{'fraction_non_alphanumeric': 0.027651858567543066, 'fraction_numerical': 0.0185856754306437, 'mean_word_length': 4.6157760814249365, 'pattern_counts': {'":': 0, '<': 1, '<?xml version=': 0, '>': 1, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
A new external stent - intimal proliferation and apoptosis in the vein graft in the animal model.

BACKGROUND
We have previously showed that the extravascular dacron mesh stent wrapped around a vein graft and implanted into the arterial system prevented the hypertrophy of the graft's wall, impeded the overgrowth of the intima and decreased the proliferation rate of venous graft cellular elements.


AIM
To determine the role of cellular proliferation and apoptosis in the process of remodelling in the stent in an animal model in a 12-week period.


METHODS
Male sheep (n = 21) received by transplantation the hybrid graft (group 1) or carotid artery radial vein grafts (group 2). A hybrid graft was composed of a radial vein, collagen fibrin glue and highly flexible torlen/dacron mesh tubing. Grafts were retrieved on day 5, 9 and then week 4, 6, 8, 10, 12, respectively. A proliferation process was assessed using a Ki-67 antigen kit. The presence of apoptosis was detected using a TUNEL kit, strictly according to the manufacturer's manual.


RESULTS
The number of proliferating cells has presented a decreasing trend in both groups, whereas the mean quantity of apoptotic cells increased over a 12-week period (p < 0.001) in both groups. Proliferation was more prominent during the first 5 weeks in both groups. The trend had a tendency to reverse during the last 7 weeks of observation. The ratio of proliferating to apoptotic cells differed between groups (1.6 vs. 1.9 on day 5 and 0.2 vs. 0.6 in week 12, in group 1 and group 2, respectively). No linear correlation between proliferation and apoptosis was observed (p > 0.05).


CONCLUSIONS
Different kinetics in the trico hybrid graft group in comparison with the radial vein graft group was observed, with a more prominent cellular turnover in the trico hybrid graft. Apoptosis in an unprotected vein wall was overcomed by the proliferation process. In trico hybrid vein grafts, beneficial remodelling of the intimal layer was predominantly dependent on inhibition of intimal proliferation rather than the effect of changes of the apoptosis ratio. There was no linear correlation between proliferation and apoptosis in the investigated grafts.