LAUSR

PurposeTo evaluate the feasibility, safety, and biocompatibility of intravitreal injection of human mesenchymal stem cells (MSCs) in immunocompetent pigmented rabbits.Materials and methodsThirty-two pigmented rabbits (24 females, 8 males; Chinchilla-New Zealand White) were divided into 8 groups of 4 animals. Commercially prepared human MSCs were injected (0.05 ml) into the post-lens vitreous of the right eyes. Groups 1 and 4 received isotonic medium (Ringer lactate-based), groups 2, 5, 7, and 8 received a low dose of 15 × 106 cells/ml. Groups 3 and 6 received a high dose of 30 × 106 cells/ml. Clinical signs were evaluated and scored before MSCs injection and weekly for 2 or 6 weeks. Animals were sacrificed at 2 or 6 weeks after injection. Eyes, liver, spleen, and gonads were assessed by histology and by fluorescent in situ hybridization to evaluate survival and extraocular migration of MSCs.ResultsThere were no relevant clinical findings between control and MSC-injected rabbit eyes at any time point. There were also no relevant histological findings between control and MSC-injected rabbits related to ocular, liver, spleen, or gonad tissues modifications. MSCs survived intravitreally for at least 2 weeks after injection. Extraocular migration of MSCs was not detected.ConclusionsMSCs are safe and well-tolerated when administered intravitreally at a dose of 15 × 106 cells/ml in pigmented rabbits. These findings enable future research to explore the intravitreal use of commercially prepared allogenic human MSCs in clinical trials of retinal diseases.