Nanopattern-induced osteogenic differentiation of stem cells - A systematic review.

It is well known that biomaterials topography can influence the behavior of stem cells. Nevertheless, the fundamentals and the impact of nanoscale topography are just emerging. The main objective of this review has been to reveal the state-of-the-art on the effects of controlled nanoscale topographies (nanopatterns) on in vitro osteogenic differentiation of mesenchymal stem cells (MSCs) in the absence of osteogenic supplements. The findings indicate that nanopatterns with specific feature sizes, spatial arrangements, or shapes may induce osteogenic differentiation of MSCs. Regardless of substrate chemistry, nanopattern-induced osteogenic differentiation is associated with large focal adhesions, enhanced cell areas, and well organized cytoskeleton. These results suggest that earlier interactions between nanopattern features and cell receptors are involved, with effects on the entire cell structure and subsequent differentiation. Such events are possibly mediated by nanotopography-induced mechanotransduction pathways. The findings so far reveal that nanoscale topography has potential for directing differentiation of MSCs towards the osteogenic lineage in non-osteogenic media and should be harnessed for possible synergistic effects in bone regenerative therapies. STATEMENT OF SIGNIFICANCE: The use of nanotopography to induce cellular responses represents a novel and rapidly growing area of research. Nevertheless, the findings and trends so far are difficult to identify and discuss mostly due to a non-systematic research approach. The present manuscript is providing a systematic review focused on nanopattern-induced osteogenic differentiation of mesenchymal stem cells. The coverage of the most relevant aspects including nanopatterns fabrication methods, their effects on osteogenic differentiation of mesenchymal stem cells as well as the related effects on adhesion and cell morphology has enabled an integrated discussion including the potential mechanotransduction mechanisms involved. Furthermore, a clear distinction between the studies that use only surface nanotopographies and the ones that mix nanotopographical features with osteogenic supplements has been made. This delineation is essential for revealing and understanding the role of biomaterial's nanotopography per se on stem cells differentiation based on which novel osteoinductive biomaterials can be developed.