The invention is directed to methods for preventing and/or treating nasal polyps. The invention is further directed to methods for preventing and/or treating rhinosinusitus. The invention is further directed to reducing inflammation of the paranasal sinuses. The invention is further directed to methods for preventing and/or treating nasal polyps and/or rhinosinusitis by administering to a subject suffering from such conditions, or at risk of developing such conditions, novel cellular factor-containing solution compositions (referred to herein as “CFS” compositions), including novel immediate-release, targeted-release, and sustained-release (SR) cellular factor-containing solution compositions (referred to herein as “SR-CFS” compositions)
