Purpose The purpose of this study was to determine if adventitial transplantation of human adipose derived mesenchymal stem cell (MSC) to the outflow vein of B6.Cg-Foxn1nu/J mice with AVF at the time of creation would reduce monocyte chemoattractant protein-1 (Mcp-1) gene expression and venous neointimal hyperplasia (VNH). The second aim was to track transplanted 89 zirconium (89Zr) labeled MSCs serially by positron emission tomography (PET) imaging for 21 days. Materials and Methods All animal experiments were performed according to protocols approved by our institutional animal care and use committee. We used fifty B6.Cg-Foxn1nu/J mice to accomplish the aims outlined in the current paper. 2.5 × 105 MSC cells were stably labeled with green fluorescent protein (GFP) and injected into the adventitia of the outflow vein at the time of AVF creation in MSC group. Eleven mice died after AVF placement. Animals were sacrificed at day 7 following AVF placement for real time polymerase chain reaction (qRT-PCR, n=6 for MSC and control groups) and histomorphometric analyses (n=6, n=6 for MSC and control groups) and at day 21 for histomorphometric analysis only (n=6 for MSC and control groups). In a separate group of experiments (n=3), transplanted 89zirconium (89Zr) labeled MSCs animals were serially imaged by PET imaging for 3 weeks. Multiple comparisons were performed with two-way ANOVA followed by Student t-test with post hoc Bonferroni’s correction. Results We observed that in MSC transplanted vessels when compared to control vessels, there was a significant decrease in the Mcp-1 gene expression (day 7: average reduction: 62%, P=0.029) with a significant increase in the average lumen vessel area (day 7: average increase: 176%, P=0.013; day 21: average increase: 415%, P=0.011); Moreover, this was accompanied with a significant decrease in Ki-67 index (proliferation, day 7: average reduction: 81%, P=0.0003; day 21: average reduction: 60%, P=0.016 Prolonged retention of MSCs at the adventitia was evidenced by serial PET images of 89Zr-labeled cells. Conclusion These results indicate that adventitial transplantation of MSC decreases Mcp-1 gene expression accompanied with a reduction in VNH.

Venous neointimal hyperplasia (VNH) at the outflow vein of hemodialysis AVF is a major factor contributing to failure. CorMatrix is an extracellular matrix that has been used in cardiovascular procedures primarily as scaffolding during surgery. In the present study, we sought to determine whether CorMatrix wrapped around the outflow vein of arteriovenous fistula (AVF) at the time of creation could reduce VNH. In mice, the carotid artery to the ipsilateral jugular vein was connected to create an AVF, and CorMatrix scaffold was wrapped around the outflow vein compared to control mice that received no scaffolding. Immunohistochemistry, Western blot, and qRT-PCR were performed on the outflow vein at 7 and 21 days after AVF creation. In outflow veins treated with CorMatrix, there was an increase in the mean lumen vessel area with a decrease in the ratio of neointima area/media + adventitia area (P < 0.05). Furthermore, there was a significant increase in apoptosis, with a reduction in cell density and proliferation in the outflow veins treated with CorMatrix compared to controls (P < 0.05). Immunohistochemical analysis revealed a significant reduction in fibroblasts, myofibroblasts, macrophages, and leukocytes with a reduction in Tnf-α gene expression (P < 0.05). In conclusion, outflow veins treated with CorMatrix have reduced VNH.

No abstract