Sustained growth factor release driven cellular therapy indicates enhanced potential for regeneration upon mechanical...

Mesenchymal stem cells (MSCs) are characterised by excellent plasticity and clonogenic potential, thus rendering them great candidates for the development of cellular therapies against damaged tissues where regeneration is needed. Nevertheless, their multipotency becomes significantly affected upon removal from their natural niches, signifying the need for developing efficient methods that will preserve their regenerative and immunomodulatory capacity. It is crucial to protect these properties beyond traditional modelling, ensuring scalability to large numbers, which will optimise their potential for use in cellular therapies. In this study, a combination of strategies was implemented to maximise the preservation of MSC multipotent phenotype, such as their growth as spheroids and their incorporation into non-bioactive polyethylene glycol (PEG)-hydrogels. Importantly, we further propose that the use of a novel continuous growth factor (GF) release technology in a crystal form can be locally administered inside the MSC spheroids. This establishes an intimate, responsive connection between the crystals and the cells, where the cell-induced degradation stimuli are proportional to the corresponding release of GFs that they receive. We report that the gradual release of NGF-β acts superiorly compared to the conventional soluble form while conferring important benefits on spheroids, such as cytoprotection from stress as well as higher persistence of multipotent markers. Subsequently, the enhanced retention translates to a more responsive phenotype upon mechanical injury, initiation of migration and upregulation in expression of markers that facilitate cytoskeletal rearrangement and homing to damaged tissues.