Design and fabrication principles of electrospinning of scaffolds

Nanotechnology allows for the construction of scaffold and devices that interact at the subcellular level. The application of nanotechnology to biomedical sciences is a rather new and quickly expanding eld. The successful use of microscale surface features to study a variety of cellular phenomena has led molecular and cell biologists, in collaboration with material scientists, to engage in the study of how nanoscale cellular extensions (e.g., lammelopodia and lopodia) interact with their environment to effect cell growth, proliferation, and expression. This change in scale (several orders of magnitude lower) is motivated by the various nanoscale structures that comprise the extracellular matrix (ECM). This natural three-dimensional (3-D) topography at the nanoscale causes an increase in the surface area of the ECM of up to three orders of magnitude. This increased area over which cell-surface interactions can take place may give rise to a number of imperative functions in regulating tissue growth. Nanofabricated matrices can play an important role in answering these types of questions through the controlled and reproducible fabrication of substrates that will allow for a systematic study of surface topographies and their effects on a variety of parameters such as cell attachment, migration, and proliferation.</p

Biomaterials/scaffolds : Design of bioactive, multiphasic PCL/collagen type I and type II-PCL-TCP/collagen composite scaffolds for functional tissue engineering of osteochondral repair tissue by using electrospinning and FDM techniques

Current clinical therapies for traumatic or chronic injuries involving osteochondral tissue result in temporary pain reduction and filling of the defect but with biomechanically inferior repair tissue. Tissue engineering of osteochondral repair tissue using autologous cells and bioactive biomaterials has the potential to overcome the current limitations and results in native-like repair tissue with good integration capabilities. For this reason, we applied two modem biomaterial design techniques, namely, electrospinning and fused deposition modeling (FDM), to produce bioactive poly(epsilon-caprolactone)/collagen (PCL/Col) type I and type II-PCL-tri-calcium phosphate (TCP)/Col composites for precursor cell-based osteochondral repair. The application of these two design techniques (electrospinning and FDM) allowed us to specifically produce the a suitable three-dimensional (3D) environment for the cells to grow into a particular tissue (cartilage and bone) in vitro prior to in vivo implantation. We hypothesize that our new designed biomaterials, seeded with autologous bone marrow-derived precursor cells, in combination with bioreactor-stimulated cell-culture techniques can be used to produce clinically relevant osteochondral repair tissue.</p

Electro-spinning of pure collagen nano-fibres – Just an expensive way to make gelatin?

Scaffolds manufactured from biological materials promise better clinical functionality, providing that characteristic features are preserved. Collagen, a prominent biopolymer, is used extensively for tissue engineering applications, because its signature biological and physico-chemical properties are retained in in vitro preparations. We show here for the first time that the very properties that have established collagen as the leading natural biomaterial are lost when it is electro-spun into nano-fibres out of fluoroalcohols such as 1,1,1,3,3,3-hexafluoro-2-propanol or 2,2,2-trifluoroethanol. We further identify the use of fluoroalcohols as the major culprit in the process. The resultant nano-scaffolds lack the unique ultra-structural axial periodicity that confirms quarter-staggered supramolecular assemblies and the capacity to generate second harmonic signals, representing the typical crystalline triple-helical structure. They were also characterised by low denaturation temperatures, similar to those obtained from gelatin preparations (p > 0.05). Likewise, circular dichroism spectra revealed extensive denaturation of the electro-spun collagen. Using pepsin digestion in combination with quantitative SDS-PAGE, we corroborate great losses of up to 99% of triple-helical collagen. In conclusion, electro-spinning of collagen out of fluoroalcohols effectively denatures this biopolymer, and thus appears to defeat its purpose, namely to create biomimetic scaffolds emulating the collagen structure and function of the extracellular matrix.The authors are grateful to Peng Yanxian, Clarice Chen and Shaoping Zhong for technical support; and Dr. Ricky R Lareu for his constructive discussion. This work was supported by grants (R-397-000-025-112 and R-279-000-168-712) of the Faculty Research Committee of the Faculty of Engineering, National University of Singapore

Colonization and Osteogenic Differentiation of Different Stem Cell Sources on Electrospun Nanofiber Meshes

Numerous challenges remain in the successful clinical translation of cell-based therapies for musculoskeletal tissue repair, including the identification of an appropriate cell source and a viable cell delivery system. The aim of this study was to investigate the attachment, colonization, and osteogenic differentiation of two stem cell types, human mesenchymal stem cells (hMSCs) and human amniotic fluid stem (hAFS) cells, on electrospun nanofiber meshes. We demonstrate that nanofiber meshes are able to support these cell functions robustly, with both cell types demonstrating strong osteogenic potential. Differences in the kinetics of osteogenic differentiation were observed between hMSCs and hAFS cells, with the hAFS cells displaying a delayed alkaline phosphatase peak, but elevated mineral deposition, compared to hMSCs. We also compared the cell behavior on nanofiber meshes to that on tissue culture plastic, and observed that there is delayed initial attachment and proliferation on meshes, but enhanced mineralization at a later time point. Finally, cell-seeded nanofiber meshes were found to be effective in colonizing three-dimensional scaffolds in an in vitro system. This study provides support for the use of the nanofiber mesh as a model surface for cell culture in vitro, and a cell delivery vehicle for the repair of bone defects in vivo

Biomimetic composite coating on rapid prototyped scaffolds for bone tissue engineering

10.1016/j.actbio.2010.09.010Acta Biomaterialia72809-82