Conclusions
We can, therefore, suggest a well-controlled standardized protocol for toluidine blue staining, which provides an easy and simple selective staining technique for the assessment of cartilage tissue and proteoglycan development in chondrogenic differentiation. If this procedure is not used, then investigators must provide sufficient technical information concerning the staining protocol to allow an assessment of the validity of the staining results.
Results
In the present study, we illustrate why such an assumption is invalid unless a detailed description of the procedure and/or reference to a detailed published method are provided. This is because the staining specificity and intensity depend, as we have shown, on the pH of the staining solution, the use of dehydration, and on staining time. Conclusions: We can, therefore, suggest a well-controlled standardized protocol for toluidine blue staining, which provides an easy and simple selective staining technique for the assessment of cartilage tissue and proteoglycan development in chondrogenic differentiation. If this procedure is not used, then investigators must provide sufficient technical information concerning the staining protocol to allow an assessment of the validity of the staining results.