Apoptosis as a strategy for enhancing decellularization and remodeling of tissue-engineered heart valves

In situ tissue-engineered heart valves (TEHVs) using human cell-derived tissue engineered matrices (hTEMs) offer a promising solution to current heart valve prosthesis limitations. Decellularization is crucial for producing hTEMs by removing cellular components while preserving ECM integrity. Current detergent decellularization protocols are inadequate for reducing intracellular proteins, some of which are damage-associated molecular patterns (DAMPs). Apoptosis could offer an alternative decellularization method for reducing intracellular proteins in hTEMs. We hypothesize that apoptosis-assisted decellularization, combined with hTEM functionalization using the apoptotic secretome, can enhance the remodeling capacity of hTEMs. hTEM-based TEHVs were decellularized using an apoptosis-assisted method and characterized by (immuno-)histology, biochemical assays, biaxial mechanical testing, and mass spectrometry. The apoptotic secretome of human dermal fibroblasts was characterized and used to functionalize hTEMs. Results showed that apoptosis-assisted decellularization met the decellularization standards as well as reduced intracellular proteins and DAMPs with no change in ECM structure and mechanics. Furthermore, the apoptotic secretome functionalization led to an increased tissue repair phenotype in seeded immune cells. TEHVs treated using the apoptosis-assisted decellularization exhibited sustained leaflet functionality in vitro under pulmonary conditions. Apoptosis is a promising strategy to reduce immunogenic DAMPs and introduce biochemical cues that can foster in situ tissue remodeling.