Biocompatibility and recellularization potential of an acellular porcine heart valve matrix

Tissue-engineered heart valves have the potential to overcome the limitations of present heart valve replacements. The study aim was to investigate the biocompatibility and recellularization potential of an acellular porcine valve matrix.

Acellular porcine valve matrix contact and extract cytotoxicity was tested against porcine fibroblasts and smooth muscle cells (SMC). Porcine cells were incubated with decellularized aortic valve leaflets and aortic wall, and then assessed for changes in morphology and contact inhibition of growth. Soluble tissue extracts were prepared from decellularized leaflets and aortic wall, and assessed for their effect on the viability of cultured porcine cells. Acellular leaflets were seeded with either fibroblasts or SMC at 1 x 10(3) to 1 x 10(6) cells/cm2 for 24 h, or 5 x 10(4) cells/cm2 for 1-4 weeks. Cell attachment onto, and migration into, the acellular matrix was assessed by scanning electron microscopy and histology.

No contact inhibition of growth, or changes in fibroblast or SMC morphology, were observed following contact with the acellular valve matrix. No soluble extract cytotoxicity was found. Intermediate cell-seeding densities (2.5 x 10(4) to 7.5 x 10(4) cells/cm2) of both cell types produced confluent cell attachment; at the lowest concentration (1 x 10(3) cells/cm2) cell attachment was sparse, and at the highest (1 x 10(6) cells/cm2) it was multilayered. The SMC migrated throughout the leaflet matrix over four weeks, but there was no fibroblast migration into the matrix.

The absence of contact and extract cytotoxicity indicated that the acellular valve matrix was biocompatible in vitro. The failure of porcine fibroblasts to grow on, or infiltrate into, the matrix suggested that the SMC may be the preferred cell type for future leaflet recellularization studies in the development of a tissue-engineered heart valve replacement.