On the Decellularization of Fresh or Frozen Human Umbilical Arteries: Implications for Small-Diameter Tissue Engineered Vascular Grafts

Most tissues, including those to be decellularized for tissue engineering applications, are frozen for long term preservation. Such conventional cryopreservation has been shown to alter the structure and mechanical properties of tissues. Little is known, however, how freezing affects decellularization of tissues. The purpose of this study was two-fold: to examine the effects of freezing on decellularization of human umbilical arteries (HUAs), which represent a potential scaffolding material for small-diameter tissue-engineered vascular grafts, and to examine how decellularization affects the mechanical properties of frozen HUAs. Among many decellularization methods, hypotonic sodium dodecyl sulfate solution was selected as the decellularizing agent and tested on fresh HUAs to optimize decellularization conditions. The efficiency of decellularization was evaluated by DNA assay and histology every 12 up to 48 h. The optimized decellularization protocol was then performed on frozen HUAs. The stiffness, burst pressure, and suture retention strength of fresh HUAs and frozen HUAs before and after decellularization were also examined. It appeared that freezing decreased the efficiency of decellularization, which may be attributed to the condensed extracellular matrix caused by freezing. While the stiffness of fresh HUAs did not change significantly after decellularization, decellularization reduced the compliance of frozen HUAs. Interestingly, the stiffness of decellularized frozen HUAs was similar to that of decellularized fresh HUAs. Although little difference in stiffness was observed, we suggest avoiding freezing if more efficient and complete decellularization is desired.     

Three-year comparable clinical outcome for Trans-Atlantic Inter-Society Consensus (TASC) D femoropopliteal occlusion: Endovascular vs bypass surgery

Aim

To evaluate the difference between endovascular surgery and bypass/hybrid approach in treating Trans-Atlantic Inter-Society Consensus (TASC) D femoropopliteal occlusion.

Patients and Methods

This is a 10-year retrospective cohort study including 75 patients with TASC D femoropopliteal occlusion with revascularisation from 2009 to 2018. Cases were retrieved from the Clinical Data Analysis and Reporting System. Demographics, lesions characteristics, operative findings and follow-up data were reviewed.

Results

A total of 65% of patients had endovascular intervention, 23% open bypass and 12% hybrid operation. The endovascular group had fewer critical limb ischaemia (endovascular 43%, bypass 94%, hybrid 100%; P < .001), and shorter length of lesion (endovascular 26.4 cm vs bypass/hybrid 31.0 cm; P = .004). The technical success rate of the endovascular group was 87.8%. Different endovascular treatment strategies were used. The 12-month primary patency rate of the endovascular group was lower (endovascular 69.7% vs bypass 81.3% vs hybrid 75.0%; P = .67) but the secondary patency rate at 3 years after the operation was similar across all groups (endovascular 83.3% vs bypass 78.6% vs hybrid 87.5%; P = .86).

Conclusion

Endovascular treatment for long and complex femoropopliteal occlusion is technically feasible with a high success rate. Close surveillance with prompt reintervention may help achieve 3 years’ comparable patency of endovascular intervention to traditional surgical bypass. Individualised plan of revascularisation should be considered.