engineering: towards a suitable membrane for a bioartificial kidney

A bioartificial kidney, which is composed of a membrane cartridge with renal epithelial cells, can substitute important kidney functions in patients with renal failure. A particular challenge is the maintenance of monolayer integrity and specialized renal epithelial cell functions ex vivo. We hypothesized that this can be improved by electro-spun, supramolecular polymer membranes which show clear benefits in ease of processability. We found that after 7¿d, in comparison to conventional microporous membranes, renal tubular cells cultured on top of our fibrous supramolecular membranes formed polarized monolayers, which is prerequisite for a well-functioning bioartificial kidney. In future, these supramolecular membranes allow for incorporation of peptides that may increase cell function even furthe

On the role and fate of LPS-dephosphorylating activity in the rat liver

Gut-derived lipopolysaccharide (LPS) plays a role in the pathogenesis of liver diseases like fibrosis. The enzyme alkaline phosphatase (AP) is present in, among others, the intestinal wall and liver and has been previously shown to dephosphorylate LPS. Therefore, we investigated the effect of LPS on hepatic AP expression and the effect of AP on LPS-induced hepatocyte responses. LPS-dephosphorylating activity was expressed at the hepatocyte canalicular membrane in normal and fibrotic animals. In addition to this, fibrotic animals also displayed high LPS-dephosphorylating activity around bile ducts. The enzyme was shown to dephosphorylate LPS from several bacterial species. LPS itself rapidly enhanced the intrahepatic mRNA levels for this enzyme within 2 h by a factor of seven. Furthermore, in vitro and in vivo studies showed that exogenous intestinal AP quickly bound to the asialoglycoprotein receptor on hepatocytes. This intestinal isoform significantly attenuated LPS-induced hepatic tumor necrosis factor-alpha and nitric oxide (nitrite and nitrate) responses in vitro. The enzyme also reduced LPS-induced hepatic glycogenolysis in vivo. This study shows that LPS enhances AP expression in hepatocytes and that intestinal AP is rapidly taken up by these same cells, leading to an attenuation of LPS-induced responses in vivo. Gut-derived LPS-dephosphorylating activity or enzyme upregulation within hepatocytes by LPS may therefore be a protective mechanism within the liver

Convenient formulation and application of a supramolecular ureido-pyrimidinone modified poly(ethylene glycol) carrier for intrarenal growth factor delivery

The development of local, intrarenal drug delivery therapies is imperative to induce a therapeutic effect without the requirement of high concentrations of drugs, thereby diminishing systemic side effects. Hydrogels are eminently suitable as drug delivery carriers in soft tissues. Here, we show that a supramolecular hydrogel carrier based on ureido-pyrimidinone (UPy) modified poly(ethylene glycol) can be easily formulated and conveniently be applied to deliver anti-inflammatory and anti-fibrotic growth factor protein BMP7 to the kidney. Short-term, immediate modulation of renal inflammation and extracellular matrix remodelling is shown in a rat model of acute kidney injury. Induction of ischemia/reperfusion injury was followed by renal subcapsular implantation of pristine and BMP7-loaded supramolecular hydrogels. The cortical area under the site of implantation was studied after 3 and 7 days. Subcapsular delivery of only 0.30 μg BMP7 from these supramolecular hydrogels led to a significant reduction in interstitial inflammatory and myofibroblast cell numbers at the site of implantation. These findings show that local, intrarenal delivery of an anti-inflammatory and anti-fibrotic drug from a supramolecular hydrogel carrier can be effective in the reduction of acute inflammation and incipient fibrosis

Convenient formulation and application of a supramolecular ureido-pyrimidinone modified poly(ethylene glycol) carrier for intrarenal growth factor delivery

\u3cp\u3eThe development of local, intrarenal drug delivery therapies is imperative to induce a therapeutic effect without the requirement of high concentrations of drugs, thereby diminishing systemic side effects. Hydrogels are eminently suitable as drug delivery carriers in soft tissues. Here, we show that a supramolecular hydrogel carrier based on ureido-pyrimidinone (UPy) modified poly(ethylene glycol) can be easily formulated and conveniently be applied to deliver anti-inflammatory and anti-fibrotic growth factor protein BMP7 to the kidney. Short-term, immediate modulation of renal inflammation and extracellular matrix remodelling is shown in a rat model of acute kidney injury. Induction of ischemia/reperfusion injury was followed by renal subcapsular implantation of pristine and BMP7-loaded supramolecular hydrogels. The cortical area under the site of implantation was studied after 3 and 7 days. Subcapsular delivery of only 0.30 μg BMP7 from these supramolecular hydrogels led to a significant reduction in interstitial inflammatory and myofibroblast cell numbers at the site of implantation. These findings show that local, intrarenal delivery of an anti-inflammatory and anti-fibrotic drug from a supramolecular hydrogel carrier can be effective in the reduction of acute inflammation and incipient fibrosis.\u3c/p\u3

Convenient formulation and application of a supramolecular ureido-pyrimidinone modified poly(ethylene glycol) carrier for intrarenal growth factor delivery

The development of local, intrarenal drug delivery therapies is imperative to induce a therapeutic effect without the requirement of high concentrations of drugs, thereby diminishing systemic side effects. Hydrogels are eminently suitable as drug delivery carriers in soft tissues. Here, we show that a supramolecular hydrogel carrier based on ureido-pyrimidinone (UPy) modified poly(ethylene glycol) can be easily formulated and conveniently be applied to deliver anti-inflammatory and anti-fibrotic growth factor protein BMP7 to the kidney. Short-term, immediate modulation of renal inflammation and extracellular matrix remodelling is shown in a rat model of acute kidney injury. Induction of ischemia/reperfusion injury was followed by renal subcapsular implantation of pristine and BMP7-loaded supramolecular hydrogels. The cortical area under the site of implantation was studied after 3 and 7 days. Subcapsular delivery of only 0.30 mu g BMP7 from these supramolecular hydrogels led to a significant reduction in interstitial inflammatory and myofibroblast cell numbers at the site of implantation. These findings show that local, intrarenal delivery of an anti-inflammatory and anti-fibrotic drug from a supramolecular hydrogel carrier can be effective in the reduction of acute inflammation and incipient fibrosis. (C) 2015 Elsevier Ltd. All rights reserved

Bioengineering of living renal membranes consisting of hierarchical, bioactive supramolecular meshes and human tubular cells

Maintenance of polarisation of epithelial cells and preservation of their specialized phenotype are great challenges for bioengineering of epithelial tissues. Mimicking the basement membrane and underlying extracellular matrix (ECM) with respect to its hierarchical fiber-like morphology and display of bioactive signals is prerequisite for optimal epithelial cell function in vitro. We report here on a bottom-up approach based on hydrogen-bonded supramolecular polymers and ECM-peptides to make an electro-spun, bioactive supramolecular mesh which can be applied as synthetic basement membrane. The supramolecular polymers used, self-assembled into nano-meter scale fibers, while at micro-meter scale fibers were formed by electro-spinning. We introduced bioactivity into these nano-fibers by intercalation of different ECM-peptides designed for stable binding. Living kidney membranes were shown to be bioengineered through culture of primary human renal tubular epithelial cells on these bioactive meshes. Even after a long-term culturing period of 19 days, we found that the cells on bioactive membranes formed tight monolayers, while cells on non-active membranes lost their monolayer integrity. Furthermore, the bioactive membranes helped to support and maintain renal epithelial phenotype and function. Thus, incorporation of ECM-peptides into electro-spun meshes via a hierarchical, supramolecular method is a promising approach to engineer bioactive synthetic membranes with an unprecedented structure. This approach may in future be applied to produce living bioactive membranes for a bio-artificial kidney

Development and in-vivo characterization of supramolecular hydrogels for intrarenal drug delivery

Intrarenal drug delivery from a hydrogel carrier implanted under the kidney capsule is an innovative way to induce kidney tissue regeneration and/or prevent kidney inflammation or fibrosis. We report here on the development of supramolecular hydrogels for this application. We have synthesized two types of supramolecular hydrogelators by connecting the hydrogen bonding moieties to poly(ethylene glycols) in two different ways in order to obtain hydrogels with different physico-chemical properties. Chain-extended hydrogelators containing hydrogen bonding units in the main chain, and bifunctional hydrogelators end-functionalized with hydrogen bonding moieties, were made. The influence of these hydrogels on the renal cortex when implanted under the kidney capsule was studied. The overall tissue response to these hydrogels was found to be mild, and minimal damage to the cortex was observed, using the infiltration of macrophages, formation of myofibroblasts, and the deposition of collagen III as relevant read-out parameters. Differences in tissue response to these hydrogels could be related to the different physico-chemical properties of the three hydrogels. The strong, flexible and slow eroding chain-extended hydrogels are proposed to be suitable for long-term intrarenal delivery of organic drugs, while the weaker, soft and fast eroding bifunctional hydrogel is eminently suitable for short-term, fast delivery of protein drugs to the kidney cortex. The favourable biological behaviour of the supramolecular hydrogels makes them exquisite candidates for subcapsular drug delivery, and paves the way to various opportunities for intrarenal therapy. © 2012 Elsevier Ltd