Many papers show that hydroxyapatite enhances osteogenic differentiation in both animal mesenchymal stem cells as well as human stem cells. I never read about the underlying mechanism of this acceleration. Are there any papers which show how hydroxyapatite exactly accelerates differentiation?
I have seen the accelerating effect of HA on osteogenic differentiation of MSC and USSC in vitro. You are correct. Very few researchers have shown the mechanism behind this effect. As the solubility of HA is very low in culture, the effect of free calcium ions on enhanced differentiation of stem cells is excluded. However, this may be happened in some form of HA when used. What is clear is that MSC attach to the surface of HA crystals using its Integrins and other cell surface proteins. This may start a signalling through these surface molecules and up-regulate some of the main osteogenic-related genes in MSC. There may be also some specific receptors for calcium or phosphate ions in the structure of HA which behave like this and start some signalling pathways. A detailed information is absent in this field and needs to be clarified in further research.
I suggest you read doctor Marta cerruti PHD thesis(even though its on bioglass but it could help you understand some concepts better) which you can find easily in Google . basically it is related to role of osteoclast and osteoblast and the effect of Ca/P composition on their behaviors . and the fact that hydroxyapatite stimulates osteoblast cells to create more collagen that is used to form new bone structures.
We have seen a enhancing effect not only in MSCs.
The HA that we used was derived from red algea and showed a nice structure for the cells to attach and invade the material. Surface properties and structure are known to influence the differentiation behavior of bone cells and thier progenitors.
G-protein coupled receptor (GPCR) 5A is said to play a role in the response to biomaterials.
Maybe you find additional information here:
http://www.ncbi.nlm.nih.gov/pubmed/23752904
I'm also interested in how hydroxyapatite (HA) accelerates osteogenic differentiation in MSCs. I'm working on my Master's Thesis now and it's quite related to this question. From my experience working with MSCs and hydroxyapatite, I could say this question it's not yet clear, as it's true that Ca++ ions induce osteoblastic differentiation in MSCs, but I also think that integrins are related in the process.
There is knowlede about how integrin-mediated signalling lead osteoblastic differentiation in MSCs (http://www.ncbi.nlm.nih.gov/pubmed/19843692). Also, I could say from some preliminary and non-planned experimental results that RGD binding integrins are involved in HA initial cell attachment, as their blockade leads to diminished cell attachment to this biomaterial. So maybe, there are a variety of mechanisms that cooperate in the process, and that need to be further characterized and clarified in detail.
If anybody have any scientific work in which the interaction between cells of the osteogenic linegae with hydroxyapatite is characterized to the cell surface adhesion receptors level, I'll be happy to hear from it.
- Badges
- Science method
- Similar topics
- Mathematics
- Statistics
- Statistical Techniques
- Structural Equation Modeling