The Effect And Molecular Mechaniasm Of TRPV4 In Expanding Choke Zone Of Perforator Flaps

The area of perforator flap has been research focus of plastic surgery for decades with its flexibility of surgical design and minimal trauma of donor site.However,one major drawback of this surgical technique is the blood supply of perforator flap is not always sufficient to meet the needs of massive trauma reconstruction.The existing concepts of perforator flap was established mainly upon the morphological studies of flaps conducted by Taylor and colleagues in the 1980's,through careful study he observed some delicate vessels which he then named “choke vessels”.Choke vessels are reduced-caliber vessels connecting adjacent in physiological vascular conditions.This structure resembles the innate collateral vessel network of coronary artery.Recent studies in cardiovascular diseases demonstrated that under circumstance of acute coronary syndrome,pressure differences between different branches of coronary arteries create elevated fluid shear stress in the collateral vessel network,causing vasodilation of these vessels.Other data showed that TRPV4 plays a vital role in sensing shear stress variation as a mechanical receptor.The proposed research hypothesized that chemical activation of TRPV4 as a therapeutic target could promote the vasodilation of choke vessels in flaps and lead to larger cross-angiosome perforator flaps with single supply vessels.In vivo,Methods of this research included the establishment of rat perforator flap model,the pharmacological intervention of TRPV4 agonist and antagonist,observation of the impact of TRPV4 activation and blockage to choke vessel dilation and flap survival.And then,we use Western blot technology to test the protein expression of TPRV4 in choke vessels area.At last,we found that the performance of the TRPV4 activation agent group just like the positive control group.Choke vessels no matter were seen under endoscope,hemodynamics,tissue metabolism,or survival area of the perforators flap were significantly superior to the control group.Furthermore,there was significant difference between the antagonist group and the control group,the antagonist group worse than the control group.Western Blot test results show that the TRPV4 protein expression level of the rats perforators flap choke zone is the positive control group > the agonist group > the blank control group > the antagonist group.This was positively correlated with the choke arterial vascularization degree of each group,it suggested that TRPV4 may participate in regulating the choke artery generate mechanism and influence the vascularization of the choke artery.Along with that,in vitro research,targeting HUVEC and VSMC was conduct to study the impact of TRPV4 activation and blockage to cell proliferation,cell migration and the cell factor secretion of downstream pathway.The experimental results show that the TRPV4 activator can improve the proliferation and migration of endothelial cells and increase the factors such as the NF-k B,MCP-1,VEGF's m RNA expression level,but the TRPV4 antactivator decrease the proliferation and migration of endothelial cells and reduce the factors such as the NF-k B,MCP-1,VEGF's m RNA expression level.For smooth muscle cell,TRPV4 activator can improve the cell's proliferation ability,and had no obvious effect on it's migration ability,TRPV4 activator has a stronger effection on smooth muscle cell's factor m RNA expression level than on endothelial cell's.The ability of TRPV4 inhibitor to effect the smooth muscle cell just like the the ability of TRPV4 activator.So we know that TRPV4 receptors has a strong effection on endothelial cell's function,the influence of it may be directly activated endothelial cells and the smooth muscle cells may be activated by indirect way,all these ways were involved in the process of arteriogenesis.Conclusions:1.Percutaneous endoscopic can be a kind of novel method to observe the choke vessels of flap on rats,it is convenient,high resolution and allows chronic,in-vivo observation of choke vessels.2.The TRPV4 receptor was actived in rat body,then choke artery generation started successfully,it promoted the choke artery dilation and improved the degree of perforators flap revascularized,expanded the scope of perforators flap survival.The Western Blot test proved that TRPV4 might participate in regulating the choke artery generate mechanism,so we think chemical activation of TRPV4 as a therapeutic target could promote the vasodilation of choke vessels in flaps.3.In vitro,TRPV4 activator has a stronger effection on endothelial cell's function than on smooth muscle cell's.After TRPV4 was activated,the NF-k B pathways stared,so some chemokines and adhesion factor of the endothelial cells expressing rise.At last,vascular endothelial cells and smooth muscle cells proliferate rapidly.