Treatment with adipose tissue-derived mesenchymal stem cells exerts anti-diabetic effects, improves long-term complications, and attenuates inflammation in type 2 diabetic rats

Background: Long-term diabetes-associated complications are the major causes of morbidity and mortality in individuals with diabetes. These diabetic complications are closely linked to immune system activation along with chronic, non-resolving inflammation, but therapies to directly reverse these complications are still not available. Our previous study demonstrated that mesenchymal stem cells (MSCs) attenuated chronic inflammation in type 2 diabetes mellitus (T2DM), resulting in improved insulin sensitivity and islet function. Therefore, we speculated that MSCs might exert anti-inflammatory effects and promote the reversal of diabetes-induced kidney, liver, lung, heart, and lens diseases in T2DM rats. Methods: We induced a long-term T2DM complication rat model by using a combination of a low dose of streptozotocin (STZ) with a high-fat diet (HFD) for 32 weeks. Adipose-derived mesenchymal stem cells (ADSCs) were systemically administered once a week for 24 weeks. Then, we investigated the role of ADSCs in modulating the progress of long-term diabetic complications. Results: Multiple infusions of ADSCs attenuated chronic kidney disease (CKD), nonalcoholic steatohepatitis (NASH), lung fibrosis, and cataracts; improved cardiac function; and lowered serum lipid levels in T2DM rats. Moreover, the levels of inflammatory cytokines in the serum of each animal group revealed that ADSC infusions were able to not only inhibit pro-inflammatory cytokines IL-6, IL-1β, and TNF-α expression but also increase anti-inflammatory cytokine IL-10 systematically. Additionally, MSCs reduced the number of iNOS(+) M1 macrophages and restored the number of CD163(+) M2 macrophages. Conclusions: Multiple intravenous infusions of ADSCs produced significant protective effects against long-term T2DM complications by alleviating inflammation and promoting tissue repair. The present study suggests ADSCs may be a novel, alternative cell therapy for long-term diabetic complications.