Current methods for diagnosing transmissible spongiform encephalopathies rely on the degradation of the cellular prion protein (PrP C ) and the subsequent detection of the protease-resistant remnant of the pathological prion isoform PrP Sc by antibodies that react with all forms of PrP. We report on a monoclonal antibody, V5B2, raised against a peptide from the C-terminal part of PrP, which recognizes an epitope specific to PrP Sc . In cryostat sections from Creutzfeldt-Jacob's disease (CJD) patients' brains, V5B2 selectively labels various deposits of PrP Sc without any pretreatment for removal of PrP C . V5B2 does not bind to non-CJD brain samples or to recombinant PrP, either in its native or denatured form. Specificity for PrP is confirmed by a sandwich enzyme-linked immunosorbent assay utilizing V5B2, which discriminates between CJD and normal samples without proteinase K treatment, and by immunoprecipitation from CJD brain homogenate. The PrP Sc -specific epitope is disrupted by denaturation. We conclude that the C-terminal part of PrP in disease-associated PrP Sc aggregates forms a structural epitope whose conformation is distinct from that of PrP C .

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Prion diseases are a group of fatal neurodegenerative disorders that affect humans and animals. They are characterized by the accumulation in the central nervous system of a pathological form of the host-encoded prion protein (PrPC). The prion protein is a membrane glycoprotein that consists of two domains: a globular, structured C-terminus and an unstructured N-terminus. The N-terminal part of the protein is involved in different functions in both health and disease. In the present work we discuss the production and biochemical characterization of a panel of four monoclonal antibodies (mAbs) against the distal N-terminus of PrPC using a well-established methodology based on the immunization of Prnp0/0 mice. Additionally, we show their ability to block prion (PrPSc) replication at nanomolar concentrations in a cell culture model of prion infection. These mAbs represent a promising tool for prion diagnostics and for studying the physiological role of the N-terminal domain of PrPC.

Mesenchymal stem cell (MSCs) therapy has already been studied in kidney transplant recipients (KTRs), and the available data showed that it is safe and well tolerated. The aim of this study was to evaluate the safety and efficacy of autologous MSCs in combination with standard therapy in KTRs with biopsy-proven chronic active antibody-mediated rejection (AMR). Patients with biopsy-proven chronic active AMR received treatment with autologous bone marrow-derived MSCs (3 × 106 cells/kg iv) after completion of standard therapy and were followed for up to 12 months. The primary endpoints were safety by assessment of adverse events. Secondary endpoints included assessment of kidney graft function, immunological and histological changes related to AMR activity and chronicity assessed by conventional microscopy and molecular transcripts. A total of 3 patients were enrolled in the study before it was terminated prematurely because of adverse events. We found that AMR did not improve in any of the patients after treatment with MSCs. In addition, serious adverse events were observed in one case when autologous MSCs therapy was administered in the late phase after kidney transplantation, which requires further elucidation.