Layered smooth muscle cell–endothelial progenitor cell sheets derived from the bone marrow augment postinfarction ventricular function

Abstract

Objective The angiogenic potential of endothelial progenitor cells (EPCs) may be limited by the absence of their natural biologic foundation, namely smooth muscle pericytes. We hypothesized that joint delivery of EPCs and smooth muscle cells (SMCs) in a novel, totally bone marrow-derived cell sheet will mimic the native architecture of a mature blood vessel and act as an angiogenic construct to limit post infarction ventricular remodeling. Methods Primary EPCs and mesenchymal stem cells (MSCs) were isolated from bone marrow of Wistar rats. MSCs were transdifferentiated into SMCs by culture on fibronectin-coated culture dishes. Confluent SMCs topped with confluent EPCs were detached from an Upcell dish to create a SMC-EPC bi-level cell sheet. A rodent model of ischemic cardiomyopathy was then created by ligating the left anterior descending artery. Rats were randomized into three groups: cell sheet transplantation (n=9), no treatment (n=12), or sham surgery control (n=7). Results Four weeks post infarction mature vessel density tended to increase in cell sheet-treated animals compared with controls. Cell sheet therapy significantly attenuated the extent of cardiac fibrosis compared with that of the untreated group (untreated vs. cell sheet, 198 degrees (IQR, 151 degrees – 246 degrees) vs. 103 degrees (IQR, 92 degrees – 113 degrees), p=0.04). Furthermore, EPC-SMC cell sheet transplantation attenuated myocardial dysfunction, as evidenced by an increase in LV ejection fraction (untreated vs. cell sheet vs sham, 33.5% (IQR, 27.8%–35.7%) vs. 45.9% (IQR, 43.6%–48.4%) vs. 59.3% (IQR, 58.8%–63.5%), p=0.001) and decreases in LV dimensions. Conclusions The bone marrow-derived, spatially arranged SMC-EPC bi-level cell sheet is a novel, multi-lineage cellular therapy obtained from a translationally practical source. Interactions between SMCs and EPCs augment mature neovascularization, limit adverse remodeling, and improve ventricular function after myocardial infarction.

Natural Heart Regeneration in a Neonatal Rat Myocardial Infarction Model

“…The LV gradually undergoes compensatory remodeling characterized by ventricular dilatation, but ultimately fails, resulting in poor contractility and reduced cardiac output. Exogenous delivery of stem cells [8,9], engineered tissues [10][11][12][13][14], cytokines [15][16][17], and growth factors [18,19] to injured myocardium have demonstrated promising results for activating intrinsic myocardial repair pathways in various adult animal models and several human clinical trials. In response to these exogenous regenerative therapies, significant improvements in scar size and cardiac function have been observed, although complete normalization to baseline cardiac health is rare in adult animals treated at the time of MI.…”

Tissue-engineered smooth muscle cell and endothelial progenitor cell bi-level cell sheets prevent progression of cardiac dysfunction, microvascular dysfunction, and interstitial fibrosis in a rodent model of type 1 diabetes-induced cardiomyopathy

“…SMC-EPC bi-level cell sheets secrete angiogenic factors and have potent paracrine effects [ 20 ]. In addition, these cell sheets have the ability to integrate into host vasculature and contribute to repair in an ischemic cardiomyopathy model [ 20 ]. We performed a fate tracking experiment to confirm that the same phenomenon occurs in DMCM.…”

“…Interestingly, VEGF expression was preserved in animals treated with cell sheet implantation as compared to untreated animals, which may explain the higher microvascular density found in the treatment group. In addition, we previously demonstrated that transplanted EPCs and SMCs integrated into the host vasculature and exerted therapeutic effects both directly and via a paracrine-mediated pathway in a rat model of acute MI [ 18 , 20 ]. There were fewer newly-forming vessels containing transplanted cells in our rat DMCM model than in our MI model, and the cell survival rate at 4 weeks was approximately 3.7% in the DMCM model.…”

“…EPCs were isolated and cultured as described previously [ 18 – 20 ]. Briefly, BM mononuclear cells were isolated from the long bones of Wistar rats and cultured on vitronectin-coated dishes (Sigma-Aldrich, St. Louis, MO) in EBM-2 supplemented with EGM-2 SingleQuot (Lonza, Walkersville, MD).…”

“…We have addressed the limitations of cell dispersion, destruction, and isolation in the hostile post-infarction environment with the creation of a tissue-engineered SMC-EPC bi-level cell sheet. The SMC-EPC bi-level cell sheet provides EPCs with a natural SMC biologic support environment, and significantly improves cardiac function in a rodent model of ischemic cardiomyopathy [ 18 – 20 ]. Furthermore, SMC-EPC bi-level cell sheets secrete an abundance of angiogenic cytokines, which directly contribute to the maintenance of a functional microvasculature [ 18 , 21 , 22 ].…”