Noninvasive assessment of an engineered bioactive graft in myocardial infarction: impact on cardiac function and scar healing

Cardiac tissue engineering, which combines cells and biomaterials, is promising for limiting the sequelae of myocardial infarction (MI). We assessed myocardial function and scar evolution after implanting an engineered bioactive impedance graft (EBIG) in a swine MI model. The EBIG comprises a scaffold of decellularized human pericardium, green fluorescent protein-labeled porcine adipose tissue-derived progenitor cells (pATPCs), and a customized-design electrical impedance spectroscopy (EIS) monitoring system. Cardiac function was evaluated noninvasively by using magnetic resonance imaging (MRI). Scar healing was evaluated by using the EIS system within the implanted graft. Additionally, infarct size, fibrosis, and inflammation were explored by histopathology. Upon sacrifice 1 month after the intervention, MRI detected a significant improvement in left ventricular ejection fraction (7.5%64.9% vs. 1.4%63.7%; p = .038) and stroke volume (11.565.9 ml vs. 364.5 ml; p = .019) in EBIG-treated animals. Noninvasive EIS data analysis showed differences in both impedance magnitude ratio (20.02 6 0.04 per day vs. 20.48 6 0.07 per day; p = .002) and phase angle slope (20.18°60.24° per day vs.23.52°60.84° per day; p = .004) in EBIG compared with control animals. Moreover, in EBIG-treated animals, the infarct size was 48% smaller (3.4%60.6% vs. 6.5%61%; p = .015), less inflammation was found by means of CD25+ lymphocytes (0.65 6 0.12 vs. 1.26 6 0.2; p = .006), and a lower collagen I/III ratio was detected (0.4960.06 vs. 1.6660.5; p = .019). An EBIG composed of acellular pericardium refilled with pATPCs significantly reduced infarct size and improved cardiac function in a preclinical model of MI. Noninvasive EIS monitoring was useful for tracking differential scar healing in EBIG-treated animals, which was confirmed by less inflammation and altered collagen deposit.Peer ReviewedPostprint (published version

Electrical stimulation of cardiac adipose tissue-derived progenitor cells modulates cell phenotype and genetic machinery

A major challenge of cardiac tissue engineering is directing cells to establish the physiological structure and function of the myocardium being replaced. Our aim was to examine the effect of electrical stimulation on the cardiodifferentiation potential of cardiac adipose tissue-derived progenitor cells (cardiac ATDPCs). Three different electrical stimulation protocols were tested; the selected protocol consisted of 2ms monophasic square-wave pulses of 50mV/cm at 1Hz over 14days. Cardiac and subcutaneous ATDPCs were grown on biocompatible patterned surfaces. Cardiomyogenic differentiation was examined by real-time PCR and immunocytofluorescence. In cardiac ATDPCs, MEF2A and GATA-4 were significantly upregulated at day 14 after stimulation, while subcutaneous ATDPCs only exhibited increased Cx43 expression. In response to electrical stimulation, cardiac ATDPCs elongated, and both cardiac and subcutaneous ATDPCs became aligned following the linear surface pattern of the construct. Cardiac ATDPC length increased by 11.3%, while subcutaneous ATDPC length diminished by 11.2% (p=0.013 and p=0.030 vs unstimulated controls, respectively). Compared to controls, electrostimulated cells became aligned better to the patterned surfaces when the pattern was perpendicular to the electric field (89.71±28.47o for cardiac ATDPCs and 92.15±15.21o for subcutaneous ATDPCs). Electrical stimulation of cardiac ATDPCs caused changes in cell phenotype and genetic machinery, making them more suitable for cardiac regeneration approaches. Thus, it seems advisable to use electrical cell training before delivery as a cell suspension or within engineered tissue.Peer ReviewedPreprin

Electrical stimulation of cardiac adipose tissue-derived progenitor cells modulates cell phenotype and genetic machinery

A major challenge of cardiac tissue engineering is directing cells to establish the physiological structure and function of the myocardium being replaced. Our aim was to examine the effect of electrical stimulation on the cardiodifferentiation potential of cardiac adipose tissue-derived progenitor cells (cardiac ATDPCs). Three different electrical stimulation protocols were tested; the selected protocol consisted of 2ms monophasic square-wave pulses of 50mV/cm at 1Hz over 14days. Cardiac and subcutaneous ATDPCs were grown on biocompatible patterned surfaces. Cardiomyogenic differentiation was examined by real-time PCR and immunocytofluorescence. In cardiac ATDPCs, MEF2A and GATA-4 were significantly upregulated at day 14 after stimulation, while subcutaneous ATDPCs only exhibited increased Cx43 expression. In response to electrical stimulation, cardiac ATDPCs elongated, and both cardiac and subcutaneous ATDPCs became aligned following the linear surface pattern of the construct. Cardiac ATDPC length increased by 11.3%, while subcutaneous ATDPC length diminished by 11.2% (p=0.013 and p=0.030 vs unstimulated controls, respectively). Compared to controls, electrostimulated cells became aligned better to the patterned surfaces when the pattern was perpendicular to the electric field (89.71±28.47o for cardiac ATDPCs and 92.15±15.21o for subcutaneous ATDPCs). Electrical stimulation of cardiac ATDPCs caused changes in cell phenotype and genetic machinery, making them more suitable for cardiac regeneration approaches. Thus, it seems advisable to use electrical cell training before delivery as a cell suspension or within engineered tissue.Peer Reviewe

Electromechanical conditioning of adult progenitor cells improves recovery of cardiac function after myocardial infarction

Cardiac cells are subjected to mechanical and electrical forces, which regulate gene expression and cellular function. Therefore, in vitro electromechanical stimuli could benefit further integration of therapeutic cells into the myocardium. Our goals were (a) to study the viability of a tissue engineered construct with cardiac adipose tissue-derived progenitor cells (cardiac ATDPCs) and (b) to examine the effect of electromechanically stimulated cardiac ATDPCs within a myocardial infarction (MI) model inmice for the first time. Cardiac ATDPCs were electromechanically stimulated at 2-millisecond pulses of 50 mV/cm at 1 Hz and 10% stretching during 7 days. The cells were harvested, labeled, embedded in a fibrin hydrogel, and implanted over the infarcted area of the murine heart. A total of 39 animals were randomly distributed and sacrificed at 21 days: groups of grafts without cells and with stimulated or nonstimulated cells. Echocardiography and gene and protein analyses were also carried out. Physiologically stimulated ATDPCs showed increased expression of cardiac transcription factors, structural genes, and calcium handling genes. At 21 days after implantation, cardiac function (measured as left ventricle ejection fraction between presacrifice and post-MI) increased up to 12% in stimulated grafts relative to nontreated animals. Vascularization and integration with the host blood supply of grafts with stimulated cells resulted in increased vessel density in the infarct border region. Trained cells within the implanted fibrin patch expressed main cardiac markers and migrated into the underlying ischemic myocardium. To conclude, synchronous electromechanical cell conditioning before delivery may be a preferred alternative when considering strategies for heart repair after myocardial infarction.Peer ReviewedPostprint (author's final draft

Electromechanical conditioning of adult progenitor cells improves recovery of cardiac function after myocardial infarction

Cardiac cells are subjected to mechanical and electrical forces, which regulate gene expression and cellular function. Therefore, in vitro electromechanical stimuli could benefit further integration of therapeutic cells into the myocardium. Our goals were (a) to study the viability of a tissue engineered construct with cardiac adipose tissue-derived progenitor cells (cardiac ATDPCs) and (b) to examine the effect of electromechanically stimulated cardiac ATDPCs within a myocardial infarction (MI) model inmice for the first time. Cardiac ATDPCs were electromechanically stimulated at 2-millisecond pulses of 50 mV/cm at 1 Hz and 10% stretching during 7 days. The cells were harvested, labeled, embedded in a fibrin hydrogel, and implanted over the infarcted area of the murine heart. A total of 39 animals were randomly distributed and sacrificed at 21 days: groups of grafts without cells and with stimulated or nonstimulated cells. Echocardiography and gene and protein analyses were also carried out. Physiologically stimulated ATDPCs showed increased expression of cardiac transcription factors, structural genes, and calcium handling genes. At 21 days after implantation, cardiac function (measured as left ventricle ejection fraction between presacrifice and post-MI) increased up to 12% in stimulated grafts relative to nontreated animals. Vascularization and integration with the host blood supply of grafts with stimulated cells resulted in increased vessel density in the infarct border region. Trained cells within the implanted fibrin patch expressed main cardiac markers and migrated into the underlying ischemic myocardium. To conclude, synchronous electromechanical cell conditioning before delivery may be a preferred alternative when considering strategies for heart repair after myocardial infarction.Peer Reviewe

Noninvasive assessment of an engineered bioactive graft in myocardial infarction: impact on cardiac function and scar healing

Cardiac tissue engineering, which combines cells and biomaterials, is promising for limiting the sequelae of myocardial infarction (MI). We assessed myocardial function and scar evolution after implanting an engineered bioactive impedance graft (EBIG) in a swine MI model. The EBIG comprises a scaffold of decellularized human pericardium, green fluorescent protein-labeled porcine adipose tissue-derived progenitor cells (pATPCs), and a customized-design electrical impedance spectroscopy (EIS) monitoring system. Cardiac function was evaluated noninvasively by using magnetic resonance imaging (MRI). Scar healing was evaluated by using the EIS system within the implanted graft. Additionally, infarct size, fibrosis, and inflammation were explored by histopathology. Upon sacrifice 1 month after the intervention, MRI detected a significant improvement in left ventricular ejection fraction (7.5%64.9% vs. 1.4%63.7%; p = .038) and stroke volume (11.565.9 ml vs. 364.5 ml; p = .019) in EBIG-treated animals. Noninvasive EIS data analysis showed differences in both impedance magnitude ratio (20.02 6 0.04 per day vs. 20.48 6 0.07 per day; p = .002) and phase angle slope (20.18°60.24° per day vs.23.52°60.84° per day; p = .004) in EBIG compared with control animals. Moreover, in EBIG-treated animals, the infarct size was 48% smaller (3.4%60.6% vs. 6.5%61%; p = .015), less inflammation was found by means of CD25+ lymphocytes (0.65 6 0.12 vs. 1.26 6 0.2; p = .006), and a lower collagen I/III ratio was detected (0.4960.06 vs. 1.6660.5; p = .019). An EBIG composed of acellular pericardium refilled with pATPCs significantly reduced infarct size and improved cardiac function in a preclinical model of MI. Noninvasive EIS monitoring was useful for tracking differential scar healing in EBIG-treated animals, which was confirmed by less inflammation and altered collagen deposit.Peer Reviewe