Ultrafast Laser Processing of Nanostructured Patterns for the Control of Cell Adhesion and Migration on Titanium Alloy

Abstract

Femtosecond laser texturing is a promising surface functionalization technology to improve the integration and durability of dental and orthopedic implants. Four different surface topographies were obtained on titanium-6aluminum-4vanadium plates by varying laser processing parameters and strategies: surfaces presenting nanostructures such as laser-induced periodic surface structures (LIPSS) and ‘spikes’, associated or not with more complex multiscale geometries combining micro-pits, nanostructures and stretches of polished areas. After sterilization by heat treatment, LIPSS and spikes were characterized to be highly hydrophobic, whereas the original polished surfaces remained hydrophilic. Human mesenchymal stem cells (hMSCs) grown on simple nanostructured surfaces were found to spread less with an increased motility (velocity, acceleration, tortuosity), while on the complex surfaces, hMSCs decreased their migration when approaching the micro-pits and preferentially positioned their nucleus inside them. Moreover, focal adhesions of hMSCs were notably located on polished zones rather than on neighboring nanostructured areas where the protein adsorption was lower. All these observations indicated that hMSCs were spatially controlled and mechanically strained by the laser-induced topographies. The nanoscale structures influence surface wettability and protein adsorption and thus influence focal adhesions formation and finally induce shape-based mechanical constraints on cells, known to promote osteogenic differentiation.

Dental Pulp Stem Cells on Implant Surface: An In Vitro Study

“…Most of the studies are aimed at assessing the rate of cell growth and not long-term biocompatibility, without considering that faster may not necessarily mean better [58][59][60][61]. Klos et al [62] evaluated cell adhesion on laser-induced periodic surface structures. Human mesenchymal stem cells were grown on simple nanostructured surfaces.…”

Femtosecond Laser-Processing of Pre-Anodized Ti-Based Bone Implants for Cell-Repellent Functionalization

“…Both cell types, osteoblasts and fibroblasts, are closely related with mesenchymal origin. But it is known that they react differently to topographical stimuli of surface structures in the micrometer and nanometer range and that the differentiation of mesenchymal stem cells can be driven into the osteoblast direction by these stimuli, while flat surfaces promote the differentiation into the fibroblast direction [4,5,15]. This could be an important part of the explanation of why the same conditions repel fibroblasts but activate osteoblasts.…”

“…This interest is triggered by the fact that Ti and Ti-alloys are often used materials for medical implants, for instance in dentistry, orthopedics, and for cardio-vascular applications. The main focus up to now was improved osseo-integration (e.g., the integration into the jaw bone for dental implants) due to the activation of bone-forming osteoblasts for enhanced production of bone material or the differentiation of mesenchymal stem cells into Nanomaterials 2021, 11, 1342 2 of 9 osteoblast cells, which can be induced by certain nano-features [4,5]. However, for many other applications, the medical implants may have to be removed from the patient's body after several months or years.…”

Implant Fibrosis and the Underappreciated Role of Myofibroblasts in the Foreign Body Reaction

“…When arranged in highly regular geometries, topographical features can prevent force-dependent alignment of cell-ECM focal adhesions and reduce cell adhesion by preventing elongation of the spreading cells [ 105 ]. Likewise, laser-generated complex but regular surface abrasions with nanometer-deep and micrometer-wide topographical features guide the formation of focal adhesions, control cell spreading area, and direct basic cell functions of human mesenchymal stromal cells towards osseointegration of titanium materials [ 106 ]. Similar topographical patterning approaches have been used to provide innovative bulk metallic glass materials with brush-like arrays of rods with cross-sectional diameters ranging from 55 nm to 200 nm and heights of ~0.5 µm [ 107 ].…”