Adenovirally transduced bone marrow stromal cells differentiate into pigment epithelial cells and induce rescue effects in RCS rats.
OBJECTIVE
To determine the potential of adenovirally transduced bone marrow stromal cells (BMSCs) to differentiate into retinal pigment epithelial-like cells and to evaluabe possible rescue effects after transplantation into the retinas of Royal College of Surgeons (RCS) rats.


METHODS
Through a high-capacity adenoviral vector expressing either green fluorescent protein (GFP) or pigment epithelial-derived factor (PEDF), rat MSCs were transduced in vitro before subretinal transplantation into Wistar rats or, alternatively, RCS rats. Two months after cell injection, the rats were killed and the eyes enucleated. The eyes were then investigated light microscopically or processed for electron microscopic investigations. Cell differentiation and integration were analyzed immunocytochemically using antibodies against cytokeratin and the tight junction protein ZO-1. Electroretinography was performed 16 days after injection of cells, to check whether a functional rescue could be detected.


RESULTS
In vitro experiments in cocultured human MSCs and human RPE cells showed that MSCs adopted RPE-like characteristics. In grafting experiments, some rat MSCs integrate into the host RPE cell layer of Wistar and RCS rats, indicated by their hexagonal morphology. Subretinally transplanted cells express the epithelial marker cytokeratin and establish tight junctions with the host RPE cells. Furthermore, rescue effects can be demonstrated after grafting of vector-transduced and nontransduced MSCs in semithin sections of dystrophic retinas. Ultrastructurally, MSCs can be detected on top of host RPE and in close contact with photoreceptor outer segments phagocytosing rod outer segments.


CONCLUSIONS
Taken together, these results raise the possibility that MSCs have the potency to replace diseased RPE cells and deliver therapeutic proteins into the subretinal space to protect photoreceptor cells from degeneration.
Arnhold
Stefan
S
Department of Anatomy I, University of Cologne, Cologne, Germany. stefan.arnhold@uni-koeln.de
Heiduschka
Peter
P
Klein
Helmut
H
Absenger
Yvonne
Y
Basnaoglu
Serkan
S
Kreppel
Florian
F
Henke-Fahle
Sylvia
S
Kochanek
Stefan
S
Bartz-Schmidt
Karl-Ulrich
KU
Addicks
Klaus
K
Schraermeyer
Ulrich
U
D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology* / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology*; D002470:Cell Survival; D018920:Coculture Techniques; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005136:Eye Proteins / Q000378:metabolism; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D007633:Keratins / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D045164:Mesenchymal Stem Cell Transplantation; D008875:Middle Aged; D009414:Nerve Growth Factors / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010857:Pigment Epithelium of Eye / Q000166:cytology* / Q000378:metabolism; D051381:Rats; D011922:Rats, Mutant Strains; D017208:Rats, Wistar; D012162:Retinal Degeneration / Q000378:metabolism / Q000473:pathology / Q000601:surgery*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015843:Serpins / Q000378:metabolism; D017154:Stromal Cells / Q000166:cytology / Q000378:metabolism; D062826:Zonula Occludens-1 Protein; D000099174:Pigment Epithelium-Derived Factor
D005136:Eye Proteins; D049452:Green Fluorescent Proteins; D007633:Keratins; D008565:Membrane Proteins; D009414:Nerve Growth Factors; D010750:Phosphoproteins; D015843:Serpins; D062826:Zonula Occludens-1 Protein; D000099174:Pigment Epithelium-Derived Factor; C569042:TJP1 protein, human; C569044:Tjp1 protein, rat