There are various types of polysaccharides used in regenerative medicine, and due to space limitations, a detailed list cannot be provided here, so please refer to reviews in references [1–3]. In particular, cellulose, chitin, chitosan, alginate, hyaluronic acid, etc. are produced, distributed, and used in relatively large quantities as bulk materials. These materials are processed into various shapes such as fibers (diameter: nm to mm), hydrogels, porous sponges, thin films, devices with uneven surfaces, etc. and are used as biomaterials for medical devices and scaffolds for tissue engineering. Besides cellulose and chitin, they have little mechanical strength, so they are often reinforced with physical cross-linking with non-covalent bonds or chemical cross-linking with covalent bonds. In addition to the above, many glycosaminoglycans (GAGs) containing various molecular species have various physiological activities such as cell adhesion and immune activation. However, few GAGs are cheaply mass-produced, except for heparin, which has antithrombotic properties and a relatively low molecular weight. This paper will discuss the use and challenges of polysaccharides, mainly focusing on hydrogels used for cell culture. The phrase “used in regenerative medicine” at the beginning includes not only implantable devices and scaffolding materials for cell transplantation therapy but also temporally and spatially controlled drug delivery systems (DDS), mass culture of cells, induction of differentiation from stem cells, and the production of test devices such as chip substrates and microchannels, in a somewhat broader sense.