Showing posts with label Tissue (biology). Show all posts
Showing posts with label Tissue (biology). Show all posts

Friday, October 31, 2014

Artificial Connections

Capsule of right knee-joint (distended). Poste...
Capsule of right knee-joint (distended). Posterior aspect. (Photo credit: Wikipedia)
By C.CLAIBORNE RAY


For joint replacements, like a knee or hip, is muscle attached to the artificial implant?

Ordinarily “no muscle attaches to any hip or knee implant,” said Dr. Mathias P. Bostrom of the Hospital for Special Surgery in Manhattan. The only human tissue that adheres to an implanted joint is bone.

The link is made either with cement or directly to the bone. When the connection is direct, the bone-producing cells grow new material that forms a bond with the implant, a process called osseointegration.

“A lot of knee implants use a kind of cement, really more of a grout, that fixes to the bone itself,”
 Dr.Bostrom said. “It is an acrylic, similar to Plexiglas, called PMMA, for polymethyl methacrylate.”

In the case of a tumor prosthesis for a bone like the femur – in which a lot of bone is removed and large segments are replaced with metal – there may be some linkage of muscle and tendon to implant, he said.

In most joint implants, however, the muscle is still attached to the bone via the tendon, and the surgeon especially tries to avoid detaching any muscle insertion in the hip or knee.

“We want the tendon’s attachment to the bone to be intact,” Dr. Bostrom said.


Taken from TODAY Saturday Edition, June 15, 2013

Thursday, May 28, 2009

Stem cell breakthrough gets closer to the clinic


Time is GMT + 8 hours
Posted: 29-May-2009 01:41 hrs 

Embryonic stem cells are pictured through a microscope viewfinder in a laboratory. The quest for versatile, grow-in-a-dish transplant tissue took a step towards clinical use Thursday when researchers announced they have found a safe way to transform skin cells into stem cells.

The quest for versatile, grow-in-a-dish transplant tissue took a step towards clinical use Thursday when researchers announced they have found a safe way to transform skin cells into stem cells.

Researchers say the method is so promising they hope to apply for approval to begin clinic trials by the middle of next year.

"This is the first safe method of generating patient specific stem cells," said study author Robert Lanza, the chief scientific officer at Stem Cell & Regenerative Medicine International.

"This technology will soon allow us to expand the range of possible stem cell therapies for the entire human body," Lanza told AFP.

"This allows us to generate the raw material to solve the problem of rejection (by the immune system) so this is really going to accelerate the field of regenerative medicine."

The research builds on an award-winning breakthrough in 2007 by Shinya Yamanaka of Kyoto University.

Yamanaka and his team introduced four genes into skin cells, reprogramming them so that they became indistinguishable from embryonic stem cells.

That achievement conjured the distant vision of an almost limitless source of transplant material that would be free of controversy, as it would entail no cells derived from embryos.

But the downside of the technique for creating these so-called induced pluripotent stem cells (iPS) is that the genes are delivered by a "Trojan horse" virus.

Reprogramming cells using a virus modifies their DNA in such a way that they cannot be given to patients without boosting the risk of cancer and genetic mutation.

Other researchers have succeeded in delivering the genes with a method called DNA transfection or using a chemical wash, but these techniques also posed health risks.

Lanza's team succeeded in delivering the genes by fusing them with a cell penetrating peptide which does not pose the risk of genetic mutation.

While this method took twice as long to generate pluripotent stem cells, Lanza said he believes his team can increase the efficiency of the transmission by purifying the protein.

The study was published in the online edition of Cell Stem Cell. — AFP

From TODAYOnline.com; see the source article here.

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