In-vitro seeding of human umbilical cord vein endothelial cells on hydroxyapatite for mechanical heart valve applications.

BACKGROUND AND AIM OF THE STUDY: Although heart valve replacement with either a mechanical or biological prosthesis is an effective method to treat valvular heart disease, both approaches have limitations, including thrombus formation, thromboembolism and degeneration problems. The study aim was to demonstrate the in-vitro endothelialization of hydroxyapatite (HAp) to be used as a biomaterial in heart valve prostheses. METHODS: The HAp samples were characterized using X-ray diffractometry to identify the crystalline phase, while the surface morphology of HAp discs was examined using scanning electron microscopy (SEM). Human umbilical vein endothelial cells (HUVECs) were cultured on HAp discs for 1, 3, 5, and 7 days, and on pyrolytic carbon discs for 7 days; cytotoxicity was assessed using the methyl thiazolyl tetrazolium (MTT) assay. The cells were incubated in three groups: (i) an experimental group (cultured with HAp extract); (ii) a negative control (cultured with high-density polyethylene chaff); and (iii) a positive control (culture medium containing 0.1% phenol solution). RESULTS: A morphological examination of the HAp discs revealed the presence of micropores on the disc surface, together with cultured HUVECs. After seven days of culture, the HUVECs began to form a confluent endothelial cell layer covering the HAp discs. There were no visible cells attached to the pyrolytic carbon surface. The MTT assay indicated that HAp did not exert any cytotoxic effect on HUVECs, and low optical density values were obtained in the positive controls. CONCLUSION: The study results showed that HUVECs were able to grow well on HAp discs, and that HAP possessed a good in-vitro bioactivity and biocompatibility towards these cells. Consequently, HAp might be used as a film on mechanical heart valve prostheses, and serve as a promising biomaterial for heart valve replacement.