Recombinant production of human transferrin for cell culture

描述（由申请人提供）：转铁蛋白通过调节细胞铁摄取、转运和利用在控制细胞生长和存活中起关键作用，因此是用于基于细胞培养生产治疗性蛋白质和疫苗的基本培养基成分。随着对通过使用动物/人源性蛋白质成分传播传染性病原体的风险增加的关注，生物制药工业优选重组转铁蛋白来替代血浆血清源性人或牛转铁蛋白。在第一阶段SBIR项目中，我们成功地完成了在水稻谷粒中表达重组人转铁蛋白的可行性研究，通过显示重组转铁蛋白在可逆结合铁和促进细胞生长的能力方面与天然人转铁蛋白功能等同。表达量达到水稻种子干重的0.88%，比我们的目标表达量（0.1%）高出8倍以上，比商业化应用所需的阈值水平（0.01%）高出88倍。在本II期计划中，我们建议将I期选择的转基因植物进一步培育成转铁蛋白稳定高水平表达和高产量的纯合转基因株系;对重组转铁蛋白进行全面的成分和生化分析;并将重组转铁蛋白与商业天然人转铁蛋白进行比较，以检查它们在增殖杂交瘤细胞和培养干细胞方面的等效性。我们预期，作为第II阶段的结果，作为人或牛血浆衍生转铁蛋白的替代品的安全且可负担的重组转铁蛋白将以比目前可获得的重组转铁蛋白低约20倍的价格在商业上可用于生产疫苗和治疗剂的细胞培养市场以及用于再生疗法的干细胞研究。这将使数百万患者和包括儿童和老年人在内的大量健康人群的健康受益。 公共卫生相关性：转铁蛋白通过调节细胞铁摄取、转运和利用在控制细胞生长和存活中起关键作用，因此是用于基于细胞培养的治疗性蛋白质和疫苗生产的必需培养基成分。为了解决通过使用动物/人源性蛋白质成分传播传染性病原体的风险增加的安全性问题，我们使用大米来生产重组人转铁蛋白，作为血浆来源的人或牛转铁蛋白的安全且负担得起的替代品，用于基于细胞培养的疫苗和治疗剂的生产以及基于干细胞的再生治疗。

DESCRIPTION (provided by applicant): Transferrin plays a crucial role in controlling cell growth and survival by regulating cellular iron uptake, transport and utilization, and thus is an essential culture media ingredient used for cell culture-based production of therapeutic proteins and vaccines. With the concerns over the increasing risks of transmission of infectious pathogenic agents through the use of animal/human-derived protein ingredients, recombinant transferrin is preferred to replace the plasma serum-derived human or bovine transferrin by the biopharmaceutical industry. In a Phase I SBIR project, we successfully completed the feasibility study of expressing recombinant human transferrin in rice grain by showing that the recombinant transferrin is functionally equivalent to the native human transferrin in terms of their capacity of binding iron reversibly and promoting cell growth. The expression level of the bioactive recombinant transferrin is up to 0.88% of rice seed dry weight, which is over eight fold higher than our targeted expression level (0.1%) and 88 fold higher than the threshold level (0.01%) required for commercial application. In this phase II proposal, we propose to further develop the transgenic plants selected in Phase I into homozygous transgenic lines with stable high level expression of transferrin and high grain yield; perform comprehensive compositional and biochemical analysis of the recombinant transferrin; and compare the recombinant transferrin to commercial native human transferrin for examining their equivalency in proliferating hybridoma cells and culturing stem cells. We anticipate that as a result of phase II, a safe and affordable recombinant transferrin as an alternative to human or bovine plasma-derived transferrin will be made commercially available to both the cell culture market for the production of vaccines and therapeutics and the stem cell research for regenerative therapies at a price of about 20 times less than that of the currently available recombinant transferrin. This will benefit millions of patients and the health of a large population of healthy people including children and the elderly. PUBLIC HEALTH RELEVANCE: Transferrin plays a crucial role in controlling cell growth and survival by regulating cellular iron uptake, transport and utilization, and thus is an essential culture media ingredient used for cell culture-based production of therapeutic proteins and vaccines. To address the safety concerns over the increasing risks of transmission of infectious pathogenic agents through the use of animal/human-derived protein ingredients, we use rice to produce recombinant human transferrin as a safe and affordable alternative to plasmas-derived human or bovine transferrin for cell-culture-based production of vaccines and therapeutics and the stem cell-based regenerative therapies.