Secreted factors from dental pulp stem cells improve glucose intolerance in streptozotocin-induced diabetic mice by increasing pancreatic β-cell function

• Published in: BMJ open diabetes research & care Vol. 3; no. 1; p. e000128
• Main Authors: Izumoto-Akita, Takako, Tsunekawa, Shin, Yamamoto, Akihito, Uenishi, Eita, Ishikawa, Kota, Ogata, Hidetada, Iida, Atsushi, Ikeniwa, Makoto, Hosokawa, Kaori, Niwa, Yasuhiro, Maekawa, Ryuya, Yamauchi, Yuichiro, Seino, Yusuke, Hamada, Yoji, Hibi, Hideharu, Arima, Hiroshi, Ueda, Minoru, Oiso, Yutaka
• Format: Journal Article
• Language: English
• Published: England BMJ Publishing Group 01-01-2015
• Subjects: Islet Studies; Beta Cell Function; Proliferation; Beta Cell(s); Beta Cell Secretion
• ISSN: 2052-4897; 2052-4897
• DOI: 10.1136/bmjdrc-2015-000128

ObjectiveMany studies have reported that stem cell transplantation promotes propagation and protection of pancreatic β-cells in streptozotocin (STZ)-induced diabetic mice without the differentiation of transplanted cells into pancreatic β-cells, suggesting that the improvement is due to a paracrine effect of the transplanted cells. We investigated the effects of factors secreted by dental pulp stem cells from human exfoliated deciduous teeth (SHED) on β-cell function and survival.Research design and methodsConditioned medium from SHED (SHED-CM) was collected 48 h after culturing in serum-free Dulbecco's modified Eagle's medium (DMEM). The insulin levels in SHED-CM and serum-free conditioned media from human bone marrow-derived mesenchymal stem cells (BM-CM) were undetectable. STZ-induced diabetic male C57B/6J mice were injected with DMEM as a control, SHED-CM, exendin-4 (Ex-4), or BM-CM for 14 days. Mouse pancreatic β-cell line MIN6 cells were incubated with different concentrations of STZ with SHED-CM, DMEM, Ex-4, or BM-CM for 6 h.ResultsAdministration of 1 mL of SHED-CM twice a day improved glucose intolerance in STZ-induced diabetic mice and the effect continued for 20 days after the end of treatment. SHED-CM treatment increased pancreatic insulin content and β-cell mass through proliferation and an intraperitoneal glucose tolerance test revealed enhanced insulin secretion. Incubation of MIN6 cells (a mouse pancreatic β-cell line) with SHED-CM enhanced insulin secretion in a glucose concentration-dependent manner and reduced STZ-induced cell death, indicating that the amelioration of hyperglycemia was caused by the direct effects of SHED-CM on β-cell function and survival. These effects were more pronounced than with the use of Ex-4, a conventional incretin-based drug, and BM-CM, which is a medium derived from other stem cells.ConclusionsThese findings suggest that SHED-CM provides direct protection and encourages the propagation of β-cells, and has potential as a novel strategy for treatment of diabetes.