Electrospun poly(d/l-lactide-co-l-lactide) hybrid matrix: a novel scaffold material for soft tissue engineering

Electrospinning is a long-known polymer processing technique that has received more interest and attention in recent years due to its versatility and potential use in the field of biomedical research. The fabrication of three-dimensional (3D) electrospun matrices for drug delivery and tissue engineering is of particular interest. In the present study, we identified optimal conditions to generate novel electrospun polymeric scaffolds composed of poly-d/l-lactide and poly-l-lactide in the ratio 50:50. Scanning electron microscopic analyses revealed that the generated poly(d/l-lactide-co-l-lactide) electrospun hybrid microfibers possessed a unique porous high surface area mimicking native extracellular matrix (ECM). To assess cytocompatibility, we isolated dermal fibroblasts from human skin biopsies. After 5 days of in vitro culture, the fibroblasts adhered, migrated and proliferated on the newly created 3D scaffolds. Our data demonstrate the applicability of electrospun poly(d/l-lactide-co-l-lactide) scaffolds to serve as substrates for regenerative medicine applications with special focus on skin tissue engineering

Microvascular coaptation methods: device manufacture and computational simulation

The practice of joining blood vessels has been ongoing since the late nineteenth century, although it was initially restricted to animal studies and experimental techniques. At this time, fine silk thread and curved needles had been introduced (1), which was a significant advancement on previous suture materials such as leather, tendon and catgut (2) – although these were used for wound closure rather than vascular repair. It was not until the mid twentieth century, circa World War II, that vascular anastomoses were performed whilst repairing or reconstructing traumatic injuries (3). The natural progression from repairing vascular injuries was to perform these procedures in smaller and smaller vessels. Of course, this necessitated use of an operating microscope and development and manufacture of finer suture materials, needles, and more delicate instruments. This chapter aims to provide details of the common microvascular anastomotic devices and their manufacture

Biomechanics of the press-fit phenomenon in dental implantology: an image-based finite element analysis

<p>Abstract</p> <p>Background</p> <p>A fundamental pre-requisite for the clinical success in dental implant surgery is the fast and stable implant osseointegration. The press-fit phenomenon occurring at implant insertion induces biomechanical effects in the bone tissues, which ensure implant primary stability. In the field of dental surgery, the understanding of the key factors governing the osseointegration process still remains of utmost importance. A thorough analysis of the biomechanics of dental implantology requires a detailed knowledge of bone mechanical properties as well as an accurate definition of the jaw bone geometry.</p> <p>Methods</p> <p>In this work, a CT image-based approach, combined with the Finite Element Method (FEM), has been used to investigate the effect of the drill size on the biomechanics of the dental implant technique. A very accurate model of the human mandible bone segment has been created by processing high resolution micro-CT image data. The press-fit phenomenon has been simulated by FE analyses for different common drill diameters (D_A = 2.8 mm, D_B = 3.3 mm, and D_C = 3.8 mm) with depth L = 12 mm. A virtual implant model has been assumed with a cylindrical geometry having height L = 11 mm and diameter D = 4 mm.</p> <p>Results</p> <p>The maximum stresses calculated for drill diameters D_A, D_B and D_C have been 12.31 GPa, 7.74 GPa and 4.52 GPa, respectively. High strain values have been measured in the cortical area for the models of diameters D_A and D_B, while a uniform distribution has been observed for the model of diameter D_C . The maximum logarithmic strains, calculated in nonlinear analyses, have been ϵ = 2.46, 0.51 and 0.49 for the three models, respectively.</p> <p>Conclusions</p> <p>This study introduces a very powerful, accurate and non-destructive methodology for investigating the effect of the drill size on the biomechanics of the dental implant technique.</p> <p>Further studies could aim at understanding how different drill shapes can determine the optimal press-fit condition with an equally distributed preload on both the cortical and trabecular structure around the implant.</p

Identification of genetic polymorphisms associated with risk for pulmonary hypertension in sickle cell disease

Up to 30% of adult patients with sickle cell disease (SCD) will develop pulmonary hypertension (pHTN), a complication associated with significant morbidity and mortality. To identify genetic factors that contribute to risk for pHTN in SCD, we performed association analysis with 297 single nucleotide polymorphisms (SNPs) in 49 candidate genes in patients with sickle cell anemia (Hb SS) who had been screened for pHTN by echocardiography (n = 111). Evidence of association was primarily identified for genes in the TGFβ superfamily, including activin A receptor, type II–like 1 (ACVRL1), bone morphogenetic protein receptor 2 (BMPR2), and bone morphogenetic protein 6 (BMP6). The association of pHTN with ACVRL1 and BMPR2 corroborates the previous association of these genes with primary pHTN. Moreover, genes in the TGFβ pathway have been independently implicated in risk for several sickle cell complications, suggesting that this gene pathway is important in overall sickle cell pathophysiology. Genetic variation in the β-1 adrenergic receptor (ADRB1) was also associated with pHTN in our dataset. A multiple regression model, which included age and baseline hemoglobin as covariates, retained SNPs in ACVRL1, BMP6, and ADRB1 as independently contributing to pHTN risk. These findings may offer new promise for identifying patients at risk for pHTN, developing new therapeutic targets, and reducing the occurrence of this life-threatening SCD complication