Feasibility and Monitorization of Stem-Cell Replacement Therapy

Abstract

Purpose: : To evaluate the feasibility and the monitorization of the stem-cell replacement therapy in the rabbit tapetoretinal degeneration model.

Methods: : The fourth passage mesenchymal stem-cells (MSC) harvested from proximal femur of an adult New Zealand albino rabbit and differentiated from stromal cells were transfected with plasmid encoding Monster Green^TM fluorescent protein phMGFP were injected intravitreally in the pigmented rabbits with tapetoretinal degeneration at GATA Medical Research Center. Tapetoretinal degeneration was induced with intravenous injection of Sodium iodate, 40mg/kg. Subsequently, the MSC (2.5x10(5) cells/0.1ml) were injected intravitreally in the right eyes of 9 pigmented rabbits with tapetoretinal degeneration (study group) and in those of 3 pigmented rabbits without degeneration (control group). BSS was injected in the left eyes. Ophthalmoscopy, FA, OCT, ERG and histopathologic examinations were performed 1, 5, 10, 20, and 30 days after the intravitreal injection.

Results: : Extinguished ERG b-wave amplitudes were evident on the 5^th day, and extensive RPE damage on the 10^th day. FA and OCT findings corresponding to the changes in the retinal layers and the RPE were observed in the study group. Mean retinal thickness (MRT) was 135mikrom in both eyes of the control group throughout the experiment; it was similar (163microm and 160mikrom) in the right and the left eyes of the study group on the 5^th day. Contrary to the left eyes MRT in the right eyes was normalized on the 20^th day in this group. GFP loading MSC were surveyed with autofluorescence technique employed with HRA-2. Immunhistopathologic examinations revealed enrollment of MSC in the repairment process. Contrary to time-dependant decrease in autofluorescence in the vitreous bodies of the study group, it was observed in the outer retinal layers throughout the examination period; however, autofluorescence was not observed in the retinas of right eyes in the control group.

Conclusions: : The replacement therapy with intravitreally injected allogenic MSC in eyes with tapetoretinal degeneration model seems to be feasible. The efficacy of the repacement therapy can be monitored in-vivo in experimental and clinical studies.

Keywords: retinal degenerations: cell biology • gene transfer/gene therapy • detection