Micro and Nanofabrication methods to control cell-substrate interactions and cell behavior: A review from the tissue engineering perspective

Cell-substrate interactions play a crucial role in the design of better biomaterials and integration ofimplants with the tissues. Adhesion is the binding process of the cells to the substrate through interactionsbetween the surface molecules of the cell membrane and the substrate. There are severalfactors that affect cell adhesion including substrate surface chemistry, topography, and stiffness. Thesefactors physically and chemically guide and influence the adhesion strength, spreading, shape and fate ofthe cell. Recently, technological advances enabled us to precisely engineer the geometry and chemistry ofsubstrate surfaces enabling the control of the interaction cells with the substrate. Some of the mostcommonly used surface engineering methods for eliciting the desired cellular responses on biomaterialsare photolithography, electron beam lithography, microcontact printing, and microfluidics. Thesemethods allow production of nano- and micron level substrate features that can control cell adhesion,migration, differentiation, shape of the cells and the nuclei as well as measurement of the forces involvedin such activities. This review aims to summarize the current techniques and associate these techniqueswith cellular responses in order to emphasize the effect of chemistry, dimensions, density and design ofsurface patterns on cell-substrate interactions. We conclude with future projections in the field of cellsubstrateinteractions in the hope of providing an outlook for the future studies.

Human adipose derived stem cells are superior to human osteoblasts (HOB) in bone tissue engineering on a collagen-fibroin-ELR blend

The ultrastructure of the bone provides a unique mechanical strength against compressive, torsional andtensional stresses. An elastin-like recombinamer (ELR) with a nucleation sequence for hydroxyapatitewas incorporated into films prepared from a collagen-silk fibroin blend carrying microchannel patternsto stimulate anisotropic osteogenesis. SEM and fluorescence microscopy showed the alignment ofadipose-derived stem cells (ADSCs) and the human osteoblasts (HOBs) on the ridges and in the groovesof microchannel patterned collagen-fibroin-ELR blend films. The Young's modulus and the ultimatetensile strength (UTS) of untreated films were 0.58 ± 0.13 MPa and 0.18 ± 0.05 MPa, respectively. After 28days of cell culture, ADSC seeded film had a Young's modulus of 1.21 ± 0.42 MPa and UTS of0.32 ± 0.15 MPa which were about 3 fold higher than HOB seeded films. The difference in Young'smodulus was statistically significant (p: 0.02). ADSCs attached, proliferated and mineralized better thanthe HOBs. In the light of these results, ADSCs served as a better cell source than HOBs for bone tissueengineering of collagen-fibroin-ELR based constructs used in this study. We have thus shown theenhancement in the tensile mechanical properties of the bone tissue engineered scaffolds by usingADSCs.