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Porous collagen–based scaffolds are biostructures with demonstrated ability to induce regeneration in animal models as well as in human patients. In addition to their porous structure and physicochemical properties that have been shown to affect the regeneration process, channel-like features inside the scaffolds could provide additional beneficial effects to cells since they provide favorable orientation guidance to cells and favor the transport of required nutrients. Among other methods, ablation by ultra-short laser pulses can be used to fabricate smooth high-precision micro-scale patterns in biomaterials due to their confined damage region. This work presents a holistic approach for the precise generation of complex micron-sized features in porous collagen-based scaffolds, implemented via computer-driven 2½D layer micromachining by a focused femtosecond laser. Tool paths in G code format are generated by a computer program which enables the fabrication of geometric features (straight lines, circular and curved shapes) at specific planes. By taking into account the dependence of ablation volume on key process parameters, such as mean power, feed rate, and focal depth, complex features were fabricated on top and beneath the surface of porous scaffolds at ± 30 μm maximum dimensional tolerance of using optimized cutting parameters. [ABSTRACT FROM AUTHOR]

Over the past years, direct printing techniques have been increasingly utilized in biomedical research applications including the fabrication of biosensors by printing biomaterials on electronic devices [1] and the fabrication of cell constructs for tissue engineering and regenerative medicine [2,3]. In particular, the combination of natural and/or synthetic scaffolds (that provide cells with a 3D extracellular matrix analog that can support and modulate their phenotypes) with emerging direct printing techniques that can place specific cell types into specific locations, can lead to the development of novel 3D tissue models and cell constructs whose sophistication lies beyond the current state of the art. In this work we introduce a direct laser induced forward transfer (LIFT) technique for the targeted printing of hepatocyte cancer cells (line Huh7) at precise locations on porous collagen scaffolds (PCS), in order to form patterns on the scaffold [4]. We present a detailed study of the LIFT conditions that enable repeatable printing of viable cells on the scaffold and investigate the dynamic mechanisms that occur during the cell printing process by time-resolved imaging via a high-speed camera. Cell viability and the ability to form specific cell structures inside the PCS was examined 2h and 24h after cell printing via fluorescence microscopy. [ABSTRACT FROM AUTHOR]

The success of tissue engineering hinges on the rapid and sufficient vascularization of the neotissue. For efficient vascular network formation within three-dimensional (3D) constructs, biomaterial scaffolds that can support survival of endothelial cells as well as formation and maturation of a capillary network in vivo are highly sought after. Here, we outline a method to biofabricate 3D porous collagen scaffolds that can support extrinsic and intrinsic vascularization using two different in vivo animal models-the mouse subcutaneous implant model (extrinsic vascularization, capillary growth within the scaffold originating from host tissues outside the scaffold) and the rat tissue engineering chamber model (intrinsic vascularization, capillary growth within the scaffold derived from a centrally positioned vascular pedicle). These in vivo vascular tissue engineering approaches hold a great promise for the generation of clinically viable vascularized constructs. Moreover, the 3D collagen scaffolds can also be employed for 3D cell culture and for in vivo delivery of growth factors and cells.