Bicyclic RGD peptides with high integrin α v ß 3 and α 5 ß 1 affinity promote cell adhesion on elastin-like recombinamers.

Biomaterial design in tissue engineering aims to identify appropriate cellular microenvironments in which cells can grow and guide new tissue formation. Despite the large diversity of synthetic polymers available for regenerative medicine, most of them fail to fully match the functional properties of their native counterparts. In contrast, the few biological alternatives employed as biomaterials lack the versatility that chemical synthesis can offer. Herein, we studied the HUVEC adhesion and proliferation properties of elastin-like recombinamers (ELRs) that were covalently functionalized with each three high-affinity and selectivity α v ß 3- and α 5 ß 1-binding bicyclic RGD peptides. Next to the bicycles, ELRs were also functionalized with various integrin-binding benchmark peptides, i.e. knottin-RGD, cyclo-[KRGDf] and GRGDS, allowing for better classification of the obtained results. Covalent functionalization with the RGD peptides, as validated by MALDI-TOF analysis, guarantees flexibility and minimal steric hindrance for interactions with cellular integrins. In addition to the covalently modified RGD-ELRs, we also synthesized another benchmark ELR comprising RGD as part of the backbone. HUVEC adhesion and proliferation analysis using the PicoGreen® assay revealed a higher short-term adhesion and proliferative capacity of cells on ELR surfaces functionalized with high affinity, integrin-binding bicyclic RGD-peptides compared with the ELRs containing RGD in the backbone.

Electrospun silk-elastin-like fibre mats for tissue engineering applications.

Protein-based polymers are present in a wide variety of organisms fulfilling structural and mechanical roles. Advances in protein engineering and recombinant DNA technology allow the design and production of recombinant protein-based polymers (rPBPs) with an absolute control of its composition. Although the application of recombinant proteins as biomaterials is still an emerging technology, the possibilities are limitless and far superior to natural or synthetic materials, as the complexity of the structural design can be fully customized. In this work, we report the electrospinning of two new genetically engineered silk-elastin-like proteins (SELPs) consisting of alternate silk- and elastin-like blocks. Electrospinning was performed with formic acid and aqueous solutions at different concentrations without addition of further agents. The size and morphology of the electrospun structures was characterized by scanning electron microscopy showing its dependence on the concentration and solvent used. Treatment with methanol-saturated air was employed to stabilize the structure and promote water insolubility through a time-dependent conversion of random coils into ß-sheets (FTIR). The resultant methanol-treated electrospun mats were characterized for swelling degree (570-720%), water vapour transmission rate (1083 g/m(2)/day) and mechanical properties (modulus of elasticity ∼126 MPa). Furthermore, the methanol-treated SELP fibre mats showed no cytotoxicity and were able to support adhesion and proliferation of normal human skin fibroblasts. Adhesion was characterized by a filopodia-mediated mechanism. These results demonstrate that SELP fibre mats can provide promising solutions for the development of novel biomaterials suitable for tissue engineering applications.

Thyroid function tests and mortality in aged hospitalized patients: a 7-year prospective observational study.

CONTEXT: Several alterations in thyroid function test (TFT) results have been associated with mortality in elderly patients. OBJECTIVE: Our aim was to investigate the relationship between TFT results and all-cause and cardiovascular (CV) mortality in aged hospitalized patients. DESIGN: A 7-year prospective observational study was conducted. TFTs were performed at hospital admission, and mortality was registered in the follow-up period. PATIENTS: Participants were 404 patients aged >65 years admitted to the Department of Geriatrics, Hospital General, Segovia, Spain, for any reason during 2005. MAIN OUTCOME MEASURES: The study evaluated the association between TFT results and mortality from all causes and CV diseases. METHODS: TSH, free T4, and free T3 (FT3) were measured on the first day of admission. In-hospital and total survival times, number of deaths, and all-cause and CV mortality were registered until the census date on January 1, 2012. RESULTS: During the study, 323 patients (80%) died. Kaplan-Meier analysis showed that median survival time for all-cause mortality was significantly lower in patients in the first tertile of serum FT3, in the first tertile of TSH, and in the first tertile of serum free T4 concentrations. Multivariate adjusted Cox regression analysis showed that the history of cancer (hazard ratio, 1.60; 95% confidence interval, 1.12-2.28; P = .009), age (1.03; 1.01-1.06; P = .003), and FT3 levels (0.72; 0.63-0.84; P < .001) were significant factors related to all-cause mortality. The cause of death was known in 202 patients. Of this group, 61 patients (30.2%) died of CV disease. Patients in the first tertile of TSH and FT3 exhibited a significant higher mortality due to CV disease. In the adjusted Cox regression analysis, FT3 was a significant predictor of CV mortality (0.76; 0.63-0.91; P = .004). CONCLUSIONS: Alterations in TFT results during hospitalization are associated with long-term mortality in elderly patients. In particular, low FT3 levels are significantly related to all-cause and CV mortality.

Immunomodulatory nanoparticles from elastin-like recombinamers: single-molecules for tuberculosis vaccine development.

This study investigates both the physicochemical properties and immunogenicity of a genetically engineered elastin-like block corecombinamer (ELbcR) containing a major membrane protein sequence from Mycobacterium tuberculosis. The recombinant production of this ELbcR allows the production of large quantities of safe, antigenic particle-based constructs that directly and reversibly self-assemble into highly biocompatible, multivalent, monodisperse, and stable nanovesicles with a diameter of 55 nm from the same gene product using a highly efficient and cost-effective inverse transition cycling (ITC) procedure. The compositional complexity of these vesicles is retained after secondary processes such as endotoxin removal, sterilization, and lyophilization. An initial pro-chemotactic cytokine response (IL-1ß) followed by a pro-Th2/IL-5 response was observed in mice plasma following subcutaneous administration of the antigen-loaded nanovesicles in mice. This biphasic model of cytokine production was coupled with humoral isotype switching from IgM- to IgG-specific antibodies against the antigen, which was only observed in the presence of both the antigen and the polymer in the same construct and in the absence of additional adjuvants.

Emerging applications of multifunctional elastin-like recombinamers.

Elastin-like recombinamers have grown in popularity in the field of protein-inspired biomimetic materials and have found widespread use in biomedical applications. Modern genetic-engineering techniques have allowed the design of multifunctional materials with an extraordinary control over their architecture and physicochemical properties, such as stimuli-responsiveness, monodispersity, biocompatibility or self-assembly, amongst others. Indeed, these materials are playing an increasingly important role in a diverse range of applications, such as drug delivery, tissue engineering and 'smart' systems. Herein, we review some of the most interesting examples of recent advances and progressive applications of elastin-like recombinamers in biomaterial and nano-engineering sciences in recent years.

Recombinamers: combining molecular complexity with diverse bioactivities for advanced biomedical and biotechnological applications.

The rapid development of polymer science has led to literally thousands of different monomers and an almost endless number of possibilities arising from their combination. The most promising strategy to date has been to consider natural products as macromolecules that provide the best option for obtaining functional materials. Proteins, with their high levels of complexity and functionality, are one of the best examples of this approach. In addition, the development of genetic engineering has permitted the design and highly controlled synthesis of proteinaceous materials with complex and advanced functionalities. Elastin-like recombinamers (ELRs) are presented herein as an example of an extraordinary convergence of different properties that is not found in any other synthetic polymer system. These materials are highly biocompatible, stimuli-responsive, show unusual self-assembly properties, and can incorporate bioactive domains and other functionalities along the polypeptide chain. These attributes are an important factor in the development of biomedical and biotechnological applications such as tissue engineering, drug delivery, purification of recombinant proteins, biosensors or stimuli-responsive surfaces.

Acute and one-year effects of cinacalcet in patients with persistent primary hyperparathyroidism after unsuccessful parathyroidectomy.

OBJECTIVE: We report the acute effects of cinacalcet on calcium and parathyroid hormone (PTH) levels and the effects of 1 year of therapy on calcium and phosphorus metabolism in 4 patients with persistent primary hyperparathyroidism (PHPT) after unsuccessful parathyroidectomy. PATIENTS: Four patients (3 women; age, 24 to 71 years) were studied after 1 to 3 parathyroid operative procedures. All of them had elevated serum total and ionized calcium levels, decreased serum phosphorus, and increased concentrations of intact PTH. METHODS: Calcium and PTH responses to an acute dose of oral cinacalcet (30 mg) were studied at baseline. Effects of cinacalcet (30 mg b.i.d.) on serum calcium, phosphorus, and PTH, and urinary calcium and phosphorus were studied at 1, 3, 6, and 12 months of therapy. RESULTS: PTH concentrations were reduced by 13.0% to 86.7% after acute cinacalcet administration. Chronic therapy with cinacalcet was followed by a decrement in serum total calcium (10.2% at 12 months) and ionized calcium (10.1%) and an increase in serum phosphorus (20.8%), with only a modest decrement in PTH levels (5.1%). All patients had normal serum total and ionized calcium levels at 3 to 12 months of therapy. Urinary calcium decreased by 20.0% at 12 months. CONCLUSIONS: Cinacalcet was effective in normalizing calcium and phosphorus concentrations in patients with persistent PHPT after unsuccessful parathyroidectomy.