Regenerative medicines offer the potential for treatment and possibly cure of debilitating diseases
including heart disease, diabetes, Parkinson’s disease and liver failure. Approaches using stem cells from
various sources are in pre clinical and clinical testing. The goal of these studies is to deliver cellular products
capable of replacing damaged tissue and/or cells. However, the balance between cellular proliferation and
differentiation is a carefully controlled process involving a range of growth factors and cytokines produced in
large part by tissue stromal cells. These stromal cells make up the tissue microenvironment and appear to be
essential for normal homeostasis. We hypothesize that tissue damage in many instances involves damage to the
microenvironment resulting in a lack of signals through growth factor networks necessary to maintain survival
and proliferation of tissue specific stem cells and progenitor cells. Therefore, optimal repair of disease tissue
must account for the damage to the stromal environment. We propose that optimal cellular therapies for
regenerative medicine will require combination cellular products consisting of a stromal cell population to
reconstitute the microenvironment and to support the survival, proliferation and differentiation of the tissue
specific stem cells or progenitor cells.
