CCL2/MCP‐1 and CXCL12/SDF‐1 blockade by L‐aptamers improve pancreatic islet engraftment and survival in mouse

The blockade of pro‐inflammatory mediators is a successful approach to improve the engraftment after islet transplantation. L‐aptamers are chemically synthesized, nonimmunogenic bio‐stable oligonucleotides that bind and inhibit target molecules conceptually similar to antibodies. We aimed to evaluate if blockade‐aptamer‐based inhibitors of C‐C Motif Chemokine Ligand 2/monocyte chemoattractant protein‐1 (CCL2/MCP‐1) and C‐X‐C Motif Chemokine Ligand 12/stromal cell‐derived factor‐1 (CXCL12/SDF‐1) are able to favor islet survival in mouse models for islet transplantation and for type 1 diabetes. We evaluated the efficacy of the CCL2‐specific mNOX‐E36 and the CXCL12‐specific NOX‐A12 on islet survival in a syngeneic mouse model of intraportal islet transplantation and in a multiple low doses of streptozotocin (MLD‐STZ) diabetes induction model. Moreover, we characterized intrahepatic infiltrated leukocytes by flow cytometry before and 3 days after islet infusion in presence or absence of these inhibitors. The administration for 14 days of mNOX‐E36 and NOX‐A12 significantly improved islet engraftment, either compound alone or in combination. Intrahepatic islet transplantation recruited CD45⁺ leucocytes and more specifically CD45+/CD11b+ mono/macrophages; mNOX‐E36 and NOX‐A12 treatments significantly decreased the recruitment of inflammatory monocytes, CD11b⁺/Ly6C^high/CCR2⁺ and CD11b⁺/Ly6C^high/CXCR4⁺ cells, respectively. Additionally, both L‐aptamers significantly attenuated diabetes progression in the MLD‐STZ model. In conclusion, CCL2/MCP‐1 and CXCL12/SDF‐1 blockade by L‐aptamers is an efficient strategy to improve islet engraftment and survival.