Figure 1.
Experimental protocol. (a) Preparation of dental pulp stem cells (DPSCs) and secretory factors from dental pulp stem cells (DPSC-SFs). DPSCs were isolated from extracted dental pulp and cultured in an alpha modification of Eagle’s medium (α-MEM). The culture medium was collected after a 24-h culture of DPSCs in the serum-free medium and concentrated by a factor of 10 using 3-kDa centrifugal filters as secreted factors from the DPSCs (DPSC-SFs). (b) Animal experimental protocol. Eight weeks after the streptozotocin injection, DPSCs (1 × 106 cells/rat) or DPSC-SFs (1.0 mL/rat) were administered. Neurophysiological measurements and tissue collection were performed 4 weeks after the administration of DPSCs/DPSC-SFs. (c) Experimental groups. There were four groups: normal + vehicle group, diabetes + vehicle group, diabetes + DPSCs group, and diabetes + DPSC-SFs group. DPSCs or DPSC-SFs were administered into the unilateral hindlimb skeletal muscles of the diabetic rats.