Fabrication of Pulsatile Cardiac Tissue Grafts Using a Novel 3-dimensional Cell Sheet Manipulation Technique and Temperature-Responsive Cell Culture S
Fabrication of Pulsatile Cardiac Tissue Grafts Using a Novel 3-dimensional Cell Sheet Manipulation Technique and Temperature-Responsive Cell Culture Surfaces
Tatsuya Shimizu, Masayuki Yamato, Yuki Isoi, Takumitsu Akutsu, Takeshi Setomaru, Kazuhiko Abe, Akihiko Kikuchi, Mitsuo Umezu, Teruo Okano
This article documents research regarding the use of a special type of polymer for a successful tissue culture and subsequent transplantation. What is special about this polymer is it is temperature responsive. The surface undergoes a change from being hydrophobic, cell adhesive, at 37 deg C to hydrophilic, non cell-adhesive, below 32 deg C. It is thought to produce a more viable transplant tissue culture, one could culture a sheet of cells on this sheet, easily detach them, and then transplant the cell sheet into a patient. What is advantageous about this polymer is that one more easily culture and transplant cell sheets. The change in cell adhesiveness of the polymer allows the detachment of cell sheets while preserving the ECM of the culture versus more traditional methods which involves enzymatic digestion i.e. trypsinization. It is then thought that a 3d-tissue culture could be constructed by layering cell sheets that have been cultured with this polymer.
The polymer was effective in the way that the researchers intended it to work. Myoblasts were successfully cultured as a sheet. The resulting sheet of cardiac tissue would uniformly pulse when growing on the sheet and when detached from from the sheet. A 3D culture was created by growing multiple sheets and then layering them on top of one another through a scaffold structure of collagen membrane. What is interesting to note is that the cell sheet would shrink and thicken significantly once detached from the sheet due to cytoskeletal reorganization. In addition, depending on the thickness of the sheet, it was take some time before the sheet would be able to pulse synchronously. Transplant efficacy was tested by transplanting sheets of various thickness of cultured cardiac tissue into the heart area of rats. The transplantation effectiveness was compared to injection of myoblasts, muscle stem cells, directly into the heart area.
While the research team did demonstrate the efficacy of the use of the polymer to culture cell sheets, there are some trade offs in their approach. The researchers do not construct true vascularized 3d-cell culture. As a result their culturing methods is still limited by mass-transport. In addition, in testing the efficacy of their treatment, they did not compared transplantation of their 3d culture to other methods of 3d culture the transplantation of cells cultured in a biodegradable polymer. So while they do demonstrate the efficacy of their method, we only know this relative to the worst case scenario.
6 comments:
I think it's really interesting that the polymer's temperature sensitivity influences its cell adhesion properties - does the paper go into the details of the polymer (material science)?
First, same question as Rustin regarding the material and chemical properties of the actual polymer. Second, is it possible that such a change in temperature may disturb the cells that were previously grown on the polymer since the optimal temperature for such cells is body temperature?
The paper mentioned that the grafted cells pulsed at a slower rate, and initially don't pulse. This environment seems to be not very healthy for the cells, have they tried changing the composition/and or rigidity of the sheet?
Did the researchers find that the released cell sheet shrunk by a predictable amount when they were released from the polymer? They would need to be able to predict shrinkage of the cell sheets if they want to be able to try and create 3D cultures with any kind of pattern involving two cell types or more.
Have thought about carting tissues with different cell types in each layer, or did they limit their tests to the single cell type mentioned?
Although this article mentions a particular surface undergoes a change from being hydrophobic, cell adhesive, at 37 deg C to hydrophilic, non cell-adhesive, below 32 deg C—this is essentially useless in vivo, but extremely important in vitro. It is this property that allows the sheets of cells to be layered on top of each other and to be removed easily. Like the rest of the comments made prior, it is important to consider this temperature responsiveness’s effect, when the cells are actually inside the body. Lastly, the consequences of mass transport via the 3D-cell structure comprises the essence of tissue engineering and the research team should continue to focus on constructing true-vascularized 3D cell scaffolds using this new polymer.
This paper seems to be investigating something that needs a lot more research. Without vascularization, the device would not work as an implant. Also, the temperature variation seems like it could become an issue. Just a five degree difference between properties seems like such a small amount.
Post a Comment