The Absence and Need for Certified Xenofree iPSC Culture Conditions in Disease Modeling: From Alzheimer's to COVID‐19

Abstract

Human‐induced pluripotent stem cells (iPSCs) and their differentiated derivatives are a powerful way to study disease processes and healthy function in conditions ranging from Alzheimer's disease (AD) to COVID‐19. However, these models often remain limited due to their contamination with non‐human animal‐derived components. As such, there is a need for a major shift to entirely xenofree methodologies so experimental conditions are free of non‐human animal contaminants. Here, we evaluate the availability of xenofree stem cell lines and the extent of xenogenicity in major public sources of AD and control cell lines that could also be used in COVID‐19 iPSC‐related research. In order to assess the extent of xenogenicity, we analyzed three primary catalogs of stem cell repositories for AD and control cell lines. The iPSC catalogs were chosen based on their efforts to create accessible, high quality cell lines and recognition of the need to improve reproducibility in stem cell research. These public collections included the Coriell Institute for Medical Research, the California Institute for Regenerative Medicine (CIRM), and the European Bank for induced Pluripotent Stem Cells (EBiSC). Over 300 cell lines were reviewed in this study. Although all cells were obtained from human donors, none of the collections were determined to meet fully verifiable xenofree criteria. A large numbers of cell lines were generated with one or more known xenogenic components (e.g., fetal bovine serum, Matrigel). Others lines were classified as 'suspected exposure to xenogenic components', based on the composition of the culture reagent and/or lack of manufacturer product information to verify whether animal‐free reagents were used (e.g., Eagle's Minimum Essential Medium). Even CIRM, a repository clearly dedicated to producing xenofree cell lines, included Vitronectin (VTN‐N) Recombinant Human Protein that was manufactured using Casein Peptone Type I derived from bovine milk. The results show that major stem cell collections ‐‐ despite substantial efforts to improve accessibility, consistency and reproducibility ‐‐ either fail to be xenofree or make it difficult to establish truly xenofree research conditions. The absence of xenofree resources fundamentally undermines the clinical, scientific and ethical integrity of stem cell research and raises specific concerns for readiness to study AD and COVID‐19 using iPSCs. There is a clear need for xenofree sources, not only for clinical applications but also for the discovery and testing phases of research. This will likely require the development of open and transparent xenofree certification. By establishing truly xenofree research criteria, the field can build a foundation for accurately and effectively studying conditions that affect large parts of the population, including AD and COVID‐19. Xenofree conditions for the study of long‐term sequelae will be important in COVID‐19 research as sources for iPSC cells from recovered and vaccinated individuals become available. Beyond population impact ...