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Myocardial Injection With GSK-3β– Overexpressing Bone Marrow–Derived Mesenchymal Stem Cells Attenuates Cardiac Dysfunction After Myocardial Infarction Circ Res. 2011 Feb 18;108(4):478-89. 指導老師：鄭伯智老師、林宏榮老師 學生：張維真 報告日期：100.05.08 Outline • Introduction • Methods & Results • Conclusion Introduction • The myocardium has been regarded as a terminally differentiated organ lacking regenerative potential. Kajstura J, et al. Circ Res. 2010; 107:305–15. • Cardiac progenitor cells localized in niches have the ability to differentiate into cardiomyocytes (CMs), thereby replenishing the CMs lost because of basal turnover. Beltrami AP, et al. Cell. 2003;114:763–76； Bradfute SB, et al. Proc Natl Acad Sci U S A. 2003;100:12313–8 • The capacity for cardiac regeneration is insufficient to maintain cardiac function when a massive loss of CMs occurs in response to myocardial infarction (MI) and heart failure. • Various adult stem cells, including bone marrow– derived cells, endothelial progenitor cells and mesenchymal stem cells (MSCs), have been shown to be capable of differentiation into CMs, support survival of residential CMs, induce angiogenesis, or promote infarct healing when introduced into the heart after MI, clearly establishing the proof of concept that cell-based therapy (CBT) has the potential to improve cardiac function in the post-MI heart. • Macs have the ability to differentiate into various cell types in the heart, and secrete paracrine factors stimulating the survival of residential CMs, the tissue repair process, and angiogenesis, making MSCs an ideal source for cardiac CBT. Zimmet JM & Hare JM. Basic Res Cardiol. 2005;100:471–81.; Shujia J et al. Cardiovasc Res. 2008;77:525–33.; Zeng L et al. Circulation. 2007;115:1866 –75. • CBT with MSCs in post-MI animal models caused only modest or transient functional improvement, possibly because of the rare survival and the very inefficient CM differentiation of MSCs in vivo. Hill JM et al. Circulation. 2003;108:1009 –14. • For example, ex vivo introduction of Akt increased the survival of MSCs and improved cardiac function of the post-MI heart in mice subjected to CBT. Mangi AA et al. Nat Med. 2003;9:1195–1201 Glycogen synthase kinase-3β • Glycogen synthase kinase (GSK)-3βis a serine/threonine kinase that phosphorylates many intracellular substrates, including β-catenin, glycogen synthase, eIF2B, GATA4, myocardin, c-Jun, cyclin D1, and N-Myc, thereby regulating various intracellular functions. Hirotani S et al. 2007;101:1164 –1174. Haq S et al. Proc Natl Acad Sci U S A. 2003;100:4610–4615. Adam Young D et al. Wiley Interdiscip Rev Syst Biol Med. 2010 Dec 31. Aim • To evaluate whether myocardial injection of GSK-3β– overexpressing MSCs (GSK-3β– MSCs) improves survival of the animals and left ventricular (LV) function and attenuates cardiac remodeling in the post-MI heart compared with injection of control MSCs. • To investigate the underlying mechanism through which injection of GSK-3β–MSCs improves the efficiency of CBT. Study Design Lac-Z、GSK-3β transduced 2-3-week-old C57BL/6 mice MSCs were isolated from bone marrow LacZ-overexpressing MSCs GSK-3β-overexpressing MSCs MI Surgery Three-month-old C57BL/6 mice MI Sham Saline 30μL LacZ-MSCs 1.5×105 cells/ 30μL GSK-3β-MSCs 1.5×105 cells/ 30μL after 2、6 and 12 weeks Survival、LVEDD、LVESD、FS％、 （-）dp/dt（mmHg）、EDP（mmHg） Injection of GSK-3β-Overexpressing MSCs prevents cardiac dysfunction after MI Summary Ι • Injection of untreated MSCs alone does not have long-term therapeutic effects, but ex vivo introduction of GSK-3βsignificantly improves the therapeutic effect of CBT with MSCs after MI. GSK-3βOverexpressing MSCs prevents cardiac hypertrophy Remodeling Summary ІІ Injection with GSK-3β–MSCs promotes repair of MI and/or suppresses MI progression, thereby alleviating the cardiac remodeling seen with injection with saline or LacZ-MSCs. The Tet-Off Tetracycline-regulated expression system Stable Expression of GSK-3β in MSCs Improves the Efficiency of CBT for Chronic Myocardial Infarction Summary ІІІ Stable overexpression of GSK-3β in MSCs is beneficial and inhibits cardiac remodeling after MI. GSK-3β Overexpression in MSCs Enhances Survival and CM Differentiation of MSCs In Vivo Injection of GSK-3β-MSCs increases c-Kit and Ki67-positive cells Summary Ⅳ • Injection of GSK-3β–MSC into the MI • mice induces CM differentiation more • efficiently than that of control MSCs. The Therapeutic Benefits of GSK-3β-Overexpressing MSCs Is, in Part, Mediated by Angiogenesis Through Vegfa Production in MSCs Injection of GSK-3 β-MSCs enhances Vegfa expression, which partially mediates their therapeutic benefits Summary Ⅴ • Upregulation of Vefga is partially involved in the improvement of LV function in the GSK-3β– MSC injected MI mice, and that the therapeutic benefit of GSK-3β–MSCs injection is mediated by both Vegfa-dependent and -independent mechanisms. Conclusion • Ex vivo genetic reprogramming of MSCs with GSK-3β improves the therapeutic efficiency of MSCs in the post-MI heart. GSK-3β overexpression in MSCs achieves several therapeutic benefits, most likely by predirecting MSCs to CM differentiation and inducing secretion of paracrine factors, including Vegfa. Thanks !! Masson’s trichrome stain Introduction • Masson's Trichrome is most useful to differentiate collagen from other fibres, particularly smooth muscle and elastin. Results • Nuclei- Black • Cytoplasm, muscle and erythrocytes- Red • Collagen- Green Masson Trichrome&H.E.(10x40)