Researchers grow mice jawbone by injecting protein-peptide combo

Researchers at Tokyo Medical and Dental University have successfully caused new bones to grow in mouse jaws by injecting a mix of bone-augmenting agents -- a protein/peptide combination.

Use of aninjectable gelatin-based gel to carry the agents avoided the need for surgical implantation and resulted in no swelling or other such complications in the experimental mice, the researchers reported in the Journal of Dental Research.

For the experiment, th researchers used the combination of peptide OP3-4 and bone morphogenetic protein 2 (BMP-2).

Recombinant human bone morphogenetic protein 2 has been used to stimulate osteogenesis (bone formation) in humans, but high levels can cause inflammation and tumour development.

The supplementation of other bone-augmenting agents is considered helpful in preventing such side effects by reducing the amount of BMP-2 required to obtain a sufficient amount of bone.

So the researchers investigated the role of the peptide OP3-4 that has been shown to inhibit bone decay and stimulate the differentiation of cells (osteoblasts) that form bone.

The researchers observed a region of increased bone mass around the BMP-2 plus OP3-4 injection site that was larger than that seen in mice injected with BMP-2 alone, or with other controls.

This mass also had a significantly higher bone mineral content and density, the study said.

Microscopic examination revealed the deposition of calcified tissue (mineralisation) throughout the newly formed bone of mice treated with the protein/peptide combination.

"Mineralisation of the outer region evidently took place before that of the inner region," said lead author Tomoki Uehara.

"We speculate that the size of the new bone is determined before calcification starts, and that OP3-4 plays an important role in making a regeneration site at the early stage of bone formation," Uehara said.

--IANS

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