Combining Hydrogels With Tuned Stiffness and Metabolomics to Identify Small Molecules that Drive Mesenchymal Stem Cell Differentiation

Here we demonstrate how materials can be used as a simple and rapid means of identifying important small molecules, in this report we demonstrate osteogenesis, osseochondral development and neural marker expression from mesenchymal stem cells (MSCs). We do this using nanofibrous, stiffness-tunable hydrogel biomaterials that can be used to target different mesenchymal stem cell (MSC) differentiation (expression of neuronal, chondrogenic and osteoblastic markers) through simple adjustment of gelation pH providing biomaterial stiffness of 2, 6 or 38 kPa. The hydrogels comprise self-assembling short chain peptides that form a nanofibrous scaffold and do not require coating with e.g. collagen before cell culture. As the MSCs underwent targeted differentiation, metabolic phenotype was tracked using an unbiased mass spectrometry approach and bioinformatics performed to inform which metabolites, or biological small molecules, were of greatest importance in each lineage. Data revealed novel small molecules that could be used to influence stem cell behaviour in vitro in a predictable manner. The study highlights how material properties can be used to discover novel therapeutic targets for enhanced cell development and function in in vitro applications. It also highlights the potential role of materials in replacing complex media formulations to control stem cell fate in pharmaceutical research