Characteristics and viral propagation properties of a new human diploid cell line, walvax-2, and its suitability as a candidate cell substrate for vaccine production

Abstract

Human diploid cell strains (HDCSs), possessing identical chromosome sets known to be free of all known adventitious agents, are of great use in developing human vaccines. However it is extremely difficult to obtain qualified HDCSs that can satisfy the requirements for the mass production of vaccines. We have developed a new HDCS, Walvax-2, which we derived from the lung tissue of a 3-month-old fetus. We established primary, master and working cell banks successfully from reconstituted frozen cells. Observations during the concurrent propagation of Walvax-2 and MRC-5 cells revealed differences in terms of growth rate, cell viability and viral sensitivities. Specifically, Walvax-2 cells replicated more rapidly than MRC-5 cells, with Walvax-2 cells attaining the same degree of confluence in 48 hours as was reached by MRC-5 cells in 72 hours. Moreover, Walvax-2 cells attained 58 passages of cell doublings whereas MRC-5 reached 48 passages during this period. We also assessed the susceptibility of these cells to rabies, hepatitis A, and Varicella viruses. Analysis of virus titers showed the Walvax-2 cells to be equal or superior to MRC-5 cells for cultivating these viruses. Furthermore, in order to characterize the Walvax-2 cell banks, a series of tests including cell identification, chromosomal characterization, tumorigenicity, as well as tests for the presence of microbial agents, exogenous viruses, and retroviruses, were conducted according to standard international protocols. In conclusion, results from this study show that Walvax-2 cell banks are a promising cell substrate and could potentially be used for the manufacturing of HDCVs.

Holistic Approach of Swiss Fetal Progenitor Cell Banking: Optimizing Safe and Sustainable Substrates for Regenerative Medicine and Biotechnology

“…Additionally, aging of the MRC-5 cells, recurrent doubts about the identity of currently marketed MRC-5 cells, and unavailability of these in different geographical regions have led to the establishment of replacement cell types. Modern alternatives were reportedly developed (e.g., Walvax-2 cell type, PRC), with particular attention being paid to the ethnicity of the donor, in order to optimize industrial outputs by exploiting shorter doubling times, improved robustness, or cell viability (Ma et al, 2015). Recently established primary lung FPCs, such as the FE002-Lu cell type, benefit from all the aforementioned technical advantages of FPCs, and may be expanded at full industrial scale within specific multi-tiered cell banking workflows, therefore potentially constituting a tangible candidate for the replacement of the MRC-5 cell type.…”

Evolution of Diploid Progenitor Lung Cell Applications: From Optimized Biotechnological Substrates to Potential Active Pharmaceutical Ingredients in Respiratory Tract Regenerative Medicine

“…Despite extensive use of such materials, as well as ethical and moral debates centered mainly upon the original tissue procurement, such diploid cells have been instrumental in the development and therapeutic application of several life-saving products over a half-century [8][9][10][11][12][13][14][15][16][17][18]. The increasing material demand driven by modern biotechnological industrial development and aging of the original cell sources (i.e., stability issues) has recently prompted renewed consideration for novel substrate cell type establishment and qualification [19][20][21][22]. The unique sustainability and safety aspects of diploid progenitor cell sources, exploited as safe and stable multi-tiered biobanks, are emerging as critical advantages in modern manufacturing and quality assurance environments [23][24][25][26].…”

“…Due to the optimal qualification of human diploid cell sources as vaccine substrates and despite the considerable sustainability of such derived cell banks, a major bottleneck is currently arising with the transiently high activity in the vaccine industry and the aging of the original cell sources developed in the 1960s (e.g., MRC-5, WI-38 cell types) [3,5,20]. While optimization of product manufacturing workflows has been widely undertaken by vaccine and biologics pharmaceutical industries, relatively low attention has been set on the optimization of cell sourcing and the re-establishment of robust cell types or cell lines.…”

The hUC-MSCs cell line CCRC-1 represents a novel, safe and high-yielding HDCs for the production of human viral vaccines

“…HDCs, such as WI-38 and MRC-5, derived from human fetal lungs, maintain normal karyotype as well as non-tumourigenic characteristics during a finite serial propagation. They have been used in the manufacture of human vaccines for many years without causing serious vaccine-associated adverse events and are thus considered as the safest cell substrates for the production of human viral vaccines 10 , 11 . However, because of the limited propagation capacity as well as ethical issues, continuous supply of low-passage HDCs has always being a critical problem in the field of vaccine production 3 .…”