Transplantation without rejection -
a lifelong solution

Understanding the Invisible Tissue

Immune System’s Mechanism
to identify allogenetic cells

The immunogenicity of a transplant is determined by the gene products of the Major Histocompatibility Complex (MHC), which in humans are referred to as Human Leukocyte Antigens (HLA). The mechanism by which the immune system recognizes allogeneic cells as foreign is based on the recognition of these HLA-antigens on the cell surface by cytotoxic T-cells and antibodies.

The HLA antigens are extremely polymorphic, so that thousands of variants exist which trigger organ rejection in case of a mismatched organ transplant.

But even in the case of an extremely rare complete HLA match between donor and recipient, rejection occurs regularly because short peptides from all endogenous proteins are presented in the HLA molecules, which exhibit countless disparities between genetically distinct individuals and are referred to as minor histocompatibility antigens (mHag).

The route to no immunosuppression

The concept of tissue marker deactivation is based on a genetic modification of the organs by viral transduction during ex vivo perfusion in an organ preservation system. The cells are genetically modified in such a way that the MHC genes can no longer be expressed as proteins on the cell surface.

The elimination of these target structures of immunological rejection at the donor-recipient interface leads to immunological invisibility of the modified cells to the recipient's immune system.

An immunological recognition as foreign is thus no longer possible despite a fully functional immune system of the recipient. In previous investigations with cells and tissues, rejection could be completely prevented in this way without the need for immunosuppression.