One might speculate that different clinicopatholgical features would follow depending on the regional propensity for such events to occur for any given protein, much in the same way that Braak and Braak staging describes typical Alzheimer’s disease progression.[54] There is also a potentially important practical corollary to the idea of prion-like spread, which may affect future stem cell therapies

for neurodegenerative diseases. Presumably therapeutic stem cell-derived neurons would be equally susceptible to “infection” (with misfolded protein aggregates) as the patient’s own cells, unless steps were taken to prevent this,[55] the most obvious of which would be to prevent expression of the gene product that can be converted to a pathological prion-like isoform. The suggestion that a prion-like mechanism of spread of molecular pathology underlies diseases as diverse as Alzheimer’s disease selleck inhibitor and Parkinson’s disease has led some researchers to explore whether the molecular pathology of these diseases is transmissible in an experimental setting[56-58] and to suggest that perhaps some cases of these more common neurodegenerative illnesses might,

like CJD, be acquired.[58, 59] The apparent absence of a nucleic acid-based genome and the difficulties associated with culturing prions has meant that much prion disease research (including human prion disease research) continues to be done in experimental Lepirudin NVP-LDE225 mouse animals. However, this is beginning to change. The development and application of techniques that can be used to probe the conformation and/or aggregation state

of human prions extracted from human tissue have allowed for “molecular strain typing” as an alternative to biological strain typing by animal transmission.[37, 38, 60] Specific cell lines and strategies that allow for the replication of a widening range of prions in cultured cells are being developed. This has practical application in the form of rapid end-point titration of scrapie prions and the possibility of scrapie prion strain differentiation using a cell panel assay.[61, 62] These technical innovations can be put to basic scientific purpose as demonstrated by the recent finding that, although devoid of nucleic acid, scrapie agent replication in culture displays properties analogous to mutation, competition and selection.[63] Cell-free PrPSc seeded conversion assays, such as protein misfolding cyclic amplification (PMCA) allow prion propagation to be studied in vitro, in a flexible system in which the effects of species, strain and genotype of the seed (containing PrPSc) and substrate (containing PrPC) can be controlled and manipulated.[64, 65] Ancillary molecules involved in PMCA can also be studied and the minimal components required for the formation of infectious prions defined.