The Heterogeneity of Renal Stem Cells and Their Interaction with Bio- and Nano-materials.

For a long time, the kidney has been considered incapable of regeneration. Instead, in recent years, studies have supported the existence of heterogeneity of renal stem/progenitor cells with the ability to regenerate both glomerular and tubular epithelial cells. Indeed, several studies evidence that renal progenitor cells, releasing chemokines, growth factors, microvesicles, and transcription factors through paracrine mechanisms, can induce tissue regeneration and block pathological processes of the kidney. In this chapter the potentiality of the kidney regenerative processes is considered and reviewed, and the main classes of stem/progenitor cells that might contribute to the renal tissue renewal is analyzed. Moreover, we evaluate the role of biomaterials in the regulation of cellular functions, specifically addressing renal stem/progenitor cells. Materials can be synthesized and tailored in order to recreate a finely structured microenvironment (by nanostructures, nanofibers, bioactive compounds, etc.) with which the cells can interact actively. For instance, by patterning substrates in regions that alternately promote or prevent protein adsorption, cell adhesion and spreading processes can be controlled in space. We illustrate the potentiality of nanotechnologies and engineered biomaterials in affecting and enhancing the behavior of renal stem/progenitor cells. Although there are still many challenges for the translation of novel therapeutics, advances in biomaterials and nanomedicine have the potential to drastically change the clinical and therapeutic landscape, even in combination with stem cell biology.