RESUMEN
PURPOSE: To evaluate the feasibility, safety, and biocompatibility of intravitreal injection of human mesenchymal stem cells (MSCs) in immunocompetent pigmented rabbits. MATERIALS AND METHODS: Thirty-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. RESULTS: There 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. CONCLUSIONS: MSCs 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.
