Nanostructured fibrin-based hydrogel membranes for use as an augmentation strategy in Achilles tendon surgical repair in rats.

Hydrogels are polymeric biomaterials characterised by their promising biological and biomechanical properties, which make them potential alternatives for use in tendon repair. The aim of the present study was to generate in vitro, and determine the therapeutic efficacy in vivo, of novel nanostructured fibrin-based hydrogels to be used as an augmentation strategy for the surgical repair of rat Achilles tendon injuries. Fibrin, fibrin-agarose and fibrin-collagen nanostructured hydrogels (NFH, NFAH and NFCH, respectively) were generated and their biomechanical properties and cell-biomaterial interactions characterised ex vivo. Achilles tendon ruptures were created in 24 adult Wistar rats, which were next treated with direct repair (control group) or direct repair augmented with the generated biomaterials (6 rats/group). After 4 and 8 weeks, the animals were euthanised for macroscopical and histological analyses. Biomechanical characterisation showed optimal properties of the biomaterials for use in tendon repair. Moreover, biological analyses confirmed that tendon-derived fibroblasts were able to adhere to the surface of the generated biomaterials, with high levels of viability and functionality. In vivo studies demonstrated successful tendon repair in all groups. Lastly, histological analyses disclosed better tissue and extracellular matrix organisation and alignment with biomaterial-based augmentation strategies than direct repair, especially when NFAH and NFCH were used. The present study demonstrated that nanostructured fibrin-collagen hydrogels can be used to enhance the healing process in the surgical repair of tendon ruptures.

Towards a comprehensive human cell-surface immunome database.

The human immune system is a complex machinery involving numerous proteins. Proteins located at the cell surface of immune cells are of particular relevance due not only to their participation in the network of interactions that regulate the immune response but also to their potential as excellent targets for diagnostic and therapeutic interventions. The main objective of this project is to generate a comprehensive database of the human cell-surface proteins expressed in immune cells and lymphoid tissues. For this purpose, we have integrated information collected from primary literature, databases and electronic information sources. This manually curated database includes the gene symbol and name of the protein, describes the family that each protein belongs to, indicates their type of extracellular domains, and compiles data regarding their expression. Thus far we have identified and catalogued 1015 genes and proteins. The largest families in this compendium are the Ig superfamily with 195 members (~20%) and the G-protein coupled receptor superfamily with 147 members (~14%). Other abundant families include the C-type lectin and the cytokine receptor families with 43 and 42 members respectively (4%). About 25% of the proteins belong to minor families and approximately 4% lack any clear family assignment. More than 60% of the genes encode proteins without a CD number. This database will serve to boost the production of new monoclonal antibodies and to stimulate studies aimed at characterizing the function of these proteins in the immune system as well as identifying potential new biomarkers and therapeutic targets.