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Figure 1 Pre-Treatment of MSCs With GFs Augmented the Expression of Cardiac Specific Genes and Connexin-43 in MSCs, Which Was Induced by Coculture With CMCs

(A) Reverse transcriptase-polymerase chain reaction. In the single mesenchymal stem cell (MSC) culture condition, treatment of MSCs with cocktails of growth factors (GFs) does not affect the expression of cardiac specific genes except for the alpha-sarcomeric actin. But in coculture condition with cardiomyocytes (CMCs), treatment of GFs significantly augmented the induction of cardiac specific genes in MSCs, such as atrial natriuretic peptide, connexin-43 (Cx43), cardiac troponin-I (cTnI), alpha and beta myosin heavy chain (MHC) genes. (B) Western blot analysis in the single MSC culture condition. The expression of GATA-4 and NKx-2.5 were distinctively induced only in GF-treated MSCs. (C) Western blot analysis after 2 days of coculture with CMCs. The GF treatment augmented the induction of cTnI and Cx43 protein expression in MSC by coculture with CMCs. (D) The percentage of MSCs expressing Cx43 was significantly higher in the GF-treated MSCs than in naïve ones. Data were derived from 5 randomly chosen microscopic fields of 3 separate experiments. (E) Representative images after 2 days of coculture of MSCs with CMCs. The MSCs were labeled with DAPI (blue). The CMCs were stained with TnI (red) without DAPI. Connexin-43 (green) was expressed more frequently in the treated MSCs compared with the untreated ones. Connexin-43, which indicates the formation of gap junction (arrows), was expressed linearly between MSCs and CMCs (TnI positive cells without DAPI). Arrowheads indicate MSCs expressing both TnI (red) and Cx43. *The MSCs expressing only Cx43 (magnification x200). T = treated; UT = untreated.