Abstract
Purpose :
Subconjunctival injection of mesenchymal stem cells (MSCs) has been applied in the treatment of ocular surface chemical burn, while the fate of MSCs in the local microenvironment after injection remains unknown. In this study, we investigated the survival, migration, proliferation, differentiation and paracrine of human MSCs, as well as their impact on the ocular surface microenvironment after subconjunctival implantation in rat.
Methods :
MSCs were isolated from umbilical cord characterized by flow cytometry on the basis of published criteria. Overall, 27 SD rats were subjected to MSCs injection. For each rat, the left eye was injected subconjunctivally with 2X105 MSCs suspended in 50ml DMEM, and the right eye was served as a control. On the 3rd, 6th and 9th day after injection, the rats were examined by slit-lamp to evaluate conjunctival edema and hyperemia. Immunohistochemistry was performed to investigate the expression patterns of Vimentin, a-SMA, Ki67 and PMN. TUNEL assay was performed to detect cell apoptosis. Furthermore, the proportion of CD11b+ and CD45+ cells in conjunctiva were quantified by flow cytometry.
Results :
MSCs were isolated and their specific markers, such as CD29, CD44, CD105 and CD90, were expressed at high levels, while CD31, CD34, CD45 and MHC-DR could not be detected. Rat conjunctiva showed mild hyperemia at the injection site on the second day and diminished on day 3. All the injected cells remained in the engrafted regions and showed no migration. Majority of the MSCs survived 3 days after implantation. However, the number of cells gradually decreased thereafter, and completely disappeared on day 9 after implantation. Using Ki67 as a marker, we could only observe quite a number of positive staining cells surrounding the cell mass. Immunostaining against a-SMA was negative from day 3 to day 9, indicating that the injected cells did not differentiate into myofibroblasts. TUNEL positive cells were present in the injected cell mass. The quantities of infiltrated CD11b+, CD45+ and PMN+ cells were increased in the injected eyes at day 3, and gradually reduced to normal basal levels at day 9.
Conclusions :
MSCs were gradually eliminated from the injection site without cell migration, proliferation and differentiation. However, MSCs activated proliferation of host cells and recruited immune cells to the microenvironment.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.