7, July 2014

Scientists can now 3D print human blood vessels

Washington: Scientists have figured out how to create blood vessels in 3D printed organs, a breakthrough that may eventually lead to artificial organs.

Scientists have been steadily advancing towards the goal of building lab-grown organs out of a patient's own cells, but a few major challenges remain.

One of them is making vasculature, the blood vessel plumbing system that delivers nutrients and remove waste from the cells on the inside of a mass of tissue. Without these blood vessels, interior cells quickly suffocate and die.

Scientists can already grow thin layers of cells, so one proposed solution to the vasculature problem is to "print" the cells layer by layer, leaving openings for blood vessels as necessary.

But this method leaves seams, and when blood is pumped through the vessels, it pushes those seams apart.

Researchers from the University of Pennsylvania have turned the problem inside out by using a 3D printer called a RepRap to make templates of blood vessel networks out of sugar.

Once the networks are encased in a block of cells, the sugar can be dissolved, leaving a functional vascular network behind.

Bioengineering postdoc Jordan Miller, along with Christopher Chen, other members of Chen's lab and colleagues from Massachusetts Institute of Technology (MIT), set out to show that this method of developing sugar vascular networks helps keep interior cells alive and functioning.

After the researchers design the network architecture on a computer, they feed the design to the RepRap. The printer begins building the walls of a stabilising mold.

Then it draws filaments across the mold, pulling the sugar at different speeds to achieve the desired thickness of what will become the blood vessels.

After the sugar has hardened, the researchers add liver cells suspended in a gel to the mold. The gel surrounds the filaments, encasing the blood vessel template.

After the gel sets it can be removed from the mold with the template still inside. The block of gel is then washed in water, dissolving the remaining sugar inside. The liquid sugar flows out of the vessels it has created without harming the growing cells.

"This new technology, from the cell's perspective, makes tissue formation a gentle and quick journey," said Chen.

Source: www.zeenews.india.com

07.07.2014

Older women's eggs 'just as good'?

Washington: An old hypothesis that claims that as a woman ages, the eggs she will produce will have more faulty chromosomes - leading to miscarriages and developmental abnormalities - does not hold much water, says a new research.

The production-line hypothesis stated that the first eggs produced in a female's foetal stage tend to have better connections or "crossovers" between chromosomes.

But after counting the actual chromosome crossovers in thousands of eggs, researchers at Washington State University found that eggs produced later were no different from those produced early in the foetal stage.

"If the production-line hypothesis was true, you would expect lots of abnormal cells and you would expect them all to be happening late," said Ross Rowsey, one of the researchers.

"We do see a pretty high incidence of abnormal cells, but they are just as likely to be happening early as late," he added.

Rowsey studied more than 8,000 eggs from 191 second-trimester fetal ovaries. He saw a lot of variation within women and between women, but no relationship to a woman's age.

"There have to be other factors involved," he said.

"The abnormal crossovers cannot be explaining all of it," Rowsey added.

The production-line hypothesis was put forth in 1968 by Alan Henderson and Robert Edwards, winner of the Nobel Prize for development of in-vitro fertilisation.

Source: www.zeenews.india.com

07.07.2014

A pessimist is somebody who complains about the noise when opportunity knocks