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Tissue engineering vascular grafts (TEVGs) have the potential to replace small-diameter grafts in bypass surgery which is good news for patients with cardiovascular disease. Decellularized arteries can be ideal TEVGs because their natural three-dimensional structures support the migration of host cells and vascular remodeling. There are many methods for decellularization without a standard protocol. In this study, a combination of Triton X-100 and sodium dodecyl sulfate (SDS) were used to prepare decellularized arteries. However, decellularization may damage the biochemical and mechanical properties to some degree. We used the cross-linking agents N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to improve mechanical properties and immobilize heparin to inhibit thrombogenesis. Histological analysis, scanning electron microscopy, biomechanical properties test, determination of immobilized heparin, active partial thrombin time assay, and subcutaneous embedding experiment were used to evaluate the efficiency of decellularization and the efficacy of heparinized cross-linked vascular scaffold. Results showed 1% Triton X-100 combined with 0.3% SDS can decellularize successfully. EDC and NHS cross-linking can improve the mechanical properties, reduce the inflammatory reaction and slow the degradation time. Heparin immobilized on the scaffolds can inhibit thrombogenesis effectively. This study indicated the heparinized cross-linked vascular scaffolds may be ideal scaffolds for TEVGs.

We here report a case of a 52-year-old man who underwent simultaneous bypass grafting surgery on his carotid–axillary arteries bilaterally (axillary–carotid and carotid–axillary bypasses) after a failed endovascular treatment. This has rarely been reported. Imaging follow-up at 5 days showed bypass graft patency, and he developed no complications. At 1-month follow-up, the patient had no discomfort or recurrence of vertigo and ataxia and his blood pressure was steady and normal bilaterally. The results in this patient indicate that axillary–carotid and carotid–axillary bypasses using expanded polytetrafluoroethylene grafts are a safe and valuable techniques for revascularizing common carotid artery and subclavian artery occlusive diseases, achieving patency and freedom from stroke in the short term. Long-term outcomes are yet to be determined.

Vascular grafts prepared from synthetic polymers have serious shortcomings that can be resolved by surface modification, such as by immobilizing heparin. In this study, the mechanical properties, biocompatibility, anticoagulation property, and water contact angle of two heparin-conjugated poly(ε-caprolactone) scaffolds (PCL-hexamethylendiamine-heparin, PCL-HMD-H. PCL-lysine-heparin, PCL-LYS-H) were compared to identify a preferred heparin conjugation method. An evaluation of the subcutaneous tissue biocompatibility of the scaffolds demonstrated that PCL-HMD-H had better endothelial cell proliferation than the PCL-LYS-H and was therefore a promising scaffold candidate for use in vascular tissue-engineering.

Decellularized arteries have been considered as promising scaffolds for small-diameter vascular substitutes. However, weakened mechanical properties, immunological rejection and rapid degradation after transplantation still exist after decellularization. Previous studies indicated that genipin cross-linking can solve these problems. Therefore, genipin was selected as the cross-linking agent for the pre-treatment of decellularized arteries in our study. Histological analysis, scanning electron microscopy, mechanical properties analysis and subcutaneous embedding experiment were adopted to investigate the efficiency of decellularization and the effect of genipin cross-linking on improving mechanical, structural and biological properties of decellularized arteries. Decellularization protocols based on three trypsin concentrations were used to prepare decellularized arteries, after decellularization, arteries were cross-linked with genipin. Results showed that 0.5% trypsin was the most efficient concentration to remove cellular components and preserve ECM. However, mechanical properties of 0.5% trypsin decellularized arteries weakened significantly, while genipin cross-linking improved mechanical properties of decellularized arteries to the same level as fresh arteries. After 4 weeks subcutaneous embedding, cross-linked arteries caused the mildest inflammatory response. In conclusion, genipin could be employed as an ideal cross-linking agent to strengthen mechanical properties, enhance the resistance to degradation and reduce the antigenicity of decellularized arteries for small-diameter blood vessel tissue engineering applications.

Background Diabetic foot ulcer (DFU) is a severe complication of diabetes, preceding most diabetes-related amputations. DFUs require over US$9 billion for yearly treatment and are now a global public health issue. DFU occurs in the setting of ischemia, infection, neuropathy, and metabolic disorders that result in poor wound healing and poor treatment options. Recently, stem cell therapy has emerged as a new interventional strategy to treat DFU and appears to be safe and effective in both preclinical and clinical trials. However, variability in the stem cell type and origin, route and protocol for administration, and concomitant use of angioplasty confound easy interpretation and generalization of the results. Methods The PubMed, Google Scholar, and EMBASE databases were searched and 89 preclinical and clinical studies were selected for analysis. Results There was divergence between preclinical and clinical studies regarding stem cell type, origin, and delivery techniques. There was heterogeneous preclinical and clinical study design and few randomized clinical trials. Granulocyte-colony stimulating factor was employed in some studies but with differing protocols. Concomitant performance of angioplasty with stem cell therapy showed increased efficiency compared to either therapy alone. Conclusions Stem cell therapy is an effective treatment for diabetic foot ulcers and is currently used as an alternative to amputation for some patients without other options for revascularization. Concordance between preclinical and clinical studies may help design future randomized clinical trials.

Random copolyester of poly(ɛ-caprolactone-co-L-lactide) (PCLA) with a 50:50 feeding molar ratio was synthesized via the ring-opening polymerization and functionalized by the end-capping reaction with acryloyl chloride. The resulting acrylated PCLA was then fabricated into small diameter tubular scaffolds by electrospinning technique and the formed scaffolds were followed by photocrosslinking under UV irradiation in the absence of photoinitiator. The mechanical strengths including tensile, suture retention and burst pressure were greatly enhanced after the photocrosslinking. The in vitro degradation data clearly revealed that the mechanical properties of the crosslinked scaffolds still remained after one month degradation in PBS solution, while those of the non-crosslinked ones lost heavily. The cytotoxicity assay on the mouse fibroblast L929 cells was conducted via MTT measurement. Furthermore, the observation on endothelial and fibroblast cell adhesion and proliferation was also made by using scanning electron microscopy (SEM). The initiator-free photocrosslinked tubular scaffolds show the potential to be used in vascular tissue engineering.

Recent studies have demonstrated that mesenchymal stem cells (MSCs) can differentiate into endothelial cells. The effect of shear stress on MSC differentiation is incompletely understood, and most studies have been based on two-dimensional systems. We used a model of tissue-engineered vascular grafts (TEVGs) to investigate the effects of shear stress on MSC differentiation.MSCs were isolated from canine bone marrow. The TEVG was constructed by seeding MSCs onto poly-epsilon-caprolactone and lactic acid (PCLA) scaffolds and subjecting them to shear stress provided by a pulsatile bioreactor for four days (two days at 1 dyne/cm(2) to 15 dyne/cm(2) and two days at 15 dyne/cm(2)).Shear stress significantly increased the expression of endothelial cell markers, such as platelet-endothelial cell adhesion molecule-1 (PECAM-1), VE-cadherin, and CD34, at both the mRNA and protein levels as compared with static control cells. Protein levels of alpha-smooth muscle actin (alpha-SMA) and calponin were substantially reduced in shear stress-cultured cells. There was no significant change in the expression of alpha-SMA, smooth muscle myosin heavy chain (SMMHC) or calponin at the mRNA level.Shear stress upregulated the expression of endothelial cell-related markers and downregulated smooth muscle-related markers in canine MSCs. This study may serve as a basis for further investigation of the effects of shear stress on MSC differentiation in TEVGs.