Coated nano-hydroxyapatite for improved Bone scaffolds

Sometimes, bone replacements are weakened by injury, trauma, or surgery. Bone loss has become a significant health care concern globally with an increase in the average population age and constitutes  about 10 percent of annual healthcare expenses. Furthermore, in the United States alone, bone tissue repair accounts for nearly 500,000 surgical procedures each year. Extensive research has therefore been aimed at developing potential treatment methods using tissue engineering techniques for appropriate bone regeneration.

This current  research was publish in Journal of Biomaterials Applications under title " The effect of coated nano-hydroxyapatite concentration on scaffolds for osteogenesis"

The author said "We manufactured a silk scaffold for bone tissue engineering applications containing nano-hydroxyapatite (nano-HAp). To enhance the strength coating of nano-HAp in amount of 0.30, 0.15, and 0.03 g was selected" .

For preparation these scaffolds were soaked and lyophilized in a type I solution of atelocollagen. Scaffolds were crosslinked and lyophilized for 48 h with 0.02 percent carbodiimide, followed by sterilisation at 10 kGy with γ-irradiation. 

Energy-dispersive X-ray spectroscopy and atomic force microscope were performwd for the scaffold properties. For calcium, phosphorus, and oxygen atoms, a standard spectrum of the inorganic crust and electron diffraction patterns showed peaks. 5.60 and 40.32 nm were the root mean square values of the control and experimental surfaces. The nano-HAp width was in the estimated range of 100-150 nm, and the height was around 350 nm. In a growth medium, dental pulp cells were seeded at a density of  104 cells/cm2 and cultured for 3 weeks.

In the differentiation medium, the cells were then cultured for 4 weeks and were transplanted into a nude mouse. After 8 weeks, the biopsy was collected. The use of 0.15 g of nano-HAp resulted in the highest levels of in vitro type III collagen, fibronectin, osteocalcin, osteopontin, osteonectin, osteoprotegerin, and BMP-2 mRNA after 4 weeks of differentiation.

The author further explain "Analysis of western blotting was performed to elucidate signalling pathways. Compared to the control group, β-Catenin, phosphorylated-ERK, p38 phosphorylation increased the most when 0.15 g of nano-HAp was used. In histological contrast, for the silk scaffold containing 0.15 g of nano-HAp, osteocalcin and osteopontin synthesis were higher. Among the scaffolds, the most effective for osteogenesis were samples containing 0.15 g nano-HAp. This would also be a good substrate as a biomaterial for applications in the engineering of bone tissue ".

The Energy-dispersive X-ray spectroscopy was carried out to studied the chemical composition of the HAp-coated silk scaffolds (EDX). A standard spectrum on the surface-modified silk scaffold of the inorganic crust deposited. For calcium, phosphorus, and oxygen atoms, the electron diffraction patterns showed peaks. As the concentration of HAp increased compared to noncoated silk scaffold, the EDX results showed a concentration-dependent trend.

A 3D scaffold coated with nano-HAp applied at three different concentrations was established in this research, which is different from the method used in other previous studies. They assessed the proliferation and differentiation of DP cells. The silk scaffold containing 0.15 g nano HAp seemed to provide an adequate environment for DP cell growth, whereas when the HAp concentration was greater than 0.15 g, the cell differentiation decreased. A similar finding was also observed through RT-PCR and immunohistochemical studies. Thus, the authors claim that HAp can be used as a material to facilitate bone formation at suitable concentrations.

In addition, HAp bioceramic significantly improved cell attachment, cell viability, ALP function, and increased osteoblastrelated gene mRNA expression levels, including stromal cells of Runx2, BMP-2, BSP, and osteocalcin of bone marrow.