Effects of Autologous Bone Marrow Mesenchymal Stem Cell Transplantation on Angiogenesis in Rabbit Ischemic Limbs A high-frequency Ultrasound Evaluation

BACKGROUND: Several studies have demonstrated that stem cells can differentiate into vascular endothelial cells, and then further differentiate and form blood capillary. Based on this principle, autologous bone marrow mesenchymal stem cell (BMSC) transplantation promotes angiogenesis to treat ischemia in lower limb. OBJECTIVE: To evaluate the angiogenesis in rabbit ischemic limbs following autologous BMSC transplantation using high-frequency two-dimensional ultrasound detection in conjunction with Doppler color-flow imaging examination. DESIGN, TIME AND SETTING: A randomized, controlled, animal experiment was performed in the Third People's Hospital of Wuxi between March 2007 and April 2008. MATERIALS: Twenty-four New Zealand rabbits were randomized to a control group and a cell transplantation group, with 12 rabbits in each. METHODS: Ischemia in lower limbs was induced in all rabbits. One week following ischemia induction, the cell transplantation group was injected with 0.5 mL cell suspension, comprising 2×10^6 BrdU-labeled autologous BMSCs cultured in vitro, through multiple sites in the region of gastrocnemius muscle. Simultaneously, the control group received the same amount of physical saline in the same region. MAIN OUTCOME MEASURES: The initial segment of rabbit femoral artery and superficial femoral artery was subjected to high-frequency two-dimensional ultrasound and Doppler color-flow imaging examinations to measure femoral artery vascular internal diameter, blood flow peak velocity, and blood flow acceleration time. Ischemic muscular tissue was taken for immunohistochemical staining to detect transplanted cell distribution and for pathological examination of angiogenesis. RESULTS: Two weeks following autologous BMSC transplantation, high-frequency ultrasound results revealed that femoral artery internal diameter and blood flow peak velocity were greater, but blood flow acceleration time was shorter, in the cell transplantation group than in the control group (P＜0.01). Immunohistochemical staining results demonstrated the presence of BrdU-positive cells. Pathological sections displayed that vascular density was significantly higher in the cell transplantation group than in the control group. CONCLUSION: Autologous BMSC transplantation is a promising, simple, and effective method of treating ischemia in lower limbs owing to its promotion of angiogenesis. Meanwhile, high-frequency ultrasound detection of femoral artery is an effective, practical method to evaluate the clinical outcomes of autologous BMSC transplantation.