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

Inclusion Criteria:

1) Conforms to the ICD-10 diagnosis of schizophrenia; 2) age between 18 and 60 years old; 3) course of more than 5 years of long-term inpatients; 4) the last 6 months without acute aggravating period, and no change in recent two months regimen; 5) to including clozapine, two different antipsychotics enough poor foot therapy treatment response; 6) positive and negative symptoms scale - negative symptom factor (PANSS - FSNS) 24 or more; 7) three core of PANSS negative symptoms (N1, N4 interchange and N6) at least 2 or 4; 6) clinical overall impression scale - illness severity (-s) CGI score of 4 or more points; 7) signed a written informed consent.

Exclusion Criteria:

1) Has a history of severe allergies; 2) there is a clear brain organic disease; 3) with serious body disease (such as the instability of coronary artery disease, malignant arrhythmia, liver and kidney function is not complete, bronchial asthma, COPD acute aggravating period, autoimmune diseases, etc.); 4) there is accord with the ICD - 10 patients with other psychiatric diagnosis standard sample obstacles (such as schizoaffective disorder, schizophrenia, bipolar I disorder, bipolar type Ⅱ dysfunction, broad developmental disabilities, mental retardation, delirium, dementia, forgotten obstacles or other cognitive impairment, etc.); 5) condition fluctuation, the need to adjust the drug solution; 6) don't cooperate with treatment, 7) with severe rhinitis, nasal allergies; 8) for nearly three months has a history of MECT therapy; 9) suicide risk; 10) during pregnancy or lactation women, female or male subjects and spouse has pregnancy at the time of test plan or over 3 months to test is not willing to use effective contraception (effective contraceptive measures such as birth control pills and condoms or intrauterine device, etc.); 11) other unfavorable into groups.