Human adipose tissue-derived mesenchymal stem cells (hASCs) have the power to differentiate into various cell types including chondrocytes, osteocytes, adipocytes, neurons, cardiomyocytes, and smooth muscle cells. We characterized the functional expression of ion channels after TGF-β1-induced differentiation of hASCs, providing insights into the differentiation of vascular smooth muscle cells. The treatment of hASCs with TGF-β1 dramatically increased the contraction of a collagen-gel lattice and the expression levels of smooth muscle specific genes including α-smooth muscle actin, calponin, SM-MHC, smoothelin-B, myocardin, and h-caldesmon. We observed Ca2+ (n=5), big-conductance Ca2+-activated K+ (BKCa, n=4), and voltage-dependent K+ (Kv, n=4) currents in TGF-β1-induced, differentiated hASCs and not in undifferentiated hASCs. The currents share the characteristics of vascular smooth muscle cells (SMCs). RT-PCR and western blotting revealed that the L-type (Cav1.2), T-type (Cav3.1, 3.2, and 3.3), known to be expressed in vascular SMCs, dramatically increased along with the Cavβ1 and Cavβ3 subtypes in TGF-β1-induced, differentiated hASCs (P<0.05, n=4). Although the expression-level changes of the β-subtype BKCa channels varied, the major α-subtype BKCa channel (KCa1.1) clearly increased in the TGF-β1-induced, differentiated hADSCs(P<0.05, n=4). Most of the Kv subtypes; also known to be expressed in vascular SMCs, dramatically increased in the TGF-β1-induced, differentiated hASCs (P<0.05, n=3). Our results suggest that TGF-β1 induces the increased expression of vascular SMC-like ion channels and the differentiation of hASCs into contractile vascular SMCs. (P<0.05 was regarded significant, and data analysis was done with student t-test.)