Figure 9.

Human cardiac stem cell (CSC) niche in the myocardium. A, c‐kit+ (green) human cardiac stem cells (hCSCs) are nested in the interstitium and are surrounded by fibronectin (Fn, bright blue). These hCSCs are connected by gap junctions represented by connexin 43 (Cx43, yellow dots) and adherens junctions shown by N‐cadherin (N‐cadh, magenta) to cardiomyocytes (α‐sarcomeric actin, α‐SA, red). B, These cell‐to‐cell communications between CSCs and cardiomyocytes are indicated by arrowheads. C, Cell–Cell interactions between endogenous and exogenous stem cells. C and D, Immature mesenchymal stem cells (MSCs, green) are found within the swine myocardium to interact with resident c‐kit+ CSCs (red) by connexin‐43 (C, white) and N‐cadherin (D, white arrow) connections, closely resembling CSC niches. Panels A and B reproduced with permission from Leri et al, Circulation, 2013,⁷⁰ panels C and D from Hatzistergos et al, Circulation Research 2010.⁴¹DAPI indicates 4',6‐diamidino‐2‐phenylindole; GFP, green fluorescent protein.