Table 1 Inclusion and exclusion criteria

(1) Patients within 14 days ± 2 days (from 12 to 16 days) after spinal cord injury

(2) Patients aged 16 years or older but younger than 75 years at the time of consent (regardless of sex)

(3) Patients who provided written consent themselves. In the case of patients who were minors, consent was obtained from the legal representative in writing, and whenever possible, consent was also obtained from the patient themselves through a consent document. In cases where the patient’s condition made it difficult for them to sign, a family member or equivalent partner (e.g., common-law spouse) could sign as a witness. However, once a patient was able to sign on their own, written consent was obtained from the patient themselves

(4) Patients with a modified Frankel classification of B1 or B2 at the start of screening

(5) Patients who can receive CL2020 administration within 21 days ± 3 days (from 18 to 24 days) after spinal cord injury. (6) Patients with the primary site of spinal cord injury in the cervical spine (C4 to C7)

(6) Patients who can visit for the specified evaluation periods

[Exclusion Criteria]

(1) Patients with Japan Coma Scale III-200 or III-300 consciousness disorders at the time of obtaining consent

(2) Patients with severe respiratory disorders

(3) Patients with systolic blood pressure exceeding 140 mmHg or diastolic blood pressure exceeding 90 mmHg despite antihypertensive treatment

(4) Patients with a current or past history of malignant tumors (patients who have achieved complete remission for at least 5 years are eligible for enrollment)

(5) Patients with concurrent neurological disorders, cerebrovascular disorders, or musculoskeletal disorders that may affect neurological assessment

(6) Patients who are expected to experience a rapid deterioration of symptoms related to spinal cord injury during the trial period

(7) Patients who are unable to start rehabilitation early due to complications or other reasons

(8) Patients with severe dementia or mental disorders

(9) Patients with severe spinal cord or spinal disorders (including osteoporosis, spinal tumors, spinal vascular malformations, or syringomyelia)

(10) Patients who require medical treatment for positive HBs antigen, HCV antibody, HIV antibody, or syphilis test

(11) Patients with severe connective tissue diseases and related disorders

(12) Patients with severe diabetes mellitus (HbA_1c ≥ 10%), regardless of treatment

(13) Patients with severe systemic conditions, such as severe infections (sepsis, etc.)

(14) Patients with severe complications or conditions deemed inappropriate by the responsible/investigating physician

(15) Patients receiving systemic administration of immunosuppressive agents

(16) Female patients who are pregnant or breastfeeding or potentially pregnant female patients

(17) Male patients who cannot agree to contraception based on the guidance of the responsible/investigating physician from consent acquisition to observation completion or female patients of childbearing potential who cannot agree to contraception

(18) Patients who participated in another clinical trial within the past 3 months before obtaining consent or received administration or use of regenerative medicine products within the past 1 year

(19) Patients with a history of hypersensitivity to aminoglycoside antibiotics, including kanamycin

(20) Patients with a history of hypersensitivity to human serum albumin products or xenogeneic proteins (bovine and porcine)

(21) Patients deemed inappropriate for participation in the clinical trial by the responsible/investigating physician for general safety reasons