Recombinant human serum albuminfrom OsrHSA (Wuhan Healthgen)

To solve the large size faultiness of Oryza sativa recombinant human serum albumin nanoparticle (OsrHSA NP), the structural discrepancies between OsrHSA and plasma-derived human serum albumin (pdHSA) were analyzed deeply in this research. It demonstrated that there were some subtle structural discrepancies located in subdomain IA and IIA between OsrHSA and pdHSA, which included peptide backbone, disulphide bridge and some amino acids. Firstly, the structural discrepancies were investigated through literature comparison, it inferred that the structural discrepancies resulted from the fatty acid (FA) binding to OsrHSA at site 2 of subdomain IA and IIA. To form a cavity for accommodation of FA molecule in OsrHSA, the peptide backbone structure of subdomain IA and IIA would change, accompanied by the conformational transition of disulphide bridges and side chain structure change of some amino acids in subdomain IA and IIA. These alterations induced the exposure of tryptophan (Trp) and tyrosine (Tyr) residues in subdomain IA and IIA and the decrease of net negative charges of molecular surface. The former would promote more OsrHSA molecules aggregate, and the latter would weaken the electrostatic repulsion. As a result, the size of OsrHSA NP was more extensive than that of pdHSA NP (175.84 ± 15.63 nm vs. 31.67 ± 1.31 nm) when the concentration of Dimethyl Sulphoxide (DMSO) was 30% (v/v). In this study, the experimental scheme of OsrHSA NP preparation was improved. There were two changes in the enhanced preparation scheme: pH 8.2 PBS buffer and 63% DMSO. It indicated that the improved OsrHSA NP carrier was comparable to the pdHSA NP carrier. The size and drug loading of paclitaxel-loaded improved OsrHSA NP were 53.57 ± 3.63 nm and 7.25 ± 0.46% (w/w), and those of docetaxel-loaded improved OsrHSA NP were 44.75 ± 2.26 nm and 8.43 ± 0.74% (w/w). Moreover, both NPs exhibited good stability for 168 h at 7.4 pH values. It is established that the improved OsrHSA NP is comparable to the pdHSA NP as a taxane delivery system.

To investigate the potential allergenicity of oryza sativa recombinant human serum albumin(OsrHSA)in BALB/c mice.

Eighty BALB/c mice were randomly divided into four groups i. e ovalbumin(OVA) positive control group, potato acid phosphatase(PAP) negative control group, Oryza sativa recombinant HAS(OsrHSA) group and solvent control group(phosphate buffer saline, PBS), respectively. Mice were administered by intraperitoneal injections of tested proteins and histamine levels in plasma and sIgE, sIgG, sIgG1, sIgG2 a, and tIgE antibody levels in serum were measured.

Compared with the other groups, serum tIgE, sIgE, sIgG, sIgG1 and plasma histamine levels in the OVA group were significantly increased, while serum sIgG2 a levels were decreased(P<0. 05). There was no significant difference in serum sIgE level and histamine level between the OsrHSA group and the control group(P>0. 05). Serum sIgG, sIgG1 and sIgG2 a levels were lower than those in the PAP group(P<0. 05). There was no significant difference in serum tIgE content between PAP group and OsrHSA group(P>0. 05).

The potential allergenicity of OsrHSA through traperitioneal injection in BALB/c mice was very low.