Microstructured platforms to study nanotube-mediated long-distance cell-to-cell connections.

Recently, numerous innovative approaches have attempted to overcome the shortcomings of standard tissue culturing by providing custom-tailored substrates with superior features. In particular, tunable surface chemistry and topographical micro- and nanostructuring have been highlighted as potent effectors to control cell behavior. Apart from tissue engineering and the development of biosensors and diagnostic assays, the need for custom-tailored platform systems is accentuated by a variety of complex and poorly characterized biological processes. One of these processes is cell-to-cell communication mediated by tunneling nanotubes (TNTs), the reliable statistical analysis of which is consistently hampered by critical dependencies on various experimental factors, such as cell singularization, spacing, and alignment. Here, the authors developed a microstructured platform based on a combination of controlled surface chemistry along with topographic parameters, which permits the controllable attachment of different cell types to complementary patterns of cell attracting/nonattracting surface domains and-as a consequence-represents a standardized analysis tool to approach a wide range of biological questions. Apart from the technical complementation of mainstream applications, the developed surfaces could successfully be used to statistically determine TNT-based intercellular connection processes as they are occurring in standard as well as primary cell cultures.

Nanotube action between human mesothelial cells reveals novel aspects of inflammatory responses.

A well-known role of human peritoneal mesothelial cells (HPMCs), the resident cells of the peritoneal cavity, is the generation of an immune response during peritonitis by activation of T-cells via antigen presentation. Recent findings have shown that intercellular nanotubes (NTs) mediate functional connectivity between various cell types including immune cells - such as T-cells, natural killer (NK) cells or macrophages - by facilitating a spectrum of long range cell-cell interactions. Although of medical interest, the relevance of NT-related findings for human medical conditions and treatment, e.g. in relation to inflammatory processes, remains elusive, particularly due to a lack of appropriate in vivo data. Here, we show for the first time that primary cultures of patient derived HPMCs are functionally connected via membranous nanotubes. NT formation appears to be actin cytoskeleton dependent, mediated by the action of filopodia. Importantly, significant variances in NT numbers between different donors as a consequence of pathophysiological alterations were observable. Furthermore, we show that TNF-α induces nanotube formation and demonstrate a strong correlation of NT connectivity in accordance with the cellular cholesterol level and distribution, pointing to a complex involvement of NTs in inflammatory processes with potential impact for clinical treatment.