The Advancement of Biomaterials in Regulating Stem Cell Fate.

Stem cells are well-known to have prominent roles in tissue engineering applications. Embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) can differentiate into every cell type in the body while adult stem cells such as mesenchymal stem cells (MSCs) can be isolated from various sources. Nevertheless, an utmost limitation in harnessing stem cells for tissue engineering is the supply of cells. The advances in biomaterial technology allows the establishment of ex vivo expansion systems to overcome this bottleneck. The progress of various scaffold fabrication could direct stem cell fate decisions including cell proliferation and differentiation into specific lineages in vitro. Stem cell biology and biomaterial technology promote synergistic effect on stem cell-based regenerative therapies. Therefore, understanding the interaction of stem cell and biomaterials would allow the designation of new biomaterials for future clinical therapeutic applications for tissue regeneration. This review focuses mainly on the advances of natural and synthetic biomaterials in regulating stem cell fate decisions. We have also briefly discussed how biological and biophysical properties of biomaterials including wettability, chemical functionality, biodegradability and stiffness play their roles

Sustainable Carbododiimine and Triazine Reagents as Collagen Cross-Linking Agents in the Presence of PAMAM Dendrimers

This work reports a general outline on sustainable technologies for the stabilization of collagen and comparative study of 1-ethyl-3-(3-dimethyla-minopropyl)carbodiimide (EDC) versus 4-(4,6-dimethoxy [1, 3, 5] triazin-2-yl)-4-methyl-morpholinium chloride (DMTMM) as cross-linking agents of collagen powder. The cross-linking efficiency of these agents on collagen matrixes in the presence of different polyamidoamine dendrimers (PAMAM) has been tested in order to determine the influence of steric hindrance and aminic groups abundance

Enhanced keratinocyte cell attachment to atelocollagen thin films through air and nitrogen plasma treatment

Collagen films (Atelocollagen from bovine Achilles tendon) were prepared in tissue culture dishes and their surfaces were modified by using air and nitrogen plasma treatment. The treated samples were characterised by surface probe techniques including attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy imaging (SEM) and X-ray photoelectron spectroscopy (XPS). In addition, human immortalised nontumorigenic keratinocyte cell line (HaCaT) was seeded on the treated and untreated films and cell proliferation was measured by using MTT assay test. The characterisation results confirmed physical and chemical changes on the collagen surface, such as increase in the extent of surface oxidation and surface roughness as well as, the treated samples showed better cell growth than untreated ones, and therefore this approach may be taken into account in the development of promising materials for tissue regeneration applications. © Springer-Verlag Berlin Heidelberg 2011

Lasers Med Sci

Cell oxygenation and nutrition are crucial for the viability of tissue-engineered constructs, and different alternatives are currently being developed to achieve an adequate vascularisation of the engineered tissue. One of the alternatives is the generation of channel-like patterns in a bioconstruct. Here, the formation of full-formed channels inside hydrogels by laser-induced cavitation was investigated. A near-infrared, femtosecond laser beam focused with a high numerical aperture was employed to obtain intra-volume modifications of a block of gelatine hydrogel. Characterisation of the laser-processed gelatine was carried out by optical microscopy and epifluorescence microscopy right after and 24 h after the laser process. Rheology analyses on the unprocessed gelatine blocks were conducted to better understand the cavitation mechanism taking place during the intense laser interaction. Different cavitation patterns were observed at varying dose values by changing the repetition rate and the overlap between successive pulses while keeping the laser fluence and the number of passes fixed. This way, cavitation bubble features and behaviour can be controlled to optimise the formation of intra-volume channels in the gelatine volume. Results showed that the generation of fully formed channels was linked to the formation of large non-spherical cavitation bubbles during the laser interaction at high dose and low repetition rates. In conclusion, the formation of fully formed channels was made possible with a near-infrared, femtosecond laser beam strongly focused inside gelatine hydrogel blocks through laser-induced cavitation at high dose and low repetition rates