Marrow Stromal Stem Cells Seeding Participating In Vascular Endothelium Repair And Its Effect On Partial Biological Characteristics Of Smooth Muscle Cells

Background: The proliferation and migration of vascular smooth muscle cells (SMCs) share the same common pathophysiological processes of many vasoproliferative disorders, such as atherosclerosis, restenosis and hypertension. As a result, intense effort has been done to explore the molecular mechanisms of regulating SMCs proliferation and the strategies of inhibiting SMCs overgrowth. Although with the rapid development of molecular biology, role of cytokines, signal tranduction pathway and related genes in proliferative diseases has been studied more and more extensively, it remains unclear about the target cytokine, key gene and final pathway which regulate SMCs proliferaion. The strategies targeting directly to cell mitosis and DNA synthesis, such as drug eluting stents and intravascular radiation, can inhibit SMCs overgrowth and reduce restenosis rate significantly. However, these therapies can also disturb endothelial recover, and their long-term consequences are also unsure. Vascular endothelial cells (ECs) line the intima of the vessel wall and play the important role in maintaining normal vascular function. Accumulating evidence indicates that in normal vessel wall the vasoactive substances secreted by ECs maintain a dynamic balance. Vascualr injury can destory this balance, and the vasoconstrictive and proliferative substances secreted by damaged ECs play the dominant role. These studies suggest that although SMCs proliferation is the culprit pathological change, ECs damage may play the trigger and aggravating role in proliferative disorders. These studies also imply that we should not only consider the "antitumor" approach to the prevention and treatment of proliferative diseases, but also should pay more attention to restore the normal endothelium biology. Cell transplantation or seeding has become a novel way in tissue regeneration. This work was funded by National Natural Science Foundation of China(NO.30270568)Although previous studies have shown that autologous venous ECs seeding can repopulate the ECs denuded arterial wall and reduce neointimal proliferation, the mature autologous venous ECs have heterogeneity compared with arterial ECs, and surgical operation is also unavoidable to acquire the autologus ECs. Marrow stromal stem cells (MSCs) are self-renewing adult stem cells in bone marrow. They can elicit cytokine-dependent differentiation toward ECs in vitro. Nevertheless, MSCs can be isolated and expanded relative easily. Therefore, MSCs seem to be the ideal candidate for tissue repair. Several studies have also shown that MSCs transplantation can promote neovascularization and regenerate damaged myocardium. However, it remains unknown whether MSCs seeding can be used to repair damaged endothelium and inhibit SMCs overgrowth. Objectives: 1. To investigate the relation between the altered ECs growth states and the proliferation, migration of vascular SMCs.2. To study the plasticity of MSCs toward ECs and its effect on the proliferation and migration of SMCs during ex vivo repair of endothelium by MSCs seeding.3. To explore the effect of paclitaxel on the quantitative growth of rabbit vascular ECs and SMCs during ex vivo endothelium repair.4. To study the effect of paclitaxel combined with MSCs seeding on the proliferation of SMCs during ex vivo endothelium repair.Methods: 1. The relation between the altered ECs growth states and the proliferation, migration of vascular SMCs: In the cell coculture system, ECs were seeded in the lower chamber and SMCs in the upper chamber. 3H-TdR incorporation, flow cytometry analysis and PCNA protein expression were used to determine the effects of altered ECs growth states on the proliferation of vascular SMCs. The number of SMCs migration was counted. RT-PCR was used to analyze the influence of altered ECs growth state on the expression of α-SM-actin mRNA.2. The plasticity of MSCs toward ECs and its effect on the proliferation and migration of SMCs during ex vivo repair of endothelium by MSCs seeding: In the cell coculture system, EC...