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