Effect of cryopreservation on cell proliferation and immunogenicity of transplanted human heart cells.

BACKGROUND Cell preservation is essential for successful cell transplantation and/or tissue engineering. We examined the effects of cryopreservation on the transplantation of human heart cells. METHODS Cells isolated from human atrial tissues were cultured for 15 days (control group), cryopreserved for 1 week, and rapidly thawed and cultured for 15 days. Proliferation was compared among control and cryopreserved cells or tissues by constructing growth curves. Growth factors, cytokines, biochemical features, and cell cycle phase were measured immediately before and after cryopreservation, and immunogenicity was evaluated from growth curves generated from heart cells after 7 days in mixed-lymphocyte culture. Control or cryopreserved cells were transplanted into rat connective tissues and evaluated histologically 2 weeks later. RESULTS Cryopreserved cells proliferated more effectively than control cells. Levels of basic fibroblast growth factor and transforming growth factor-β1 were significantly higher, and those of interleukin (IL)-6 and IL-8 were significantly lower after cryopreservation. Fewer peripheral blood lymphocytes were produced in cryopreserved cells than in noncryopreserved cells, and the cell cycle phase of cryopreserved heart cells shifted primarily to G2 + M from G1 + G0. Noncryopreserved and cryopreserved cells both survived in connective tissue. CONCLUSION Human atrial cells can be cultured, cryopreserved, and transplanted. Cryopreservation might increase the proliferation of human cells and tissues and also reduce the immunogenicity of heart cells.