Abstract

This chapter will focus on the main immunological issues in stem cell approaches. The scientific world faces an important immunological dilemma when investigating stem cells immunogenicity. One is the need to have low stem cell’s immunogenicity, property that provides modest inflammatory reaction microenvironment and hence lack of rejection of the transplanted stem cells. On the other side any neoplastic transformation can increase the natural immune evasive properties of stem cells linking immune escape and tumorigenicity. In this light oncogenes expression can directly orchestrate inflammation and immune escape to drive the multistep process of cancer progression, independent of any immuno-editing in the tumor microenvironment. The chapter starts with characterizing the immunogenicity of stem cells, where major histocompatibility expression is the immune mold that can drive toward generation or tumorigenesis. The chapter continues with the processes that are involved in stem cells modulating the immune system elements whether in Regeneration or Tumorigenesis. The chapter ends with the main immune hurdles in the most recent clinical trials using stem cells.