title: Assessment of PAXgene Fixation on Preservation of Morphology and Nucleic Acids in Microdissected Retina Tissue.
abstract: To compare the effect of the two fixatives on tissue morphology and utility to obtain good quality nucleic acids for molecular analysis from micro-dissected retinal samples.
  
  
  
  Enucleated specimens from New Zealand white rabbits were fixed in formalin or PAXgene fixative according to standard protocols, and then processed and embedded in paraffin for sectioning. Sections were stained with hematoxylin and eosin to assess the structural integrity of retina. Retinal tissue on slides was micro-dissected. DNA/RNA were extracted and assessed for preservation of the quality and quantity of the retinal tissue.
  
  
  
  The retinal morphology was well preserved with both PAXgene and formalin fixation. The RNA yield obtained using both fixation methods was similar, but RNA from PAXgene fixed paraffin embedded (PFPE) samples had better purity than that from formalin fixed paraffin embedded (FFPE) samples. There was a twofold greater yield of DNA in PFPE compared to FFPE samples but with similar purity. Quantitative reverse transcription PCR analyses showed that the mean cycle threshold values for beta-actin, beta-microglobin, Opsin 1-sw, Rhodopsin, and 18S RNA of the PFPE group were significantly lower than those of the FFPE group (p < 0.01). Greater than 10-fold greater levels of gene expression were detected in PFPE relative to FFPE for the above genes.
  
  
  
  PAXgene fixed tissue retinal morphology is comparable to FFPE tissue. PAXgene may be a good alternative to formalin, providing good tissue morphology and ability to isolate high quality nucleic acids from micro-dissected paraffin embedded retinal samples.
authors.affiliation: a Wilmer Eye institute, Johns Hopkins University School of Medicine , Baltimore , Maryland , USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.affiliation: a Wilmer Eye institute, Johns Hopkins University School of Medicine , Baltimore , Maryland , USA.|b King Khaled Eye Specialist Hospital , Riyadh , Saudi Arabia.
authors.forename: Deepak P
authors.initials: DP
authors.lastname: Edward
mesh_terms: D000818:Animals; D005136:Eye Proteins / Q000235:genetics*; D005404:Fixatives / Q000494:pharmacology; D005557:Formaldehyde / Q000494:pharmacology; D015870:Gene Expression; D042282:Microdissection; D009696:Nucleic Acids / Q000378:metabolism*; D051761:Paired Box Transcription Factors / Q000235:genetics*; D016612:Paraffin Embedding; D051419:Paxillin; D011817:Rabbits; D060888:Real-Time Polymerase Chain Reaction; D012160:Retina / Q000166:cytology* / Q000378:metabolism; D016707:Tissue Fixation / Q000379:methods*; D014021:Tissue Preservation
chemical_list: D005136:Eye Proteins; D005404:Fixatives; D009696:Nucleic Acids; D051761:Paired Box Transcription Factors; D051419:Paxillin; D005557:Formaldehyde
keywords: Fixation; microdissection; nucleic acids; quantitative RT PCR; retina