ABSTRACT
【Objective】 To compare the effects of human albumin products from different domestic manufacturers on human stem cell culture. 【Methods】 Human CD34+ cells were cultured by supplementing human albumin from different manufacturers to serum-free medium, and the expansion ratios of cells within 15 days were counted. Post translational modifications of human albumin products were studied by LC-MS. 【Results】 Supplementing plasma-derived human albumin(pd-alb) to serum-free medium, the expansion ratios of cells could reach up to 20.6±5.7, while the recombinant human albumin(rhAlb) resulted in no significant expansion within 15 days. LC-MS showed significant differences in post-translational modifications from different human albumin products. 【Conclusion】 Different human albumin products showed significantly different effects in the expansion of stem cells due to different sources, processes and stabilizers. Pd-alb products were better for stem cell culture than rhAlb products. There are significant differences between pd-albs and rhAlbs in post-translational modification, but whether these differences are related to stem cell expansion remains to be studied.
ABSTRACT
OBJECTIVE: To determine glycoprotein content in recombinant human albumin from different expression systems with different methods. METHODS: Recombinant human albumin samples from Saccharomyces cerevisiae expression system, Pichia pastoris expression system, Oryza sativa expression system as well as plasma derived human albumin were investigated by phenol sulfuric acid method, HPLC peak area method and ConA combining elution HPLC method. RESULTS: For 10 batches of samples expressed in pichia pastoris expression system, the total contents of mannose were 2.7 mg•g(Pro)-1 (A manufacturer, n = 4) and 1.7 mg•g (Pro)-1 (B manufacturer, n = 6), respectively. The HPLC peak area percentages of ConA binding protein in recombinant human albumin from Pichia pastoris expression system were the highest, which showed 2.65% (A manufacturer) and 0.71% (B manufacturer) respectively, the peak area percentage of ConA binding protein in Oryza sativa expression system was 0.05% (E manufacturer, n = 3), and the ConA binding protein peak area of plasma derived human albumin was 0.01% (W manufacturer). The results of ConA binding and elution analysis with HPLC method for Quantitative determination of ConA binding protein showed that the ConA binding protein contents in the samples from pichia pastoris expression system were much higher: 27.58 mg•g(Pro)-1 (A manufacturer), 21.48 mg•g(Pro)-1 (B manufacturer), 32.02 mg•g(Pro)-1 (C manufacturer); the ConA binding protein content in the sample from Saccharomyces cerevisiae expression system was lower, 2.29 mg•g(Pro)-1 (D manufacturer); the ConA binding protein content in the samples from oryza sativa expression system was the lowest, 1.27 mg•g(Pro)-1 (E manufacturer); the plasma derived human albumin ConA binding protein content was 31.16 mg•g(Pro)-1 (S manufacturer). CONCLUSION: In terms of the results of the samples and methods involved in this study, there were glycosylated or glycol forms of protein in all recombinant human albumin samples from different expression systems; the glycosylated protein content in samples of Pichia pastoris expression system is higher than Saccharomyces cerevisiae expression system, while the glycoformed protein in samples of Oryza sativa expression system is the lowest. Plasma derived human albumin also contains glycoprotein or glycosylated protein.
ABSTRACT
OBJECTIVE: To evaluate the applicability of UPLC/MS method for the identification test of human serum albumin (HSA) products including plasma derived and recombinant HSA samples. METHODS: ACQUITY UPLC with Vion IMS QT of LC/MS system was used combined with on-line HSA sample desalting with ACQUITY UPLC BEH C18 column. The acquired multiplycharged mass spectrum was processed with MaxEnt1 automatic protein deconvolution software in UNIFI, which can transfer the raw mass spectrometry data to zero charge molecular mass or mass distribution of the intact protein. RESULTS: Intact protein mass analysis not only provided the accurate mass of HSA, but also provided an overall view of the heterogeneity of HSA and the relative amounts of various forms. From this study, a very specific mass signal [(66 437 ± 1), which is the theoretical average MW of human serum albumin ]was obtained from all the six HSA samples. And the characteristic spectra of different samples were also got. CONCLUSION: UPLC/MS method has very good specificity and high sensitivity and can distinguish HSA products made by different manufacturers and processes. The total analytical time is 10 min, which is ideal for the QC identification test of HSA products.
ABSTRACT
OBJECTIVE: To develop and verify a magnetic beads-based extraction combined with quantitative PCR(q-PCR)method for determination of residual host cell DNA in recombinant human albumin products expressed in Pichia pastoris. METHODS: The residual Pichia pastoris host cell DNA in samples were extracted by magnetic beads-based extraction method and then determined by Taqman probe-based q-PCR. The residual DNA content was calculated according to the standard curve. The developed method was verified for accuracy and precision with different derivation albumin matrixes and concentrations, and the residual DNA of 3 batches of recombinant human albumin products expressed in Pichia pastoris were detected. RESULTS: The minimum detection limit of Pichia pastoris residual DNA by the developed method was 3 fgμL-1, the linear range was 3 fgμL-1-300 pgμL-1, and the correlation coefficient(r2) was 0.998 3. The recovery rates of spiked samples in rHA matrix were 93.58%(RSD 19.6%, n=4)at 100 fgμL-1 and 215.56%(RSD 42.9%, n=4) at 10 fgμL-1, respectively. The recovery rates of spiked samples in HSA matrix were 67.09%(RSD 6.9%,n=3)at 100 fgμL-1 and 113.40%(RSD 11.1%, n=3) at 10 fgμL-1, respectively. The residual Pichia pastoris DNA contents in 3 batches of recombinant human albumin products expressed in Pichia pastoris determined by the developed method were 5.98, 4.16, 4.49 fgμL-1(n=7) respectively and not more than 1 ng per 10 g protein. CONCLUSION: Magnetic beads extraction method combined with fluorescence quantitative PCR method solves the technical problem of quantitative determination of trace DNA in recombinant human albumin products with ultra-high concentration protein. The method is accurate and reproducible, and can be used for quantitative determination of DNA residue in recombinant human albumin expressed by Pichia pastoris.