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Current surgical therapy for diseased vessels less than 6mm in diameter involves bypass grafting with autologous arteries or veins. Although this surgical practice is common, it has significant limitations and complications, such as occlusion, intimal hyperplasia and compliance mismatch. As a result, cardiovascular biomaterials research has been motivated to develop tissue-engineered blood vessel substitutes. In this study, vascular tissue engineering scaffolds were fabricated using two different approaches, namely melt spinning and electrospinning. Small diameter tubes were fabricated from an elastomeric bioresorbable 50:50 poly(l-lactide-co-epsilon-caprolactone) copolymer having dimensions of 5mm in diameter and porosity of over 75%. Scaffolds electrospun from two different solvents, acetone and 1,1,1,3,3,3-hexafluoro-2-propanol were compared in terms of their morphology, mechanical properties and cell viability. Overall, the mechanical properties of the prototype tubes exceeded the transverse tensile values of natural arteries of similar caliber. In addition to spinning the polymer separately into melt-spun and electrospun constructs, the approach in this study has successfully demonstrated that these two techniques can be combined to produce double-layered tubular scaffolds containing both melt-spun macrofibers (<200microm in diameter) and electrospun submicron fibers (>400nm in diameter). Since the vascular wall has a complex multilayered architecture and unique mechanical properties, there remain several significant challenges before a successful tissue-engineered artery is achieved., (Copyright 2010. Published by Elsevier Ltd.)

Electrospinning has recently received much attention in biomedical applications, and has shown great potential as a novel scaffold fabrication method for tissue engineering. The nano scale diameter of the fibers produced and the structure of the web resemble certain supramolecular features of extracellular matrix which is favorable for cell attachment, growth and proliferation. There are various parameters that can alter the electrospinning process, and varying one or more of these conditions will result in producing different nanofibrous webs. So the aim of this study was to investigate the effect of material variables and process variables on the morphology of electrospun 50:50 poly(L-lactide-co-epsilon-caprolactone) (PLCL) nanofibrous structures. The morphology of the nanofibers produced was strongly influenced by parameters such as the flow rate of the polymer solution, the electrospinning voltage and the solution concentration. The diameter was found to increase with solution concentration in a direct linear relationship. Finally, it has been successfully demonstrated that by increasing the rotation speed of the collector mandrel, the alignment of the fibers can be controlled in a preferred direction. These findings contribute to determining the functional conditions to electrospin this biodegradable elastomeric copolymer which has potential as a scaffold material for vascular tissue engineering.

In good agreement with previous observations, D-3-hydroxybutyrate dehydrogenase (OHBD) activity in disrupted liver mitochondria decreased significantly in chronic diabetic rats, whereas insulin treatment prevented this decrease. Similar effects were observed with kidney mitochondria. Adrenalectomy increased OHBD activity in liver and brain mitochondria from normal rats and in liver mitochondria from diabetic rats. Corticosterone depressed OHBD activity in liver mitochondria of normal rats and restored the normal level of OHBD in adrenalectomized rats. Hypophysectomy increased OHBD activity in normal rats, this effect being further increased by growth hormone administration. D-3-hydroxybutyrate (OHB) oxidation by liver mitochondria from diabetic, adrenalectomized or hypophysectomized rats varied as expected from OHBD activity in disrupted mitochondria, but to a relatively lesser degree. Submitochondrial particles from diabetic rats showed significant diminution in OHB-, succinate- and NADH-oxidase activities, whereas mitochondria from diabetic rats oxidized succinate and L-malate + L-glutamate at a slower rate than the corresponding controls.