Biology Reference
In-Depth Information
26
Tissue Engineering of Cartilage
Ronda E. Schreiber and Anthony Ratcliffe
1. Introduction
Cartilage is a dense connective tissue that functions to withstand and dis-
tribute load (1) . Articular cartilage lines the ends of long bones and distributes
loads across the joints. It consists of a dense collagenous matrix (primarily
collagen type II, with smaller amounts of other collagens, including types I, V,
VI, IX, and XI), embedded in a high concentration of aggregating proteoglycan,
aggrecan. The collagen provides tensile properties, and the proteoglycans con-
fer compressive properties and resiliency. There is a sparse population of a
single cell type, the chondrocyte, distributed throughout the tissue. These cells
synthesize and maintain the cartilaginous matrix in a regulated fashion that
involves breakdown of matrix components, release of proteolytic products from
the tissue, and synthesis and incorporation of new components into the matrix.
Articular cartilage has a limited capacity to repair. Degeneration of this
tissue in diarthrodial joints is a major component of osteoarthritis and related
diseases. The options for treatment are limited, and many patients may be con-
signed to pain and joint dysfunction until joint replacement is a reasonable
treatment option. A major motivation for tissue engineering cartilage is to pro-
vide a biological repair for cartilage degeneration.
One particularly promising method for cartilage tissue engineering is the
growth of tissue by in vitro culture of chondrocytes after seeding them onto
bioresorbable scaffolds (2 , 3) . After seeding, there is a period of cell prolifera-
tion, followed by matrix deposition. This growth phase has been achieved using
a variety of methods, including implantation of the seeded scaffold subcutane-
ously in nude mice (2) , extended tissue culture (4) , and culture in perfusion
chambers (5-7) . A variety of biodegradable scaffolds have been used, includ-
ing poly (glycolic acid) and poly ( L -lactic acid) polymers fabricated as non-
Search WWH ::




Custom Search