Latest studies have shown that these stem cells have huge potential in heart therapies. However, understanding of these studies is needed. The important thing is to separate things what stem cells can do with heart cells, and what they cannot. Researchers at Rice University and Texas Children's Hospital have founded that communication between these two cell types is possible. Mature heart cells and stem cells have ability to create electrical couplings between themselves like heart cells in heart tissue. During this electrical connection, stem cells cannot transform themselves to mature heart cells, and this is limitation of this method. Patients with Tetralogy of Fallot have biocompatible patches surgically placed across right ventricular outflow tract of the heart.
Procedure of stem cell implementation and scaffold types
Procedure of stem cell transplantation cannot be done without special scaffold patches. Idea of biocompatible patches seeded with stem cells is brilliant, because scaffold patches would ideally support stem cells implementation.
Current patches are made from synthetic fabrics or they can be obtained from cows or from patient himself. This kind of treatment is not bad, but it has limitations. These patches are more like plastic, and they don’t have ability to grow together with patients. Therefore, they have to be replaced in correlation with patients growth. Also these patches are implanted in heart and it's good for heart contraction. However, electrical signals have to go around this dead tissue. This implicates that heart has less contraction power and surely it can lead to heart failure or arrhythmias and fibrillations. When we summarize these facts we can conclude that these scaffolds have high short- and medium- term success rate and, unfortunately, long- term complications.
Newest scaffold research
Researchers have tried to discover the perfect scaffold. This perfect scaffold should be strong enough for heart contractions, porous enough to allow migration of the new differentiated cells, tough enough, but also able to degrade itself after certain amount of time. The newest discovery is scaffold which is created of polycaprolactone and double layer made from mixture of chitosan and gelatin. Researchers believe that this could be a tremendous discovery, because this scaffold has shown good properties. When in water, this scaffold degrades, but if it is placed in human body, it will degrade very slowly, over a month. This scaffold should be strong for a certain period of time that will help heart muscle to recover and to take over support process. However, many years of testing await scientists before they begin human trials, but they are very optimistic, and they expect positive results.
Directions in future researches
If scientists want to implant perfectly grown tissue that will not be rejected, they have to find out how intercellular signals can guide transformation of an amniotic stem cell into a heart cell. Research on the rats have shown that stem cells can only communicate with heart cells through channels in their membrane that provide exchange of the ions and small molecules.
A certain part of scientists suggested that physical contact between amniotic stem cells and heart cells have positive influence in differentiation of stem cells. However, scientists on the newest researches have proved that this is not correct. The newest researches showed that previous claim was incorrect because they saw only fusion of amniotic stem cell and heart cell. That is what this research was based on. Researchers wanted to see if amniotic stem cells could have characteristics of heart cells if fusion between these two cells were not allowed. They revealed results, and results have shown that it is not possible to convert an amniotic stem cell into a heart cell, but certain change in gene expression was present. The finding was connection between stem cells with a gap junction connections. This gap junction connection can transfer some really small molecules and electrical ions. These ions and molecules can diffuse between two cells connected with this junction. However, this diffusion is not possible when amniotic stem cells are not in connection with heart cells.
This research has unique approach, because other researchers approach is directly injection in heart tissue. This other approach is studying how directly injected amniotic stem cells can help in treatment of heart attack recovery. Researches from the Rice University and Texas Children's Hospital are not enthusiastic about this other research, because they think that this research will show them role of paracrine signal effects. They think that stem cells directly injected can help only in stabilization of the cells, but they cannot differentiate and create new heart tissue.
Conclusion of the research
The biggest discovery of this research is fact that cell contact between amniotic stem cells and heart cells cannot induce transformation of the stem cells, but it produces more functional gap junction connection than amniotic stem cell cultures without cell contact. However, if we want a bigger results right now, probably additional cues and maybe tighter connection between stem cells and heart cells, or maybe fusion, is required.
The ease of obtaining this type of stem cells, widely multipotent nature and rapid proliferation rate make this cell type promising source for future researches in tissue engineering.
Researchers are sure that there are plenty of methods to get amniotic fluid- derived stem cells differentiate into desired tissue for medical uses, and this research has revealed only small part of stem cell differentiation.