Discussion On The Safety And Efficacy Of Stem Cells From Human Exfoliated Deciduous Teeth In The Treatment Of Diabetic Patients With Significantly Reduced Islet Function

[Background]Diabetes is a chronic metabolic disease with high morbidity and mortality.Type 1diabetes and type 2 diabetes are the most common types.The onset of type 1 diabetes is characterized by islet reduction to less than 20%of normal levels,while type 2 diabetes is characterized by insulin resistance and progressive myocyte dysfunction.None of the current hypoglycemic treatments can delay or prevent the progressive decline of islet function,so it is of great clinical significance to find a safe and effective treatment method to prevent islet damage.In recent years,mesenchymal stem cells from different adult tissues have been regarded as an ideal new treatment for diabetes.Mesenchymal stem cells have the ability to differentiate into insulin-secreting cells and protect endogenous islet cells through immune regulation.Compared with other tissue-derived mesenchymal stem cells,stem cells from human exfoliated deciduous teeth have unique advantages,including easier access,stronger proliferation,and longer preservation at low temperature.Currently,animal models have demonstrated that pulp stem cells and their culture matrix in human deciduous teeth can improve hyperglycemia and insulin resistance in diabetes mellitus,as well as protect pancreatic islet cells.Previous animal experiments conducted by our research group also showed that stem cells from human exfoliated deciduous teeth have a good therapeutic effect on type 2 diabetic rats.In order to verify its effect on diabetic patients,our research group conducted the first study on the treatment of multiple intravenous infusion of human deciduous dental pulp stem cells in diabetic patients with pancreatic islet failure,exploring a better plan for the clinical treatment of diabetes.[Objective]Preliminary study on the safety and efficacy of multiple peripheral intravenous infusion of stem cells from human exfoliated deciduous teeth in the treatment of diabetic patients with significantly reduced islet function to provide scientific basis for the clinical application of mesenchymal stem cells in the treatment of diabetes mellitus.[Methods]1.Based on inclusion and exclusion criteria,a total of 15 eligible diabetic patients with significantly decreased islet function were enrolled in this study from March 2019 to September 2019.2.All patients underwent adequate physical and laboratory examinations before enrollment.Including age,gender,height,weight,duration of diabetes,blood routine,liver and kidney function,electrolyte,blood fat,resisting glutamic acid decarboxylase antibodies,insulin resistance,routine urine,hepatitis,infection,tumor,electrocardiogram,chest X-ray,abdominal ultrasound surface markers,carotid artery ultrasound,fundus photography,pulmonary function,etc.3.Stem cell therapy:each patient received 6 intravenous injections of human deciduous teeth pulp stem cell therapy.The time sequence was:enrollment,2 weeks after enrollment,6 weeks after enrollment,12 weeks after enrollment,18 weeks after enrollment and 24 weeks after enrollment.All patients received a dose of 0.11 IU/Kg of cells per treatment,the cell concentration was 1×10⁷/ml.4.Routine treatment:during the treatment follow-up period,all patients maintained the routine treatment plan before enrollment,and the endocrinologist gave instructions on diet,exercise and medication during the whole process.The insulin dose is adjusted according to changes in blood sugar,but the type and dose of the oral hypoglycemic agent remains the same unless there are drug side effects or the patient frequently experiences hypoglycemia.5.Main safety evaluation indexes:the body temperature,pulse,respiratory rate,blood pressure,blood glucose and other vital signs were recorded at the time of each transplant.Adverse reactions,including fever,dizziness,headache,insomnia,allergic reactions,gastrointestinal discomfort,were recorded.During the follow-up period,liver and kidney function,blood lipid index,electrocardiogram and chest radiography were monitored.6.Efficacy evaluation indexes:weekly total dose of insulin was used as the main efficacy evaluation indexes,Hb A1c,fasting blood glucose,area under the curve of steamed bread meal test(AUC_0-180min),and fasting C-peptide was used as the secondary efficacy evaluation indexes.Patients in the clinical study follow-up period 6 times steamed bread meal test,respectively for the baseline,3 weeks afte the second stem cell transplantation,5 weeks after the third time stem cell transplantation,5 weeks after the forth time stem cell transplantation,5 weeks after the fifth time stem cell transplantation,two weeks after the sixth stem cell transplantation.Blood glucose was recorded at 5 time points in each steamed bread meal test,namely 0min,30min,60min,120min and 180min,and the AUC value of blood glucose at these 5 time points was calculated.computational formula was:AUC_0-180min（mmol/L·h）=[（BG 0min+BG 30min）×30/60]/2+[（BG30min+BG 60min）×30/60]/2+[（BG 60min+BG 120min）×60/60]/2+[（BG120min+BG 180min）×60/60]/2.7.Immunoregulatory indicators:serum concentrations of MCP-1、IL-1β、IL-6、IL-17A、TGF-β1、IFN-γ、CRP were measured before and after treatment.[Results]1.General characteristics and the index of glycolipid metabolism before treatmentThe mean age of the patients in this clinical study was 53.47±11.17 years,including11 males（73.33%）,11 patients with type 2 diabetes（73.33%）,5 patients with oral medication（33.33%）,the mean value of Hb A1c was 8.96±1.57%,the mean value of fasting blood glucose was 8.09±2.02mmol/L,mean value of total cholesterol was4.88±0.94mmol/L,the mean value of low-density lipoprotein cholesterol was 3.06±0.82mmol/L and the mean value of high-density lipoprotein cholesterol was 1.50±0.37mmol/L.2.EfficacyThe weekly total dose of insulin decreased with time（p=0.0010）.Six of the patients had at least a 50%reduction in their weekly insulin dose,and two had stopped taking insulin.Hb A1c decreased with time（p=0.0097）.3.The safetyNo severe acute adverse reactions occurred in all patients after treatment.There was no statistical difference in the levels of alanine aminotransferase,alanine aminotransferase,total cholesterol,low density lipoprotein,high density lipoprotein,urea nitrogen and creatinine before and after the stem cell treatment,but there was only a statistical difference in the levels of glutamyl transpeptidase,which decreased compared with that before the treatment.4.Immunomodulatory cytokinesThe serum concentrations of proinflammatory cytokines MCP-1 and IL-1βdecreased over time（p=0.0316,p=0.0430）.[Conclusions]1.In this study,stem cells from human exfoliated deciduous teeth were used for the first time for the treatment of diabetic patients with significantly reduced islet function by multiple intravenous infusion.No serious acute or chronic adverse reactions occurred during the follow-up period.Therefore,this treatment method is safe and simple.2.Multiple intravenous infusion of stem cells from human exfoliated deciduous teeth can reduce insulin dependence in diabetic patients with significantly reduced islet function and improve blood glucose control.3.The mechanism of stem cells from human exfoliated deciduous teeth in the treatment of diabetes may be related to immunoregulation.