[Comparison between canine decellularized venous valve stent combined with endothelial progenitor cells and native venous valve on venous valve closure mechanism in normal physiological conditions].
OBJECTIVE
To compare canine decellularized venous valve stent combining endothelial progenitor cells (EPC) with native venous valve in terms of venous valve closure mechanism in normal physiological conditions.


METHODS
Thirty-six male hybrid dogs weighing 15-18 kg were used. The left femoral vein with valve from 12 dogs was harvested to prepare decellularized valved venous stent combined with EPC. The rest 24 dogs were randomly divided into the experimental group and the control group (n=12 per group). In the experimental group, EPC obtained from the bone marrow through in vitro amplification were cultured, the cells at passage 3 (5 x 10(6) cells/mL) were seeded on the stent, and the general and HE staining observations were performed before and after the seeding of the cells. In the experimental group, allogenic decellularized valved venous stent combined with EPC was transplanted to the left femoral vein region, while in the control group, the autogenous vein venous valve was implanted in situ. Color Doppler Ultrasound exam was performed 4 weeks after transplantation to compare the direction and velocity of blood flow in the distal and proximal end of the valve, and the changes of vein diameter in the valve sinus before and after the closure of venous valve when the dogs changed from supine position to reverse trendelenburg position.


RESULTS
General and HE staining observations before and after cell seeding: the decellularized valved venous stent maintained its fiber and collagen structure, and the EPC were planted on the decellularized stent successfully through bioreactor. During the period from the reverse trendelenburg position to the starting point for the closure of the valve, the reverse flow of blood occurred in the experimental group with the velocity of (1.4 +/- 0.3) cm/s; while in the control group, there was no reverse flow of blood, but the peak flow rate was decreased from (21.3 +/- 2.1) cm/s to (18.2 +/- 3.3) cm/s. In the control group, the active period of valve, the starting point for the closure of the valve, and the time between the beginning of closure and the complete closure was (918 +/- 46), (712 +/- 48), and (154 +/- 29) ms, respectively; while in the experimental group, it was (989 +/- 53), (785 +/- 43), and (223 +/- 29) ms, respectively. There was significant difference between two groups (P < 0.05). After the complete closure of valve, no reverse flow of blood occurred in two groups. The vein diameter in the valve sinus of the experimental and the control group after the valve closure was increased by 116.8% +/- 2.0% and 118.5% +/- 2.2%, respectively, when compared with the value before valve closure (P > 0.05).


CONCLUSIONS
Canine decellularized venous valve stent combined with EPC is remarkably different from natural venous valve in terms of the valve closure mechanism in physiological condition. The former relies on the reverse flow of blood and the latter is related to the decreased velocity of blood flow and the increased pressure of vein in the venous sinus segment.
Wei
Zhiqing
Z
Department of Vascular Surgery, Drum Tower Hospital Affiliated to Medical College of Nanjing University, Nanjing Jiangsu, 210008, P.R. China.
Liu
Changjian
C
Zhou
Min
M
Qiao
Wei
W
D000818:Animals; D004285:Dogs; D042783:Endothelial Cells / Q000000981:diagnostic imaging / Q000637:transplantation*; D005268:Femoral Vein / Q000000981:diagnostic imaging; D008297:Male; D013234:Stem Cells / Q000166:cytology; D015607:Stents; D023822:Tissue Engineering; D014463:Ultrasonography; D055422:Venous Valves / Q000000981:diagnostic imaging / Q000637:transplantation*