Adult human articular cartilage harbors a population of CD166+ mesenchymal stem cell-like progenitors that become more numerous during osteoarthritis (OA).
Most cells isolated from the normal and OA patients were CD105(+) and CD166(+) positive (Normal subjects: CD105(+)/CD166(+), 94.6% ± 1.1%; OA: CD105(+)/CD166(+), 93.5% ± 1.1%).
There was a correlation between worsening of OA and increased TLR immunostaining in the superficial and middle cartilage zones, while chondrocytes assumed a CD166(×) progenitor phenotype.