An Imaging and Histological Study on Intrahepatic Microvascular Passage of Contrast Materials in Rat Liver

Allogeneic abdominal non-vascularized rectus fascia transplantation without immunosuppression equals syngeneic transplantation in a rabbit model at short-term follow-up

Complex abdominal wall repair remains a major surgical challenge. In transplant patients, non-vascularized rectus fascia (NVRF) is successfully used to bridge the defect. To extrapolate this to non-transplant patients, we developed a rabbit model of NVRF-transplantation without immunosuppression comparing syngeneic versus allogeneic transplants. Short-term outcome (4 weeks) was evaluated macroscopically (ingrowth, seroma/hematoma, herniation, and infection), histologically at the graft interface and center (inflammation, neovascularization, and collagen deposition) and by mechanical testing. In both groups a similar macroscopic ingrowth of the NVRF was observed. In the syn-group, one seroma and one hematoma was seen. Two small herniations were detected at the suture line in the allo-group. No surgical site infections were observed. Histologically, graft neovascularization was observed in all animals. Infiltration of T-lymphocytes was seen at the graft interface in both groups, but more in the allo-group (p < 0.0001). Deposition of collagen was not different between groups. Macrophages were present in both groups around sutures and in the center more abundantly in the allo-group (p = 0.0001). Graft stiffness and strength were similar for both groups. With this model, we showed that allogeneic transplantation without immunosuppression results in favorable short-term inflammatory and mechanical outcomes. Long-term experiments are needed to further evaluate the effect on graft integration and hernia development.

Comparison of Three-Dimensional Micro-CT Angiography of Cervical Spinal Cord between Two Contrast Agents

Purpose

Barium sulfate and lead oxide are commonly used for angiographic studies, but there is no report on the comparison of two contrast agents in angiography of cervical spinal cord. This study was aimed to compare the microvascular architecture of cervical spinal cord in rats after angiography with the barium sulfate agent to the lead oxide agent.

Methods

Twelve adult Sprague-Dawley rats were randomly divided into the barium sulfate group (n=6) and the lead oxide group (n=6). Each rat was perfused under the same protocol using either two contrast agents. The angiography was evaluated with the vascular number at different ranks. The cervical spinal cord samples were scanned using micro-CT with low resolution and high resolution. The microvascular parameters, including ratio of vascular volume to tissue volume (VV/TV), vascular number (V.N), diameter (V.Dm), separation (V.Sp), connectivity density (Conn.D), structure model index (SMI), percentage, and volume of vessels at different diameters were measured.

Results

The perfusion was better in the barium sulfate group, with more blood vessel trees of rank II and III visible compared to the lead oxide group. Low-resolution micro-CT analysis showed no difference in microvascular parameters except SMI between the two groups. High-resolution micro-CT analysis results showed that V.N and Conn.D of barium sulfate group were 60% and 290% more than those of the lead oxide group; however, V.Sp was 41% less than the lead oxide group. The percentage of vessels with diameter of 10 μm and 20 μm, and the volume of vessels with diameter of less than 100 μm was higher in the barium sulfate group than in the lead oxide group. The SMI index in the barium sulfate group was higher than that in the lead oxide group at both low resolution and high resolution.

Conclusions

Compared with lead oxide, barium sulfate is more suitable for perfusion of cervical spinal cord microvessels, and cheap and nontoxic with high resolution.