„CULTURED MEAT“ ; MANUFACTURING OF MEAT PRODUCTS THROUGH “TISSUE-ENGINEERING” TECHNOLOGY.
In-Vitro meat is the manufacturing of meat products through “tissue-engineering” technology. Cultured meat (= in-vitro meat) could have financial, health, environmental, and animal welfare advantages over traditional meat. The idea: To produce animal meat, simply without using an animal. Starting cells are taken painlessly from live animals, they are put into a culture media where they start to proliferate and grow, independently from the animal. Theoretically, this process would be efficient enough to supply the global demand for meat. All this would happen without any genetic manipulation, i.e. without the need to interfere with the cells’ genetic sequences. 

Producing cultured meat for processed meat products, such as sausages, burgers and nuggets should be relatively simple, whereas cultured meat which should be more highly structured, such as for an in-vitro steak is considerably more of a challenge. A steak is made of muscle tissue which is threaded through with extremely long, fine capillaries which transport blood and nutrients directly to the cells. It is much more difficult to reproduce such a complex structure than it is to put together the small balls of cells which grow to larger balls of cells which in turn become in-vitro chicken nuggets.

The most important challenges to overcome in order to outperform animal derived meat in terms of taste and economics are:

Starter Cells: 
These can be taken painlessly from live animals via biopsy. The question is: Which type of cells should be used? Stem cells are cells which, in a manner of speaking, have not yet decided what they will become; muscle cells, bones cells or one of so many other kinds of cells? This is a disadvantage because very specific cells are needed for the production of in-vitro meat. However, the advantage of stem cells is that they proliferate rapidly. The alternative to using stem cells would be to use fully defined muscle cells that “know what they are” although the problem here is that they hardly multiply at all. A compromise is to use cells which are between the two extremes, in other words, cells that proliferate at an acceptable pace and that are at the same time sufficiently differentiated from other cell types, for example, myoblast cells.
Growth Medium / Culture Media: 
The aim is to find a medium in which the cells can grow that is cost effective and free from animal ingredients. Serum from calves, for example, cannot be used with cultured meat. Because cultured meat does not have the digestive organs that a live creature has, which convert nutrients to feed the cells, the medium must be able to supply the cells directly with what they need.
Material for an edible scaffold for the cells to attach themselves to: 
In order to produce three-dimensional in-vitro meat, it is necessary to have a scaffold. The ideal is an edible scaffold that would not need to be extracted from the end product. To simulate the stretching that muscle cells undergo as a living creature moves around it is highly desirable to develop a scaffold that could periodically shift its form thus “exercising” the cells. This could be achieved by using a stimuli-sensitive scaffold made of alginate, chitosan or collagen, from non-animal sources. The scaffold would then stretch periodically in response to small changes in temperature or pH levels. The cells could also attach themselves to a membrane or tiny beads which could be layered on top of each other and connected together.
Bioreactor: 
It is in the bioreactor that everything comes together; the cells, the culture medium and the scaffold. Through fluctuations in temperature an environment is created which can be likened to a fitness centre with movement training for the muscle cells. Cultured meat must consist of small and large fibres of muscle cells in addition to connective tissue which produces collagen and elastin as well as fat cells which are important for the taste of the end product.
Economically viable solutions for the above listed points have not yet been fully researched. We are still waiting for the big breakthrough.
We would like to briefly remark on the idea of food being natural: It is intended that cultured meat should replace industrialised intensive farming; this poses no threat or competition to farming organic vegetables, for example. Compared to the unnaturalness of industrial animal farming, cultured meat would be undoubtedly a progressive step in terms of health, animal welfare and ecology.

FOR INTERESTED SCIENTISTS: WHAT WE CAN ACHIEVE TOGETHER
see http://www.futurefood.org/biotechnology/index_en.php