Composite chitosan-human bone granulates for bone tissue regeneration

Authors:

• Piotr Kowalczyk,
• Rafał Kamil Podgórski,
• Michał Wojasiński,
• Grzegorz Gut,
• Witold Bojar,
• Tomasz Ciach

Abstract

Regeneration of lost bone is necessary after fractures and resections, most often caused by cancer, when diseased tissue is removed. Human bone is ideal for replacing lost tissue, however the procedure of autografting is highly morbid and risks complications. A large focus of tissue engineering is placed on materials which can emulate the human bone – polymers, ceramics, composites of those, both: natural and synthetic origin. The primary objective of these materials is to support the growth of cells, blood vessels, and new, regenerated bone tissue. We have developed a granulate composed of β- tricalcium phosphate, pulverized human bone and biopolymer – chitosan, a highly potent compound applied in tissue engineering, regenerative medicine and biotechnology. For repair of bone losses, granulation allows easy application and formation of an interconnected porous structure. The granulate was obtained with gelation of chitosan in alkaline pH, dissolved in acetic acid beforehand and added to the coagulation bath with an encapsulator. Additives (10% β-TCP or 5% β-TCP and 5% human bone) were suspended in the dissolved polymer and formed together as a composite material. The obtained granulates were freezedried and sterilized with an autoclave. Granulates were contacted with L929 cells and proven non-cytotoxic via XTT assay. MG63 cells were seeded on the surface of prepared materials, and within 2 weeks, they have entirely colonized the surface of composite materials, opposed to pure chitosan. Alkaline phosphatase activity after 2 weeks was increased in the composites with human bone compared to these with β-TCP only. A chitosan/β-TCP/human bone composite material with better osteoinductive properties than chitosan/β-TCP composite was prepared and described. The prepared granules are also suitable for autoclave sterilization, which is a very convenient alternative to other methods of implant sterilization (gamma rays, ethylene oxide, or ethanol soaking).