This review provides an overview of a novel intracellular substance delivery technique that leverages the concentration effect occurring during freezing (freeze-concentration). Our previous studies have reported on the effectiveness of polymeric cryoprotectants. In this technique, when a cell suspension is frozen in the presence of such polymeric cryoprotectants, solutes expelled from the forming ice crystals become concentrated in the residual unfrozen water surrounding the cells. As a result, the target substances are enriched in the immediate vicinity of the cells.

Furthermore, by encapsulating the target substances (e.g., proteins, genes) in carriers with high affinity for the cell membrane, these carriers remain localized on the cell membrane upon thawing. It was confirmed that cells spontaneously internalize the delivered substances via endocytosis. This method represents an innovative delivery technology that enables the efficient intracellular transport of target substances simply through the freezing and thawing process.

Since its first application in humans in 1979, natural coral exoskeletons have been used clinically as bone substitutes. Natural coral (Porites digitata) was chosen because it has a structure similar to cancellous bone and has similar initial mechanical properties after implantation. Coral exoskeletons are composed of aragonite, a type of calcium carbonate crystal, and are characterized by their porous nature. In vitro and in vivo experiments have revealed the biocompatibility, osteoconductivity, and bioresorbability of coral exoskeletons. It has been reported that natural coral exoskeletons are excellent bone substitutes because they function as a suitable carrier for growth factors, allowing cell attachment, growth, diffusion, and differentiation. This paper reviews research related to bone substitutes derived from the exoskeleton of Montipora digitata, a species of coral that has been artificially cultivated as a replacement for natural corals, whose survival is of concern due to environmental destruction issues.

The excellent tissue regeneration ability of the planarian flatworm has attracted attention from the perspective of regenerative medicine and dentistry. Dugesia japonica is the model organism and has pluripotent stem cells throughout its body. When physically damaged it regenerates its body, which has anterior-posterior polarity and dorso-ventral polarity including the brain, nervous system, digestive system, etc. The Wnt signaling pathway is deeply involved in the polarity of the anterior-posterior and dorsal-ventral axes. Activation of the Wnt signaling pathway promotes tail regeneration, whereas inactivation promotes head regeneration. Several regulatory factors involved in this process are also known. The Wnt gene family are highly conserved across multicellular animals including cnidarians, arthropods and chordates. Whether or not a tissue has advanced regenerative abilities is depend on how the expression of these genes is regulated. This will have various implications for the future prospects of regenerative dentistry.

Smoking rates are declining worldwide and are also declining in Japan. However, new forms of tobacco are becoming more widespread, and smoking rates are accompanied by unseen risks. Smoking has a wide range of effects on the body and is responsible for around 120 000 deaths, according to some reports. Appropriate medical intervention before death occurs and complete cure through regenerative medicine as a means of treatment will also account for an important proportion in the future. Before treatment, smoking cessation education is linked to self-care and patient awareness may determine whether future treatment is best. Progress in regenerative medicine using human ES and iPS cells is expected to further expand the range of treatments available. Although it remains state-of-the-art medicine, we as medical professionals have to fulfil our responsibility to raise awareness in the pre-treatment phase, and therefore we need to make efforts to ensure that knowledge is acquired in pre-graduate education at medical faculties and returned to many patients.

American science fiction novelist E.E. Smith is said to be the first writer to mention tooth regeneration in his works. In Grey Lensman published in 1939, regenerative medicine appears as the technology to repair various body parts including teeth. The injuries suffered in fierce battles as well as hair and teeth lost due to old age are recovered using regenerative medicine. This article introduces the author’s brief biography, his writings, the popularity of science fiction of the time, and the use of regenerative medicine (and regenerative dentistry) in the plot. E.E. Smith’s knowledge of contemporary regenerative medicine combined with his exceptional imagination produced this science fiction masterpiece.