Long-term studies on allotransplantation of rabbit retinal pigment epithelial cells double-labelled with 5-bromodeoxyuridine and natural pigment.
OBJECTIVE
To facilitate the identification of transplanted retinal pigment epithelial (RPE) cells, we sought to double-label the cells with 5-bromodeoxyuridine (BrdU) and with natural pigment. The BrdU is not lost during cell division but does require immunohistochemical methods for visualization; the pigment on the other hand, allows immediate, obvious identification, but is gradually lost with cell division. Together they provide a convenient, long-term double label.


METHODS
Non-confluent RPE cells at the second to the fifth passages were labelled with 5-BrdU and pigment. The double-labelled RPE cells were transplanted onto Bruch's membrane of 72 eyes of New Zealand albino rabbits. The labelled cells were localized by anti-BrdU antibody and the avidin biotin-alkaline phosphatase complex (ABC-AP) method, and by visible inclusions of pigment.


RESULTS
The transplanted RPE cells had distinct basal and apical morphology, and were in close contact with the photoreceptor outer segments of the host. The BrdU label was restricted to the nuclei of the RPE cells, which were stained blue. The pigment was located in the cytoplasm of the apical portion of these RPE cells. No evidence of severe rejection was seen.


CONCLUSIONS
Using this double-label method, transplanted RPE cells could be readily and reliably identified till one year after transplantation. The transplanted RPE cells revealed normal morphology with some function: they had distinct basal and apical morphology as seen in close contact with the outer segment of photoreceptor cells. The junctional complexes were well formed with neighboring RPE cells. The transplanted RPE cells phagocytose shed outer segments of the host. No evidence of rejection was observed, suggesting that the subretinal space of the rabbit may possess some degree of immunologic privilege. This experiment provides reliable evidence for the clinical research of allotransplantation of RPE cells.
Department of Ophthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China.
J
J
Ye
W
W
Li
S J
SJ
Ryan
D000345:Affinity Labels; D000818:Animals; D001973:Bromodeoxyuridine; D016570:Bruch Membrane / Q000601:surgery*; D017690:Cell Transplantation; D002478:Cells, Cultured; D003470:Culture Media; D010857:Pigment Epithelium of Eye / Q000166:cytology*; D010860:Pigments, Biological; D011817:Rabbits
D000345:Affinity Labels; D003470:Culture Media; D010860:Pigments, Biological; D001973:Bromodeoxyuridine