Degradation of eschar from venous leg ulcers using a recombinant chymotrypsin from Lucilia sericata.

BACKGROUND: Larvae of the greenbottle Lucilia sericata are used to debride nonhealing wounds and stimulate the production of fresh granulation tissue. Previous publications have shown that secretions from L. sericata contain a number of proteolytic activities including a chymotrypsin that degrades a number of extracellular matrix components such as fibronectin, laminin and collagen.
OBJECTIVES: To produce a recombinant L. sericata chymotrypsin (chymotrypsin I) and determine its effects on the degradation of patient wound eschar.
METHODS: An active recombinant chymotrypsin I from L. sericata was cloned and expressed in Sf9 cells and its subsequent effects ex vivo on eschar from venous leg ulcers were determined by two-dimensional electrophoresis.
RESULTS: The recombinant enzyme had the attributes of a chymotrypsin, possessing sequence homology with other chymotrypsins and demonstrating attributes of the native enzyme including cleavage of the chymotrypsin substrate succinyl-alanyl-alanyl-prolyl-phenylalanyl-7-amino-4-methyl coumarin, inhibition by phenylmethylsulphonyl fluoride and lack of inhibition by amidinophenylmethylsulphonyl fluoride. Importantly, the recombinant chymotrypsin cleaved the majority of proteins from slough/eschar from venous leg ulcers in a superior manner to chymotrypsins from human and bovine sources.
CONCLUSIONS: The ex vivo degradation of eschar from venous leg ulcers indicates the potential value of recombinant chymotrypsin I as a novel, stand-alone debridement agent.