Hematopoietic stem cells in the blood vessels differentiate into osteoclasts on the bone tissue. We hypothesized that the differentiation from hematopoietic stem cells to osteoclasts is affected by the substrate elastic modulus. The purpose of this study is demonstration of this hypothesis by evaluating the effect of the substrate elastic modulus on the differentiation from hematopoietic stem cells to osteoclasts. Hematopoietic stem cells were cultured and differentiated on substrates with different elastic modulus using M-CSF and RANKL. We prepared collagen gel substrates with different elastic modulus by changing cross-linking agent concentration and collagen concentration. The differentiation from hematopoietic stem cells to osteoclasts was checked by using observation of cellular morphology and TRAP staining. As a result, number of osteoclasts differentiated from hematopoietic stem cells on the hard substrate was more than 10 times of that on the soft substrate. This suggests that mechanosensing of substrate elastic modulus is one of the keys of the differentiation from hematopoietic stem cells to osteoclasts.
