triglycidylamine and Calcinosis

Since bioprosthetic valve dysfunction may arise due to histological calcification in the crosslinking process by glutaraldehyde (GA), non-GA crosslinking reagents have been investigated. We compared the efficacy of triglycidylamine (TGA), a newly synthesized epoxy compound, and GA as crosslinking reagents for the treatment of autologous tissues. We assessed the strength of crosslinked tissues using shrinkage temperature (Ts) measured by differential scanning calorimetry. We also conducted subdermal allografting of the crosslinked pericardium and thoracic aorta in rats, and verified the anti-calcification efficacy of TGA by histological evaluations with von Kossa stain, and immunological evaluations using tenascin-C (TN-C) or matrix metalloproteinase-9 (MMP-9). TGA treatment resulted in slower increases in Ts of the pericardium, and it required 9-12 h to reach Ts achieved by GA. In subdermal implantation of rat tissues, calcium content was lower in the TGA group than in the GA groups (p < 0.005). The expression site of TN-C and MMP-9 differed from the primary location of calcium deposition in the thoracic aorta treated with TGA suggesting a different underlying mechanism in calcification between GA and TGA crosslinking. In conclusion, TGA crosslinking in the allograft showed superior anti-calcification effect as compared to brief treatment by GA, although TGA crosslinking process was slow.

Topics: Animals; Aorta, Thoracic; Bioprosthesis; Calcinosis; Cross-Linking Reagents; Disease Models, Animal; Epoxy Compounds; Glutaral; Heart Valve Prosthesis; Humans; Male; Pericardium; Rats; Rats, Wistar; Temperature; Transplantation, Autologous

One of the most important factors responsible for the calcific failure of bioprosthetic heart valves is glutaraldehyde crosslinking. Ethanol (EtOH) incubation after glutaraldehyde crosslinking has previously been reported to confer anticalcification efficacy for bioprostheses. The present studies investigated the anticalcification efficacy in vivo of the novel crosslinking agent, triglycidyl amine (TGA), with or without EtOH incubation, in comparison with glutaraldehyde.. The TGA crosslinking (±EtOH) was used to prepare porcine aortic valves for both rat subdermal implants and sheep mitral valve replacements, for comparisons with glutaraldehyde-fixed controls. Thermal denaturation temperature, an index of crosslinking, cholesterol extraction, and hydrodynamic properties were quantified. Explant endpoints included quantitative and morphologic assessment of calcification.. Thermal denaturation temperatures after TGA were intermediate between unfixed and glutaraldehyde-fixed. EtOH incubation resulted in almost complete extraction of cholesterol from TGA or glutaraldehyde-fixed cusps. Rat subdermal explants (90 days) demonstrated that TGA-EtOH resulted in a significantly greater level of inhibition of calcification than other conditions. Thus, TGA-ethanol stent mounted porcine aortic valve bioprostheses were fabricated for comparisons with glutaraldehyde-pretreated controls. In hydrodynamic studies, TGA-EtOH bioprostheses had lower pressure gradients than glutaraldehyde-fixed. The TGA-ethanol bioprostheses used as mitral valve replacements in juvenile sheep (150 days) demonstrated significantly lower calcium levels in both explanted porcine aortic cusp and aortic wall samples compared with glutaraldehyde-fixed controls. However, TGA-EtOH sheep explants also demonstrated isolated calcific nodules and intracuspal hematomas.. The TGA-EtOH pretreatment of porcine aortic valves confers significant calcification resistance in both rat subdermal and sheep circulatory implants, but with associated structural instability.

Topics: Animals; Bioprosthesis; Calcinosis; Calorimetry; Disease Models, Animal; Drug Combinations; Epoxy Compounds; Ethanol; Heart Valve Diseases; Heart Valve Prosthesis; Organ Preservation; Organ Preservation Solutions; Rats; Sheep; Swine

We investigated a novel polyepoxide crosslinker that was hypothesized to confer both material stabilization and calcification resistance when used to prepare bioprosthetic heart valves. Triglycidylamine (TGA) was synthesized via reacting epichlorhydrin and NH(3). TGA was used to crosslink porcine aortic cusps, bovine pericardium, and type I collagen. Control materials were crosslinked with glutaraldehyde (Glut). TGA-pretreated materials had shrink temperatures comparable to Glut fixation. However, TGA crosslinking conferred significantly greater collagenase resistance than Glut pretreatment, and significantly improved biomechanical compliance. Sheep aortic valve interstitial cells grown on TGA-pretreated collagen did not calcify, whereas sheep aortic valve interstitial cells grown on control substrates calcified extensively. Rat subdermal implants (porcine aortic cusps/bovine pericardium) pretreated with TGA demonstrated significantly less calcification than Glut pretreated implants. Investigations of extracellular matrix proteins associated with calcification, matrix metalloproteinases (MMPs) 2 and 9, tenascin-C, and osteopontin, revealed that MMP-9 and tenascin-C demonstrated reduced expression both in vitro and in vivo with TGA crosslinking compared to controls, whereas osteopontin and MMP-2 expression were not affected. TGA pretreatment of heterograft biomaterials results in improved stability compared to Glut, confers biomechanical properties superior to Glut crosslinking, and demonstrates significant calcification resistance.

Topics: Animals; Aortic Valve; Biocompatible Materials; Biomechanical Phenomena; Calcinosis; Cross-Linking Reagents; Epoxy Compounds; Models, Animal; Pericardium; Prostheses and Implants; Swine