BackgroundSmall intestine submucosa extracellular matrix (SIS-ECM) is a clinically relevant biomaterial that retains its native matrix architecture and bioinductive proteins. After myocardial infarction (MI), the elevation of profibrotic transforming growth factor-β1 (TGF-β1) results in myofibroblast activation, leading to extracellular matrix (ECM) dysregulation, structural remodeling and progression to heart failure (HF). We have previously demonstrated that SIS-ECM biomaterial favorably impacts post-MI remodeling and prevents HF, but its influence on local myofibroblast activity is poorly understood. Accordingly, we have developed an in vitro cell-matrix platform to study the bioinductive properties of biomaterials on human cardiac myofibroblasts.Methods/ResultsA novel 3D cell culture platform that utilizes single cells within a floating collagen microgel on a synthetic nylon scaffold was employed. This platform permits the visualization and measurement of cell-matrix interactions via confocal microscopy. The model was adapted, incorporating SIS-ECM biomaterial (CorMatrix-ECM, CorMatrix Cardiovascular Inc., GA, USA) to examine the bioinductive properties of SIS-ECM on myofibroblast-mediated matrix remodeling. NIH 3T3 fibroblasts were seeded onto 3D collagen microgels supported within nylon (biologically inert) or SIS-ECM (biologically active) scaffolds. Constructs were then floated in complete medium or medium supplemented with TGF-β1 (10 ng/mL) to induce myofibroblast activation. Cell-matrix constructs were fixed, stained and imaged using confocal laser scanning microscopy to visualize cells and the 3D matrix. Within the nylon scaffolds, TGF-β1 increased the number of cell extensions (5.5±2.38 vs. 2.4±1.29, p<0.05) and cell extension lengths (65.89 μm ± 24.64 vs. 29.23 μm ± 4.78, p<0.05) demonstrating myofibroblast activation. SIS-ECM attenuated myofibroblast activation in response to TGF-β1 demonstrated by the fewer (2.44±0.53) and shorter (40.68 μm ±14.08) cell extensions (p<0.05). To translate these findings, human cardiac myofibroblasts isolated from atrial heart biopsies were seeded into our biologically active and inert scaffolds. Figure 1 shows TGF-β1 treated cardiac myofibroblasts within the inert nylon scaffold displaying long cell extensions representing an activated myofibrotic phenotype. In contrast, cardiac myofibroblasts within the bioactive SIS-ECM show short cell extensions consistent with decreased activation. In addition, cells within the SIS-ECM group show an attenuated response to TGF-β1 stimulated myofibroblast-mediated matrix remodeling.ConclusionCorMatrix BackgroundSmall intestine submucosa extracellular matrix (SIS-ECM) is a clinically relevant biomaterial that retains its native matrix architecture and bioinductive proteins. After myocardial infarction (MI), the elevation of profibrotic transforming growth factor-β1 (TGF-β1) results in myofibroblast activation, leading to extracellular matrix (ECM) dysregulation, structural remodeling and progression to heart failure (HF). We have previously demonstrated that SIS-ECM biomaterial favorably impacts post-MI remodeling and prevents HF, but its influence on local myofibroblast activity is poorly understood. Accordingly, we have developed an in vitro cell-matrix platform to study the bioinductive properties of biomaterials on human cardiac myofibroblasts. Small intestine submucosa extracellular matrix (SIS-ECM) is a clinically relevant biomaterial that retains its native matrix architecture and bioinductive proteins. After myocardial infarction (MI), the elevation of profibrotic transforming growth factor-β1 (TGF-β1) results in myofibroblast activation, leading to extracellular matrix (ECM) dysregulation, structural remodeling and progression to heart failure (HF). We have previously demonstrated that SIS-ECM biomaterial favorably impacts post-MI remodeling and prevents HF, but its influence on local myofibroblast activity is poorly understood. Accordingly, we have developed an in vitro cell-matrix platform to study the bioinductive properties of biomaterials on human cardiac myofibroblasts. Methods/ResultsA novel 3D cell culture platform that utilizes single cells within a floating collagen microgel on a synthetic nylon scaffold was employed. This platform permits the visualization and measurement of cell-matrix interactions via confocal microscopy. The model was adapted, incorporating SIS-ECM biomaterial (CorMatrix-ECM, CorMatrix Cardiovascular Inc., GA, USA) to examine the bioinductive properties of SIS-ECM on myofibroblast-mediated matrix remodeling. NIH 3T3 fibroblasts were seeded onto 3D collagen microgels supported within nylon (biologically inert) or SIS-ECM (biologically active) scaffolds. Constructs were then floated in complete medium or medium supplemented with TGF-β1 (10 ng/mL) to induce myofibroblast activation. Cell-matrix constructs were fixed, stained and imaged using confocal laser scanning microscopy to visualize cells and the 3D matrix. Within the nylon scaffolds, TGF-β1 increased the number of cell extensions (5.5±2.38 vs. 2.4±1.29, p<0.05) and cell extension lengths (65.89 μm ± 24.64 vs. 29.23 μm ± 4.78, p<0.05) demonstrating myofibroblast activation. SIS-ECM attenuated myofibroblast activation in response to TGF-β1 demonstrated by the fewer (2.44±0.53) and shorter (40.68 μm ±14.08) cell extensions (p<0.05). To translate these findings, human cardiac myofibroblasts isolated from atrial heart biopsies were seeded into our biologically active and inert scaffolds. Figure 1 shows TGF-β1 treated cardiac myofibroblasts within the inert nylon scaffold displaying long cell extensions representing an activated myofibrotic phenotype. In contrast, cardiac myofibroblasts within the bioactive SIS-ECM show short cell extensions consistent with decreased activation. In addition, cells within the SIS-ECM group show an attenuated response to TGF-β1 stimulated myofibroblast-mediated matrix remodeling. A novel 3D cell culture platform that utilizes single cells within a floating collagen microgel on a synthetic nylon scaffold was employed. This platform permits the visualization and measurement of cell-matrix interactions via confocal microscopy. The model was adapted, incorporating SIS-ECM biomaterial (CorMatrix-ECM, CorMatrix Cardiovascular Inc., GA, USA) to examine the bioinductive properties of SIS-ECM on myofibroblast-mediated matrix remodeling. NIH 3T3 fibroblasts were seeded onto 3D collagen microgels supported within nylon (biologically inert) or SIS-ECM (biologically active) scaffolds. Constructs were then floated in complete medium or medium supplemented with TGF-β1 (10 ng/mL) to induce myofibroblast activation. Cell-matrix constructs were fixed, stained and imaged using confocal laser scanning microscopy to visualize cells and the 3D matrix. Within the nylon scaffolds, TGF-β1 increased the number of cell extensions (5.5±2.38 vs. 2.4±1.29, p<0.05) and cell extension lengths (65.89 μm ± 24.64 vs. 29.23 μm ± 4.78, p<0.05) demonstrating myofibroblast activation. SIS-ECM attenuated myofibroblast activation in response to TGF-β1 demonstrated by the fewer (2.44±0.53) and shorter (40.68 μm ±14.08) cell extensions (p<0.05). To translate these findings, human cardiac myofibroblasts isolated from atrial heart biopsies were seeded into our biologically active and inert scaffolds. Figure 1 shows TGF-β1 treated cardiac myofibroblasts within the inert nylon scaffold displaying long cell extensions representing an activated myofibrotic phenotype. In contrast, cardiac myofibroblasts within the bioactive SIS-ECM show short cell extensions consistent with decreased activation. In addition, cells within the SIS-ECM group show an attenuated response to TGF-β1 stimulated myofibroblast-mediated matrix remodeling. ConclusionCorMatrix CorMatrix