Effect of adipose tissue derived stem cell (ADSC) on transvers rectus abdominis musculocutaneous (TRAM) flap viability after abdominoplasty: Experimental study

It is known that abdominoplasty permanently damage the nutritional musculocutaneous perforator arteries of the TRAM flap skin island. In order to reduce the damage caused by abdominoplasty and to increase vascularity of the TRAM flap, surgical delay procedures, vasculogenic growth factors, pharmacological agents and gene therapies have been studied. No study investigating the impact of locally administered ADSC on TRAM flap viability after abdominoplasty have been found in the literature. A total of 7 groups were formed. In group 1 only TRAM flaps were prepared. In groups 2, 3 and 4 TRAM flaps were elevated, 1 week, 2 weeks and 4 weeks after abdominoplasty. In group 5, 6 and 7 same surgeries were performed at the same days and ADSC injections were administered during abdominoplasty. 7 days after TRAM flap elevation the assesment of flap live area percentage was performed. Microangiographic image of one rat's flap from each group were taken. At this point we dissected the TRAM flaps to show and count if any newly formed musculocutaneous perforator arteries were developed. The TRAM flap tissues were taken for histopatological examination. On the histopatological examination; capillary density and fibrosis gradient was measured. ADSCs marked with DiI were examined under fluorescent microscope to track them in the tissues. Plasma levels of VEGF were studied at the days of abdominoplasy, TRAM flap elevation and sacrification. The average viable flap area was 82,90 ± 7,59 % in group 1. The average viable flap areas were 2,24 ± 3,71 %, 3,31 ± 3,29 %, 9,40 ± 6,18 % in groups 2, 3 and 4 respectively. The average viable flap areas were 15,83 ± 6,41 %, 31,92 ± 9,29 %, 64,98 ± 10,95 % in groups 5, 6 and 7 respectively. The viable flap area percentages of grups 5, 6 and 7 were statistically higher than groups 2, 3 and 4 respectively. The viable flap areas of group 7 and group 6 were statistically higher than groups 6 and group 5 respectively. 7.98 ± 1.10 musculocutaneous perforator arteries were counted arising from both of the rectus abdominis muscles. The groups were examined in terms of the newly formed musculocutaneous perforating arteries. We couldn't show any newly formed musculocutanous perforating arteries in groups 2 and 3. The number of newly formed musculocutanous perforating arteries were 0,29 ± 0,49, 0,43 ± 0,53, 1,14 ± 0,69, 2 ± 0,82 for groups 4, 5, 6 and 7 respectively. The number of perforating arteries counted after abdominoplasty was statistically significantly lower than the number of perforating arteries counted before abdominoplasty in all groups. The number of newly formed perforating arteries after abdominoplasty in group 7 was statistically significantly higher than the other groups. Mean capillary density was 6,86 ± 0,50; 0,36 ± 0,05; 0,67 ± 0,13; 2,79 ± 0,53; 2,46 ± 0,58; 3,71 ± 0,47; 7,01 ± 0,70 in groups 1, 2, 3, 4, 5, 6 and 7 respectively. Mean capillary density of groups 5, 6 and 7 were statistically higher than groups 2, 3 and 4 respectively. Mean capillary density of group 7 was statistically higher than group 5. The difference between the groups in terms of fibrosis gradients were not statistically significant. It was shown that ADSCs marked with DiI, participated in the vessel wall structure as endothelial cells by immunohistochemical examination under fluorescence microscopy. There were statistically significant increase between the baseline VEGF values and the second VEGF values in groups 5, 6 and 7. The results of this experimental study showed that local injection of ADSC increases TRAM flap viability after abdominoplasty. It has also been shown that the time passed after abdominoplasty was another variable affecting the flap viability. The increase in tissue vascularization and formation of new musculocutaneous perforator arteries emerged the increase in the viability of TRAM flap. It is shown that ADSCs increase tissue vascularization via increasing plasma VEGF levels and also by transformation into endothelial cells. Successful results are obtained in experimental research with ADSC applications in order to increase flap viability. We believe that in the future ADSCs may be used successfully in the clinics where there is risk for flap viability. Key words: TRAM flap, abdominoplasty, adipose derived stem cell, vascularization.