Effect of Application of Mesenchymal Stem Cells Cultured With Different Immunosuppressive Agents On Rejection of Discordant Skin Xenograft

Skin is the most immunogenic organ of the body. Especially in xenogeneic

transplantation it is rejected quickly. Xenogeneic skin graft rejection is

primarily dependent on CD8+ T cells.in this study, we investigated the effect

of Mesenchymal Stem Cells(MSCs) modified with different immunosuppressant

agents on CD8+ T cell dependent cellular rejection of skin xenografts.

We cocultured the rat MSCs with cyclosporine A, tacrolimus, everolimus

and mycophenolate mofetil for 72 hours to get modified MSCs(mMSCs).

mMSCs cocultured with rat T cells activated with phyto-hemagglutinin (PHA)

in different cell ratios. The expressions of CD25 on CD8+ T cells were evaluated

with flow cytometer. Proinflamatory cytokines (IL-2, IL-6, IFN gamma)

and anti-inflammatory cytokines levels evaluated with Enzyme-Linked Immunosorbent

Assay (ELISA).The proliferation response of MSCs to immunsuppressants

was evaluated with 3- (4,5- Dimethylthiazol - 2-yl) - 2,5-

diphenyltetrazolium bromide, tetrazole(MTT) test. Full thickness skin defects

at 2x2cm dimensions were created on rat dorsum and defects were grafted

with human skin graft. During the follow up the skin grafts with %90 or above

necrosis were accepted as rejected.

We found decreased inhibitor effect of MSCs' on CD8+ T cell activation

in the groups of cyclosporine A,tacrolimus and everolimus modified

MSCs compared with naive MSCs and the mycophenolate modified

MSCs(p<0.05).Proinflammatory cytokines, IL-2,IL-6 and IFN gamma, levels

were high in the groups of cyclosporine A,tacrolimus and everolimus modified

MSCs compared with naive MSCs and the mycophenolate modified

MSCs(p<0.05).MSCs proliferation was suppressed by all immunosuppressive

agents in 72 hours(p<0.05).The mean skin xenograft survival was 7.3

days in the control group. In the naive MSCs group the mean skin xenograft

survival was longer than the control group with 11.7 days (p<0.05). The

mean skin xenograft survival was similar in the the naive MSCs group and

the modified groups (p>0.05).