Contrast sonography enables noninvasive and quantitative assessment of neovascularization after stem cell transplantation.

Stem cell transplantation is one of the attractive therapeutic strategies for the treatment of hindlimb ischemia. However, few studies have quantitatively assessed perfusion noninvasively in deep tissues after cell transplantation. In this study, we examined the feasibility of contrast sonography for the assessment of perfusion after bone marrow-derived mesenchymal stem cell (MSC) transplantation by using a rat unilateral hindlimb ischemia model. The quantitative parameters derived from contrast sonography were compared with the colored microspheres-derived blood flow and the capillary density. Nine rats were assigned each to a control (saline injection) or a treated (MSC transplantation) group. Video intensity vs. pulsing interval plots were acquired with ultraharmonic imaging of SONOS5500 during IV infusion of Levovist. The left-to-right ratio of hindlimb blood volume (A-ratio), microbubble velocity (beta-ratio) and hindlimb blood flow (Abeta-ratio) were calculated. The MS-ratio, the ratio of the left to the right hindlimb blood flow determined using colored microspheres, was also calculated. Although A-ratio did not change, beta- and Abeta-ratio in the treated group were significantly higher than those in the control group. In addition, MS-ratio and capillary density in the treated group were significantly higher than those in the control group. Compared with A- and Abeta-ratio, beta-ratio had the highest correlation with MS-ratio and capillary density (vs. MS-ratio: r = 0.66, p < 0.01; vs. capillary density: r = 0.52, p < 0.05). The results of our study imply that the contrast sonography-derived beta-ratio is a useful parameter that reflects the perfusion after cell transplantation in ischemic hindlimb.

Quantitative assessment of microcollateral recruitment during coronary occlusion using real-time intravenous myocardial contrast echocardiography.

BACKGROUND: Residual collateral-derived myocardial blood flow (MBF) (A x beta) is important to protect against myocardial ischemia after acute coronary occlusion. METHODS: Recruitment of microcollateral was assessed in 22 dogs with left circumflex coronary artery occlusion by analysis of MBF and regional wall thickening (WT) using real-time myocardial contrast echocardiography. RESULTS: Video intensity and WT at the center of risk area were significantly lower than those at the border of risk area. The video intensity, A value, beta value, and MBF correlated well with WT after left circumflex coronary artery occlusion. The WT of the area with above 25% of normal MBF was preserved and was higher than that at below 25%. However, the deterioration of WT was not distinguished according to A value. CONCLUSION: Real-time myocardial contrast echocardiography is a useful noninvasive method to evaluate collateral-derived MBF, which can be a reliable index of protection against myocardial ischemia.