114-OR: Overexpression of Alpha-1 Antitrypsin in MSCs Delays Onset of Type 1 Diabetes in the NOD Mice by Increasing Their Antiinflammatory and Protection Functions

We have shown that overexpression of human alpha-1 antitrypsin (hAAT) in mesenchymal stromal cells (hAAT-MSCs) improves mobility and function of MSCs. In this study we further characterized hAAT MSCs and control MSCs and compared their therapeutic effects in the prevention of type 1 diabetes in the spontaneous non-obese diabetic (NOD) mice. Bone marrow specimens from three individual donors were purchased from StemExpress. Cells were grown to passage 3-4 and infected with hAAT-containing virus for hAAT-overexpression. Single Cell RNAseq was performed by the 10X Genomic System. Proteomic Analysis of exosomes was performed at the MUSC Proteomic Core. MSCs and hAAT-MSCs from one donor were injected into the NOD mice at 8 weeks of age. Mice blood glucose levels were measured twice per week. Cell infiltration into islets was analyzed by H&E staining of pancreatic tissues. Single cell RNAseq analysis showed that hAAT-MSCs and control MSCs have different gene expression signatures, in which hAAT-MSCs showed increased expressions of chemokine (C-X-C motif) ligands (CXCL1, 3, 8), HES5 and others. Exosome proteomic analysis indicates that exosomes from these two types of cells have distinct protein patterns. In hAAT-MSCs cells, platelet degranulation proteins were upregulated and proteins involved in cell-cell adhesion, and cell division were been downregulated. In the NOD mice, a single dose of hAAT-MSCs led to delayed onset of T1D, associated with reduced cell infiltration into the islets. hAAT-MSC therapy showed more profound protection compared to control MSCs. It is likely that overexpression of hAAT enhanced the anti-inflammatory function (via regulating chemokines) promoting the Notch signaling pathway (via regulating HES5) and lead to improved protection in the NOD mice.