The Effect of Clay Nanoparticles on Surface Topography of Polymeric Scaffolds and Mesenchymal Stem Cell Attachment

Background and Aim: The unique properties of nanomaterials in tissueengineering have captured a great deal of attention as experimental toolsin biomedical applications. A plenty of researches has provided a strongevidence that nanostructures not only passively interact with stem cellsbut also actively engage and mediate these cells functions. To address thisissue, we have decorated clay nanoparticles in the electrospun nanofiberscaffolds, characterized the composite material, and investigated theireffect on the surface topography of nanofiber scaffolds and mesenchymalstem cells attachment.Methods: First of all, we used the enzymatic process for isolation ofmesenchymal stem cells from human adipose tissue which characterizedby flow cytometry. Then, we fabricated electrospun fiber scaffolds andevaluated the fibers by scanning electron microscope (SEM). Fibercoverage by the clay nanoparticles and the scaffold topography wasalso evaluated by a transmitting electron microscope (TEM) and anatomic force microscope (AFM), respectively. To assess the cytotoxiceffect of scaffold for mesenchymal stem cells, MTT assay was done. Theattachment of mesenchymal stem cells within the scaffolds was shownby DAPI staining on day 7. For further evaluation of the mesenchymalstem cells’ interaction with the fibrous scaffolds, the cell constructs werefirst fixed and then imaged using a scanning electron microscope (SEM).Results: The flow cytometric analysis demonstrated that the isolatedmesenchymal stem cells expressed CD90 and CD105 while they werenegative for CD34 and CD45. The fabricated electrospun fiber scaffoldsdiameter was evaluated near 260 ± 70 nm. SEM images showed thatnanoclay-fiber scaffolds were homogeneous. Also, TEM images of thefibers revealed the ideal internal morphology of constructs. AFM resultsprovided evidence for modification of the surface of the fibers withnanoscale roughness providing topographic cues. We have shown thatthe scaffolds are not toxic for mesenchymal stem cells via MTT assay.Also, mesenchymal stem cells attachment were demonstrated by DAPIstaining fluorescence microscopy images. In addition, SEM imagesconfirmed mesenchymal stem cells’ attachment to the nanofiber scaffold.Conclusion: Nowadays, biomaterials with topographical properties arewell known because they can influence cell − surface interactions. Also,nanoscale features at guiding cell behavior are of particular interestsbecause of many interactions occurring at that scale, which are keys incell survival process. In this study, we demonstrated the ideal topographyof clay decorated scaffolds and its positive effects on mesenchymal stemcell attachment. Therefore, we envision that such cellular constructsmay be useful in the future as implantable cellular devices for repairingdamaged tissues.

Keywords:

Clay Nanoparticles , Scaffold , Topography , Mesenchymal stem cell