Cell and drug delivery therapeutics for controlled renal parenchyma regeneration☆

Denk²

2013

Transplant Technol

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Stem/progenitor cells are in the focus of research as a therapeutic perspective to cure acute and chronic renal failure. Following this innovative strategy one has to consider that stem/progenitor cells are first kept in the beneficial atmosphere of a CO 2 -dependent culture medium, while after implantation they are exposed to unbalanced interstitial fluid of diseased parenchyma. However, this abrupt transition has consequences, since it limits survival of implanted stem/progenitor cells. To offer a constant environment during isolation, culture, surgical processing and initial seeding within diseased parenchyma, an improved concept is under current work. In present experiments stabilization of fluid environment was investigated by isolating renal stem/progenitor cells in chemically defined and CO 2 -stabilized culture media. Interstitial influences on spatial development of tubules were tested by mounting stem/progenitor cells in a polyester fleece as a substitute for extracellular matrix and by transporting always fresh medium in perfusion culture for 13 days. Finally, morphological quality of raised constructs was analyzed by histochemistry, light and transmission electron microscopy. The present results demonstrate that three different culture media can be short-listed for protecting stem/progenitor cells during the process of implantation. Earlier approved Iscove´s Modified Dulbecco´s Medium buffered by HEPES revealed formation of numerous tubules. Also application of Leibovitz's L-15 Medium and CO 2 Independent Medium demonstrated unexpected promoting effects on the generation of tubules. In all series typical features of transporting tubule cells were registered. Formation of an excess of vacuoles as an indicator for cytotoxicity was not observed. In conclusion, although very different in chemical composition the tested culture media reflect an advantageous microenvironment for isolation, implantation and development of stem/ progenitor cells.

Section: Resultsmentioning

confidence: 99%

Section: Isolation Of Renal Stem/progenitor Cellsmentioning

confidence: 99%

Section: Applied Chemically Defined Culture Mediamentioning

confidence: 99%

Section: Histochemistry On Generated Tubulesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Initial steps to stabilize the microenvironment for implantation of stem/progenitor cells in diseased renal parenchyma

Denk²

2013

Transplant Technol

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Interstitial interfaces show marked differences in regenerating tubules, matured tubules, and the renal stem/progenitor cell niche

J Biomedical Materials Res

Denk

2012

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Stem/progenitor cells are promising candidates for the regeneration of parenchyma in acute and chronic renal failure. After an implantation stem/progenitor cells must migrate through the interstitial space to concentrate at the site of damage. However, information is lacking to what extent the interstitial interface is influencing the development of stem/progenitor cells into nephron structures. In consequence, tubule regeneration within an artificial polyester interstitium was analyzed by electron microscopy in comparison with the interstitial interface of matured tubules and the interstitium within the renal stem/progenitor cell niche. The experiments demonstrate that fixation of specimens with glutaraldehyde (GA) is leading in all cases to inconspicuously looking interstitial interfaces. In contrast, fixation of regenerating tubules in GA containing ruthenium red and tannic acid shows a dense network of fibers lining along the basal lamina. In contrast, matured tubules reveal after ruthenium red label an extremely thickened basal lamina, while only a punctate pattern is obtained after tannic acid treatment. Finally, within the renal stem/progenitor cell niche ruthenium red and tannic acid label reveals large amounts of extracellular matrix spanning through the interstitium. Thus, fixation of tissue in GA containing ruthenium red and tannic acid exhibits an unexpectedly regional heterogeneity of the renal interstitial interface. This fact has to be considered for an optimal therapeutic repair of parenchyma, since contacts between stem/progenitor cells with the interstitial interface influence further development.

Peculiarities of the extracellular matrix in the interstitium of the renal stem/progenitor cell niche

Denk

Miess

et al. 2011

Histochem Cell Biol

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The development of the nephron is piloted by interactions between epithelial and surrounding mesenchymal stem/progenitor cells. Data show that an astonishingly wide interstitial space separates both kinds of stem/progenitor cells. A simple contrasting procedure was applied to visualize features that keep renal epithelial and mesenchymal stem/progenitor cells in distance. The kidney of neonatal rabbits was fixed in solutions containing glutaraldehyde (GA) in combination with alcian blue, lanthanum, ruthenium red, or tannic acid. To obtain a comparable view to the renal stem/progenitor cell niche, the tissue was exactly orientated along the axis of collecting ducts. Fixation with GA or in combination with alcian blue or lanthanum revealed an inconspicuous interstitial space. In contrast, fixation with GA containing ruthenium red exhibits strands of extracellular matrix lining from epithelial stem/progenitor cells through the interstitium up to the surface of mesenchymal stem/progenitor cells. Fixation with GA containing tannic acid shows that the basal lamina of epithelial stem/progenitor cells, the adjacent interstitial space and also the surface of mesenchymal stem/progenitor cells are connected over a net of extracellular matrix. The applied technique appears to be a suitable method to illuminate the interstitium in stem/progenitor cell niches of specialized tissues, the microenvironment of tumors and extension of degeneration.