Secreted Factors from Dental Pulp Stem Cells Ameliorated Diabetic Polyneuropathy in Streptozotocin-Induced Diabetic Mice

Abstract

We previously reported that stem cell transplantation into limb skeletal muscle improved diabetic polyneuropathy (DPN) in diabetic animal models without the differentiation of transplanted cells into neuron, suggesting that the improvement was due to a paracrine effect. The aim of our study is to examine whether the secreted factors from dental pulp stem cells from human exfoliated deciduous teeth (SHED) has a beneficial effect on DPN. Conditioned medium from SHED (SHED-CM) was collected 48 hours after culturing in serum-free DMEM. Incubation of dorsal root ganglion (DRG) neurons excised from C57BL/6J mice with SHED-CM significantly promoted neurite outgrowth compared that with DMEM. (SHED-CM: 3793.2±907.9 um/neuron, DMEM: 370.9±321.7 um/neuron) Among 4 fractions of SHED-CM according to molecular weight (less than 6kDa, 6-20kDa, 20-100kDa, and more than 100kDa), only fraction of less than 6kDa significantly increased neurite outgrowth. Incubation of DRG neurons with exosome isolated from SHED-CM didn’t have any effect on neurite outgrowth, indicating that only soluble factors from SHED-CM contributed to neurite outgrowth of DRG neurons. In in vivo study, 12 weeks after streptozotosin (STZ) administration, 100ul of SHED-CM or DMEM was injected into unilateral lower limb muscle of STZ-induced diabetic mice twice a week over a 4 weeks period. SHED-CM or DMEM injections didn’t change serum glucose levels and body weight in diabetic mice. SHED-CM significantly prevented decline in sensory nerve conduction velocity (SNCV), compared with DMEM. In diabetic mice, capillary number-to-muscle fiber ratio (CNMFR) and intraepidermal nerve fiber densities (IENFDs) decreased less than those in nondiabetic mice. SHED-CM significantly improved the decline of CNMFR, but not IENFDs, suggesting that SHED-CM in in vivo alleviated SNCV by improving of nerve blood flow. These data suggested that SHED-CM might have potential as a novel strategy for treatment of DPN. Disclosure E. Miura-Yura: None. S. Tsunekawa: None. T. Himeno: None. K. Naruse: None. M. Motegi: None. H. Shimoda: None. M. Kato: None. Y. Yamada: None. M. Kondo: None. Y. Kato: Speaker's Bureau; Self; Merck Sharp & Dohme Corp., Sanofi, Takeda Pharmaceutical Company, Eli Lilly Japan. H. Kamiya: Other Relationship; Self; MSD K.K., Ono Pharmaceutical Co., Ltd., Sanofi K.K., AstraZeneca, Astellas Pharma KK, Eli Lilly and Company, Novartis Pharma K.K., Dainippon Sumitomo Pharma Co., Ltd, Boehringer Ingelheim Pharmaceuticals, Inc., Takeda Pharmaceutical Co., Ltd, Ono Pharmaceutical Co., Ltd. J. Nakamura: Other Relationship; Self; Astellas Pharma US, Inc., AstraZeneca, Ono Pharmaceutical Co., Ltd., MSD K.K., Kyowa Hakko Kirin Co., Ltd., Kowa Pharmaceuticals America, Inc., Sanofi K.K., Taisho Pharmaceutical Co., Ltd., Takeda Development Center Asia, Pte. Ltd., Mitsubishi Tanabe Pharma Corporation, Eli Lilly and Company, Novartis Pharma K.K., Pfizer Inc..