Novel cellulose/hydroxyapatite scaffolds for bone tissue regeneration: In vitro and in vivo study

Abstract

Cellulose scaffolds containing nano- or micro-hydroxyapatite (nHA or μHA) were prepared by the regeneration of cellulose from its acetylated derivative and the mechanical immobilization of inorganic particles, followed by freeze-drying. Microtomographic (micro-computed tomography) evaluation revealed that both scaffolds presented a highly interconnected porous structure, with a mean pore diameter of 490 ± 94 and 540 ± 132 μm for cellulose/nHA and cellulose/μHA, respectively. In vitro and in vivo characterizations of the developed scaffolds were investigated. Commercially available bone allograft was used as a control material. For the in vitro characterization, osteoblastic cell cultures were used and characterized over time to evaluate cell adhesion, metabolic activity, and functional output (alkaline phosphatase activity and osteoblastic gene expression). The results revealed greater spreading cell distribution alongside an increased number of filopodia, higher MTT values, and significantly increased expression of osteoblastic genes (Runx-2, alkaline phosphatase, and BMP-2) for cellulose/nHA, compared with cellulose/μHA and the control. The in vivo biocompatibility was evaluated in a rabbit calvarial defect model. The investigated scaffolds were implanted in circular rabbit calvaria defects. Four- and 12-week bone biopsies were investigated using micro-computed tomography and histological analysis. Although both cellulose/HA scaffolds outperformed the assayed control, a significantly higher amount of newly formed mineralized tissue was found within the defects loaded with cellulose/nHA. Within the limitations of this study, the developed cellulose/HA scaffolds showed promising results for bone regeneration applications. The biological response to the scaffold seems to be greatly dependent on the HA particles' characteristics, with cellulose scaffolds loaded with nHA eliciting an enhanced bone response.

Electrical stimulation-induced osteogenesis of human adipose derived stem cells using a conductive graphene-cellulose scaffold

“…The device may be useful in research for tissue engineering and modelling, as well as prospective therapeutics, including preclinical assays for drug screening and tissue development for regenerative medicine. The latter is supported by evidence for graphene based materials being able to promote in vivo bone repair and reconstruction [43,44], in vivo biocompatibility of cellulose [45], and the recognised benefits of ES for bone healing.…”

Applications of bacterial-synthesized cellulose in veterinary medicine – a review

“…A wide range of grafts and graft substitutes are available. Autograft, allograft, and xenograft are the most commonly used natural bone substitutions; however, autogenous bone remains the gold standard (Daugela et al 2018). Their use is limited because they can cause donor site morbidity, increased postoperative pain, prolonged healing and, eventually, delayed revascularization (Zimmermann et al 2011;Shi et al 2012).…”

Polysaccharide-Based Systems for Targeted Stem Cell Differentiation and Bone Regeneration

“…As one of the most abundant polysaccharides, cellulose may be derived from either plants or bacteria and is investigated together with its derivatives like carboxymethylcellulose (CMC) as matrix material due to its inherent biocompatibility and biodegradability [126]. Combinations with different CaPs like HA [127][128][129][130], CDHA [131], CPC [132], and BCP [133][134][135] are recently evaluated for bone tissue regeneration.…”

“…The size of HA particles incorporated in a cellulose solution via physical mixing and subsequent freeze-drying of the resulting suspension has major impact on the scaffolds performance in vitro and in vivo. Compared to HA-particles with of 20 µm in diameter, particles with 100 nm in diameter have exceeding properties regarding cell adhesion, proliferation, and expression of osteogenic markers in vitro using MG-63 osteoblast-like cells, as well as pronounced formation of newly mineralized tissue in a rabbit calvarial defect model (Figure 4) [127]. Cellulose and CDHA are used to fabricate a latticed scaffold via a 3D-printing process.…”

“…* indicate a significant deviation from control; ** indicate a significant deviation from cellulose/µHA. Reproduced from work in[127] with permission from John Wiley and Sons, 2019.…”