Scar outcomes in dermatological surgery.

BACKGROUND/OBJECTIVES: Significant functional impairment and psychological burden may result from poor scar quality and its impact on patient's quality of life has been well-established. It is important to identify measures to reduce the risk of surgical complications. METHOD: 212 patients undergoing dermatological surgery were recruited from March 2011 to February 2014. Their age, sex, surgical site, closure type, defect size (length and width), scar length, number of deep sutures, suture type and size were recorded. The patients were followed up at 6 weeks and 6 months for complications including abscess formation, granuloma formation, scar spreading, suture spitting and hypertrophic scar formation. RESULTS: At 6 weeks complications included suture spitting (14%), granuloma (11%), scar spreading (7%), hypertrophic scarring (3%) and abscess formation (1%), and at 6 months; scar spreading (17%), hypertrophic scarring (2%) and suture spitting (1%). In our multivariate analysis there were no predictors for spreading or spitting at 6 weeks, and only the defect size width was a predictor for granulomas in the stepwise analysis. For scar spreading at 6 months, younger age, site (trunk or limbs), higher number of deep sutures and surgeon were independent predictors (P < 0.0001 for the model). CONCLUSION: Complications following dermatological surgery are low and tend to resolve with time, except for scar spreading. The surgeon who experienced more complications was placing sutures more superficially to the skin surface and was throwing more knots per closure; factors that we did not record in our study and merit further study.

High Modulus Biodegradable Polyurethanes for Vascular Stents: Evaluation of Accelerated in vitro Degradation and Cell Viability of Degradation Products.

We have recently reported the mechanical properties and hydrolytic degradation behavior of a series of NovoSorb™ biodegradable polyurethanes (PUs) prepared by varying the hard segment (HS) weight percentage from 60 to 100. In this study, the in vitro degradation behavior of these PUs with and without extracellular matrix (ECM) coating was investigated under accelerated hydrolytic degradation (phosphate buffer saline; PBS/70°C) conditions. The mass loss at different time intervals and the effect of aqueous degradation products on the viability and growth of human umbilical vein endothelial cells (HUVEC) were examined. The results showed that PUs with HS 80% and below completely disintegrated leaving no visual polymer residue at 18 weeks and the degradation medium turned acidic due to the accumulation of products from the soft segment (SS) degradation. As expected the PU with the lowest HS was the fastest to degrade. The accumulated degradation products, when tested undiluted, showed viability of about 40% for HUVEC cells. However, the viability was over 80% when the solution was diluted to 50% and below. The growth of HUVEC cells is similar to but not identical to that observed with tissue culture polystyrene standard (TCPS). The results from this in vitro study suggested that the PUs in the series degraded primarily due to the SS degradation and the cell viability of the accumulated acidic degradation products showed poor viability to HUVEC cells when tested undiluted, however particles released to the degradation medium showed cell viability over 80%.

Properties and in vitro evaluation of high modulus biodegradable polyurethanes for applications in cardiovascular stents.

This study examined the suitability of a family of biodegradable polyurethanes (PUs) NovoSorb developed for the vascular stent application. These segmented PUs are formulated to be biodegradable using degradable polyester and PU blocks. A series of PUs comprising different hard segment weight percentage ranging from 60 to 100 were investigated. The mechanical properties of the PUs were evaluated before and after gamma sterilization to assess their suitability for vascular implants. The real-time (PBS/37°C/pH 7.4) hydrolytic degradation studies were carried out under sterile conditions and PU glass transition temperature, molecular weight, and mass loss at 3, 6, and 9 months were determined. The viability and growth of Human Umbilical Vein Endothelial Cells (HUVEC) on PU surfaces were determined to assess the effect of PU degradation. The effect of coating of extracellular matrix (ECM) components on cell viability was also investigated. The study showed that the PUs possess excellent mechanical properties exhibiting high tensile strength (41-56 MPa) and tensile modulus (897-1496 MPa). The PU films maintained mechanical strength during the early phase of the degradation but lost strength at latter stages. The unmodified polymer surface of each PU promotes endothelial cell growth and proliferation, with a HUVEC retention rate of >70%.

Collagen type I together with fibronectin provide a better support for endothelialization.

Endothelialization of vascular implants is limited by the inability of cells to retain adhesion when exposed to flow. Extracellular matrix proteins, including fibronectin and collagen, enhance cell adherence on materials. This study investigated the behaviour of Human Umbilical Vein Endothelial Cells (HUVEC) on extracellular matrix coated polystyrene. Collagen and fibronectin were coated as single and double layers to analyse differences in cell proliferation, morphology, and cell-protein interactions. Significantly higher endothelial cell proliferation and migration rates were observed on the collagen and collagen+fibronectin coating compared to the uncoated or fibronectin-coated sample. Immmunofluorescent microscopy showed evidence of extracellular matrix remodelling in the double, collagen+fibronectin coating. These results strongly suggest that a double coating of collagen+fibronectin provides a better support structure for endothelial cell growth and contributes to improve the ability of vascular implants to become and remain endothelialized.

Polyethyleneterephthalate provides superior retention of endothelial cells during shear stress compared to polytetrafluoroethylene and pericardium.

BACKGROUND: Polyethyleneterephthalate (PET) and polytetrafluoroethylene (PTFE) are polymers successfully used as large diameter arterial grafts for peripheral vascular surgery. However, these prosthetic grafts are rarely used for coronary bypass surgery because of their low patency rates. Endothelialisation of the lumenal surface of these materials may improve their patency. This study aimed to compare the endothelialisation of PET, PTFE and pericardium by examining their seeding efficiency over time and the effect of various shear stresses on retention of endothelial cells. METHODS: Ovine endothelial cells at 4x10(5)cells/cm(2) were seeded onto PET, PTFE and pericardium, and cultured for 1-168 hours. Cell coverage was determined via en face immunocytochemistry and cell retention was quantified after being subjected to shear stresses ranging from 0.018 to 0.037N/m(2) for 15, 30 and 60 minutes. RESULTS: Endothelial cells adhered to all of the materials one hour post-seeding. PET exhibited better cell retention rate, ranging from 66.9+/-5.6% at 0.018N/m(2) for 15min to 44.7+/-1.9% at 0.037N/m(2) for 60 minutes, when compared to PTFE and pericardium (p<0.0001, three-way ANOVA). CONCLUSION: PET shows superior retention of endothelial cells during shear stress compare to PTFE and pericardium.