Tissue Engineering is nowadays a blooming field of research that cleverly combines living cells with sustaining materials, often called biomaterials, in order to generate a functional tissue for a human organ (skin, brain, bone ….). The purpose of this intense activity is twofold. On one hand, a successful tissue engineering can lead to human models of tissues of very high predictive value for testing drug activities or toxicity. This could reduce drastically the use or abuse of animal testing in medical research and pharmacology. On the other hand, the tissue elaborated by engineering could be employed as an implant, that once surgically positioned in a deficient or destroyed organ is capable inside the host and by interaction with the surrounding tissues, to regenerate the lost functions. In this context of regenerative medicine, attempts to regenerate brain tissues, bones, cardiac muscles after trauma or stroke injuries or to regenerate brown adipose tissues for treating obesity are the object of numerous research articles, among others. In this contribution we would like to describe this specific engineering activity with a different perspective because to our mind, the role and the function played by the material (in this case a biomaterial) is very original compared to other fields of material science.