The purpose of this study is to evaluate the efficacy and safety of allogeneic umbilical cord mesenchymal stem cells in the treatment of radiation-induced rectal injury.

radiation-induced rectal injury (RRI) is a common clinical disease. The symptoms of RRI often include: Abdominal pain, diarrhea, hematochezia, etc., especially chronic radiation-induced late rectal injury (RLRI), are easy to cause the disease to prolong and not heal. Some patients will have severe complications such as massive rectal bleeding, rectal stenosis, intestinal obstruction, deep ulcer, intestinal perforation, and fistula formation after the disease progresses to the advanced stage, most of which occur 2-5 years after the end of radiotherapy. The incidence of radiation rectal injury is high, which has a serious impact on the health and quality of life of patients. Currently, the commonly used treatment methods include non-steroidal anti-inflammatory drugs, mucosal protective agents, hemostatic agents, compound enema preparations, hyperbaric oxygen, surgical treatment, etc., but there is still no standard treatment strategy and effective plan, and clinical treatment is extremely difficult.

Mesenchymal stem cells have the properties of proliferation, differentiation, immune regulation and angiogenesis. There are few clinical studies on the use of mesenchymal stem cells in the treatment of radiation-induced rectal injury. Good therapeutic effect was achieved in vivo and in vitro in the preliminary experiment. The aim of this study was to verify the safety and efficacy of allogeneic mesenchymal stem cells from healthy donors in RRI patients.

Primary objective: To assess the safety (incidence of treatment emergent adverse-events) of TH-SC01.

Inclusion Criteria:

1. Fully understand and sign the informed consent form;
2. Age ≥18 years and <80 years;
3. Patients diagnosed with chronic radiation rectal injury after radiation therapy;
4. Patients with LENT-SOMA scale score ≥1;
5. Good physical condition (WHO functional status score 0-1).

Exclusion Criteria:

1. The patient had severe liver and kidney disease;
2. Severe congestive heart failure or coronary heart disease;
3. Patients have allergic constitutions or severe systemic immune diseases;
4. The patient had active gastrointestinal hemorrhage or acute intestinal obstruction;
5. Patients were pregnant or had other conditions that the investigators deemed unsuitable for inclusion in the study.