Multicenter Trial Evaluating the Safety and Efficacy of Autologous Volar Fibroblast Injection Into the Terminal Limb of Amputees.

The study will enroll 20 adults ages 18-75 with a transtibial amputation with mature residual limbs who are ambulatory prosthesis users. Participants will be randomized to either treatment with low dose volar fibroblast injections (n=10) or to vehicle control (n=10). Participants will undergo a biopsy to harvest volar skin for fibroblast expansion and tattooing to identify injection sites on the residual limb. Fibroblasts will be processed at the Hopkins Cellular Therapy Core Lab and volar cells primed for injection will be sent to participating centers for administration. Participants randomized to the treatment group will be treated with low-dose cells. Injections will be administered on at least 1 and up to three separate days over the course of one week. Participants randomized to the vehicle control group will receive injection of cryoprotectant. All participants will be followed at 2 weeks, 1, 2, and 3 months after the last injection. These visits will include a clinical evaluation for complications, non-invasive assessments of skin firmness and thickness, skin appearance, and patient-reported outcomes. After the final monitoring visit, individuals randomized to the vehicle control group will have the opportunity to receive the volar fibroblast injections and will be followed for an additional 3 months. The investigators hypothesize that (1) There will be no difference in the rate of serious adverse events among patients treated with volar fibroblast injections compared with patients treated with vehicle control, and (2) Patients treated with volar fibroblast injections will have firmer skin on the residual limb compared with patients tread with vehicle alone.