RecruitingCombination productA Study to Investigate Safety and Effectiveness of Porcine Pancreatic Cells (OPF-310) in Patients With Type 1 Diabetes MellitusThis study is First In Human study for Encapsulated Porcine Islet Cells for Xenotransplantation (OPF-310). The purpose of this study to assess the safety, tolerability, and efficacy of OPF-310 transplantation and to define the recommended Phase 2 dose (RP2D) in adult subjects with unstable Type 1 Diabetes Mellitus (T1DM) and a level 3 (severe) hypoglycemic episode at least three times within the 1 year prior to enrollment despite treatment with a closed loop system (CLS) for at least 6 months.