Immunoprotective primary mesenchymal stem cells and methods

A method for treating or preventing outbreak of a disease caused by a pathogen or ameliorating exposure to a toxin comprising the step of:

• administering immunoprotective primary mesenchymal stem cells (IP-MSC) to a subject exposed to or at risk of being exposed to the pathogen or toxin;
• wherein the IP-MSC are transfected with one or more episomal vectors encoding at least two immunoreactive polypeptides, which specifically target the pathogen or toxin, each immunoreactive polypeptide comprising an antigen-binding region of a neutralizing antibody specific for the pathogen or toxin, or encoding a variant of the antigen-binding region, wherein the variant includes one or more substitutions in the amino acid sequence of the antigen-binding region and shares at least 50% sequence identity with the antigen-binding region of the neutralizing antibody.

A method for preparing prophylactic or therapeutic mesenchymal stem cells for treating or preventing an outbreak of a disease caused by a pathogen or for ameliorating exposure to a toxin comprising the step of:

• transfecting primary mesenchymal stem cells with one or more episomal vectors encoding at least two immunoreactive polypeptides comprising an amino acid from an antigen-binding region of a neutralizing antibody specific for the pathogen or toxin, or encoding a variant of the antigen-binding region sequence, to produce immunoprotective primary mesenchymal stem cells (IP-MSC) that express the immunoreactive polypeptides;
• wherein the variant includes one or more substitutions in the amino acid sequence from the antigen-binding region and shares at least 50% sequence identity with the antigen-binding region sequence of the neutralizing antibody.

An episomal vector encoding an expressible amino acid sequence of an immunoprotective polypeptide;

• wherein each immunoreactive polypeptide comprises an amino acid sequence from an antigen-binding region of a neutralizing antibody specific for an antigen produced by the pathogen or specific for the toxin, or an amino acid sequence of a variant of the antigen-binding region sequence comprising one or more substitutions in the amino acid sequence thereof and sharing at least about 50% sequence identity with the antigen-binding region sequence;
• the antigen-binding region sequence or variant thereof being arranged to specifically bind to and neutralize the pathogen or toxin;
• and wherein the episomal vector optionally includes an inducible apoptosis gene.