Please assess the completion status of the following clinical trial:

Trial Title: Clinical Study of Umbilical Cord Mesenchymal Stem Cells Combined With Collagen Scaffold in the Treatment of Thin Endometrium

Study Design Characteristics:
- Allocation: None
- Intervention Model: SINGLE_GROUP
- Observational Model: None
- Primary Purpose: TREATMENT
- Time Perspective: None
- Masking: NONE
- Phase: None
- Number of Arms: 1.0

Eligibility Criteria:
Inclusion Criteria:~1. According to the GCP regulations, obtain the informed consent of the subject, volunteer for the test, and have signed the informed consent form.~2. Women aged 20-40 years with fertility requirements~3. Infertility patients who are treated in this hospital~4. After more than 2 times of hysteroscopic adhesion separation surgery, the uterine cavity morphology has basically returned to normal. The patient has a normal menstrual cycle or an estrogenic dose of 6 mg per day, and the highest thickness of the endometrium is 5.5 mm in 6 cycles by ultrasound.~5. or receive adjuvant reproductive treatment, the endometrial thickness is less than 5.5mm for unknown reasons, the treatment of estrogen, colony stimulating factor, aspirin, sildenafil and other drugs up to 8mg / day is invalid.~6. HBVAg negative, HCV negative, HIV negative, syphilis negative~7. Normal bone marrow morphology, normal blood routine~8. Previously failed to receive relevant stem cell therapy~Exclusion Criteria:~1. Those who cannot accept the treatment observation process required by the test~2. There are contraindications for hysteroscopic surgery;~3. congenital uterine malformation; severe adenomyosis; uterine fibroids that may affect embryo implantation; the investigators judged that there are other uterine factors that are not suitable for embryo implantation~4. Patients with chromosomal abnormalities~5. contraindications to estrogen therapy; systemic diseases such as thrombosis, cardiopulmonary disease, hematopoietic diseases, malignant tumors, etc.~6. Patients without fertility requirements

- Gender: FEMALE
- Minimum Age: 20 Years
- Maximum Age: 40 Years
- Healthy Volunteers: f

Study Arms:
- stem cell therapy (Type: EXPERIMENTAL): None

Based on this trial design, predict the completion outcome and termination type (if applicable).