RecruitingEarly Phase 1Biological interventionA Clinical Study Evaluating the Safety and Efficacy of GT729 Universal Cell Injection in the Treatment of Refractory or Relapsed Chronic Graft-versus-host Disease (cGVHD)The goal of this clinical study is to evaluate the safety and efficacy of GT729 universal cell injection in the treatment of refractory or relapsed chronic graft-versus-host disease (cGVHD).