Influence of the Degree of Deacetylation of Chitosan and BMP-2 Concentration on Biocompatibility and Osteogenic Properties of BMP-2/PLA Granule-Loaded Chitosan/β-Glycerophosphate Hydrogels

Abstract

Compositions based on chitosan/β-glycerophosphate hydrogels with highly porous polylactide granules can be used to obtain moldable bone graft materials that have osteoinductive and osteoconductive properties. To eliminate the influence of such characteristics as chain length, degree of purification, and molecular weight on a designed material, the one-stock chitosan sample was reacetylated to degrees of deacetylation (DD%) of 19.5, 39, 49, 55, and 56. A study of the chitosan/β-glycerophosphate hydrogel with chitosan of a reduced DD% showed that a low degree of deacetylation increased the MSCs (multipotent stromal cells) viability rate in vitro and reduced the leukocyte infiltration in subcutaneous implantation to Wistar rats in vivo. The addition of 12 wt% polylactide granules resulted in optimal composite mechanical and moldable properties, and increased the modulus of elasticity of the hydrogel-based material by approximately 100 times. Excessive filling of the material with PLA (polylactide) granules (more than 20%) led to material destruction at a ~10% strain. Osteoinductive and osteoconductive properties of the chitosan hydrogel-based material with reacetylated chitosan (39 DD%) and highly porous polylactide granules impregnated with BMP-2 (bone morphogenetic protein-2) have been demonstrated in models of orthotopic and ectopic bone formation. When implanted into a critical-size calvarial defect in rats, the optimal concentration of BMP-2 was 10 μg/mL: bone tissue areas filled the entire material’s thickness. Implantation of the material with 50 μg/mL BMP-2 was accompanied with excessive growth of bone tissue and material displacement beyond the defect. Significant osteoinductive and osteoconductive properties of the material with 10 μg/mL of BMP-2 were also shown in subcutaneous implantation.

Comparative Efficiency of Gene-Activated Matrices Based on Chitosan Hydrogel and PRP Impregnated with BMP2 Polyplexes for Bone Regeneration

“…To ensure targeted delivery of the plasmid DNA and achieve a high local concentration of the corresponding osteogenic factor in the area of bone regeneration, polyplexes were included in polylactide particles, which were introduced in chitosan hydrogel or PRP-based fibrin hydrogel. Earlier, in the course of comparative experiments to assess the biocompatibility of hydrogels based on chitosan with different degrees of deacetylation, we determined that chitosan with 39% degrees of deacetylation [ 18 ] was optimal. As a result of the polymerization of the fibrinogen contained in PRP, a fibrin clot filled with a large amount of growth factors and cytokines can be obtained, and these play an important role in reducing inflammation and stimulating the migration and differentiation of progenitor cells in the damaged area [ 21 ].…”

“…PRP-based matrices had a positive effect on cell viability and promoted their proliferation in vitro because of the presence of growth factors ( Figure 2 ) and, at the same time, did not cause an immune response in vivo ( Figure 3 ). Similarly, chitosan hydrogels did not cause cytotoxicity in vitro but led to a more noticeable reaction of immune cells during intramuscular implantation ( Figure 3 ), which may be caused by the positive charge of the acyl groups of chitosan [ 18 ].…”

“…It has been shown that chitosan hydrogel has antibacterial properties and promotes wound healing [ 17 ]. The properties of chitosan hydrogel can be varied by physical or chemical exposure [ 18 ]. In addition, chitosan, as a polycationic molecule, can be a transfecting agent for gene delivery into cells [ 19 , 20 ], which makes it a suitable candidate for use in the creation of gene-activated matrices.…”

Ultrasonic assessment of the distribution of tricalcium phosphate filler over the volume of swollen porous matrices based on chitosan for biomedical applications

“…При этом особый интерес в этой области представляют матриксы, имеющие открытые поры, которые обеспечат проникновение клеток в объём импланта и неоваскуляризацию. Улучшить свойства матрикса можно за счёт добавления остеоиндуктивных факторов роста, например BMP-2, которые будут стимулировать биоминерализацию импланта [10].…”

Osteoinductive Moldable and Curable Bone Substitutes Based on Collagen, BMP-2 and Highly Porous Polylactide Granules, or a Mix of HAP/β-TCP

“…Previously, we carried out several successful studies on preparing thermosetting biocompatible materials based on chitosan hydrogels and polylactide (PLA) fillers with BMP-2 [9,10]. The materials showed the ability to cure at the body temperature, high biocompatibility and resorbability, and demonstrated marked osteoinductive and osteoconductive properties in vitro and in vivo.…”