Multi-layer approaches to scaffold-based small diameter vessel engineering: A review.

Cardiovascular disease is one of the leading causes of death in the world. A characteristic symptom of cardiovascular disease is occlusion of vessels. Once vascular occlusion occurs there is a critical need to re-establish flow to prevent ischemia in the downstream tissues.

Periadventitial atRA citrate-based polyester membranes reduce neointimal hyperplasia and restenosis after carotid injury in rats.

Oral all-trans retinoic acid (atRA) has been shown to reduce the formation of neointimal hyperplasia; however, the dose required was 30 times the chemotherapeutic dose, which already has reported side effects. As neointimal formation is a localized process, new approaches to localized delivery are required. This study assessed whether atRA within a citrate-based polyester, poly(1,8 octanediolcitrate) (POC), perivascular membrane would prevent neointimal hyperplasia following arterial injury.

Effect of bilateral oophorectomy on wound healing of the rabbit vagina.

We aimed to assess the effect of bilateral oophorectomy on vaginal wound healing in three groups of New Zealand White rabbits (24 rabbits each). Group 1 underwent bilateral oophorectomy, group 2 underwent a sham surgery, and group 3 served as control. Standardized vaginal tissue specimens were harvested and assessed for wound and scar surface area and tensiometric analysis before wounding, and sequentially thereafter, showing that vaginal wound closure, scar contraction, and recovery of biomechanical properties are significantly slower in oophorectomized rabbits.

Citric acid-based elastomers provide a biocompatible interface for vascular grafts.

Prosthetic vascular bypass grafting is associated with poor long-term patency rates. Herein, we report on the mid-term performance of expanded polytetrafluoroethylene (ePTFE) vascular grafts modified with a citric acid-based biodegradable elastomer. Through a spin-shearing method, ePTFE grafts were modified by mechanically coating a layer of poly(1,8 octanediol citrate) (POC) onto the luminal nodes and fibrils of the ePTFE.

In vitro characterization of a compliant biodegradable scaffold with a novel bioreactor system.

The influence of scaffold compliance on blood vessel tissue engineering remains unclear and compliance mismatch issues are important to an in vivo tissue-engineering approach. We have designed and constructed a modular bioreactor system that is capable of imparting pulsatile fluid flow while simultaneously measuring vessel distension with fluid pressure changes in real time. The setup uses a pneumatic PID control system to generate variable fluid pressure profiles via LabVIEW and an LED micrometer to monitor vessel distension to an accuracy of +/-2 microm.

Hemocompatibility evaluation of poly(glycerol-sebacate) in vitro for vascular tissue engineering.

Poly(glycerol-sebacate) (PGS) is an elastomeric biodegradable polyester that could potentially be used to engineer blood vessels in vivo. However, its blood-material interactions are unknown. The objectives of this study were to: (a) fabricate PGS-based biphasic tubular scaffolds and (b) assess the blood compatibility of PGS in vitro in order to get some insight into its potential use in vivo.

Biomechanical characterization of vaginal versus abdominal surgical wound healing in the rabbit.

Objective: The objective of the study was to compare biomechanical properties of vaginal versus abdominal surgical wound healing in the rabbit.

Study Design: Bilateral 6-mm full-thickness circular segments were excised from the vagina and abdominal skin in 38 New Zealand White female rabbits. Animals were killed 0, 4, 7, 10, 14, 21, 28, and 35 days after wounding, and the wounds were assessed for surface area and tensile properties.

Novel biphasic elastomeric scaffold for small-diameter blood vessel tissue engineering.

Compliance mismatch, thrombosis, and long culture times in vitro remain important challenges to the clinical implementation of a tissue-engineered small-diameter blood vessel (SDBV). To address these issues, we are developing an implantable elastomeric and biodegradable biphasic tubular scaffold. The scaffold design uses connected nonporous and porous phases as a basis to mimic, respectively, the intimal and medial layers of a blood vessel.

Synthesis and evaluation of poly(diol citrate) biodegradable elastomers.

Herein, we report the synthesis and evaluation of a novel family of biodegradable and elastomeric polyesters, poly(diol citrates). Poly(diol citrates) were synthesized by reacting citric acid with various diols to form a covalent cross-linked network via a polycondensation reaction without using exogenous catalysts. The tensile strength of poly(diol citrates) were as high as 11.

Biodegradable polyester elastomers in tissue engineering.

Tissue engineering often makes use of biodegradable scaffolds to guide and promote controlled cellular growth and differentiation in order to generate new tissue. There has been significant research regarding the effects of scaffold surface chemistry and degradation rate on tissue formation and the importance of these parameters is widely recognised. Nevertheless, studies describing the role of mechanical stimuli during tissue development and function suggest that the mechanical properties of the scaffold will also be important.