This study tests a new nasal spray for adults (18-65 years) with chronic rhinosinusitis (CRS) without nasal polyps. The spray contains a temperature-sensitive gel (thermosensitive gel) that turns into a soft gel inside the nose to slowly release three active ingredients: human umbilical cord mesenchymal stem cell exosomes (hUC-MSC-Exo) to help heal the nasal lining, mupirocin (an antibiotic that kills Staphylococcus aureus bacteria), and DNase I (an enzyme that breaks down thick mucus). The study aims to check the safety of this triple combination and see if it can reduce infection, clear mucus, and improve symptoms. Participants will be randomly assigned to one of three groups: triple spray, a dual spray (without exosomes), or a placebo (gel only). The treatment is used twice daily for 4 weeks, with follow-up visits up to day 90. The study is single-centre, double-blind, and placebo-controlled. Outcome measures include safety (adverse events graded by Common Terminology Criteria for Adverse Events version 5.0, CTCAE v5.0), bacterial clearance rate, changes in nasal endoscopy score (Lund-Kennedy), quality of life (Sino-Nasal Outcome Test-22, SNOT-22), and nasal symptom visual analog scale (VAS).