Subsequently, the in vivo studies demonstrated the ability of the IL-10-loaded collagen hydrogels to deliver and retain the cytokine within the striatum (relative to bolus injection of the cytokine), and most importantly in the context of cell-based brain repair for Parkinson’s disease, to reduce the microglial neuroinflammatory response to dopaminergic grafts. The gene discussed is IL10; the disease is Parkinson disease.