To explore the space-filling growth of adherent mesenchymal stem cells (MSC) into tissue-like structures invitro, human bone marrow derived MSC were exposed to fibronectin-coated, millimeter-sized, triangular channels casted in poly(dimethyl siloxane) carriers. The results revealed that the three dimensional (3D) growth of MSC differs in dependence on differentiation status and availability of extracellular matrix (ECM) proteins: Massive 3D structure formation was observed for MSC under pro-osteogenic stimulation but not for undifferentiated MSC nor for MSC under pro-adipogenic stimulation; boosting cellular matrix secretion and addition of soluble ECM proteins caused extensive 3D tissue formation of undifferentiated MSC. The reported findings may contribute to bridge the gap between invitro and invivo analyses and guide the application of MSC in tissue replacement approaches.