# A Cross-Linked Cyclosiloxane Polymer Matrix as a Platform Enabling Long-Term Culture of Human Induced Pluripotent Stem Cells with Naïve-Like Features

## TL;DR

A new polymer matrix supports long-term growth of human stem cells with properties similar to the more potent naïve state, improving regenerative medicine potential.

## Contribution

A cross-linked cyclosiloxane polymer matrix, poly-Z, enables long-term hiPSC culture with naïve-like features without feeder cells or undefined ECMs.

## Key findings

- hiPSC spheroids on poly-Z maintained pluripotency markers and normal karyotypes for 60 days.
- mRNA sequencing showed up-regulation of naïve pluripotency genes compared to primed states on conventional surfaces.
- Reduced cell–ECM interaction genes in poly-Z cultures contributed to naïve-like features.

## Abstract

Culture platforms for human induced pluripotent stem cells (hiPSCs) that rely on feeder cells or extracellular matrices (ECMs) face substantial limitations for practical regenerative medicine applications, including undefined components, high costs, and a tendency to maintain hiPSCs in the primed pluripotent state, which has lower differentiation potential than the naïve state. To overcome these challenges, we developed a long-term hiPSC culture platform based on a cross-linked cyclosiloxane polymer matrix that preserves pluripotency with naïve-like characteristics. Through optimization, we identified an ideal cyclosiloxane polymer matrix, designated as poly-Z, which supported the growth of hiPSCs as spheroids. Even after 60 d of continuous culture, hiPSC spheroids maintained on poly-Z retained pluripotency markers and normal karyotypes at levels comparable to those of hiPSC colonies cultured on conventional vitronectin (VN)-coated plates. Furthermore, mRNA sequencing revealed that hiPSC spheroids cultured on poly-Z not only exhibited up-regulation of typical pluripotency-related genes but also showed increased expression of genes associated with the naïve pluripotent state, in contrast to the primed state observed in hiPSCs cultured on VN-coated plates or in suspension culture. Gene ontology (GO) analysis and gene set enrichment analysis (GSEA) further suggested that the down-regulation of genes involved in cell–ECM interactions contributed to the induction of naïve-like features in poly-Z-cultured hiPSC spheroids. These findings highlight the potential of cross-linked cyclosiloxane-based polymer matrices as an innovative platform for human pluripotent stem cell research and regenerative medicine.