Fundamentals of light-cell-polymer interactions in photo-cross-linking based bioprinting.

Biofabrication technologies that use light for polymerization of biomaterials have made significant progress in the quality, resolution, and generation of precise complex tissue structures. In recent years, the evolution of these technologies has been growing along with the development of new photocurable resins and photoinitiators that are biocompatible and biodegradable with bioactive properties. Such evolution has allowed the progress of a large number of tissue engineering applications. Flexibility in the design, scale, and resolution and wide applicability of technologies are strongly dependent on the understanding of the biophysics involved in the biofabrication process. In particular, understanding cell-light interactions is crucial when bioprinting using cell-laden biomaterials. Here, we summarize some theoretical mechanisms, which condition cell response during bioprinting using light based technologies. We take a brief look at the light-biomaterial interaction for a better understanding of how linear effects (refraction, reflection, absorption, emission, and scattering) and nonlinear effects (two-photon absorption) influence the biofabricated tissue structures and identify the different parameters essential for maintaining cell viability during and after bioprinting.

Characterization of different functionalized lipidic nanocapsules as potential drug carriers.

Lipid nanocapsules (LNC) based on a core-shell structure consisting of an oil-filled core with a surrounding polymer layer are known to be promising vehicles for the delivery of hydrophobic drugs in the new therapeutic strategies in anti-cancer treatments. The present work has been designed as basic research about different LNC systems. We have synthesized-and physico-chemically characterized-three different LNC systems in which the core was constituted by olive oil and the shell by different phospholipids (phosphatidyl-serine or lecithin) and other biocompatible molecules such as Pluronic(®) F68 or chitosan. It is notable that the olive-oil-phosphatidyl-serine LCN is a novel formulation presented in this work and was designed to generate an enriched carboxylic surface. This carboxylic layer is meant to link specific antibodies, which could facilitate the specific nanocapsule uptake by cancer cells. This is why nanoparticles with phosphatidyl-serine in their shell have also been used in this work to form immuno-nanocapsules containing a polyclonal IgG against a model antigen (C-reactive protein) covalently bounded by means of a simple and reproducible carbodiimide method. An immunological study was made to verify that these IgG-LNC complexes showed the expected specific immune response. Finally, a preliminary in vitro study was performed by culturing a breast-carcinoma cell line (MCF-7) with Nile-Red-loaded LNC. We found that these cancer cells take up the fluorescent Nile- Red molecule in a process dependent on the surface properties of the nanocarriers.

Role of alpha-actin in muscle damage of injured athletes in comparison with traditional markers.

OBJECTIVE: In order to identify a reliable marker for the early detection of muscle injuries in sports, alpha-actin protein and other markers of muscle damage were studied in sera of uninjured sportspeople and those with skeletal muscle injury. METHODS: Blood samples were obtained from 20 sportspeople with skeletal muscle injury and 48 uninjured sportspeople. Immunoassays were performed to determine cardiac troponin I (TnI), troponin T, lactate dehydrogenase and myoglobin concentrations. Western blot and densitometry were used to measure alpha-actin concentrations. Skeletal muscle damage was diagnosed according to physical examination, MRI findings and the biochemical criterion of a creatine kinase value >500 IU/l (Rosalki method, Beckman Instruments SL, Fullerton, California, USA). Results were also compared with previously obtained data on injured and uninjured non-sportspeople. RESULTS: The mean serum concentration of alpha-actin was significantly higher in sportspeople with muscle damage (10.49 microg/ml) than in uninjured sportspeople (3.99 mcirog/ml). Sera from injured sportspeople showed higher levels of alpha-actin than of troponin or myoglobin. No significant difference in TnI levels was observed between the groups. CONCLUSIONS: According to these results, alpha-actin is a new and reliable marker of skeletal muscle damage in sportspeople which can be used for the detection of muscle injury. Possible cross interference between skeletal and cardiac muscle damage can be discriminated by the combined use of alpha-actin and TnI. These data suggest that early measurement of alpha-actin in sportspeople with suspected muscle damage will allow them to receive earlier and more effective treatment and to return sooner to the practice of their sport.