Isolation of Hymenolepis diminuta cysticercoids for therapeutic use: The need for fully disclosed methodology

Background Helminth therapy holds considerable theoretical promise for clinical and public health applications. Unfortunately, clinical trials have often used helminths produced using methods that are both highly variable and insufficiently described in the literature, which may hinder reproducibility and troubleshooting. This study aimed to devise a method for purification of helminths that avoids mechanical filtration, which may damage some organisms. In particular, the goal was to devise a method to separate large quantities of cysticercoids of the cestode species Hymenolepis diminuta (HDCs), a process that has not been described previously but that would be necessary before HDCs can be used clinically. Methods The physical size and behavior of HDCs in solution were assessed and used to create a patented washing device. Results The cross-sectional area of HDCs varied over a 10-fold range, from approximately 0.06 to 0.6 mm 2 , dependent in large part upon the host. That cross-sectional area correlated in a linear fashion with the steady-state speed of HDCs while falling through solution, which varied over a 5-fold range, from approximately 0.4 mm/s to 2.0 mm/s in the solution tested. These parameters were used to develop a washing device that utilized a variable flow speed dictated by changing column diameter and an upward flowing column of liquid that effectively and simultaneously suspended HDCs of various sizes in a wash solution. Conclusions This study describes a detailed method of purification of HDCs, organisms that could potentially be used for helminth therapy. It is hoped that government agencies or non-profit organizations can use such technology to conduct rigorous clinical trials, potentially leading to the production of reasonably priced therapeutics.