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Biophysical and Biochemical Characterization of Peptide, Protein, and Bioconjugate Products
Published in Sandeep Nema, John D. Ludwig, Parenteral Medications, 2019
Tapan K. Das, James A. Carroll
There are several types of sialic acids possible, and these types depend on the production cell line [51]. For example, murine cell lines such as NS0 produce mainly N-glycolylneuraminic acid, while CHO cell lines produce mainly N-acetylneuraminic acid. These sialic acid types can be distinguished using sialic acid typing, in which the sialic acid residues are removed from the glycans by acid hydrolysis, labeled with a fluorescent tag, and separated by reversed-phase HPLC. The identities of the sialic acids are determined by comparison of the retention times to a sialic acids reference panel of standards.
A human pericardium biopolymeric scaffold for autologous heart valve tissue engineering: cellular and extracellular matrix structure and biomechanical properties in comparison with a normal aortic heart valve
Published in Journal of Biomaterials Science, Polymer Edition, 2018
Frantisek Straka, David Schornik, Jaroslav Masin, Elena Filova, Tomas Mirejovsky, Zuzana Burdikova, Zdenek Svindrych, Hynek Chlup, Lukas Horny, Matej Daniel, Jiri Machac, Jelena Skibová, Jan Pirk, Lucie Bacakova
The changes in the mechanical behavior and in the structural properties of decellularized heart valve leaflets may also have a negative impact on the durability of xenogeneic heart valve prostheses [80]. In addition, remnant cellular components (such as DNA, mitochondria, membrane lipids, and cytosolic proteins) can also elicit an adverse inflammatory response and inhibit constructive remodeling, if they are not adequately removed [80]. There is also an association between macrophage phenotype (a shift in macrophage phenotype predominance from M1 to M2) and remodeling outcome [80]. Several antigens are involved in the human immune response to xenogeneic heart valve tissue, and glutaraldehyde fixation cannot sufficiently eliminate or inactivate these foreign antigens [81]. It was confirmed that the immune response in patients towards glutaraldehyde-fixed porcine heart valves is induced by porcine proteins albumin, collagen 6A1, and also αGal epitopes (α 1,3 galactose modifications) [82]. However, there are also other non-Gal carbohydrate antigens in xenogeneic tissues, e.g. non-acid and acid glycosphingolipids. Two common sialic acids in mammals, N-acetylneuraminic acid (Neu5Ac) and its hydroxylated form N-glycolylneuraminic acid (Neu5Gc), have been described in bioprosthetic heart valves [64,65]. These xeno-antigens were recognized by human anti-Neu5Gc IgG, which supports their immunogenic nature and may play a role in valve deterioration within human patients [83,84]. Magnetic resonance imaging (MRI) and a histologocal evaluation revealed a high frequency of in vivo graft failure early after implantation, due to inflammation and fibrosis of Matrix P (a decelularized porcine graft) tissue-engineered pulmonary valves (TEPV) [85]. Surgical or transcatheter TEPV replacement was needed in 52% of patients 19 months after Matrix P TEPV implantation [85].