Cartilage Regeneration by Yunfeng Lin

Author:Yunfeng Lin
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

3.5 Irregular Patterns-Roughness

The roughness of material surface also can be regarded as a kind of micro-pattern, which is not as regular as the patterns already-mentioned. Surface roughness is more easily fabricated than regular patterns and it has been possible to extend this technique to some fields such as oral implants. Studies have shown that the anisotropy topographies change the behavior of individual cell, while the isotropic patterns, such as the surface roughness, change the morphology, migrate, proliferation and differentiate of collective cells [4].

Studies in vivo have shown that roughened surfaces helps better osteo-integration than smoother surfaces, suggesting that the surface modulates the bone response including osteoblast adherence, extracellular matrix deposition and calcification [63–65]. In addition, cell differentiation has been shown to be enhanced by surface roughness, despite close association of this process with reduced proliferation [66–68]. Park JW reported that ALP activity and mineralization increased in parallel with the roughness [64]. A number of researches have shown that more osteoblast-like cells attach to micro-structured surfaces [69–72]. At the roughened titanium surfaces, the focal adhesions for cellular adherence are enhanced, cytoskeleton is assembled and membrane receptors organized [73, 74]. Furthermore, it has been reported by some in vitro studies that adsorption of fibronectin and albumin which are significant factors for cellular adherence and differentiation are promoted at rough implant surfaces [70, 73, 75].

Nevertheless, the side effect of roughened surfaces compared to smooth surfaces is that the roughened surfaces also enhance the accumulation of infectious bacteria such as staphylococci, S. aureus and Staphylococcus epidermidis [76–79]. And the existence of bacteria may disrupt the biological process of osteo-integration. It is suggested that if the surface features are considerably larger than the microbial cells, then bacterial adhesion and retention do not matter [80, 81]. However, if these features are of microbial dimensions, bacterial adhesion and reservation will be of great significance.

The sensitivity of cellular behavior changing on roughness surface infers that the isotropic patterns, such as the surface roughness, may have a widely application in bone tissue engineering, especially in the surface design of titanium-based bio-materials. Titanium-based materials are employed extensively as dental and orthopaedic implant materials because of their mechanical strength, corrosion resistance, and bio-compatibility [82–85]. After the implant into the body, a series of reactions occur at its surface. Corresponding molecular mechanisms are not explained, but by regulation of cell behavior, growth factor release and osteogenic associated gene expression, the physical and chemical properties of the surface are of great importance in the implant-surface interactions [80, 86–88].

Kinds of methods as follows have been used to investigate varying degrees of roughness surfaces: acid-etching, plasma-spraying, grit-blasting anodization, vapor deposition, and so on [89, 90]. Several studies reported that titanium surfaces can been appropriately roughened to promote the process and success rate of osteo-integration [91–93]. We believe that, in addition to the surface of the implant, the roughness of substrate will be applied to tissue engineering bio-materials in the future.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.