Table 1.

Questions on the biology and epigenetics of chondrocytes

1. What is the epigenetic relationship between chondrocytes and other differentiated cells and amongst chondrocytes from different cartilaginous tissues?

2. To what degree does a chondrocyte have a range of responses to local physical, mechanical, chemical signals that determine its phenotype, or do changes in its phenotype involve epigenetic switches between different differentiation states?

3. What are the epigenetic changes that accompany chondrocyte de-differentiation and are they reversible without gene transfer?

4. How far is the differentiation pathway to articular chondrocytes and to epiphyseal chondrocytes, separate and epigenetically distinct, or similar and interconvertible?

5. How similar and interconvertible are chondrocytes from hyaline cartilages (articular, nasal) and how less similar and less interconvertible are chondrocytes from meniscus cells, nucleus/annulus pulposus cells and from tendon and ligament cells?