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Dr Neil Riordan and Arnold Caplan PhD, Cell Biologists
of Mesenchymal Stem Cells and Regenerative Medicine


Extracellular vesicles (EVs): are lipid bilayer-delimited particles that are naturally released from a cell

Cell based therapies: Mesenchymal stem cells cause regeneration of own stem cells, control inflammation, modulate the Immune system, anti tumorigenic, stimulate repair of a wide variety of cell types

Exosomes: Cell culturing tissue does not require Isolating Cells "in Vitro" to expanded mesenchymal stem cells using FACS Machine. No need for Cryogenic freezing cells, thus simple process of low cost using DMEM Culture Medium (Exosomes) to give patients Cytokine Therapy, also no issues of engraftment and immunogenicity.

Dr Neil Riordan, Dr Ed Park and Duncan Ross PhD, Cell Biologists and Immunologist


The secretion of allogeneic (same species but genetically dissimilar) younger cells into the supernatant DMEM Culture Medium transfered in contact to older cells causes the phenomenon of vitality and freshness being restored, restoring to a more youthful condition despite being genetically dissimilar cells.

Paracrine signaling: Cell signaling or cell-to-cell communication in which a cell produces a signal to induce changes in nearby cells, altering the behaviour dividing cells faster (regeneration)

Microchimerism: The presence of two genetically distinct and separately derived populations of cells, one population being at a low concentration, in the same individual

MHC class II are safe in allogeneic exosomes: MHC class II molecules are a class of major histocompatibility complex (MHC) molecules normally found only on professional antigen-presenting cells such as dendritic cells, mononuclear phagocytes, some endothelial cells, thymic epithelial cells, and B cells. These cells are important in initiating immune responses.The antigens presented by class II peptides are derived from extracellular proteins (not cytosolic as in MHC class I)

Diagram of an Exosome

Duncan Ross PhD, speaking on Exosomes

Professor Bob Elliott, speaking on Porcine endogenous retrovirus (PERV)


Xenogenic (being a member of another species) cells secrete Exosomes. Isolated via differential ultracentrifugation, observed under transmission electron microscopy, measured by dynamic light scattering, and confirmed by immunoblot. Exosomes exist in blood, urine, sweat, amniotic fluid, saliva, semen and even in milk, so when humans drink milk they express cow proteins for a month.

Xenomicrochimerism: The presence of genetically distinct, from another species, separately derived populations of cells, one population being at a low concentration, in the same individual

PERV detection by polymerase chain reaction (PCR) is required for potential (false positive) rejection.

    • Exosomes are too small ( about 30 to 150 nanometres (nm) in diameter ) to contain intact (infectious) porcine endogenous retroviruses (PERVs)
    • Exosomes are smaller than bacteria
    • Exosomes behave like other nanocarriers regarding tissue distribution
    • Exosomes have remarkable transfer of RNA in vivo
    • Exosomes can travel through the body quite quickly and distribute efficiently
    • Exosomes cannot be rejected (immune reaction) by third party (host) as they cannot be seen
    • (Whole) Cord Blood can be contaminated and unsterile, Exosomes are smaller than a cell

    Theoretically it is possible that the surface of the exosomes, viral proteins, specifically surface envelope protein gp70, may be expressed which could direct the exosomes to the receptor of PERV on target cells in the living organism or the immunosuppressive transmembrane envelope protein p15E which may distribute immunosuppressive properties. In addition, the viral genome may be transported to target cells. Investigating PERV genomic RNA, purified exosomes are checked by RT-PCR and for the presence of viral proteins by Western blot analysis using specific sera against p15E and gp70.

    Blood and faecal samples can be analysed in the lab for about 30 different disease-causing pathogens, including hepatitis E, swine flu, circovirus, porcine herpesvirus and porcine endogenous retrovirus
    Polymerase chain reaction (PCR) tests for the presence of viral DNA in samples. A new form of PCR that can copy, detect and quantify viral DNA is fast, sensitive and specific methods can be used to detect specific viruses (p15E and gp70).Serology is the testing of samples for the presence of antibodies to viruses that would indicate a viral infection. Standard serology methods measure antibodies, such as enzyme-linked immunosorbent assays (ELISA) and latex agglutination tests (LAT). PERV: a pig retrovirus Porcine endogenous retrovirus (PERV) found in all pigs’ DNA. PERV has two forms – a harmless provirus, which is locked into the pigs’ DNA, and a viral particle that could potentially infect other species.

    Is PERV a risk for pig cell transplant recipients?
    In 1997, Robin Weiss, MD , found that PERV from a pig cell line could infect human cells in a petri dish ,in the interview he states "One experiment that tested whether they could infect human cells gave a negative result. We exposed human cells in culture to the semi-purified virus particles, and found only one human cell type, amongst about 15 or 20 that we tested, which could readily become infected with this virus. The virus wasn't a ripping hot virus for human cells. But if you allowed the pig cells and the human cells to be next to each other, given enough time, the virus would get in. A whole organ lasting a long time gives you a higher potential dose of virus. The PERV retroviruses grows in a rather wimpy way, poorly to low levels, living pig cells for one reason or another showed no evidence using sensitive PCR techniques"

    The PERV discovery led to a worldwide ban or moratorium on all pig to human transplants. However, since then, pre-clinical animal data have found no evidence of PERV infecting human cells, and PERV has never been found in recipients of pig tissue.The ban on pig to human transplants has now been lifted in some countries. Pig cell transplant research is proceeding under rigorous controls. Pathogen-free pigs have copies of the provirus in their DNA, but it has never been shown in evidence based medicine (EBM) cell therapy to release a viral particle in some studies.

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