Thorac Cardiovasc Surg 2013; 61 - SC81
DOI: 10.1055/s-0032-1332579

Oxygen diffusion in fibrin-based engineered heart tissue and the effect of artificial oxygen carriers

M Seiffert 1, 2, M Sander 2, I Vollert 2, A Eder 2, S Schaaf 2, L Conradi 1, 2, T Schulze 2, J Uebeler 2, B Aksehirlioglu 2, H Reichenspurner 1, A Hansen 2, T Eschenhagen 2
  • 1Universitäres Herzzentrum Hamburg, Klinik für Herz- und Gefäßchirurgie, Hamburg, Germany
  • 2Universitätsklinikum Hamburg Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Hamburg, Germany

Aims: A major constraint for the potential clinical use of engineered heart tissue (EHT) in regenerative medicine constitutes the limited size due to diffusion limits of oxygen and nutrients within the three-dimensional constructs. We aimed to assess the characteristics of oxygen diffusion within fibrin-based EHT and aimed to optimize this vital factor.

Methods: EHT were generated from neonatal rat heart cells, fibrinogen, and thrombin in 24- and 2-well-formats and analyzed under cell culture conditions with 40% oxygen saturation for 3 weeks. Functional assessment was performed using an automated video-optical recording unit. Oxygen diffusion profiles within the EHT were created employing a motorized oxygen microsensor and immunohistochemical staining for pimonidazole and dystrophin, detecting areas of hypoxia and overall cardiomyocyte density. To evaluate the effect of artificial oxygen carriers on oxygen diffusion, perfluorodecalin was dissolved in cell culture media and results were compared to a control group.

Results: Within the EHT, a gradient in oxygen saturation was observed with increasing distance from the border of the three-dimensional constructs, correlating with a decline in cardiomyocyte density and viability towards the center as observed in histologic samples. Oxygen saturation within the center of the EHT gradually decreased from 10% to 0% within 5 days of cell culture and persisted at this anoxic stage. Addition of perfluorodecalin to cell culture media led to a decrease of hypoxia and an increase in cardiomyocyte density. Forces achieved by EHT cultured in perfluorodecalin-enriched medium were approximately 30% higher than controls over two weeks of culture but this effect diminished over time.

Conclusion: We report on our first efforts to characterize oxygen profiles in spontaneously contracting fibrin-based EHT. Due to the increasing density of fibrin during EHT maturation and the rising oxygen demand of viable cardiomyocytes, a growing anoxic region was noted within the EHT, potentially impeding further development of cellular constructs. Addition of artificial oxygen carriers temporarily improved oxygen diffusion but further obstacles have to be overcome to allow for the generation of EHT at sizes suitable for cardiac tissue replacement therapy.