The PROSTEM project concerns the improvement of cellular therapies based on adult mesenchymal stem cells. More precisely, its objective is to develop innovative biomaterials to improve the ex vivo production processes of mesenchymal stem cells, to guarantee a better quality of the batches produced and to control more effectively the fate of the cells after their in vivo application. In this perspective, biomaterials are used in the form of microcarriers and nanofibrillar matrices, two configurations with specific advantages for different steps of the production process and use in cell therapy. The developments carried out for the development of these biomaterials concern their processing method, microstructure, physical properties, coating (bioadhesiveness, mechanical properties, morphology, bioactivity), and their perfect compatibility with the requirements of in vivo applications.