Infection reported in Takahashi animal trial of ocular iPSC transplantation
Takahashi et al has reported acute severe inflammation in primates that received a subretinal graft transplantation of induced pluripotent stem cell-derived retinal pigment epithelial cells.
In results published in Investigative Ophthalmology & Visual Science, primates involved a trial led by Masayo Takahashi have experienced acute severe inflammation due to mycoplasma-contamination of the induced pluripotent stem cell (iPSC)-derived retinal pigment epithelial cells that were transplanted into their eyes. This incident highlights issues that could be faced by human patients receiving cell-based therapies.
“In the present study, although we did not consider using any treatments in the experimental animals, as the monkeys were to be killed, it is likely that they probably would have been unable to see due to the severe ocular inflammation,” commented the authors in the study. “For human retinal cell transplantations, multiple sterility tests for mycoplasma have been recommended. However, the possibility still exists that mycoplasma ocular infection could potentially occur by accident.”
Although mycoplasma is a common contaminant of cell culture, as far as the authors were aware this is the first report of mycoplasma causing severe inflammation through direct invasion of the eye during surgery. The infection was confirmed through molecular analysis of vitreous fluids and the transplanted cells, as well as clinical and pathology examinations of the inflamed eyes. However, the source of the contamination was not established.
Source: Makabe K, Sugita S, Hono A, Kamao H, Takahashi M. Mycoplasma Ocular Infection in Subretinal Graft Transplantation of iPS Cells-Derived Retinal Pigment Epithelial Cells. Investig. Ophthalmol. Vis. Sci. 60, 1298-1308 (2019)