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1. Introduction
1.1. A Brief History of Tissue-Engineering Techniques
Throughout history, as the lifestyle of hunters and gatherers shifted towards a sedentary one, population demographics changed drastically. These changes in lifestyle combined with rich diets lead to an increased lifespan and the emergence of new diseases. The ageing population correlates with an increase in the prevalence of chronic disorders, which represent a large burden on the healthcare system. Chronic disorders can ultimately result in organ failure and may require organ replacement. However, the waiting lists for organ transplantation keep growing every year and the supply of organs does not meet the existing demand. To circumvent this extensive organ shortage, many efforts are being devoted to the reconstruction of tissue-engineered organs [1].
Tissue engineering represents an interesting alternative that aims at reconstructing biological substitutes for the replacement of damaged tissues and organs. This emerging discipline comprises several techniques, most of which use biomaterials such as preformed scaffolds that mimic the morphology of specific tissues and serve as an anchorage point for cells. These scaffolds consist of synthetic or biological materials [2]. Since the biomaterials used for scaffolds are different from the original components of the extracellular matrix (ECM) of the target organs, the differentiation of cells, stem cells in particular, is often partial or inadequate. Also, the use of biomaterials may trigger unknown side effects upon implantation in the human body.
New techniques have recently been developed to improve the functionality of biomaterials, such as the modification of their surface compounds [3], the introduction of bioprinting using bioink made of cells directly embedded in elements of the ECM [4–7], the use of decellularized tissue [8], and, finally, the reconstruction of autologous tissues using only patients’ cells.
1.2. The Self-Assembly Technique
The self-assembly technique is a method used to reconstruct tissues free of exogenous materials using only patients’ cells (Figure 1). The self-assembly technique relies on the ability of mesenchymal cells to secrete and assemble their own ECM. This approach originates from two main discoveries. Firstly, in 1972 ascorbate, an enzymatic cofactor of lysyl- and prolyl-hydroxylase, was...