Ask AI: Describe the mechanisms via which mesenchymal stem cells are proposed to promote vascularisation upon implantation in vivo

1. Cell-Cell Interactions: Mesenchymal stem cells stimulate the proliferation and migration of endothelial cells (ECs), which plays a key role in the process of vessel formation and vascularization. This is achieved through the release of several paracrine factors, such as VEGF, Angiopoietin-1, FGFs, TGFs, and EGFs. These factors not only stimulate ECs differentiation, but also promote angiogenesis by inducing the expression of adhesion molecules and extracellular matrix components. 2. Direct Angiogenic Activity: Mesenchymal stem cells can also directly promote vascularization by forming tube-like structures, which can facilitate the formation of blood vessels. 3. Immunomodulatory Activity: MSCs can also modulate the immune response and reduce inflammation. This helps to promote angiogenesis by reducing the inhibitory effect of certain cytokines, such as TNF-α, which can suppress the growth of new blood vessels. 4. Stromal Modulation: MSCs can also modulate the stromal components, such as extracellular matrix components and cell-cell adhesion molecules, to promote local tissue remodeling, which is important for the formation of new vessels.