Histologic demonstration of glycosaminoglycans in inner ear fluids

A method for MS(E) differential proteomic analysis of archival formalin-fixed celloidin-embedded human inner ear tissue

Proteomic analysis of cadaveric formalin-fixed, celloidin-embedded (FFCE) temporal bone tissue has the potential to provide new insights into inner ear disorders. We have developed a liquid chromatography-mass spectrometry (LC-MS) method for tissue sections embedded with celloidin. Q-TOF (Quadrupole-time of flight mass spectrometry) MS(E) (mass spectrometry where E represents collision energy) and Identity(E)™ were used in conjunction with nano-UPLC (capillary ultrahigh pressure liquid chromatography) for robust identification and quantification of a large number of proteins. Formalin-fixed paraffin-embedded (FFPE) mouse liver sections were used to evaluate formalin de-cross-linking by five different methods. Unfixed fresh mouse liver tissue was used as a control. Five different methods for preparation of FFPE tissue for MS analysis were compared, as well as four methods for celloidin removal with FFCE mouse liver tissue. The methods judged best were applied to FFCE 20 μm sections of mouse inner ear samples, and FFCE 20 μm human inner ear and human otic capsule bone sections. Three of the five-tissue extraction methods worked equally in detecting peptides and proteins from FFPE mouse liver tissue. The modified Liquid Tissue kit protocol was chosen for further studies. Four different celloidin removal methods were compared and the acetone removal method was chosen for further analysis. These two methods were applied to the analysis of FFCE inner ear and otic capsule sections. Proteins from all major cellular components were detected in the FFCE archival human temporal bone sections. This newly developed technique enables the use of FFCE tissues for proteomic studies.

Techniques of celloidin removal from temporal bone sections

OBJECTIVES

We sought to determine whether the technique of celloidin removal influences the results of immunostaining in celloidin-embedded cochleae.

METHODS

We compared four protocols of celloidin removal, including those using clove oil, acetone, ether-alcohol, and methanol saturated with sodium hydroxide. By optimally fixing our tissue (perfused mice), and keeping constant the fixative type (formalin plus acetic acid), fixation time (25 hours), and decalcification time (ethylenediaminetetraacetic acid for 7 days), we determined whether the technique of celloidin removal influenced the immunostaining results. Six antibodies were used with each removal method: prostaglandin D synthase, sodium, potassium adenosine triphosphatase (Na+,K(+)-ATPase), aquaporin 1, connective tissue growth factor, tubulin, and 200 kd neurofilament.

RESULTS

Clove oil, acetone, and ether-alcohol resulted in incomplete removal of the celloidin, thereby negatively affecting the results of immunostaining. The methanol-sodium hydroxide method was effective in completely removing the celloidin; it produced the cleanest and most reproducible immunostaining for all six antibodies.

CONCLUSIONS

Freshly prepared methanol saturated with sodium hydroxide and diluted 1:2 with methanol was the best solvent for removing celloidin from mouse temporal bone sections, resulting in consistent and reproducible immunostaining with the six antibodies tested.

Molecular cloning, genomic organization and developmental expression of the Xenopus laevis hyaluronan synthase 3

The content of hyaluronan (HA), a polymer of the extracellular matrix involved in a variety of physiological and pathological processes, depends on the activity of synthetic (HAS) and degrading enzymes. Since HA is also involved in embryogenesis, we have used Xenopus as a model organism because information is available for HAS1 and HAS2, but not for HAS3. We report the sequence of xlHAS3 mRNA, its genomic organization and its expression in adult tissues as well as during embryonic development. Interestingly, evidence from in situ hybridization indicates that xlHAS3 expression is restricted to the developing inner ear and cement gland. In addition, we have correlated the expression pattern of the enzymes involved in HA metabolism with the HA content during development.