Risk of thromboembolism after intraosseous implantation of metallic devices with extracellular vesicles derived from multipotent stromal cells: preliminary results

Background. New implantation methods are of great importance due to the development of endoprostheses in traumatology and orthopedics, restorative medicine and dentistry. Equally important is the early detection and description of the implant-associated complications.

The aim of the study is to find and describe thrombi and emboli in the heart and lungs formed after experimental implantation of metallic devices in the peripheral part of limb using extracellular vesicles of mesenchymal stromal cells.

Methods. Outbred rabbits of both genders at the age from 4 to 6 months and of weight from 3 to 4 kg underwent experimental implantation. The study enrolled 57 species in total. They were divided into two groups: 30 animals underwent implantation of metallic devices using extracellular vesicles of mesenchymal stromal cells (EV MSCs), 27 — without their use. The rabbits’ hearts and lungs were studied by light microscopy methods at different stages after integration of screw titanium implants into the proximal condyle of the tibia using EV MSCs.

Results. After implantation of metallic devices into the proximal condyle of the tibia, we detected fibrin, detritus and even the red bone marrow structures (various blast forms of hematopoietic cells: megakaryocytes, cells of the erythroid and myeloid lineages) in the right cavities of the heart. In the pulmonary arteries, we also found thrombi and emboli, which either led to the obliteration of the involved vessel or to gradual lysis, not disappearing completely within 10 days of follow-up.

Conclusions. After intraosseous implantation of the metallic devices, there is an embolism risk in the right atria and ventricle of the heart and the pulmonary arteries and veins due to the debris migration with the bloodstream from the surgery site. At the same time, one cannot exclude a thrombotic risk in the heart and pulmonary arteries as a reaction to the presence of detritus. It is advisable to take measures aimed at preventing both debris releasing into the bloodstream and pulmonary embolism during any implantations into the bone tissues, even of relatively small devices. Using EV MSCs to affect the implant engraftment processes has no significant effect on the severity and frequency of thromboembolic complications.