It must, however, be guaranteed that no pathogenic agents from animals are transmitted to the human body. Researchers at the Paul-Ehrlich-Institut have now been able to prove that although porcine endogenous retroviruses (PERV) can penetrate human blood cells under certain circumstances, they cannot replicate at these sites.
TEM-Photo: Porcine endogenous retrovirus (PERV). Green: infected cell cytoplasma; pink: so-called clathrin-coated pit; yellow: virus particle; red: virus core; blue: genetic material of the virus
Source: Dr. Klaus Boller, Paul-Ehrlich-Institut
In connection with screening methods, the aim is to minimize the risk of transmission of PERV by the xenotransplant. The journal Xenotransplantation reports on the results of these research activities in its latest online edition.
Patients often have to face long waiting periods before they can receive an organ suitable for transplantation. This has not only been a problem since the transplantation scandal of last year. Pigs have been the subject of research as a possible organ donor for a long time. First clinical trials using insulin producing cells of the porcine pancreas in patients with type-1 diabetes are already underway in New Zealand and Argentina. Transplantations of whole animal organs such as porcine hearts or kidneys are also thinkable as a medium-term solution and are studied extensively. However, a transplantation of organs from other species to humans presents the risk that endogenous retroviruses, which form an integral part of the genome of the donor animals, will be transmitted in the form of replication-competent virus particles thus causing infections. Porcine endogenous retroviruses (PERV) present in pigs are closely related to retroviruses, which can cause leukaemia in mice, cats, or gibbons. It is therefore assumed that PERV can also cause such diseases after transmission to humans.
A research team of Professor Ralf R. Tönjes, head of the section "Non-vital Tissue Preparations, Xenogeneic Cell Therapeutics" of the Division "Medical Biotechnology" at the Paul-Ehrlich-Institut has investigated whether PERV can really infect human blood cells . Although the investigators at the PEI performed their experiments in vitro, they created conditions as close as possible to the situation of a xenotransplantation to study the real risk of a PERV infection. The porcine cells were co-cultured with human lymphocytes over a period of one month – the human cells and the animal cells were separated from each other only by a membrane permeable for viruses. The researchers established that the PERV could pass the membrane and penetrate the human lymphocytes to a lesser extent. The viral DNA was then identified in these lymphocytes. However, this DNA was not functional, i.e. the genetic information could not be used by the cells to produce new intact virus particles. Productive infection involving the development of new infectious PERV was indeed not observed.
Besides, before xenotransplantations, safety experts have expressed that they require a two-step analysis of the transplant for transmissible PERV involving genetic screening and an assay with a highly sensitive human cell line. This test must be able to show that no functional PERV is present.
"Being a federal institute responsible for the authorisation of clinical trials on xenogeneic cell therapeutics, we require steps from the manufacturers and users which keep the risk of transmission of pathogenic agents during xenotransplantations to a minimum. Our experiments, which use the best screening methods currently available, indicate that no infectivity to human blood cells by PERV causing a disease would occur during xenotransplantations", as Professor Tönjes explained when discussing the research results. Even if transmission of PERV occurred, human blood cells are equipped with cellular protective mechanisms against these viruses and would counteract them in the various phases of the replication cycle .
Professor Tönjes and his co-workers are part of the special research group (Sonderforschungsbereich, SFB /Transregio 127) "Biologie der xenogenen Zell- und Organtransplantation – vom Labor in die Klinik" (Biology of xenogeneic cell, tissue and organ transplantation – from bench to bedside) with 16 sub-groups in Berlin, Dresden, Hannover, Langen and München. This research group is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation).Original publication:
Xenotransplantation Jan 21 [Epub ahead of print]. DOI: 10.1111/xen.12081Literature:
 Denner J, Tönjes RR. Infection Barriers to Successful Xenotransplantation Focusing on Porcine Endogenous Retroviruses. Clinical Microbiology Reviews 2012;25(2):318-343
The Paul-Ehrlich-Institut, Federal Institute for Vaccines and Biomedicines, in Langen near Frankfurt/Main is a senior federal authority reporting to the Federal Ministry of Health (Bundesministerium für Gesundheit, BMG). It is responsible for the research, assessment, and marketing authorisation of biomedicines for human use and veterinary vaccines. Its remit also includes the authorisation of clinical trials and pharmacovigilance, i.e. recording and evaluation of potential adverse effects.
Other duties of the institute include official batch control, scientific advice and inspections. In-house experimental research in the field of biomedicines and life science form an indispensable basis for the varied and many tasks performed at the institute.
The Paul-Ehrlich-Institut, with its roughly 800 members of staff, also has advisory functions nationally (federal government, federal states (Länder)), and internationally (World Health Organisation, European Medicines Agency, European Commission, Council of Europe etc.).
http://onlinelibrary.wiley.com/doi/10.1111/xen.12081/abstract Original Publication, Abstracthttp://www.pei.de/EN/information/journalists-press/press-releases/2014/01-xenotransplantation-no-replication-porcine-endogenous-retroviruses.html
Press Release on the Paul-Ehrlich-Institut Website
Dr. Susanne Stöcker | idw
30.04.2015 | International School of Advanced Studies (SISSA)
Rare Dune Plants Thrive on Disturbance
30.04.2015 | Washington University in St. Louis
Scientists from Nepal, Switzerland and Germany was now able to show how erosion processes caused by the monsoon are mirrored in the sediment load of a river crossing the Himalaya.
In these days, it was again tragically demonstrated that the Himalayas are one of the most active geodynamic regions of the world. Landslides belong to the...
A world-class prime systems integrator and electronic systems provider known for its rapid, innovative, and agile technology solutions, Sierra Nevada Corporation (SNC) is currently developing a new space transportation system called the Dream Chaser.
The ultimate aim is to construct a multi-mission-capable space utility vehicle, while accelerating the overall development process for this critical capability...
Today, textiles are used for more than just clothes or bags – they are high tech materials for high-tech applications. High-tech textiles must fulfill a number of functions and meet many requirements. That is why the Fraunhofer Institute for Silicate Research ISC dedicated some major developing work to this most intriguing research area. The result can now be seen at Techtextil trade show in Frankfurt from 4 to 7 May. On display will be novel textile-integrated sensors, a unique multifunctional coating system for textiles and fibers, and textile processing of glass, carbon, and ceramics fibers to fiber preforms.
Thin materials and new kinds of sensors now make it possible to integrate silicone elastomer sensors in textiles. They are suitable for applications in medical...
KAIST researchers published an article on the development of a novel technique to precisely track the 3-D positions of optically-trapped particles having complicated geometry in high speed in the April 2015 issue of Optica.
Daejeon, Republic of Korea, April 23, 2015--Optical tweezers have been used as an invaluable tool for exerting micro-scale force on microscopic particles and...
A very small and rare species of shark is swimming its way through scientific literature. But don't worry, the chances of this inches-long vertebrate biting...
23.04.2015 | Event News
23.04.2015 | Event News
13.04.2015 | Event News
30.04.2015 | Earth Sciences
30.04.2015 | Life Sciences
30.04.2015 | Press release