SP28. How Flow Dynamics Influence Angiogenic Factor Release in Endothelial Cells Undergoing Micropuncture

PURPOSE: Poor vascularization is a critical factor limiting graft survival in reconstructive surgery. Micropuncture (MP) is a novel surgical technique designed to enhance angiogenesis by disrupting the blood vessel wall in vivo. In MP, we use a 60-um diameter needle to precisely perforate the blood vessel wall at defined intervals to stimulate microvascular growth. Static in vitro testing suggests that venous MP expedites capillary formation compared to arterial MP via angiogenic factor release but the significance of flow to the process is unknown. We hypothesize that flow further augments angiogenic factor secretion following MP from both arterial and venous endothelial cells (ECs). METHODS: Arterial and venous ECs were extracted from the rat aorta and vena cava, respectively. Cells were seeded (1x10⁵) onto cell culture inserts (area = 4.2 cm²). Following confluence, 40 MPs were delivered to each insert. Non-MP arterial and venous ECs served as baseline controls. ECs were then transferred to a microslide channel and connected to a continuous infusion system (flow rate = 1.5 ml/min). At 24 hours, supernatant was analyzed using a semi-quantitative antibody array, with results compared to static culture conditions. All tests were run in duplicate. ImageJ and GraphPad Prism were used for analysis. Fold change was defined as the ratio of secreted factors in the MP group to the non-MP control. RESULTS: Under static conditions, MP was associated with >1-fold change of 17/20 (85%) angiogenic factors when venous ECs were tested but only 11/20 (55%) factors when arterial ECs were tested (Table1). The same trend was observed under flow conditions. Furthermore, flow amplified the rise of venous angiogenic factors following MP with 8/20 (40%) demonstrating >1.5-fold change when compared to static conditions (5/20, 25%). CONCLUSION: MP leads to pro-angiogenic factor release from ECs. It appears venous ECs respond differently to MP compared to arterial ECs. These changes are further amplified under flow conditions with venous ECs having a heightened factor release profile. Subsequent investigations will determine how these findings can be translated clinically.