In the field of regenerative medicine, technology for controlling stem cell functions such as differentiation and proliferation is vital. It has been reported that nanosized gold particles promote the differentiation of human mesenchymal stem cells into osteoblasts.
Mesenchymal stem cells, or MSCs, are stromal cells which can differentiate into a variety of cell types, including osteoblasts, chondrocytes (cartilage cells), myocytes (muscle cells) and adipocytes. This phenomenon has been documented in specific cells and tissues in living animals and their counterparts growing in tissue culture.
Furthermore, other studies have suggested that various functional groups such as carboxyl, amino, and hydroxyl groups can promote or inhibit stem cell differentiation.
Based on these reports, the MANA researchers theorized that gold nanoparticles with surface modified with functional groups are a promising candidate to control stem cell functions. But the specific effects of such particles on the differentiation of human mesenchymal stem cells were unknown.
Then then identified how they affect the osteogenic differentiation of mesenchymal stem cells that were derived from human bone marrow.
Among these three types of nanoparticles, those with the carboxyl groups were absorbed by cells and exhibited a strong bone differentiation-inhibitory effect compared to the other types of nanoparticles.
The researchers also investigated the effect of gold nanoparticles with carboxyl groups on the gene expression profile of mesenchymal stem cell from human bone marrow. Results indicated that the nanoparticles inhibited several gene expressions related to osteogenic differentiation.
The influence of the gold nanoparticles on promoting or inhibiting osteogenic differentiation varied depending on the types of functional groups. These findings will contribute to the ongoing effort in the creation of novel nanomaterials to facilitate the advancement of stem cell manipulation.
Photo: Human mesenchymal stem cells (hMSCs) resulted from the following steps: each type of gold nanoparticles was added to hMSCs, and the treated cells were cultured for 3 weeks. The cells received either alkaline phosphatase (ALP) staining or alizarin red staining (ARS) of calcium phosphate deposits, both of which are osteogenic differentiation indicators. Control experiments with unmodified gold nanoparticles and untreated hMSCs were also carried out for comparison. In the upper images, ALP positive cells were stained purple while agglomerates of gold nanoparticles were detected as blue dots. In the lower images, spider-web-like red stains represent calcium phosphate deposits while bluish purple dots indicate agglomerates of gold nanoparticles. All scale bars are 500 μm. Credit: MANA, NIMS