Molecular Programming of Stem-Cell Differentiation: From Soluble Factors to Agonist Antibodies

Stem-cell differentiation technologies have traditionally relied on recombinant growth factors, cytokines, and morphogens to initiate and guide lineage specification toward clinically relevant cell types. These approaches have enabled substantial progress in regenerative medicine, as exemplified by recent advances in cell-replacement therapies for Parkinson’s disease, type 1 diabetes, and retinal degeneration. However, protein-based ligands and soluble factors are often limited by short half-lives, pleiotropic signaling, condition-dependent effects, and challenges in achieving precise spatial and temporal control in scalable systems. In this review, we survey differentiation strategies driven by administered substances, organizing the field into five material-centric modules: recombinant growth factors, cytokines, morphogens, exogenous ligands, and agonist antibodies. For each module, we summarize mechanistic principles, representative studies, controllable variables, and translational considerations. While growth factors, cytokines, morphogens, and exogenous ligands remain central tools for directing lineage commitment and maturation, recent studies indicate that agonist antibodies offer an additional and distinct means of controlling differentiation outcomes. These antibodies can function as receptor agonists while also imparting tissue-selective effects, enabling lineage specification with coordinated spatial targeting. By focusing on differentiation methods driven by administered molecules and excluding direct physical stimulation or complex 3D constructs, this review provides a framework that is particularly relevant to immunology and translational practice. We highlight agonist antibody-based induction as an emerging strategy that complements established ligand-based approaches and may broaden the design space for clinically applicable stem-cell differentiation.