Regulation of mesenchymal stem cell osteogenic potential via microfluidic manipulation of microcarrier surface curvature

Microsphere-carriers have gained great interests as three-dimensional substrates for cultivation/expansion of tissue cells, required by cell-based therapy. However, how the microsphere curvature affects the cell proliferation/differentiation as well as the underlying signaling pathway of stem cells, and how to consequently regulate those cellular functionalities via manipulating microcarrier surface curvature, still remain to be explored. The current study was thus designed to develop a microfluidic manipulation technology to precisely control poly (lactic-co-glycolic) acid (PLGA) microsphere surface curvature, and subsequently to investigate the cellular responses and responding pathways of rat bone mesenchymal stem cells (BMSCs) cultured on these microspheres of predetermined curvature. A microfluidic device was developed to produce mono-distributed PLGA microspheres of diameters ranging from 52 µm to 250 µm, corresponding to curvatures (κ) from 1/26 µm−1 to 1/125 µm−1. BMSCs attachment and proliferation was evaluated on them and the one of κ = 1/82.5 µm−1 was shown to provide the most suitable microenvironment for cells to grow and undergo osteogenic differentiation. It was even found that F-actin cytoskeletal organization, nuclear distortion and expression of Lamin A were significantly enhanced by cells on the microcarriers of κ = 1/82.5 µm−1. Furthermore, a long non-coding RNA named lnc-LMNA, was found in this study to be the key factor associated with Lamin A to regulate osteogenic differentiation of BMSCs on spherical substrates. The current study thus provides a smart manipulation technology via microfluidic-manufacturing microcarriers to regulate cell functionalities, thereby enhancing desired therapeutic outcomes of cell-based regeneration or repair.