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UTHSC Researchers Test New, Safer Fixative for Tissue Samples

Sheila Criswell, PhD
Chelsea Peeler, MCP

Faculty and student researchers from the Department of Diagnostic and Health Sciences in the University of Tennessee Health Science Center’s College of Health Professions are researching safer alternatives to current methods of performing a laboratory process critical in the preservation, analysis and diagnosis of tissue samples. Their findings were recently published in the peer-reviewed Journal of Histotechnology. The paper investigates the use of glyoxal as a safer alternative to the commonly used fixative, formalin, in the fixation process for tissue samples sent to pathology laboratories.

Tissues surgically removed from patients are usually sent to a pathology laboratory for examination by a pathologist. Before the specimens can evaluated, the tissues must undergo a series of steps including fixation, processing, embedding, microtomy, and staining. Fixation is one of the most important steps of tissue preparation, because it stops destructive enzymatic and bacterial actions on tissues.

Currently, the commonly used fixative is a 10% neutral buffered formalin. While formalin is an excellent tissue preservative, it is considered a carcinogen and it cannot be used without a fume hood or grossing station.

“Our students and instructors have worked on three projects to investigate the use of glyoxal as an alternate fixative that is much safer than formalin. Glyoxal does not require special ventilation or air filtration to ensure the safety of laboratory personnel,” said UTHSC Medical Laboratory Science (MLS) and Histotechnology Instructor Sheila Criswell, PhD.

Previous studies at other institutions have shown that glyoxal is an effective fixative and glyoxal-fixed tissues produce results comparable to that of formalin-fixed tissues for most specimens. However, using glyoxal fixed tissue samples for more specialized immunohistochemistry tests, such as those used to help classify types of cancers, has been a challenge, because these tests require many well-timed steps with specific reagents to produce correct results.

Investigations performed by UTHSC College of Health Professions faculty and students examined how immunohistochemistry tests work with tissues fixed in glyoxal as compared to tissues fixed in formalin. “The results were very encouraging,” said Dr. Criswell.

Most of the immunohistochemistry results using tissues fixed in glyoxal were comparable to or of only slightly less quality to those of formalin. For those antibody-antigen interactions that produced inferior results in glyoxal-fixed tissues, the researchers believe that minor modifications in the test protocols may produce acceptable results. Standardizing immunohistochemistry tests with glyoxal fixation would remove the last barrier to replacing formalin in the histology lab.

“This type of research has significant implications in that it examines safer alternatives to using a toxic and carcinogenic solution called formalin in the process of determining treatment options for patients with cancer,” said co-investigator and COHP cytology instructor Chelsea Peeler, MCP.

Sheila Criswell, PhD, and Chelsea Peeler, MCP, were the UTHSC faculty participating in this research. Cynthia Lazar, MT, HT (ASCP), director of Pathology Services at Methodist Le Bonheur Healthcare, was a co-investigator on the project. UTHSC students Savanah Altman, Taylor Drake, Samantha Douglas and Victoria DeJarnatt also participated in the investigation.