RESUMO

Currently, oxygen supply for in vitro cell culture is one of the major challenges in tissue engineering, especially in three-dimensional (3D) structures, such as polymeric hydrogels, because oxygen is an essential element for cells survival. In this context, oxygen levels must be maintained in articular cartilage to promote the differentiation, viability, and proliferation of chondrocytes due to the low level of oxygen presence in this region. Although some technologies employ oxygen-generating materials to add sufficient oxygen levels, the limitations and challenges of current technologies include the lack of controlled, sustained, and prolonged release of the oxygen. Moreover, the fabrication methods may leave some impurities or residues resulting in toxicity to the cells. "Click" chemistry is a facile, versatile, and compatible chemical strategy to engineer hydrogels for tissue engineering applications. Herein, we disclose the engineering of oxygen-generating microparticles in chondrocytes-laden hydrogels through a versatile catalyst-free tetrazine and norbornene inverse electron demand Diels‒Alder (iEDDA) click reaction. The hydrogels combine chondroitin sulfate (CS) and poly(ethylene glycol) (PEG) crosslinked in situ, displaying tunable rheological and mechanical properties, for sustained and prolonged oxygen-release. Gene expression analysis of the chondrocytes by real-time reverse transcription polymerase chain reaction (RT-PCR) demonstrated promising cell response within the engineered hydrogel.

Assuntos

Condrócitos , Hidrogéis , Química Click , Oxigênio , Engenharia Tecidual

RESUMO

Hydroxyapatite (HAp) is a ceramic material composing the inorganic portion of bones. Ionic substitutions enhance characteristics of HAp, for example, calcium ions (Ca2+) by cerium ions (Ce3+). The use of HAp is potentialized through biopolymers, cashew gum (CG), and gellan gum (GG), since CG/GG is structuring agents in the modeling of structured biocomposites, scaffolds. Ce-HApCG biocomposite was synthesized using a chemical precipitation method. The obtained material was frozen (-20 °C for 24 h), and then vacuum dried for 24 h. The Ce-HApCG was characterized by X-Ray diffractograms (XRD), X-ray photoemission spectra (XPS), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and energy dispersive spectroscopy (EDS). XRD and FTIR showed that Ce-HApCG was successfully synthesized. XRD showed characteristic peaks at 2θ = 25.87 and 32.05, corresponding to the crystalline planes (0 0 2) and (2 1 1), respectively, while phosphate bands were present at 1050 cm-1 and 1098 cm-1, indicating the success of composite synthesis. FESEM showed pores and incorporated nanostructured granules of Ce-HApCG. The mechanical test identified that Ce-HApCG has a compressive strength similar to the cancellous bone's strength and some allografts used in surgical procedures. In vitro tests (MTT assay and hemolysis) showed that scaffold was non-toxic and exhibited low hemolytic activity. Thus, the Ce-HApCG has potential for application in bone tissue engineering.