Umbilical Cord Stem Cells for Skin Grafts in Donor Site Wounds

Inclusion Criteria: 1. Patients between 18 and 60 years old with extensive scars, large benign tumors, or fresh wounds on the body surface. 2. Patients who undergo medium-thickness skin graft surgery (donor site can be from the thigh, abdomen, or back). 3. Participants who have a thorough understanding of the study objectives, significance, implementation plan, potential benefits, risks involved, measures to address risks, and the rights and obligations of the subjects (including privacy protection and the right to withdraw), and are willing to participate in this clinical study and can cooperate effectively. Exclusion Criteria: Participants who meet any of the following criteria are not suitable for inclusion: 1. Hypertension, hypotension, heart disease (including history of myocardial ischemia, coronary heart disease, myocarditis). 2. Liver or kidney dysfunction. 3. Infectious diseases (including viral hepatitis, syphilis, HIV/AIDS, etc.). 4. Venous thrombosis, thoracic or abdominal aortic aneurysm, aortic dissection. 5. Blood disorders (abnormal coagulation function, anemia, leukemia, polycythemia vera, aplastic anemia, etc.). 6. Allergic conditions (urticaria, bronchial asthma, history of allergic reactions to two or more drugs or foods). 7. Respiratory system diseases (chronic bronchitis, emphysema, bronchiectasis, respiratory failure, chronic obstructive pulmonary disease, interstitial pneumonia). 8. Digestive system diseases (severe gastric or duodenal ulcers, chronic gastritis, chronic pancreatitis). 9. Urinary system diseases (chronic urinary tract infections, nephritis, nephrotic syndrome). 10. Endocrine system diseases (hyperthyroidism, diabetes, acromegaly, pituitary diseases, adrenal diseases, diabetes insipidus). 11. Organic neurological disorders or psychiatric illnesses (encephalitis, sequelae of traumatic brain injury, epilepsy, schizophrenia, hysteria, depression, severe insomnia, neurasthenia). 12. Chronic skin diseases (especially infectious, allergic, and inflammatory systemic skin diseases, such as extensive eczema, pemphigus, pemphigoid). 13. Autoimmune diseases and collagen diseases (such as systemic lupus erythematosus, dermatomyositis, scleroderma). 14. History of long-term smoking, alcohol abuse, or drug addiction. 15. History of major surgeries (such as gastric, lung, splenic, renal, or liver resection). 16. History of other significant malignant tumors. 17. Blood donation or organ transplantation within the past 5 years. 18. Pregnancy, lactation, menstrual period, or within 1 year after termination of pregnancy. 19. Previous circumstances of being rejected for voluntary blood donation. 20. Other situations deemed unsuitable for participation in this study by the investigators.