Detailed observations of microstructures in tissues and cells provide insights into the origins of tissues and cellular activities. In 2010, Chikara Sato of Advanced Industrial Science and Technology and scientists of the Japan Electron Optics Laboratory developed Atmospheric Scanning Electron Microscopy (ASEM), an inverted SEM that can observe tissues and cells in an aqueous solution. Using this unique microscope, Sato and I observed the endochondral ossification process, angiogenesis in the joints, and calcification of the trabecular bone. In addition, we successfully stained osteoclasts with an antibody against cathepsin K by immunogold staining. Calcification was detected as a bright signal by calcium phosphate (CaP) mineralization in primary cultures of calvaria-derived osteoblasts on ASEM dishes. In revision arthroplasty, autogenous bone grafts or bone substitute procedures are used to induce bone regeneration. By monitoring CaP crystal growth associated with osteoinductive materials in an ASEM dish, the ASEM technology could contribute to the development of ideal materials for artificial bone. In cultured autologous chondrocyte implantation, a small amount of a patient’s normal cartilage cells is collected, and the cartilage cells are mixed with atelocollagen, and further cultured outside the body to form cartilage tissue. In such clinical treatments, rapid, high-throughput ASEM imaging at EM resolution may prove to be a powerful tool for understanding the detailed mechanisms of hard tissues.

Eiko Sakai awarded Ph.D. degree at the age of 30 years from Nagasaki University, Japan. She is an Assistant professor in Dental Pharmacology at the Nagasaki University Graduate School of Biomedical Sciences, Japan. Her main interests are oxidative stress and osteoclast differentiation. She uses cell biology, molecular biology, molecular pharmacology techniques, and microstructural observations. She has over 80 publications that have been cited over 2,000 times.