Plant Cellulose Considered As Bone Implant Material

Developed by researchers at the University of British Columbia (UBC; Vancouver, Canada) and McMaster University (Hamilton, ON, Canada), the biologic aerogel material is made from chemically cross-linked cellulose nanocrystals (CNC), and is designed to support osteoblast proliferation and enhance bone regeneration. The highly porous CNC aerogels also promote and support the growth of hydroxyapatite on their surface, as was demonstrated when submerged in simulated body fluid solutions.

In an in-vivo study of the CNC aerogels, which were implanted into the calvarian bone of adult male Long Evans rats, their osteconductive properties were demonstrated, and an increase in bone volume of up to 50% was shown, as compared to sham sites. And at 3- and 12-week time points, the CNC aerogels showed an increased bone volume fraction of 33% and 50%, respectively. The study was published on March 15, 2019, in Acta Biomaterialia.

“We can see this aerogel being used for a number of applications, including dental implants and spinal and joint replacement surgeries, and it will be economical because the raw material, the nanocellulose, is already being produced in commercial quantities,” said senior author biomedical engineer Professor Kathryn Grandfield, PhD, of McMaster University. “This summer, we will study the mechanisms between the bone and implant that lead to bone growth. We'll also look at how the implant degrades using advanced microscopes.”

“Most bone graft or implants are made of hard, brittle ceramic that doesn't always conform to the shape of the hole, and those gaps can lead to poor growth of the bone and implant failure,” said lead author Daniel Osorio, MSc, a PhD student in chemical engineering at McMaster University. “We created this cellulose nanocrystal aerogel as a more effective alternative to these synthetic materials.”

Cellulose is a homopolysaccharide of glucopyranose that can be either regenerated to form organized fibers or remain non-regenerated with unorganized fibers. Structurally, cellulose consists of crystalline and amorphous regions; by treating it with strong acid, the amorphous regions can be broken up to produce CNC. Cellulose is an important structural component of the primary cell wall of green plants, and is the most abundant organic polymer on Earth. The cellulose content of cotton fiber is 90%, and of wood 40–50%.

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University of British Columbia
McMaster University