Engineers create bone that blends into tendons

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Engineers create bone that blends into tendons

http://www.eurekalert.org/pub_releases/2008-08/giot-ecb082908.php

Engineers at Georgia Tech have used skin cells to create artificial

bones that mimic the ability of natural bone to blend into other

tissues such as tendons or ligaments. The artificial bones display a

gradual change from bone to softer tissue rather than the sudden

shift of previously developed artificial tissue, providing better

integration with the body and allowing them to handle weight more

successfully. The research appears in the August 26, 2008, edition of

the Proceedings of the National Academy of Sciences.

" One of the biggest challenges in regenerative medicine is to have a

graded continuous interface, because anatomically that's how the

majority of tissues appear and there are studies that strongly

suggest that the graded interface provides better integration and

load transfer, " said Andres , professor in the W.

Woodruff School of Mechanical Engineering at the Georgia Institute of

Technology.

and former graduate student , along with

research technician Kellie Burns and their collaborators ph Le

Doux and Guldberg, were not only able to create artificial

bone that melds into softer tissues, but were also able to implant

the technology in vivo for several weeks.

They created the tissue by coating a three-dimensional polymer

scaffold with a gene delivery vehicle that encodes a transcription

factor known as Runx2. They generated a high concentration of Runx2

at one end of the scaffold and decreased that amount until they ended

up with no transcription factor on the other end, resulting in a

precisely controlled spatial gradient of Runx2. After that, they

seeded skin fibroblasts uniformly onto the scaffold. The skin cells

on the parts of the scaffold containing a high concentration of Runx2

turned into bone, while the skin cells on the scaffold end with no

Runx2 turned into soft tissue. The result is an artificial bone that

gradually turns into soft tissue, such as tendons or ligaments.

If the technology is able to pass further testing, one application

could be anterior cruciate ligament (ACL) surgery. Oftentimes, ACL

surgery fails at the point where the ligament meets the bone. But if

an artificial bone/ligament construct with these types of graded

transitions were implanted, it might lead to more successful outcomes

for patients.

" Every organ in our body is made up of complex, heterogeneous

structures, so the ability to engineer tissues that more closely

mimic these natural architectures is a critical challenge for the

next wave of tissue engineering, " said , who is now working

at Emory University as a postdoctoral research fellow in

developmental biology.

Now that they have been able to demonstrate that they can implant the

tissue in vivo for several weeks, the team's next step is to show

that the tissue can handle weight for an even longer period of time.