Epigenetic memory as a readout of environmental susceptibility defines cell manufacturability in mesenchymal stem...

Mesenchymal stem cells (MSCs) are highly sensitive to fluctuations in culture process parameters (CPPs), which remain a major barrier to consistent product quality in cell manufacturing. A mechanistic understanding of how cells respond to and encode these variations is essential to enable standardization under a quality-by-design paradigm.

To address this, we propose the concept of cell manufacturability, defined as the intrinsic ability of cells to maintain their functional phenotype in response to variable inputs. Drawing inspiration from the Japanese concept of yuragi (gentle, adaptive fluctuation), we profiled histone modifications (H3K4me3 and H3K27me3) at the promoters of critical quality attribute (CQA) genes using chromatin immunoprecipitation followed by quantitative PCR (ChIP-qPCR). We established a cell potency index based on the H3K4me3/H3K27me3 ratio. Weighted principal component analysis (PCA) was applied to derive two composite indices: the Cell Susceptibility Index (CSI), indicating environmental responsiveness, and the Cell Comparability Index (CCI), representing inter-donor and process consistency.

The CSI and CCI captured distinct, condition-dependent patterns. Under low-stress conditions (e.g., early passages and low seeding density), a positive correlation between CSI and CCI reflected reproducible adaptive plasticity. Conversely, high-stress cultures exhibited a strong negative correlation, which was indicative of unstable epigenetic responses. These patterns were consistently observed across different MSC sources, underscoring the generalizability of the framework.

This study highlights CSI and CCI as quantitative, chromatin-based metrics that offer a mechanistic basis for characterizing MSC plasticity and manufacturing robustness. Integration of these indices into the evaluation of cell manufacturability offers a predictive and scalable approach to enhance standardization and batch comparability in MSC production processes.