Improving Bone Grafts

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A new technology for dental implants that may improve construction or repair of bones in the face, skull and jaw, has been developed by researchers from the American Dental Association Foundation (ADAF) and the National Institute of Standards and Technology (NIST).

The new technology, which is described in journal articles(1, 2,3), provides a method for making scaffolds for bone tissue. The scaffold is seeded with a patient’s own cells and is formed with a cement paste made of minerals also found in natural bone. The paste is mixed with beads of a natural polymer (made from seaweed) filled with bone cells. The paste is shaped or injected into a bone cavity and then allowed to harden with the encapsulated cells dispersed throughout the structure. The natural polymer beads gradually dissolve when exposed to the body’s fluids, creating a scaffold that is filled by the now released bone cells.

The cement, a calcium phosphate material, is strengthened by adding chitosan, a biopolymer extracted from crustacean shells. The implant is further reinforced to about the same strength as spongy natural bone by covering it with several layers of a biodegradable fiber mesh already used in clinical practice.

"Bone cells are very smart," says Hockin Xu, of the ADAF and principal investigator for the project. "They can tell the difference between materials that are bioactive compared to bioinert polymers. Our material is designed to be similar to mineral in bone so that cells readily attach to the scaffold."

The researchers used mouse bone cells in their experiments, but in practice surgeons would use cells cultured from patient samples. In addition to creating pores in the hardened cement, the natural polymer beads protect the cells during the 30 minutes required for the cement to harden. Future experiments will develop methods for improving the material’s mechanical properties by using smaller encapsulating beads that biodegrade at a predictable rate.

Source: MedicalNewsToday.com

1. E.F. Burgera, H.H.K. Xu and M.D. Weir. Injectable and rapid-setting calcium phosphate bone cement with dicalcium phosphate dihydrate. Journal of Biomedical Materials Research B. April 2006.

2. H.H.K. Xu, M.D. Weir, E.F. Burguera and A.M. Fraser. Injectable and macroporous calcium phosphate cement scaffold. Biomaterials. In press.

3. M.D. Weir, H.H.K. Xu, and C.G. Simon, Jr. Strong calcium phosphate cement-chitosan-mesh construct containing cell-encapsulating hydrogel beads for bone tissue engineering, Journal of Biomedical Materials Research A. In press.

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3 Responses to “ Improving Bone Grafts ”

• Gary D. Kitzis, DMD April 18th, 2006

  
  

  I hope this doens’t get too much exposure in the lay press. It becomes very time consuming explaining to patients what the articles really mean, and their relevance and applicability to a patient’s particular case.

  I don’t want to be on the leading edge of this one in clinical use because I have serious doubts, which are admittedly anecdotal, that the patient’s cultured cells, buried within the scaffold of a cement paste mixed with beads of a natural polymer, made from seaweed, injected into a bone cavity and then allowed to harden with the encapsulated cells dispersed throughout the structure could even survive, or when dead or decomposing, could even act as a means to induce bone growth. The contention that “natural polymer beads” gradually dissolve when exposed to the body’s fluids, creating a scaffold that is filled by the now released (dead) bone cells to induce new bone growth, seems implausible.

• JT April 18th, 2006

  
  

  How about the long-term effect of this procedure?

• Anonymous April 19th, 2006

  
  

  is there any compounds relatd to the ONJ?

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