Construction of a Spontaneously Contracting Biologically Active Cardiomyocyte Scaffold

Background: While direct cell injections have been the main focus of cell-based therapies for chronic heart failure (CHF) newer approaches utilizing tissue engineered scaffolds have evolved. Previous work from our laboratory has evaluated a viable 3-dimensional fibroblast construct (3DFC) for the treatment of acute myocardial infarction and CHF. While the initial findings are impressive, the 3DFC does little to reverse maladaptive remodeling. Ideal treatment for reversing remodeling would involve revascularization of the ischemic tissue and repopulation of the anterior wall with cardiomyocytes. Hypothesis: Neonatal cardiomyocytes can be seeded onto a 3-dimensional fibroblast construct and co-cultured to generate a multicellular, biologically active cardiomyocyte scaffold for treatment of CHF. Methods: Cardiomyocytes are isolated from neonatal rats 1-2 days old and seeded onto 3DFC scaffolds (Theregen, Inc) using methods developed in our laboratory at concentrations ranging from 0.6x106 to 2.7x106 cells/cm2. The neonatal cardiomyocyte-3DFC were cultured between 110 days at 37oC with 5% CO2 in 10% FBS in DMEM-LG. Media was changed 24 hrs after initial plating then every 48 hrs. Results: Higher density cardiomyocyte seedings (1.8x106 to 2.7x106 cells/cm2) of the 3DFC show synchronized and spontaneous contractions of the entire scaffold after 48 hrs in culture. Contractions increased in robustness from 48 hrs to 5 days. At 5 days, scaffolds seeded with 2.7x106 cells/cm2 contract in a consistent rhythmic and directional fashion. Contractions were recorded at 71+3 beats BPM with a mean displacement of 2.9+0.1 mm and contraction velocity of 3.4+0.5 mm/sec (N=10). Conclusion: These findings show isolated cardiomyocytes can be seeded and co-cultured onto a biodegradable 3-dimensional construct in a manner allowing cellular survival, communication and electrical coupling. These claims are supported by the observation that the newly seeded neonatal cardiomyocyte-3DFC scaffolds beat spontaneously and in a synchronized, directional fashion with no electrical stimulation. This newly formed neonatal cardiomyocyte 3DFC scaffold is a new and unique cell delivery system to potentially treat infarcted hearts.