Abstract: In this study, we explore the synthesis of hyperbranched poly(ethylene glycol) (HBP) through kinetically controlled homopolymerization of multivinyl monomers (MVMs) and its application in stem cell culture. Using poly(ethylene glycol) diacrylate (PEGDA) as the MVM, 4-Cyano-4-(phenylcarbonothioylthio)pentanoic acid (CPADB) as the chain transfer agent (CTA), and 2,2'-azobisisobutyronitrile (AIBN) as the initiator, two HBPs with different branching degrees (BD) and multiple pendent vinyl groups were successfully synthesized in a one-pot reversible addition-fragmentation chain transfer (RAFT) polymerization, which by regulating reaction parameters to specifically promote intermolecular combination. HBP can react with thiolated gelatin (gel-SH) via thiol-ene click chemistry to form HBP/gel-SH hydrogels and used for the culture of human induced mesenchymal stem cells (iMSCs). The chemical composition and structure of the HBP were characterized using gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR). Results indicated that the BD of HBP can be effectively regulated by adjusting PEGDA concentration and the ratio of PEGDA:CPADB:AIBN. Rheological analysis showed that HBP and gel-SH could cross-link to form a hydrogel within 2 min. Cell culture experiments demonstrated that the HBP/gel-SH hydrogels exhibit no significant cytotoxicity, with the hydrogel formed by HBP with a higher BD displaying better biocompatibility. These hydrogels hold great potential for applications in stem cell culture and expansion.

Key words: Hyperbranched polymer; Hydrogel, Thiol-ene click chemistry, Cell culture