Mineralization potential of cellulose-nanofibrils reinforced gelatine scaffolds for promoted calcium deposition by mesenchymal stem cells

- Cellulose-nanofibrils (CNFs) enriched gelatine scaffolds are fabricated in-situ.
- The scaffold micro-structure is rendered by components ratios and CNF modification.
- The scaffolds possessed osteoid-like compressive strength and elasticity.
- None of the scaffolds shows cytotoxic effect to the Mesenchymal Stem Cells (MSCs).
- The Ca2 + deposition is intensified and fostered by MSCs using phosphonated-CNFs.

Cellulose-nanofibrils (CNFs) enriched gelatine (GEL) scaffolds were fabricated in-situ by the combined freeze-thawing process and carbodiimide crosslinking chemistry. The original- and variously surface anionised CNFs (carboxylated/CNF-COOH/, and phosphonated with 3-AminoPropylphosphoric Acid/CNF-COOH-ApA/) were used in order to tune the scaffolds' biomimetic structure towards a more intensive mineralization process. The pore size reduction (from 208 ± 35 μm to 91 ± 35 μm) after 50% v/v of CNFs addition to GEL was identified, while separated pore-walls' alignment vs. shorter, dense and elongated pores are observed when using 80% v/v of original-CNFs vs. anionised-CNFs, all of them possessed osteoid-like compressive strength (0.025-0.40 MPa) and elasticity (0.04-0.15 MPa). While randomly distributed Ca2 +-deficient hydroxyapatite/HAp/(Ca/P ≈ 1.4) aggregates were identified in the case of original-CNF prevalent scaffolds after four weeks of incubation in SBF, the more uniform and intensified deposition with HAp-like (Ca/P ≈ 1.69) structures were established using CNF-COOH-Apa. The growth of Mesenchymal Stem Cells (MSCs) was observed on all CNF-containing scaffolds, resulting in more extensive Ca2 + deposition compared to the positive control or pure GEL scaffold. Among them, the scaffold prepared with the 50% v/v CNF-COOH-ApA showed significantly increased mineralization kinetic as well as the capacity for bone-like patterning in bone tissue regeneration.