Regeneration of Infarcted Myocardium by Intramyocardial Implantation of Ex Vivo Transforming Growth Factor-β–Preprogrammed Bone Marrow Stem Cells

Abstract

Background-Recent studies have shown that bone marrow-derived stem cells differentiate into the phenotype of cardiomyocytes in vivo and in vitro. We tried to regenerate infarcted myocardium by implanting ex vivo transforming growth factor (TGF)-␤-preprogrammed CD117 (c-kit)-positive (CD117 ϩ ) stem cells intramyocardially. Methods and Results-CD117ϩ cells were isolated from the bone marrow mononuclear cells of GFP-transgenic or normal C57/BL6 mice. The myogenic differentiation of CD117 ϩ cells was achieved by cultivation with TGF-␤. Using an acute myocardial infarction model, we also tried to regenerate infarcted myocardium by implanting untreated (newly isolated) or preprogrammed (24 hours of cultivation with 5 ng/mL TGF-␤ 1 ) CD117 ϩ cells intramyocardially. TGF-␤ increased the cellular expression of myosin, troponins, connexin-43, GATA-4, and NKx-2.5, which suggested that it induced the myogenic differentiation of CD117 ϩ cells. Compared with the effects of PBS injection only, the microvessel density in the infarcted myocardium was increased significantly 3 months after the implantation of either TGF-␤-preprogrammed or untreated CD117 ϩ cells. Moreover, many of the TGF-␤-preprogrammed CD117 ϩ cells were stained positively for myosin, whereas few of the untreated CD117 ϩ cells were. Histological analysis revealed newly regenerated myocardium in the left ventricular anterior wall after the implantation of TGF-␤-preprogrammed cells but not untreated cells. Furthermore, the left ventricular percent fraction shortening was significantly higher after the implantation of TGF-␤-preprogrammed cells than after the implantation of untreated CD117 ϩ cells. Conclusions-TGF-␤ conducted the myogenic differentiation of CD117ϩ stem cells by upregulating GATA-4 and NKx-2.5 expression. Therefore, the intramyocardial implantation of TGF-␤-preprogrammed CD117 ϩ cells effectively assisted the myocardial regeneration and induced therapeutic angiogenesis, contributing to functional cardiac regeneration. (Circulation. 2005;111:2438-2445.)

In vitro cardiomyogenic differentiation of adipose‐derived stromal cells using transforming growth factor‐β1

“…19,36 CD117-positive BMMSCs treated with TGF-b1 increased expression of cardiac markers, such as troponin I, troponin T, connexin-43, GATA-4, and NKx-2.5. 2 Our results show that TGF-b1 promotes ADSC cardiomyogenic differentiation in vitro. A recent study showed that coaxing treatment of autologous MSCs with appropriate growth factors prior to transplantation led in vitro expression of early cardiac markers and functional improvement in chronically infarcted myocardium.…”

“…2,39 A recent study showed that CD117-positive BMMSCs cultured with a low TGF-b1 concentration (5 ng ml À1 ) did not increase ALP activity in vitro and that osteoblast differentiation was induced by a higher TGF-b1 concentration (100 ng ml À1 ). 2 In the present study, ADSCs cultured with TGF-b1 (10 ng ml À1 ) for 2 weeks did not express osteonectin or osteopontin, bone-specific markers. ADSC osteogenic differentiation could be induced by a higher TGF-b1 concentration.…”

“…Embryonic stem cells, 1 bone marrow-derived mesenchymal stem cells (BMMSCs), [2][3][4][5] umbilical cord blood cells, 6 and adipose-derived stromal cells (ADSCs) 7,8 can differentiate into cardiomyocytes (CMCs). Autologous BMMSCs have been the most investigated in clinical studies to treat ischemic myocardium.…”

“…16 Importantly, transplanting CMCs differentiated from stem cells results in better myocardiac regeneration and higher cardiac functional improvement than transplanting undifferentiated stem cells. 2 Furthermore, undifferentiated stem cells may undergo unanticipated differentiation upon implantation.…”

Research of cardiomyocyte precursors in adult rat heart

“…In particular, histologic analyses revealed newly regenerated myocardium in the left ventricular anterior wall after the implantation of TGF-beta-preprogrammed cells in comparison with untreated cells (Li et al, 2005). It is our opinion that the study of myogenic potential could be important to identify markers specific of stem cells in in vivo adult myocardium that may be used to purify these cells and evaluate their regenerative ability.…”