Engineering bacterial protein polymers to support human pluripotent stem cell growth and differentiation in culture

Induced pluripotent stem cells (iPSCs) are of significant value due to their wide ranging potential, removing the need for embryonic material. To successfully culture, expand and differentiate these cells, it is crucial to maintain a precise biological environment, including an appropriate attachment substrate. Commonly used attachment substrates include recombinant extracellular matrix (ECM) components like vitronectin, as well as animal-derived ECM mixes such as GelTrex and Matrigel. However, there is growing interest in exploring alternative approaches to support bioactivity of cells. One approach that is gaining traction is the use of the Caf1 protein of Yersinia pestis . This protein is appealing primarily due to its stability, modularity, and ease of production. In this study, we have developed novel variants of Caf1 that effectively support the growth and differentiation of iPSCs, performing at least as well as GelTrex. Our findings highlight the potential of Caf1 laminin and vitronectin mimics as viable alternatives for supporting iPSC growth and differentiation. The successful development of these Caf1 variants opens new avenues for the field, paving the way for better defined, more cost-effective and readily available attachment substrates in iPSC research and applications. ### Competing Interest Statement DTP, HW and JHL are directors of MarraBio Ltd., a spinout company set up to commercialise the Caf1 technology. The company had no role in the funding or design of the study.