Interstitial fibroblasts are principal effector cells of organ fibrosis in kidneys, lungs, and liver While some view fibroblasts in adult tissues as nothing more than primitive mesenchymal cells surviving embryologic development, they differ from mesenchymal cells in their unique expression of fibroblast-specific protein-1 (FSP1) This difference raises questions about their origin Using bone marrow chimeras and transgenic reporter mice, we show here that interstitial kidney fibroblasts derive from two sources A small number of FSP1(+), CD34(-) fibroblasts migrate to normal interstitial spaces from bone marrow More surprisingly, however, FSP1(+) fibroblasts also arise in large numbers by local epithelial-mesenchymal transition (EMT) during renal fibrogenesis Both populations of fibroblasts express collagen type I and expand by cell division during tissue fibrosis Our findings suggest that a substantial number of organ fibroblasts appear through a novel reversal in the direction of epithelial cell fate As a general mechanism, this change in fate highlights the potential plasticity of differentiated cells in adult tissues under pathologic conditions

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Evidence that fibroblasts derive from epithelium during tissue fibrosis

Severe acute renal failure (ARF) remains a common, largely treatment-resistant clinical problem with disturbingly high mortality rates. Therefore, we tested whether administration of multipotent me...

Administered mesenchymal stem cells protect against ischemic acute renal failure through differentiation-independent mechanisms.

https://www.kidney-international.org/article/S0085-2538(15)54664-4/pdf

Exosomes/microvesicles as a mechanism of cell-to-cell communication

http://materiais.dbio.uevora.pt/BD/Diferenciacao/Plasticity_marrow-derived_stem_cells.pdf

Plasticity of marrow derived stem cells

Injury to a target organ can be sensed by bone marrow stem cells that migrate to the site of damage, undergo differentiation, and promote structural and functional repair. This remarkable stem cell capacity prompted an investigation of the potential of mesenchymal and hematopoietic stem cells to cure acute renal failure. The model of renal injury induced in mice by the anticancer agent cisplatin was chosen. Injection of mesenchymal stem cells of male bone marrow origin remarkably protected cisplatin-treated syngeneic female mice from renal function impairment and severe tubular injury. Y chromosome-containing cells localized in the context of the tubular epithelial lining and displayed binding sites for Lens culinaris lectin, indicating that mesenchymal stem cells engraft the damaged kidney and differentiate into tubular epithelial cells, thereby restoring renal structure and function. Mesenchymal stem cells markedly accelerated tubular proliferation in response to cisplatin-induced damage, as revealed by higher numbers of Ki-67-positive cells within the tubuli with respect to cisplatin-treated mice that were given saline. Hematopoietic stem cells failed to exert beneficial effects. These results offer a strong case for exploring the possibility that mesenchymal stem cells by virtue of their renotropic property and tubular regenerative potential may have a role in the treatment of acute renal failure in humans.

Mesenchymal Stem Cells Are Renotropic, Helping to Repair the Kidney and Improve Function in Acute Renal Failure

In order to establish whether extra-renal cells contribute to the turnover and repair of renal tissues, this study examined kidneys of female mice that had received a male bone marrow transplant and kidney biopsies from male patients who had received kidney transplants from female donors. By using in situ hybridization to detect Y-chromosomes it could be demonstrated that circulating stem cells frequently engraft into the kidney and differentiate into renal parenchymal cells. In the human renal grafts it was confirmed that some of the recipient-derived cells within the kidney exhibited a tubular epithelial phenotype, by combining in situ hybridization with immunostaining for the epithelial markers CAM 5.2 and the lectin Ulex europaeus. Female mouse recipients of male bone marrow grafts showed co-localization of Y-chromosomes and tubular epithelial markers Ricinus communis and Lens culinaris, and a specific cytochrome P450 enzyme (CYP1A2) indicating an appropriate functional capability of clustered newly formed marrow-derived tubular epithelial cells. Y-chromosome-containing cells were observed within glomeruli, with morphology and location appropriate for podocytes. Within the murine kidney, these Y-chromosome-positive cells were negative for the mouse macrophage marker F4/80 antigen and leukocyte common antigen, but were vimentin-positive. The presence of bone marrow-derived cells was noted in both histologically normal mouse kidneys and in human transplanted kidneys suffering damage from a variety of causes. These data indicate that bone marrow cells contribute to both normal turnover of renal epithelia and regeneration after damage, and it is suggested that this could be exploited therapeutically.

Sobana Navaratnarasah

Papers

Bone marrow contributes to renal parenchymal turnover and regeneration