IMPROVED ASSESSMENT OF ISOLATED ISLET TISSUE VOLUME USING DIGITAL IMAGE-ANALYSIS

Accurate and consistent measurement of tissue volume is critical to pe rforming many types of islet research; however, conventional visual de termination of isolated islet yields through a microscope is heavily o perator dependent. An improved method of islet volume determination us ing digital image analysis (DIA) was developed to remove operator bias and automate the islet counting process. A series of 140 porcine isle t isolations were used to evaluate the DIA method in three separate st ages. In Stage 1 tit = 29 isolations), the conventional and DIA method s were correlated with two other independent islet quantitation method s: insulin extraction, and DNA extraction. It was found that volumes d etermined by DIA correlated more closely with insulin content and DNA content than did conventionally determined volumes. In Stages 2 and 3 (n = 54 and 57 isolations, respectively), it was shown that an increas e in the number of fields analyzed by DIA did not significantly improv e the quality of the correlations. Inclusion of very small tissue (<50 pm in diameter), which is ignored in the conventional protocol affect ed yields by less than 10% and did not significantly improve the corre lation with insulin or DNA content, Quantitation of isolated islet tis sue volume using DIA has been shown to be rapid, consistent, and objec tive. In the laboratory, use of this method as the standard for islet volume measurement will allow more meaningful comparison of experiment al results between centers. In the clinic, its use will allow more acc urate dosing of transplanted tissue. (C) 1998 Elsevier Science Inc.