183 | Pericyte-like adipose mesenchymal stem cells as a tool for blood-retinal barrier repair

Ivana Roberta Romano¹, Giuliana Mannino², Alessio Canovai³, Rosario Amato³, Silvia Marracci³, Matteo Fallico⁴, Claudio Bucolo¹, Rosario Giuffrida¹, Maurizio Cammalleri³, Debora Lo Furno¹ | ¹Dept Biomedical and Biotechnological Sciences, Catania University, Catania, Italy; ²Faculty of Medicine and Surgery, Kore University, Enna, Italy; ³Department of Biology, Pisa University, Italy; ⁴Department of Ophthalmology, University of Catania, Italy.

In the last few decades, adipose-derived mesenchymal stem cells (ASCs) have been widely investigated in the field of regenerative medicine because of their multipotent differentiation ability. For this reason, they represent a valuable tool to treat various pathologies, including eye diseases such as diabetic retinopathy (DR). DR is characterized by massive pericyte loss, leading to altered interactions between endothelial cells and pericytes, and impairment of the blood-retinal barrier (BRB). Previous our studies showed a successful pericyte-like differentiation of ASCs (P-ASCs) using a culture medium specifically designed for pericytes. To mimic the altered microenvironment of a diabetic eye, samples of P-ASCs were cultured in high glucose conditions, where they induced increased levels of anti-inflammatory cytokines as well as decreased expression of pro-inflammatory cytokines. Moreover, co-cultures of P-ASCs and human retinal endothelial cells showed an increased endothelial expression of junction proteins (vascular endothelial-cadherin and zonula occludens-1), suggesting an improved BRB integrity, as also indicated by higher values of trans-endothelial electrical resistance. In the present work, we tested the effects exerted by human-derived P-ASC that were intravitreally injected in a streptozotocin (STZ)-induced diabetic rat model. To this aim, after 3 weeks from P-ASC injections, retinas were flat mounted and processed for subsequent experimental procedures. Immunostaining for human nuclear antigen (HNA) showed that positive cells, consisting only of those injected, survived and were mostly found in perivascular regions, thus indicating P-ASCs ability to reach and attach to retinal blood vessel walls. In addition, these injected P-ASCs were characterized by strong alpha-smooth muscle actin (α-SMA) immunostaining, confirming their pericyte-like differentiation even after injections. Evans Blue staining showed that in healthy animals the dye was confined to the vascular lumen, whereas several focal points of blood extravasation could be detected in STZ rats, as occurs after BRB breakdown. On the contrary, intravitreal injections of P-ASCs in STZ rats markedly reduced the retinal extravasation of Evans Blue dye, indicating reduced plasma protein leakage in the retinal parenchyma and improved BRB function. It can be concluded that P-ASCs may represent a valuable tool to develop therapeutic strategies to counteract BRB disruption in cases of diabetic retinopathy.