Adipose-derived cell construct stabilizes heart function and increases microvascular perfusion in an established infarct

Abstract

We have previously shown that myocardial infarction (MI) immediately treated with an epicardial construct containing stromal vascular fraction (SVF) from adipose tissue preserved microvascular function and left ventricle contractile mechanisms. In order to evaluate a more clinically relevant condition, we investigated the cardiac recovery potential of an SVF construct implanted onto an established infarct. SVF cells were isolated from rat adipose tissue, plated on Vicryl, and cultured for 14 days. Fischer-344 rats were separated into MI groups: (a) 6-week MI (MI), (b) 6-week MI treated with an SVF construct at 2 weeks (MI SVF), (c) 6-week MI with Vicryl construct at 2 weeks (MI Vicryl), and (d) MI 2wk (time point of intervention). Emax, an indicator of systolic performance and contractile function, was lower in the MI and MI Vicryl versus MI SVF. Positron emission tomography imaging ((18)F-fluorodeoxyglucose) revealed a decreased percentage of relative infarct volume in the MI SVF versus MI and MI Vicryl. Total vessel count and percentage of perfusion assessed via immunohistochemistry were both increased in the infarct region of MI SVF versus MI and MI Vicryl. Overall cardiac function, percentage of relative infarct, and percentage of perfusion were similar between MI SVF and MI 2wk; however, total vessel count increased after SVF treatment. These data suggest that SVF treatment of an established infarct stabilizes the heart at the time point of intervention by preventing a worsening of cardiac performance and infarcted volume, and is associated with increased microvessel perfusion in the area of established infarct.

Keywords: Adipose stem cells; Angiogenesis; Cardiac; Microvasculature; Stromal cells.

Figures

Figure 1.

Cardiac function as assessed through pressure-volume (PV) loop recordings. (A): Representative single PV loop recordings during baseline. All MI hearts displayed a rightward shift in PV relationship compared with the representative control PV loop. (B): Table summarizing cardiac functional parameters during PV loop recordings and respective analysis of variance p values. Emax was significantly higher for MI SVF than either the MI or MI Vicryl groups. *, Significantly different from MI SVF. (C): Representative PV loops obtained at different preloads, showing differences in the end-systolic PV relationship (ESPVR, or Emax) between MI (left), MI SVF (center), and MI Vicryl (right). The less steep Emax in the MI and MI Vicryl loops indicate decreased systolic performance. Abbreviations: CO, cardiac output; dP/dt, maximal slope of systolic pressure increment; EDP, end diastolic pressure; EDPVR, end diastolic pressure-volume relationship; EDV, end diastolic volume; EF, ejection fraction; ESP, end systolic pressure; ESV, end systolic volume; HR, heart rate; MI, 6-week myocardial infarction; MI SVF, 6-week myocardial infarction treated with a stromal vascular fraction construct at 2 weeks; MI Vicryl, 6-week myocardial infarction with Vicryl construct at 2 weeks; SV, stroke volume.

Figure 2.

Cardiac metabolism as evaluated through the use of 18F-FDG positron emission tomography. (A):18F-FDG positron emission tomography shows an uptake defect in partitioned polar maps in all groups (anterior [top], lateral [right], and apex [center]). (B): The percentage of relative infarcted volume, calculated as a ratio of infarcted volume (regions with 18F-FDG uptake <70%) to total left ventricle volume, was significantly higher in the MI and MI Vicryl groups compared with MI SVF. Abbreviations: FDG, fluorodeoxyglucose; MI, 6-week myocardial infarction; MI SVF, 6-week myocardial infarction treated with a stromal vascular fraction construct at 2 weeks; MI Vicryl, 6-week myocardial infarction with Vicryl construct at 2 weeks.

Figure 3.

Gross pathology and histology of MI, MI SVF, and MI Vicryl hearts. Representative images of explanted hearts (A) and trichrome-stained sections (B). Scale bar = 1 mm. (C): Infarct size as a percentage of total LV per experimental group by trichrome analysis. Abbreviations: LV, left ventricle; MI, 6-week myocardial infarction; MI SVF, 6-week myocardial infarction treated with a stromal vascular fraction construct at 2 weeks; MI Vicryl, 6-week myocardial infarction with Vicryl construct at 2 weeks.

Figure 4.

Vascular density as evaluated through immunohistochemistry in MI, MI SVF, and MI Vicryl hearts. (A): Representative GS-1+ staining indicating coronary vascular density in the infarct and peri-infarct region. (B): The MI SVF group exhibited significantly more GS-1+ vessels in the area of infarct compared with both the MI and MI Vicryl groups. Scale bars = 20 μm. Abbreviations: GS-1, Griffonia simplicifolia I; MI, 6-week myocardial infarction; MI SVF, 6-week myocardial infarction treated with a stromal vascular fraction construct at 2 weeks; MI Vicryl, 6-week myocardial infarction with Vicryl construct at 2 weeks.

Figure 5.

Representative merged images of immunohistochemistry staining for dextran+ (red) and αSMC-actin+ (blue) in MI (top left), MI SVF (top right), and MI Vicryl (bottom left). MI SVF showed more perfused vessels (white arrows) compared with both MI and MI Vicryl hearts. Scale bars = 20 μm. Abbreviations: MI, 6-week myocardial infarction; MI SVF, 6-week myocardial infarction treated with a stromal vascular fraction construct at 2 weeks; MI Vicryl, 6-week myocardial infarction with Vicryl construct at 2 weeks; αSMC, α-smooth muscle cell.

Figure 6.

Cumulative data comparing MI SVF with the time point of intervention, MI 2wk. On several parameters, MI SVF hearts maintained cardiac function and vascular dynamics similar to those of the MI 2wk group. (A): Representative PV loops showing both the lack of rightward shift (vs. MI 2wk) or reversal of dysfunction (vs. control) for MI SVF. (B): Summary of cardiac functional parameters as assessed by PV loops. (C):18F-Fluorodeoxyglucose uptake positron emission tomography (PET) polar map views. (D): Percentage of relative infarct volume from PET data. (E): GS-1+ vessel density (top) and immunohistochemistry staining showing perfused vessels (bottom). Scale bars = 20 μm. (F): MI SVF had a significantly higher count of GS-1+ vessel density in the area of infarct compared with MI 2wk. (G): Graph displaying the percentage of perfused vessels in the area of infarct. Abbreviations: αSMC, α-smooth muscle cell; CO, cardiac output; dP/dt, maximal slope of systolic pressure increment; EDP, end diastolic pressure; EDPVR, end diastolic pressure-volume relationship; EDV, end diastolic volume; EF, ejection fraction; ESP, end systolic pressure; ESV, end systolic volume; HR, heart rate; GS-1, Griffonia simplicifolia I; HR, heart rate; MI 2wk, 2-week myocardial infarction; MI SVF, 6-week myocardial infarction treated with a stromal vascular fraction construct at 2 weeks; SV, stroke volume.