ABSTRACT
Addressing osteochondral defects, the objective of current study was to synthesize bilayered hydrogel, where the cartilage layer was formed by alginate (Alg)-polyacrylamide (PAAm) with and without the addition of TGF-ß3 and bone layer by laponite XLS/Alg-PAAm and characterize by in vitro and in vivo experiments. Exceeding the mechanical strength of Alg-PAAm (32.95 ± 1.23 kPa) and XLS based (317.5 ± 21.72 kPa) hydrogels, XLS/Alg-PAAm hydrogel (469.7 ± 6.1 kPa) activated macrophages towards M2 phenotype and stimulated the expression of anti-inflammatory factors. The addition of TGF-ß3 accelerated transition of macrophage polarization, especially between day 4 and 7. The expression levels of M1-related genes such as CD80, iNOS and TNF-α decreased gradually after day 4, reaching lowest values at day 13, whereas the expression levels of M2-related genes, CD206, Arg1 and STAT6 significantly increased promoting M2 macrophage polarization, which might be associated with accelerated bone repair. Moreover, bilayer structure exhibited a better cell viability as well as repairment thorough the XLS contents. In vivo histological examinations verified the significant surface regularity and hyaline like tissue formation employment, along with synchronized degradation profile of the hydrogel with tissue healing at the end of 12 weeks. A mechanically durable, biocompatible and immunocompatible hydrogel was formulated to be utilized in bone-cartilage engineering applications.
Subject(s)
Alginates , Tissue Engineering , Acrylic Resins , Alginates/pharmacology , Chondrocytes , Hydrogels/chemistry , Macrophages , Silicates , Transforming Growth Factor beta3/metabolismABSTRACT
Current implantable materials are limited in terms of function as native tissue, and there is still no effective clinical treatment to restore articular impairments. Hereby, a functionalized polyacrylamide (PAAm)-alginate (Alg) Double Network (DN) hydrogel acting as an articular-like tissue is developed. These hydrogels sustain their mechanical stability under different temperature (+4 °C, 25 °C, 40 °C) and humidity conditions (60% and 75%) over 3 months. As for the functionalization, transforming growth factor beta-3 (TGF-ß3) encapsulated (NPTGF-ß3) and empty poly(lactide-co-glycolide) (PLGA) nanoparticles (PLGA NPs) are synthesized by using microfluidic platform, wherein the mean particle sizes are determined as 81.44 ± 9.2 nm and 126 ± 4.52 nm with very low polydispersity indexes (PDI) of 0.194 and 0.137, respectively. Functionalization process of PAAm-Alg hydrogels with ester-end PLGA NPs is confirmed by FTIR analysis, and higher viscoelasticity is obtained for functionalized hydrogels. Moreover, cartilage regeneration capability of these hydrogels is evaluated with in vitro and in vivo experiments. Compared with the PAAm-Alg hydrogels, functionalized formulations exhibit a better cell viability. Histological staining, and score distribution confirmed that proposed hydrogels significantly enhance regeneration of cartilage in rats due to stable hydrogel matrix and controlled release of TGF-ß3. These findings demonstrated that PAAm-Alg hydrogels showed potential for cartilage repair and clinical application.
