Speaker
Description
Introduction
Cartilage structures can be damaged causing two types of injuries: focal; the lesion is restricted to a concrete zone or diffuse; the lesion affects a broad area of the articular cartilage. This type of lesions appears due to the reduced self-healing capacity of articular cartilage. Diffuse damage is much more difficult to treat. As the damage progresses up to the point where the majority of the cartilage is lost, the only option available is the surgical replacement of the arthritic joint with a prosthesis. More recently, cell-based approaches using autologous chondrocytes or mesenchymal stem cells (MSCs) have been tested and it can even be found in some clinics. However, the efficacy of such cell-based treatment is controversial where the main problem is the unconfinement of the cells used. The most promising approach is the combination of such cells with a biomaterial-based carrier, being the general objective of the project the development of bioadhesive and injectable cell microcarriers with the ability to regenerate the articular cartilage. This aim is materialized in the fabrication of multibiofunctional capsules that are able to promote the cell cargo with selective adhesion and location on the articular surface.
The microcapsules are based on a novel kind of biomaterials, named Recombinamers that are polypeptide materials obtained by recombinant DNA technology. In particular, the core composition of the microcarrier is the Elastin-like Recombinamers (ELRs).
Methodology
Recombinant DNA techniques have proven to be very powerful tools for the development of novel protein-based biomaterials. This class includes ELRs, which are protein-based polypeptides that comprise repetitive units of the Val−Pro−Gly−X−Gly (VPGXG)n pentapeptide, in which X (guest residue) could be any amino acid except L-proline. ELRs are inspired by elastin, showing excellent biocompatibility, and they exhibit thermo-responsiveness in aqueous media.
Gene construction were performed using standard genetic-engineering methods. Production was carried out by recombinant techniques using Escherichia coli as the cell system. Purification was performed by several cooling and heating purification cycles (Inverse Transition Cycling) following centrifugation.
The purity and molecular weight were verified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Amino acid composition analysis and infrared spectroscopy were also performed.
Results
Genetic engineering methods allowed the synthesis of the genetic construct capable of synthesizing the desired biomaterial. Biopolymer adhesion to the hyaline-cartilage matrix was demonstrated measuring the adhesion forces between our biomaterial and surfaces with collagen II and chondroitin-sulfate versus control surfaces.
Tailored layer-by-layer (LbL) approaches allowed the encapsulation of cell spheroids of autologous chondrocytes and MSCs.
In vitro and ex vivo assays were performed using cartilage explants from patients surgically intervened, this type of analysis showed the derivatized ELR adhesion efficacy to the articular surface and the final liberation of cell spheroids hoping to demonstrate the cartilage regeneration.
Conclusion
In conclusion, a novel protein-based biomaterial with adhesion to the hyaline-cartilage matrix was synthetized. Besides, cell spheroids were encapsulated by the polymer.
Hence, in this study could be possible overcome the limitations of the current treatments used in diffuse cartilage lesions and it supposes an advance in regenerative medicine.
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