The development of instructive substrates with application in tissue regeneration has become the focus of intense research in the last years. This work reports a new system that is simultaneously bioinstructive, due to the presence of immobilized growth factors (GFs) that control biological function, and bioresponsive as it promotes the assembly into microgels using cells as attachment points. It is well established that platelets are an important source of autologous and complex mixture of GFs that can modulate cell proliferation and differentiation. Herein we propose antibody-conjugated chitosan-based microparticles (μPs) as a method to select specific GFs from platelet lysates (PLs), which will then be used to modulate cell function.