Method for inducing regeneration of cartilage

#The present invention relates to a bone filler useful in cartilage tissue regeneration treatment in a joint tissue.

#A joint tissue, such as knee joint or shoulder joint tissue in particular, is covered with a cartilage tissue at the top of bones which are linked by a joint so as to prevent direct friction therebetween. Damage of the cartilage tissue due to aging, enormous or repeated loads thereon will cause inflammation in a joint, resulting in arthralgia on a patient. In fact, damaged joint cartilage tissue and arthralgia are highly frequently found in both young and aged patients. In order to improve their quality of life (QOL) and even provide more effective treatment in view of medical economics, development of effective and efficient joint treatment method is increasingly required.

#In the treatment of damaged cartilage tissue, the most major problem is to find out a method for regenerating such a cartilage tissue, which is difficult to naturally regenerate in vivo by drug administration, etc. For example, microfracture method that generates numerous microholes on a subchondral bone forms a fibrocartilage, but no hyaline cartilage as a normal articular cartilage is regenerated. Consequently, a damaged cartilage tissue is normally treated by transplanting an in vivo cartilage tissue.

#The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

#The above and other objects of this invention will be seen by reference to the description taken in connection with the drawings, in which:

#FIG. 1 is a schematic view indicative of “interpenetrating network structure” (double-network type) of this invention. A denotes a crosslinked network polymer, B denotes another crosslinked network polymer, and numerals 1 and 2 denote crosslink points of crosslinked network polymers A and B, respectively. This figure is a conceptual diagram of a gel containing a solvent (water) in a network structure;

#A bone filler of this invention comprises hydrogel having an interpenetrating network structure formed by two or more polymers having a crosslinked network structure (polymer having a crosslinked network structure is hereinafter called crosslinked network polymer) or a semi-interpenetrating network structure formed by a crosslinked network polymer and a linear polymer. The crosslinked network structure of this invention, as shown in e.g., FIG. 1 of WO2006/013612 (shown as FIG. 1 in this specification), is a network structure formed by polymers having a plurality of crosslink points. Likewise, “interpenetrating network structure” of this invention means that two or more crosslinked network polymers are intertwined so as to interpenetrate in network structures with each other, resulting in a formation or state that internally includes a plurality of network structures. As shown in FIG. 1, the “interpenetrating network structure” is composed of a crosslinked network polymers A having a plurality of crosslink points 1 and a crosslinked network polymer B having a plurality of crosslink points 2, thereby presenting a formation or state in which both crosslinked network polymers A and B interpenetrate in network structures with each other and are physically intertwined.

#“Semi-interpenetrating network structure” of this invention means that a linear polymer is intertwined in a crosslinked network polymer so as to interpenetrate therein, resulting in a formation or state of hydrogel that internally includes a plurality of network structures. As shown in e.g., FIG. 2 of WO2006/013612 (shown as FIG. 2 in this specification), the “semi-interpenetrating network structure” comprises a crosslinked network polymer C having a plurality of crosslink points 3 and a linear polymer D, thereby presenting a formation or state of hydrogel in which the linear polymer D interpenetrates in the crosslinked network polymer C and they are physically intertwined.

#A hydrogel having “interpenetrating network structure” of this invention may include the above semi-interpenetrating network structure in which a linear polymer is partially intertwined, and “semi-interpenetrating network structure” of this invention may include “interpenetrating network structure” in which another crosslinked network polymer is partially intertwined. Specifically, one hydrogel may concurrently have an interpenetrating network structure and a semi-interpenetrating network structure.