The subject invention concerns materials and methods for growing and expanding MSC while maintaining their undifferentiated phenotype, self-renewal ability, and/or multi-lineage potential. In one embodiment, a method of the invention comprises i) seeding freshly isolated MSC on a planar surface or a 3-D scaffold and growing the cells under physiological or low O2 tension for a period of time sufficient to support formation of 3-D ECM network ii) decellularizing the planar surface or 3-D scaffold and iii) reseeding the decellularized planar surface or 3-D scaffold with MSCs, whereby the reseeded MSCs can be grown on the scaffold and maintain an undifferentiated phenotype. In one embodiment, the 3-D scaffold comprises or is composed of PET. In one embodiment, the MSC are human MSC (hMSC).