Despite the ubiquity of dispersing nanoparticles in semidilute and concentrated polymer solutions, colloid stability in such solutions has received little attention. In principle, uniform dispersions can be achieved by grafting polymers to the colloid surface to form a brush. However, researchers who investigate these systems predict that both ungrafted and grafted nanoparticles, once destabilized by depletion flocculation, should restabilize in concentrated polymer solutions. In contradiction, we will show the results of recent light scattering experiments on polydimethylsiloxane (PDMS)-grafted silica nanospheres in PDMS/cyclohexane mixtures which indicate that at high free polymer volume fractions (0.5 – 1.0 v/v) the interfacial wetting of the grafted brush is needed to stabilize the nanoparticles against aggregation. To this end, we probe optically the transition between stable and aggregated PDMS-grafted nanoparticles and develop wetting diagrams that predict the stability of the soft spheres as a function of the graft and free polymer chain lengths. Ultimately, our results show that depletion restabilization depends on the interfacial properties of nanoparticles in semidilute and concentrated polymer solutions.