Novel Methodology Based on Biomimetic Superhydrophobic Substrates to Immobilize Cells and Proteins in Hydrogel Spheres for Applications in Bone Regeneration

Abstract

Cell-based therapies for regenerative medicine have been characterized by the low retention and integration of injected cells into host structures. Cell immobilization in hydrogels for target cell delivery has been developed to circumvent this issue. In this work mesenchymal stem cells isolated from Wistar rats bone marrow (rMSCs) were immobilized in alginate beads fabricated using an innovative approach involving the gellification of the liquid precursor droplets onto biomimetic superhydrophobic surfaces without the need of any precipitation bath. The process occurred in mild conditions preventing the loss of cell viability. Furthermore, fibronectin (FN) was also immobilized inside alginate beads with high efficiency in order to mimic the composition of the extracellular matrix. This process occurred in a very fast way (around 5 min), at room temperature, without aggressive mechanical strengths or particle aggregation. The methodology employed allowed the production of alginate beads exhibiting a homogenous rMSCs and FN distribution. Encapsulated rMSCs remained viable and were released from the alginate for more than 20 days. In vivo assays were also performed, by implanting these particles in a calvarial bone defect to evaluate their potential for bone tissue regeneration. Microcomputed tomography and histological analysis results showed that this hybrid system accelerated bone regeneration process. The methodology employed had a dual role by preventing cell and FN loss and avoiding any contamination of the beads or exchange of molecules with the surrounding environment. In principle, the method used for cell encapsulation could be extended to other systems aimed to be used in tissue regeneration strategies.

Natural polymers for the microencapsulation of cells

“…Cells exhibited good viability and osteogenic capability. Moreover, in vivo tests showed that these particles could stimulate bone regeneration in cranial defects [246]. More sophisticated layered particles could be obtained by the sequential deposition of hydrogel precursors over previously hardened particles allowing the distribution of cells or drugs in compartments with a radial arrangement [247].…”

Design Advances in Particulate Systems for Biomedical Applications

“…[ 123 ] Briefl y, pre-particle solutions are dispensed in a patterned mould and then they are solidifi ed by appropriated procedures (e.g., light exposure, temperature, lyophilization, among others) acquiring the shape of the pre-established patterns. As observed for the superhydrophobic technology used to produce spherical particles encapsulating drugs or cells [ 46,[124][125][126][127][128][129][130] the incorporation of drugs (for example) inside such artifi cial erythrocyte-like particles is relatively simple: just mix the bioactive compounds with the material before printing/crosslinking. Biomimetic hydrogel particles of 2-hydroxyethyl acrylate (HEA) cross-linked with PEG diacrylate (PEGDA) exhibited a negative surface charge and mechanical properties similar to those of erythrocytes.…”

In Vivo High-Content Evaluation of Three-Dimensional Scaffolds Biocompatibility

“…Color images available online at www.liebertpub.com/tec or reactive granuloma formation. 31 Carrageenans biocompatibility has been questioned in the literature. 32,33 Carrageenan is used to induce paw edema in the rat and mouse and induces IL-8 production through distinct Bcl10 pathway in normal human colonic epithelial cells.…”