Study of Hydroxyapatite (HAp) Based Biocompatible Composite Matrix for Osseous Tissue Regeneration

Abstract

Tissue Engineering is emerging as a next generation therapeutical methods to overcome shortcomings of tissue defects from within using living cells and multidisciplinary fields of science and technology. Human beings have been greatly affected by various diseases which lead to degradation of bone tissue such as osteoporosis. It is difficult for the human body to regrow bone tissue affected by such diseases. For this reason it is necessary to develop methods by which bone tissue can be grown in vitro and can then replace the degraded tissue in human beings. Hydroxyapatite (HAp) being structurally similar to bone tissue of living organisms can be actively used as a matrix for the culturing of osteoblast cells which can then be incorporated into a human being at the diseased site to regenerate osseous tissue. Moreover HAp is widely used as a matrix due to its increased biocompatibility as well as its exceptional osteoconductivity. In addition, HAp has also been used in the form of composite like HAp-chondroitin sulphate(HAp-ChS) composite matrices that have been tested on Japanese white rabbits and have yielded significant results. Furthermore, metal ions doped with HAp have also been known to yield greater osteoconductivity. One of the most prominent of these metal ions is Zinc which can be found as a trace metal in bone and aids in bone metabolism and development. Zinc is known to initiate the activity of the enzyme aminoacyl-tRNAsynthetase which thus helps in translation and leads to protein synthesis. It also helps in the expression of genes which code transcription factors such as the Runx2 transcription factor required for differentiation of osteoblast cells as well as optimises the development of osteoclast cells to regulate resorption. Furthermore, zinc ions are capable of showing antimicrobial and antifungal properties which are extremely beneficial to prevent contamination during cell culture. MG63 osteoblast cells are primarily used for cell culture on HAp matrix generally for a few weeks to observe the efficiency of the matrix. MG63 cell lines have characteristics which are nearest to human osteoblast cells. Different matrices with same composition but varying surface roughness are also prepared to increase adhesion of the cells to the matrix, determined by various cell viability assays. It is found through comparative study that zinc doped HAp matrices yield significant growth of cells in comparison to pure HAp matrices when formed at a temperature of 1250oC and that does not exhibit any cytotoxic effect. In the present report an idea of the various research work conducted for the development of zinc doped Hap matrix in the field of bone tissue engineering is provided.