Embryonic Stem Cells Improve Cardiac Function in Doxorubicin-Induced Cardiomyopathy Mediated through Multiple Mechanisms

Abstract

Doxorubicin (DOX) is an effective antineoplastic agent used for the treatment of a variety of cancers. Unfortunately, its use is limited as this drug induces cardiotoxicity and heart failure as a side effect. There is no report which describes whether transplanted embryonic stem (ES) cells or their conditioned medium (CM) in DOX induced cardiomyopathy (DIC) can repair and regenerate myocardium. Therefore, we transplanted ES cells or CM in DIC to examine apoptosis, fibrosis, cytoplasmic vacuolization and myofibrillar loss and their associated Akt and ERK pathway. Moreover, we also determined activation of endogenous c-kit+ve cardiac stem cells (CSCs), levels of HGF and IGF-1, growth factors required for c-kit cell activation, and their differentiation into cardiac myocytes, which also contributes in cardiac regeneration and improved heart function. We generated DIC in C57Bl/6 mice (cumulative dose of DOX 12mg/kg body weight, i.p), and animals were treated with ES cells, CM or cell culture medium in controls. Two weeks post-DIC, ES cells or CM transplanted hearts showed a significant (p<0.05) decrease in cardiac apoptotic nuclei and their regulation with Akt and ERK pathway. Cardiac fibrosis observed in the ES cell or CM groups was significantly less compared with DOX and cell culture medium groups (p<0.05). Next, cytoplasmic vacuolization and myofibrillar loss was reduced (p<0.05) following treatment with ES cells or CM. Moreover, our data also demonstrated increased levels of c-kit+ve CSCs in ES cells or CM hearts and differentiated cardiac myocytes from these CSCs, suggesting endogenous cardiac regeneration. Importantly, the levels of HFG and IGF-1 were significantly increased in ES cells or CM transplanted hearts. In conclusion, we reported that transplanted ES cells or CM in DIC hearts significantly decreases various adverse pathological mechanisms as well as enhances cardiac regeneration that effectively contributes to improved heart function.

Stem cell transplantation as a therapy for cardiac fibrosis

“…These beneficial effects have been attributed to decreased collagen deposition, enhanced myocardial regeneration, and possible paracrine factors released from ESCs such as the anti-apoptotic proteins cystatin C, osteopontin, and clusterin, and the anti-fibrotic tissue inhibitor metalloproteinase (TIMP)-1 [20]. ESCs were also able to stimulate the endogenous cardiac regeneration via activating the differentiation of resident cardiac stem cells (CSCs) into cardiac myocytes [21]. Paracrine factors such as hepatocyte growth factor (HGF) and insulin growth factor (IGF)-1 have been suggested to play a significant role in this activation process [21].…”

“…Transplantation of ESCs has been shown to inhibit cardiomyocyte apoptosis and myocardial fibrosis, with subsequent improvements in adverse cardiac remodelling and cardiac function following MI [20] and in doxorubicin-induced cardiomyopathy [21]. These beneficial effects have been attributed to decreased collagen deposition, enhanced myocardial regeneration, and possible paracrine factors released from ESCs such as the anti-apoptotic proteins cystatin C, osteopontin, and clusterin, and the anti-fibrotic tissue inhibitor metalloproteinase (TIMP)-1 [20].…”

“…ESCs were also able to stimulate the endogenous cardiac regeneration via activating the differentiation of resident cardiac stem cells (CSCs) into cardiac myocytes [21]. Paracrine factors such as hepatocyte growth factor (HGF) and insulin growth factor (IGF)-1 have been suggested to play a significant role in this activation process [21]. Furthermore, HGF and IGF-1 possess cardioprotective effects through anti-apoptotic, mitogenic or anti-fibrotic activities.…”

Akt—mTOR Pathway Inhibits Apoptosis and Fibrosis in Doxorubicin-Induced Cardiotoxicity following Embryonic Stem Cell Transplantation

“…Noteworthy, the exaggerated collagen synthesis in DIC coincides with extracellular matrix degradation consequent to activation of matrix metalloproteinases (MMPs) (17,34,36). Previous studies have demonstrated the ability of various factors and therapeutics to promote cytoprotection in acute DIC (16)(17)(18)30). However, investigation into the long-term potential of these approaches relative to chronic DIC is warranted.…”

“…Of interest, these studies admittedly acknowledged minimal to no engraftment of transplanted cells (1,37). More recently, the ability of embryonic stem (ES) cells and their released factors to repair and regenerate the injured DIC myocardium was assessed (30). Evidence provided suggested that ES cells and their conditioned media (CM) were capable of blunting acute DIC adverse conditions (30).…”