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Introduction
The articular cartilage plays an important role
in load transmission and decreasing joint
friction on articular joints including the knee.
Damage or degeneration of this tissue
potentially gives rise to several clinical
symptoms such as pain and eventually develops
osteoarthritis [1]. Nonetheless, it is widely
accepted that chondral injury does not usually
heal spontaneously due to its avascular
surroundings and unique matrix organization.
Therefore, a variety of approaches have been
tested to improve cartilage healing [1, 2].
Among them, chondrocyte-based therapies
have been focused in terms of their feasibility
to such incurable lesions.
Brittberg
et al.
[3] for the first time described
the successful repair of femoral condyle defects
of the knee using implantation of autologous
cultured chondrocytes. Hereafter, a number of
studies followed this procedure and suggested
that autologous cartilage implantation (ACI) is
an effective procedure for cartilage defects of
the knee (See this review). This procedure,
however, may have limitations including the
sacrifice of undamaged cartilage within the
same joint and the in vitro expansion of the
cells. Due to the degenerative change in
cartilage with aging, the availability of the cells
may be limited in elderly individuals [4].
To overcome such potential problems, stem
cell therapy has been tested in regenerative
tissue repair. Mesenchymal stem cells (MSCs)
have the capability to differentiate into a variety
of connective tissue cells including bone,
cartilage, tendon, muscle, and adipose tissue
[5]. These cells may be isolated from various
tissues such as bone marrow, skeletal muscle,
synovial membrane, adipose tissue, and
umbilical cord blood. Although stem cells have
potential feasibility to restore articular surface,
there are several issues especially associated
with safety concerns in clinical application and
therefore, as compared with chondrocyte-based
therapies, the number of stem cell-based
therapies are limited. The purpose of this study
was to assess the effectiveness and safety of
cell-based therapy, including chondrocyte-
based and stem cell-based therapies to clinically
significant, symptomatic defects of the knee.
Methods
Selection of Studies and Data
Evaluation
We searched the MEDLINE (1994 to April
2011) to identify all English-language studies
evaluating the effect of cell-based therapies for
Cell-based therapy in
articular cartilage lesions
of the knee
N. Nakamura, H. Yoshikawa, K. Shino