Evaluate the safety and preliminary efficacy of human induced pluripotent stem cell-derived extracellular vesicle (iEV) injection in the treatment of lateral epicondylitis of the humerus.

Lateral epicondylitis refers to pain at the lateral epicondyle of the humerus caused by chronic traumatic tendinopathic changes in the origin and insertion of the common extensor tendon on the lateral side of the elbow joint, which result from long-term and repeated loading.

This randomized controlled study aims to observe whether extracellular vesicles derived from human induced pluripotent stem cells (iEVs) can promote the improvement of inflammatory status in injured extensor tendons and alleviate clinical symptoms. The study design will evaluate the efficacy by assessing changes in patients' pain, grip strength, and elbow joint function after treatment with the injection, and compare the efficacy with that of the control groups.

This is an interventional, single-center clinical study. The study plans to adopt a block randomization method without stratification. A randomization list will be generated separately for each research center by a computer, and participants will be randomly assigned to the experimental group, positive control group, and negative control group. There will be 6-12 cases in the experimental group, and 3-6 cases in each of the two control groups.

Inclusion Criteria:

• Diagnosed with lateral epicondylitis by clinical symptom examination and MRI or ultrasound, without obvious tendon tear;
• Unilateral lateral elbow pain lasting for more than 12 weeks;
• Pain is provoked by at least 2 of the following methods, with a pain VAS score exceeding 3: maximum grip strength, palpation of the lateral epicondyle of the elbow and surrounding area, resisted dorsiflexion of the wrist or middle finger, or stretching of the forearm extensor muscles under a pain-free grip state;
• Having received physical therapy or non-steroidal anti-inflammatory drug treatment with poor efficacy;
• Individuals with independent behavioral capacity, who have signed the informed consent form themselves.

Exclusion Criteria:

• Complaints of ipsilateral muscle pain caused by other reasons in the past 6 months;
• Presence of ipsilateral neurogenic, inflammatory, or systemic joint diseases;
• A history of previous lateral epicondylitis (LET) surgery in the past 6 months;
• Subjects deemed unsuitable for participating in the trial due to other conditions, as judged by the researcher;
• MRI showing that the injury has involved the lateral collateral ligament, with concurrent cartilage damage.