Great importance is being given to the impact our food supply chain and consumers' food habits are having on the environment, human health, and animal welfare. One of the latest developments aiming at positively changing the food ecosystem is represented by cultured meat. This form of cellular agriculture has the objective to generate slaughter-free meat products starting from the cultivation of few cells harvested from the animal tissue of interest. As a consequence, a large number of cells has to be generated at a reasonable cost. Just to give an idea of the scale, there were billions of cells just in a bite of the first cultured-meat burger. Thus, one of the major challenges faced by the scientists involved in this new ambitious and fascinating field, is how to efficiently scale-up cell manufacture. Considering the great potential presented by cultured meat, audiences from different backgrounds are very interested in this topic and eager to be informed of the challenges and possible solutions in this area. In light of this, we will provide an overview of the main existing bioprocessing technologies used to scale-up adherent cells at a small and large scale. Thus, giving a brief technical description of these bioprocesses, with the main associated advantages and disadvantages. Moreover, we will introduce an alternative solution we believe has the potential to revolutionize the way adherent cells are grown, helping cultured meat become a reality.

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While tissue engineering is widely used to construct complex tridimensional biocompatible structures, researchers are now attempting to extend the technique into the fourth dimension. Such fourth dimension consists in the transformation of 3D materials over time, namely, by changing their shape, composition, and/or function when subjected to specific external stimuli. Herein, producing a 4D biomaterial with an internal mechanism of stimulus, using contractile cells as bio-actuators to change tissue shape and structure, is explored. Specifically, producing cornea-shaped, curved stromal tissue equivalents via the controlled, cell-driven curving of collagen-based hydrogels. This is achieved by modulating the activity of the bio-actuators in delimited regions of the gels using a contraction-inhibiting peptide amphiphile. The self-curved constructs are then characterized in terms of cell and collagen fibril reorganization, gel stiffness, cell phenotype, and the ability to sustain the growth of a corneal epithelium in vitro. Overall, the results show that the structural and mechanical properties of self-curved gels acquired through a 4D engineering method are more similar to those of the native tissue, and represent a significant improvement over planar 3D scaffolds. In this perspective, the study demonstrates the great potential of cell bio-actuators for 4D tissue engineering applications.

The increasing interest in effort towards creating alternative therapies have led to exciting breakthroughs in the attempt to bio-fabricate and engineer live tissues. This has been particularly evident in the development of new approaches applied to reconstruct corneal tissue. The need for tissue-engineered corneas is largely a response to the shortage of donor tissue and the lack of suitable alternative biological scaffolds preventing the treatment of millions of blind people worldwide. This review is focused on recent developments in corneal tissue engineering, specifically on the use of self-assembling peptide amphiphiles for this purpose. Recently, peptide amphiphiles have generated great interest as therapeutic molecules, both in vitro and in vivo. Here we introduce this rapidly developing field, and examine innovative applications of peptide amphiphiles to create natural bio-prosthetic corneal tissue in vitro. The advantages of peptide amphiphiles over other biomaterials, namely their wide range of functions and applications, versatility, and transferability are also discussed to better understand how these fascinating molecules can help solve current challenges in corneal regeneration.