Safety of Extracellular Vesicles for Burn Wounds

This study is designed to examine the safety and efficacy, in 10 patients of administration of allogeneic MSC EV to deep second degree burn wounds. The dose level delivered will be approximately 1 X 107 EV particles for each cm2 treated area. Wounds eligible for treatment will not exceed 600 cm2 per wound or collection of wounds in a defined anatomical area (e.g., arm, leg, chest) treated. Patients with 20% or greater TBSA in total (3700 cm2 in a 70 kg, 175 cm subject) will be ineligible to participate in the study. The first treatment will be administered within 48 hours of the burn injury. Two additional administrations of EV will be given approximately one week (day 5-7 post-injury) and two weeks after the first treatment (unless the wound is fully closed, in which case the patient will continue to be monitored at weekly intervals through 5 weeks, then at 8, 12, 26, and 54 weeks). Safety will be assessed by collection of adverse event data. The potential for wound healing efficacy will be evaluated by recording the percent of burns re-epithelialized within 8 weeks as well as the time to complete closure. Wound closure will be defined as complete re-epithelialization that is not subject to re-injury during dressing changes or as a result of normal daily activities (e.g., wearing clothing, eating, sleeping). The potential for tissue regeneration and restoration of pigmentation, hair growth and skin texture will be evaluated by scoring healing and scar formation using POSAS. Assessment of the potential for prevention of conversion will be done using LDI. Deep second degree wounds presenting at screening that are assessed to be deeper by LDI at the 5-7 day reading than at the initial evaluation in the first 72 hours will be considered to have undergone conversion. Exploratory endpoints will include monitoring for the presence of an immunologic response in recipients.