Investigation of tissue organelles by a combination of analytical subcellular fractionation and enzymic microanalysis: a new approach to pathology.

Classical approaches to the study of pathological tissue have relied mainly on morphological techniques. In an attempt to quantitate the abnormalities and to investigate the pathogenesis of tissue disorders at a subcellular level we have combined analytical subcellular fractionation by sucrose density gradient centrifugation with microanalysis of tissue enzymic activities. The methodological problems of performing these studies on milligram quantities of tissue are discussed. Details of the appropriate equipment are provided, and its application to the study of human liver specimens is described. As an example of this approach, biochemical and subcellular fractionation experiments on tissue from patients with both primary and secondary hepatic lysosomal storage diseases are discussed. Examination of the lysosomal changes reveals that increased enzyme activity is a common finding in these disorders but tissue damage occurs only when there is evidence of enhances lysosomal fragility with intracellular release of degradative enzymes. Other tissues which have proved amenable to study in this manner and in which profitable results in the investigation of their disorders have been obtained are listed.