In vivo behavior of epoxy-crosslinked porcine heart valve cusps and walls

Abstract

Calcification limits the long-term durability of xenograft glutaraldehyde-crosslinked heart valves. In this study, epoxy-crosslinked porcine aortic valve tissue was evaluated after subcutaneous implantation in weanling rats. Non-crosslinked valves and valves crosslinked with glutaraldehyde or carbodiimide functioned as control. Epoxy-crosslinked valves had somewhat lower shrinkage temperatures than the crosslinked controls, and within the series also some macroscopic and microscopic differences were obvious. After 8 weeks implantation, cusps from non-crosslinked valves were not retrieved. The matching walls were more degraded than the epoxy- and control-crosslinked walls. This was observed from the higher cellular ingrowth with fibroblasts, macrophages, and giant cells. Furthermore, non-crosslinked walls showed highest numbers of lymphocytes, which were most obvious in the capsules. Epoxy- and control-crosslinked cusps and walls induced lower reactions. Calcification, measured by von Kossa-staining and by Ca-analysis, was always observed. Crosslinked cusps calcified more than walls. Of all wall samples, the non-crosslinked walls showed the highest calcification. It is concluded that epoxy-crosslinked valve tissue induced a foreign body and calcification reaction similar to the two crosslinked controls. Therefore, epoxy-crosslinking does not represent a solution for the calcification problem of heart valve bioprostheses.

Tissue reactions to epoxy-crosslinked porcine heart valves post-treated with detergents or a dicarboxylic acid

“…15 Additional C/S treatment induced calcification in predominantly the spongiosa (except for the one noncalcifying cusp) and minimally at the outer edges of the walls. This again agrees with the observed morphological changes and the detergent function of C/S.…”

“…The second approach, BD45COOH crosslinking, aimed at a better balance between positively charged amine groups and negatively charged carboxylate groups on the collagen. 16,18 Compared with BD45, 15 the increase in Ts suggests that crosslinks were formed, whereas the reduction in amine groups implies that also a large number of one-sided reactions had occurred, leading to pendant carboxylic acid groups. Although not meant to result in a washed-out appearance, it certainly had this effect on cusps when compared with BD45 only.…”

“…Although not meant to result in a washed-out appearance, it certainly had this effect on cusps when compared with BD45 only. 15 Walls contained deviant subendothelial layers. Similar to BD45-C/S cusps, the calcification was particularly concentrated in the spongiosa.…”

In vivo biocompatibility of carbodiimide-crosslinked collagen matrices: Effects of crosslink density, heparin immobilization, and bFGF loading

“…44 Because a certain amount of immunologic response to commercial heart valves in an actual situation of blood flow is quite acceptable, problems due to immunologic responses to bFGF preloaded EN14-H applied as a matrix for endothelial cell seeding in vascular grafts are not to be expected.…”

Efeito da irradiação gama nas propriedades mecânicas e térmicas de redes DGEBA/amina cicloalifática com potencial para aplicações médicas

“…Os polímeros epoxídicos apresentam propriedades otimizadas tais como dureza, tenacidade, resistência química, baixa contração, assim como excelente adesão, que são associadas à natureza estrutural dos monômeros que formaram a rede tridimensional [4,5] . Estes materiais poliméricos apresentam potencialidade para serem utilizados em algumas aplicações médicas, porque manifestam boas propriedades biológicas em paralelo às propriedades mecânicas adequadas [6][7][8][9] . Esta afirmação pode ser corroborada pelos estudos prévios do grupo com estes polímeros, usando ensaios biológicos in vitro de compatibilidade que mostraram reduzida atividade trombogênica com o sangue humano e não citotoxicidade com células de ovário hanster chinês [10] .…”