Clearing of hemozoin crystals in malaria parasites enables whole cell STED microscopy

Malaria is a devastating mosquito-borne parasitic disease that manifests when Plasmodium parasites replicate within red blood cells. During the development within the red cell, the parasite digests hemoglobin and crystalizes the otherwise toxic heme. The resulting hemozoin crystals limit imaging by STED nanoscopy due to their high light-absorbing capacity which leads to immediate cell destruction upon contact with the laser. Here we establish CUBIC-P based clearing of hemozoin crystals enabling whole-cell STED nanoscopy of parasites within red blood cells. Hemozoin-cleared infected red blood cells could reliably be stained with antibodies and hence proteins in the hemozoin-containing digestive vacuole membrane as well as in secretory vesicles of gametocytes could be imaged at high resolution. Thus, providing a valuable tool to study and understand parasite biology and potential molecular mechanisms mediating drug resistance.