A study on the evaluation of stromal stem cells and stromal fibroblasts in human tissue regenerative and cancer forming potentials

Human stromal tissue is an abundant source of mesenchymal stem cells (MSCs) including stromal stem cells, fibroblasts, vascular endothelial cells, and macrophages. The stromal microenvironment tightly controls the proliferation and differentiation of tissue cells for maintenance of tissue complexity and function. Adipose tissue mesenchymal stem cells (Ad-MSCs) have shown promise in regenerative medicine. Several clinical trials have demonstrated the regenerative capacity of adipose-derived stem cells for plastic, orthopedic, oral and maxillofacial, and cardiac surgeries. However, recent studies have linked white adipose-derived stem cells with tumor genesis. To date, preclinical studies have focused on overcoming the hurdles for the use of tissue MSCs for regenerative medicine. Purification of a well-characterized population of MSCs for safe and effective transplantation is a major translational medicine priority. Our laboratory has recently successfully isolated stromal stem/progenitor cells (MS/PCs) and stromal fibroblast (SFCs) subpopulations from various tissue MSCs. We have also identified the phenotypic differences and differentiation potentials of these stromal cells. By comparing the characteristics of both isolated MS/PCs and SFCs subpopulations, we found a minor fraction of CD34+MS/PCs exhibit embryonic stem cell (ESC-like) multipotent characteristics. In contrast, the major fraction of CD34-SFCs display mature stromal fibroblast properties. Thus, we speculate that the isolated CD34+MS/PCs may play roles in both tissue renewal and tumorigenesis in injured or aging tissue. The CD34-SFCs likely function as mature stromal fibroblasts for tissue maintenance. To investigate the regenerative and tumorigenic potential of Ad-MSCs, we propose to evaluate the influence of stromal stem cells (Ad-MS/PCs) and stromal fibroblasts (Ad-SFCs) in regeneration of hepatic fibrotic tissue and induction of cancer stem cell biogenesis in vitro, as well as in vivo. The overall objective of this study is to identify the difference of Ad-MS/PCs vs. Ad-SFCs involvement in a) restoration of fibrotic liver tissue and b) biogenesis of cancer stem cells, specifically induction of hepatocellular carcinoma or HCC cells to transform into cancer stem cells. By co-culturing adipose tissue MS/PCs or SFCs with HCC cancer cells, and subsequently comparing their transcriptomes and secretory cytokine/chemokine profiles before and after co-culturing, we will investigate three specific aims Aim1: To detect changes in cancer cell expression profile changes during co-culture with MS/PCs or SFCs. We predict that stem cell secreted factors will stimulate cancer stem cell biogenesis and proliferation. Aim2: To analyze the influence of co-culture of MS/PCs or SFCs on the potential transition of HCC cells into cancer stem cells, during the stress of hypoxia and/or aging (i.e. early or late passages of cells or from different aged donors). Aim3: To examine the mechanism of MS/PCs and SFCs involved in tissue regenerative and cancer stem cell biogenesis in a murine liver fibrosis model. We anticipate the proposed study will define alterations of key cell apoptotic and tumor necrotic genes and inflammatory cytokines and chemokines be detected. The results obtained will further our understanding of cancer progression, leading to potential prevention strategies and the development of new drugs.