Towards the Development of a Biohybrid Lung as Alternative to Lung Transplantation

Purpose Lung transplantation is the only curative therapy option for patients suffering from end stage lung diseases. However, it is associated with high risks and only available for selected patients. In order to provide an alternative treatment option, this project aims for the development of an implantable biohybrid lung (BL), based on hollow fibre membrane (HFM) technology used in extracorporeal membrane oxygenators. A crucial requirement to achieve long-lasting durability of the BL is the optimized bio- and haemocompatibility of all blood contacting surfaces, which can be achieved by endothelialisation. Methods Albumin/Heparin (A/H) and Fibronectin (FN) coated HFM were compared for their eligibility to mediate the establishment of a viable, confluent and non-thrombogenic endothelial cell (EC) monolayer. Activation status of the seeded ECs was analyzed and verified by leukocyte- and thrombocyte adhesion assays. The behavior of HFM-seeded ECs under workload conditions, i.e. fluid flow and oxidative stress exposure, was assessed in a customized flow chamber setup. To identify a clinically relevant EC source, comparative studies including human cord blood derived endothelial cells (hCBECs) induced pluripotent stem cell derived endothelial cells and immunotolerable MHC-silenced hCBECs were conducted. Results A physiologic, viable and confluent EC monolayer could be sustained under both, static and flow dynamic culture conditions. All tested EC types preserved their non-thrombogenic and non-inflammatory status on both tested HMF. Exposure to relevant levels of hyperoxia or hypoxia did not affect the physiological function of the ECs. However, FN coated HFMs demonstrated an improved EC-monolayer resistance towards flow conditions. Conclusion Endothelialisation of HFM improves their hemocompatibility. Moreover, the endothelial monolayer on HFM can resist clinically relevant settings, like flow exposure and hyperoxia/hypoxia. MHC-silenced ECs could be considered as suitable cell source, escaping the recipient's immune response. These results may bring BL as alternative of lung transplantation for patients with end-stage lung diseases closer to reality.