Biomimetic supramolecular designs for the controlled release of growth factors in bone regeneration

The extracellular matrix (ECM) of tissues is an assembly of insoluble macromolecules that specifically interact with soluble bioactive molecules and regulate their distribution and availability to cells. Recapitulating this ability has been an important target in controlled growth factor delivery strategies for tissue regeneration and requires the design of multifunctional carriers. This review describes the integration of supramolecular interactions on the design of delivery strategies that encompass self-assembling and engineered affinity components to construct advanced biomimetic carriers for growth factor delivery. Several glycan- and peptide-based self-assemblies reported in the literature are highlighted and commented upon. These examples demonstrate how molecular design and chemistry are successfully employed to create versatile multifunctional molecules which self-assemble/disassemble in a precisely predicted manner, thus controlling compartmentalization, transport and delivery. Finally, we discuss whether recent advances in the design and preparation of supramolecular delivery systems have been sufficient to drive real translation towards a clinical impact. H. S. Azevedo acknowledges the financial support of the European Union under the Marie Curie Career Integration Grant SuprHApolymers (PCIG14-GA-2013-631871). I. Pashkuleva is thankful to the Portuguese foundation for science and technology (IF/00032/2013) and to the European Union (REGPOT-2012-2013-1-316331)

Sugars : burden or biomaterials of the future?

During the past few years, the field of tissue engineering (TE) has been shifting from replacement to regenerative strategies. Following this tendency, the requirements for biomaterials to be used in TE have been also changing. While a few decades ago bioinert materials that do not provoke undesired body responses were in the focus of material sciences, nowadays third generation biomaterials mimicking the nanoscale mechanisms of the interactions between cells and their in vivo environment are the target of material design. Although these mechanisms involve different bioactive molecules, until now mainly strategies involving small peptide epitopes that copycat specific sequences of complex proteins have been exploited. The breakthroughs that such approaches brought to biomaterials and TE fields are undeniable. Nevertheless, the important role that carbohydrates play in tissue structuring and function is still poorly explored and exploited in this context and we believe that this is one of the missing pieces in the TE puzzle. Carbohydrates are an integral part of our life. We are literally covered by them: from bacteria to mammalian cells, the molecular landscape of the cell surface is coated with sugars forming the so-called glycocalyx. This strategic placement of the sugars makes them crucial for the development, growth, function and/or survival of an organism. It is believed that the structural diversity of carbohydrates is the key for understanding and controlling those processes because of the huge number of ligand structures, which sugars can display in molecular recognition systems. However, their main advantages: the intricacy and the large natural diversity have turned against the scientists and have hampered their study. As a result, the field of glycomics is much less developed compared to its counterparts genomics and proteomics within TE. Recent advances in carbohydrate synthesis, sensing technologies and processing methodologies are inducing rapid changes in this field and will be discussed in this paThe authors acknowledge the funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no. NMP4-SL-2009-229292

Investigation the influence of ar plasma treatment on cell response for wet-spun starch/polycaprolactone fiber mesh scaffolds

In design of a tissue engineering scaffold, surface physicochemistry is one of the most important issues to be considered. The physicochemical properties of the surface directly influence the scaffold performance by affecting the cellular response and ultimately effecting the new tissue formation. In order to improve the cell affinity, the surface hydrophiliticy, surface energy, surface roughness and surface charge can be modify by different methods. Plasma treatment is a versatile method for surface treatment of biodegradable polymers without altering their bulk properties. By this method, it is possible to introduce or graft desired functional groups onto the surface. This study aims to investigate the influence of Ar plasma treatment on osteablast cell response for fiber mesh scaffolds from a starch-polycaprolactone blend. [...]info:eu-repo/semantics/publishedVersio

Nanocarriers based on interpolyelectrolyte complexation of Sulphated polysaccharide-b- PEG diblock copolymers and PLL

Publicado em "Journal of Tissue Engeneering and Regenerative Medicine", vol. 7, supp. 1 (2013)Glycosaminoglycans (GAGs) are integral part of the closest cellular environment: they can be found on the cells surface and in the extracellular matrix, where they interact with different proteins acting as local regulator of their activity. The use of GAGs in the preparation of protein delivery nanosystems is, therefore, prominent but so far, underexploited mainly because of the heterogeneity (composition and molecular weights) of natural glycans and the multistep procedures needed to obtain GAGs’ synthetic analogues and diblock copolymers.1 Recently, we have shown that oxime click reaction can be applied as a straightforward methodology for the synthesis of poly(ethylene glycol) (PEG)- hyaluronic acid (HA) diblock copolymers.2 These copolymers formed nanosized interpolyelectrolyte complexes (45 to 150 nm) by interaction with poly- L -lysine (PLL).3 Unfortunately, these complexes are not stable at physiological ionic strength. Herein, we describe a strategy to overcome this drawback; chondroitin sulphate-b-PEG diblock copolymers (CS-b-PEG) were obtained using the same oxime click reaction. The stronger negative charge of sulphate groups (versus the carboxilic groups present in HA) resulted in the complexes with higher stability: interpolyelectrolyte complexes between PLL and (CS-b-PEG) are stable up to 260 mM ionic strenght. Because carbohydrates do not activate Tcells, we believe that the reported herein complexes have an enormous potential in both drug delivery and vaccination fields

Hyaluronan receptors as mediators and modulators of the tumor microenvironmen

The tumor microenvironment (TME) is a dynamic and complex matter shaped by heterogenous cancer and cancer-associated cells present at the tumor site. Hyaluronan (HA) is a major TME component that plays pro-tumorigenic and carcinogenic functions. These functions are mediated by different hyaladherins expressed by cancer and tumor-associated cells triggering downstream signaling pathways that determine cell fate and contribute to TME progression towards a carcinogenic state. Here, we review the interaction of HA with several cell-surface hyaladherins â CD44, RHAMM, TLR2 and 4, LYVE-1, HARE and layilin. We discuss the signaling pathways activated by these interactions and the respective response of different cell populations within the TME, and the modulation of the TME. Potential cancer therapies via targeting these interactions are also briefly discussed.The authors thank the Portuguese FCT and FSE (Grants no: SFRH/BD/114847/2016, PTDC/NAN-MAT/28468/2017, PTDC/CTM-REF/0022/2020) for providing financial support to this project

Sweet building blocks for selfassembling biomaterials with molecular recognition

After billions of years of evolution not a single live cell has emerged that does not cover itself with a dense code of glycans: carbohydrates are involved in all essential processes within the life cycle of cells and organisms. They exercise their bioactivities via simultaneous multivalent non-covalent interactions with other biomolecules such as proteins. Supramolecular polymers are ideal systems to generate polyvalent architectures for studying and modulating these interactions: the inherent reversibility of the self-assembling process and the translation of monomers into polymers provides control over ligand density and assembly architecture. We present briefly some recent approaches to develop such systems and to use them in different biomedical applications

Hyaluronan density influences adhesion, morphology and migration of cancer cells

Hyaluronan (HA) is a linear non-sulfated glycosaminoglycan present in the extracellular matrix and known to modulate cell-cell and cell-ECM interactions. In cancer, the synthesis, degradation and signaling of HA is altered. For instance, its main receptor, CD44, is overexpressed in several types of cancer and has been correlated with disease progression through cancer cell proliferation, migration and chemoresistance. Herein, we investigated the behavior of breast cancer cells with different CD44 expression and invasion profile on HA density gradients. These gradients were achieved by deposition of colloidal gold (Au) on amino-functionalized surfaces at different ionic strengths and following binding of end-on thiol modified HA on the Au. At low HA density, small number of adherent round cells were found for all studied cell lines. Cells adherent to the areas with high HA density presented a spindle-like morphology. The differences were more pronounced for cells overexpressing CD44. These cells also form long filopodia when adhered on areas with middle and high HA density. Of note, colocalization of CD44 and actin was observed at the filopodias edges. Cell motility was also affected by the gradient – at low densities cells presented higher motility, which decreased with the increase of HA density. Besides this common trend, we observed differences among the studied cells. CD44 cells had shorter persistent length displacement than CD44 and CD44cells. Upon CD44 blockage, all types of cells (CD44++, CD44+, and CD44-) behave similarly . These results suggest that cells recognize HA gradients through CD44 receptors and that the HA density can be used to sort cells with different expression of this receptor.info:eu-repo/semantics/publishedVersio

Surface functionalization of starch/polycaprolactone fiber meshes for bone guide regeneration

[Excerpt] Surface design of biomedical devices is crucial for their acceptation or rejection by the body. One of the most versatile and effective tools to tailor surface chemistry and properties of solids is polymer grafting. This work describes the modification of starch/polycaprolactone scaffolds by surface grafting of sulfonic and phosphonic groups and the effect of those groups on osteoblast-like cells behaviour on a preliminary base. [...]info:eu-repo/semantics/publishedVersio

Highly porous and interconnected starch-based scaffolds : production, characterization and surface modification

A convenient and straightforward process for preparation of highly porous and interconnected !ber mesh scaffolds with 50 wt.% content of starch is described. The proposed methodology avoids some of the previous encountered problems associated with the processing of starch-based materials such as thermal degradation, starch entrapment in the material bulk and inability to control/minimise the thickness of the !bers obtained by melt spinning, or low porosity and lack of interconnectivity for the scaffolds obtained by extrusion or injection moulding with blowing agent. Topographical characterisation of the obtained !bers revealed rough surface commonly related with increased cell attachment and growth. The in vitro tests with osteoblast cell line con!rmed this trend and we observed higher cell number with increasing of the culture time. These results were also associated with protein adsorption from a complex solution where predominant adsorption of vitronectin over !bronectin was detected. Finally, a model modi!cation by plasma was also carried out in order to con!rm the versatility of these scaffolds by the possibility to further upgrade them via surface functionalisation. The in vitro tests con!rmed that osteoblast-like cells proliferate faster on the modi!ed scaffolds, which allows shortening the time needed for culturing prior to implantation.This work was partially supported by the European NoE EXPER-TISSUES (NMP3-CT-2004-500283), EU Marie Curie Actions, Alea Jacta Est (MEST-CT-2004-008104) and FCT project PTDC/CTM/67560/2006. The authors would also like to acknowledge Sofia G. Caridade and Dr Marina I. Santos for their excellent technical assistance with the DMA and confocal microscopy, respectively