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Adhesion of tissue cells to biomaterials is a prerequisite of paramount importance for the effectiveness of a tissue engineering construct (cell and scaffolds). Functionalization of polymeric scaffolds with organic polymers, such as collagen or proteoglycans, is a promising approach in order to improve the cytocompatibility. As a matter of fact, organic polymers, isolated directly from the extracellular matrix, contain a multitude of surface ligand (fibronectin, laminin, vitronectin) and arginine–glycine–aspartic acid-containing peptides that promote cell adhesion. In tissue engineering, the combination of organic and synthetic polymers gives rise to scaffolds characterized simultaneously by the mechanical strength of synthetic materials and the biocompatibility of natural materials. In this work, porous poly-L-lactide acid scaffolds were functionalized with a synthetic collagen–glycosaminoglycans matrix in order to improve cell adhesion. For this purpose, a protocol for collagen–glycosaminoglycans conjugation into the pores of the scaffolds was set up. Moreover, an innovative protocol for the quantification of the conjugated glycosaminoglycans inside the scaffolds was created and adopted. The results have confirmed the effectiveness of the developed protocol: a collagen–glycosaminoglycans conjugation, with an efficiency of about 21% was obtained inside the scaffold. Moreover, SEM analysis highlighted the presence of the homogeneous synthetic matrix into the bulk of porous scaffolds. Finally, cell culture assays carried out by utilizing mouse embryonic fibroblasts showed that cell proliferation on poly-L-lactide acid-collagen–glycosaminoglycans scaffold is higher than on poly-L-lactide acid collagen scaffold (utilized as control). Therefore, it can be stated that the presence of glycosaminoglycans not only increases the mechanical strength of the matrix, thanks to their cross-linking effect, but also it seems to lead to a more significant cell growth. Overall, it is reasonable to state that the concerned protocol may be proposed as a reliable route to increase the rate of proliferation and in some cases to stimulate the cell differentiation in tissue engineering devices. [ABSTRACT FROM AUTHOR]

A composite biodegradable scaffold incorporating an integrated network of synthetic blood vessels was designed and prepared, in line with the requirements of a scaffold effectively supporting the regeneration of highly vascularized tissues. In other words, this composite scaffold should allow the regeneration of complex injured tissue (e.g. dermis) and, at the same time, favour the development of a vascular network on its inner, i.e. a 3D polymeric scaffolds embedding synthetic blood vessel-like structures for nutrient supply and metabolite removal. PLLA assures a high degree of biocompatibility and a low level of inflammation response upon implantation, while the embedded tubular vessel-like structures with a porous internal surface and a porous wall should give rise to a successful in-vitro growth of the endothelial cells, leading to the generation of new vessels. In order to realize the composite scaffold, a technique for integration of vessel-like scaffolds into porous PLLA scaffolds prepared via TIPS was assessed. The scaffolds obtained present a porous bulk with a high degree of interconnection. Moreover, the vessel-like scaffold(s) are completely embedded into the porous structure produced via TIPS and a continuous porous structure at the border of the vessel-like scaffold in communication with the macropores of the “main” scaffold was detected. A preliminary in-vitro coculture test showed that both the cell types seeded into the composite scaffold are able to grow and mature towards a ”primordial” tissue. [ABSTRACT FROM AUTHOR]

PLLA scaffold suitable for dermis regeneration were realized by Thermally Induced Phase Separation (TIPS) starting from a ternary solution PLLA/dioxane/water. The reconstruction of a complex tissues as the dermis implies the use of different cellular types (coculture), with different growth behaviour (2D vs. 3D). The scaffolds present an homogeneous porous surface to allow the keratinocytes 2D growth and a porous internal structure for the fibroblasts 3D growth. Our results show that the porosity of the surface can be tuned by changing the chemical nature of the sample holder (aluminium, teflon, polypropylene). A large variety of morphologies, in terms of average pore size and interconnection were obtained upon modifying the demixing time and temperature. WAXD analysis and DSC scanning tests showed only slight differences among the scaffolds prepared at the various conditions. Finally, a biocompatibility test was carried out by using human fibroblast and keratinocytes, indicating a good proliferation of the cells both on the surface and in the bulk of the scaffold. [ABSTRACT FROM AUTHOR]

A critical obstacle in tissue engineering is the inability to maintain large masses of living cells upon transfer from the in vitro culture conditions into the host in vivo. Capillaries, and the vascular system, are required to supply essential nutrients, including oxygen, remove waste products and provide a biochemical communication “highway”. For this reason it is mandatory to manufacture an implantable structure where the process of vessel formation – the angiogenesis – can take place. In this work PLLA scaffolds for vascular tissue engineering were produced by dip-coating via Diffusion Induced Phase Separation (DIPS) technique. The scaffolds, with a vessel-like shape, were obtained by performing a DIPS process around a nylon fibre whose diameter was 700 μm. The fibre was first immersed into a 4% PLLA dioxane solution and subsequently immersed into a second bath containing distilled water. The covered fibre was then rinsed in order to remove the excess of dioxane and dried; finally the internal nylon fibre was pulled out so as to obtain a hollow biodegradable PLLA fiber. SEM analysis revealed that the scaffolds have a lumen of ca. 700 μm. The internal surface is homogeneous with micropores 1–2 μm large. Moreover, a cross section analysis showed an open structure across the thickness of the scaffold walls. A cell culture of endothelial cells was carried out into the as-prepared scaffolds. The result showed that cells are able to grow within the scaffolds and after 3 weeks they begin to form a “primordial” vessel-like structure. [ABSTRACT FROM AUTHOR]