A Novel Biomaterial for Cartilage Repair Generated by Self-Assembly: Creation of a Self-Organized Articular Cartilage-Like Tissue

摘要

Recently, attention has been drawn to tissue engineering and other novel techniques aimed at reconstruction of the joint. Regarding articular cartilage tissue engineering, three-dimensional materials created in vitro by cultivation of autologous chondrocytes or mesenchymal stem cells with a collagen gel have been implanted to replace defective parts of the articular cartilage in limited cases with the diseases such as trauma or arthritis. However, several passages of chondrocyte culture are required to obtain a sufficient number of cells for tissue engineering. Additionally, several other problems arise including dedifferentiation of chondrocytes during cell culture, which need to be solved from a viewpoint of cellular resources. The purpose of our study is to create a novel biomaterial possessing functions and structures comparable to native hyaline articular cartilage by utilizing the physicochemical properties of the cartilage matrix components themselves, in other words, employing a self-assembly technique instead of using chondrocytes to produce cartilage matrices eventually leading to articular cartilage tissue formation. We verified the conditions and accuracy of the self-organization process and analyzed the resulting micro structure using electron beam microscopy in order to study the technique involved in the self-organization which would be applicable to creation of cartilage-like tissue. We demonstrated that self-assembly of several cartilage components including type II collagen, proteoglycan and hyaluronic acid could construct self-assembled cartilage-like tissues characterized by nano composite structures comparable to human articular cartilage and by low friction coefficients as small as those of native cartilage.