Patent Application
20110159582
The WO 2006/088029 describes and shows a bioreactor in which cells grow in a laminar flow of a nutrient fluid (Weyand B, Israelowitz M, von Schroeder H, Vogt P M. 2009. Fluid dynamics in bioreactor design: considerations for the theoretical and practical approach. In: Kasper C, van Griensven M and Portner R., eds. Bioreactor Systems for Tissue Engineering. Advances in Biochemical Engineering/Biotechnology 112. Heidleberg: Springer Berlin; p 251-268; Israelowitz M, Rizvi S, Weyand B, von Schroeder H P. 2010. Development of a laminar flow bioreactor using computational fluid dynamics. J. Healthcare and Engineering [In press]). This growth is insufficient to create human or animal skin. Skin is a flat item/organ with profound differences between its inner and outer sides and organized in layers. In order to produce a larger piece of skin, it is necessary to stretch a piece of lesser dimension, and allow for the accumulation and growth of cells during the stretching process of the original skin. This is not possible in the WO 2006/088029 apparatus.
The inventors have found that the growth of skin (Weyand B, Reimers K, Vogt P M. 2010. Influences of extracellular matrix properties and flow shear stresses on stem cell shape in a three-dimensional dynamic environment, IFMBE Proceedings, 2010) is possible if a slowly stretched piece of skin is in contact with the nutrient fluid only on its inner side, and in contact with a gas, especially with air, on the outer side of the skin.
Therefore, the apparatus of the invention consists of a chamber that is only partly filled with a flowing nutrient fluid. This chamber contains a holder for keeping the organic item such as skin on the surface of the nutrient fluid and includes items to stretch the skin. The chamber has an inlet and an outlet for the nutrient fluid under the surface of the skin; and, it has another inlet and an outlet for a gas, such as air, above the surface of the skin. With this apparatus, it is possible to enlarge a piece of skin by stretching and allowing for the growth of the tissue with the supply of cells and nutrient fluid such that there is no essential enlargement or reduction of the thickness of the skin.
To ensure that the inner side of the skin or another organic item is always in contact with the nutrient fluid, the organic item, in this device, is fastened on the under side of the holder in such a way as to have contact with the surface of the nutrient fluid (Kuhbier J W, Weyand B, Radtke C, Vogt P M, Kasper C, and Reimers K, 2010. Isolation, Characterization, Differentiation and Application of Adipose-Derived Stem Cells, Adv Biochem Eng Biotechnol, (PMID: 20091288); Kuhbier J W, Weyand B, Sorg H, Radtke C, Vogt P M, and Reimers K, 2010. [Stem cells from fatty tissue: A new resource for regenerative medicine?], Chirurg, 81: 826-832). In order to stretch the skin, this device has moveable clamps that hold the organic item.
The holder is made from sheet metal, with one or more openings covered with the organic item. It is maintained in a completely horizontal position and parallel to the surface of the fluid over its dimensions and in contact with the nutrient fluid.
The apparatus has a holder with more than one opening. Each opening can be covered with one organic item.
It is beneficial if the apparatus has a valve in the fluid inlet, that consists of two displaceable sheets with openings one upon another to create a laminar flow of the nutrient fluid.
This apparatus is advantageously part of a circuit consisting of pipes for the transport of the nutrient fluid, a pump, and a source of nutrients mixed in the flow.
To control the function of this apparatus, it is provided with glass portals to observe the flow, and growth of the organic item.
This apparatus is supplied with adjusters for the exact horizontal position of the holder.
The block diagram of
The holder
Each of the rectangular holes (1.4) are surrounded with clamps for holding the samples of cell masses and tools for moving the clamps in a direction to stretch and enlarge the samples (1.3) of cell masses. The clamps and tools are not shown.
The nutrient fluid is circulated by a pump (1.5) through pipes (1.6).
A supply tank (1.7) with nutrient fluid is connected to the system of pipes (1.6) to refill the stock of the fluid.
Because the flow of fluid has to be a laminar flow at the entrance to the under part of the bio-reactor (1.1a), a valve (1.8) is installed at this entrance. This valve consists of two disks (1.9), perforated in the same way and at the same locations. These disks (1.9) can be rotated one against the other in small degrees to change the rate of flow and circulation. The result of this small rotation of the two perforated disks (1.9), one against the other is the control of the upper level of the fluid and the kind of flow that has to be a laminar flow. The thickness of the holder (2.1) gives the range of the surface of fluid.
