System To Build Transplant Tissue Created

Source:

http://www.sciencedaily.com/releases/2007/10/071008161609.htm

Science Daily — One day soon, laboratories may grow synthetically engineered tissues such as muscle or cartilage needed for transplants. In a major step forward, Cornell engineers describe in the journal Nature Materials a microvascular system they have developed that can nourish growing tissues.

The researchers have engineered tiny channels within a water-based gel that mimic a vascular system at the cellular scale and can supply oxygen, essential nutrients and growth factors to feed individual cells. The so-called gel scaffold can hold tens of millions of living cells per milliliter in a 3-D arrangement, such as in the shape of a knee meniscus, to create a template for tissue to form.
In theory, the system could accommodate many kinds of tissue.
"A significant impediment to building engineered tissues is that you can't feed the core," said Abraham Stroock, Cornell assistant professor of chemical and biomolecular engineering and one of the paper's senior authors. "Simply embedding this mimic of a microvascular system allows you to maintain the core of the tissue during culture." Gel scaffolds, he said, "are the culture flasks of the future."
The embedded microchannels allow fluid with oxygen, sugar and proteins to travel through the system. The researchers can control the distributions of these solutes over both time and space within the developing tissue, allowing the fine-tuning of the biochemical environment of the cells while the tissue develops. For example, the tissue may need to develop into bone on one side and cartilage on the other. Now the researchers can supply the right nutrients and proteins to certain parts of the growing tissue to ensure an intended outcome.
The research provides solutions to the physical engineering aspects of growing tissues synthetically. Still, many biological challenges remain, such as finding a source of cells that can be harvested from a patient and grown without changing the cell's characteristics. Co-author Lawrence Bonassar, a Cornell associate professor of biomedical engineering who was instrumental in developing the gel for tissue growth and in determining the proper biological requirements for cell growth, is also among those trying to direct stem cells to produce desired tissue types. Currently, stem cell-derived cartilage has been made but is not functional.
As new tools develop, researchers hope to use these engineered tissues in non-clinical applications, such as replacements for animals in the testing of pharmaceuticals and chemicals. The technology, researchers believe, also offers the hope of growing implants from the patient's own cells to replace damaged or diseased tissue.
The research was funded by the Office of Naval Research, Cornell's Nanobiotechnology Center, Beckman Foundation, the Center for Life Science Enterprise at Cornell and the Cornell Center for Materials Research.
Note: This story has been adapted from material provided by Cornell University.

Fausto Intilla

www.oloscience.com

The Petri Dish Is Taken To New Dimensions

Source:

http://www.sciencedaily.com/releases/2007/09/070919115955.htm

Science Daily — A team of Brown University biomedical engineers has invented a 3-D Petri dish that can grow cells in three dimensions, a method that promises to quickly and cheaply produce more realistic cells for drug development and tissue transplantation.

The technique employs a new dish – cleverly crafted from a sugary substance long used in science laboratories – that allows cells to self-assemble naturally and form “microtissues.” A description of how the 3-D dish works appears in the journal Tissue Engineering.
“It’s a new technology with a lot of promise to improve biomedical research,” said Jeffrey Morgan, a Brown professor of medical science and engineering.
Morgan conceived and created the 3-D Petri dish with a team of Brown students led by Anthony Napolitano, a Ph.D. candidate in the biomedical engineering program. Napolitano spent two years perfecting the new dish and recently won a $15,000 award from the National Collegiate Inventors and Innovators Alliance to develop the patent-pending technology into a commercially viable product.
“This technology is an inexpensive and easy-to-use alternative to current 3-D cell culture methods,” Napolitano said. “It’s the next generation.”
The technology tackles a topic of increasing interest to scientists: creating hothouse cells that look and behave more like cells grown in the human body. Since 1877, scientists have relied on the Petri dish to grow, or culture, cells. The cells stick to the bottom of the dishes and spread out as they multiply. In the body, however, cells don’t grow that way. They are surrounded by other cells in three dimensions, forming tissues such as skin, muscle, and bone. This is what happens in Morgan’s 3-D dish.
The clear, rubbery dish is the size of a silver dollar. It is made from a water-based gel made of agarose, a complex carbohydrate long used in molecular biology. This gel has a few benefits. It is porous, allowing nutrients and waste to circulate. And it is non-adhesive, so cells won’t stick to it. At the bottom of the dish sit 820 tiny recesses or wells. When cells are added to the dish –about 1 million at a time – roughly 1,000 sink to the bottom of each well and form a pile. These close quarters allow cells to self-assemble, or form natural cell-to-cell connections, a process not possible in traditional Petri dishes.
The result: microtissues consisting of hundreds of cells, even of different types. In Tissue Engineering, the Brown team describes how they combined human fibroblasts, which make connective tissue, and endothelial cells, which line the heart and blood vessels. The cells came together to form spheres and doughnut-shaped clusters. The process was quick – self-assembly took place in less than 24 hours.
“These microtissues have several potential uses,” Morgan said. “They can be used to test new cancer compounds and other drugs. And they can be transplanted into the body to regenerate tissue, such as pancreatic cells for diabetics. While there are other methods out there for making microtissues, our 3-D technology is fast, easy and inexpensive. It can make hundreds of thousands of microtissues in a single step.”
Differences in culture techniques matter in biomedicine, according to a growing body of research. Studies show sometimes dramatic differences in the shape, function and growth patterns of cells cultured in 2-D compared with cells cultured in 3-D. For example, a recent Brown study found that nerve cells grown in 3-D environments grew faster, had a more realistic shape and deployed hundreds of different genes compared to cells grown in 2-D environments.
That’s why several laboratories are pursuing 3-D cell culture methods. Brown Technology Partnerships has filed a patent application based on the technology developed in the Morgan lab and is actively pursuing licensing partners.
Napolitano was lead author of the Tissue Engineering article, and Morgan was senior author. Other members of the research team included Peter Chai, a student at The Warren Alpert Medical School of Brown University and Dylan Dean, an M.D./Ph.D. graduate student in the molecular pharmacology and physiology program.
The National Science Foundation funded the research.
Note: This story has been adapted from a news release issued by Brown University.

Fausto Intilla

www.oloscience.com