Safety and Feasibility of Nasal Delivery of Human Dental Follicle Mesenchymal Stem Cell-Derived Exosomes for Negative Symptoms in Treatment-Resistant Schizophrenia: A Pilot Study

The goal of this clinical trial is to determine the safety and feasibility of nasal delivery of human dental follicle mesenchymal stem cell-derived exosomes in the treatment of negative symptoms of treatment-resistant schizophrenia. It will also learn about the preliminary efficacy of the exosomes. The main questions it aims to answer are: Is the safety of the exosomes enough for participants? Is the feasibility of nasal delivery of exosomes for participants? Do the exosomes exert any benefits on the negative symptoms of treatment-resistant schizophrenia? Participants will: Take a nasal spray of exosomes twice weekly for 2 months Take vital sign checks every day, regular visits for an interview, and lab examinations