Recent upsurge in the interest of breast cancer metastasis is partly attributed to the discovery of novel, yet unclear, mechanisms of breast cancer interaction with sites of distant metastasis such as the bone marrow microenvironment. In this review, we discuss the significance of the interactions between breast cancer cells and cells of the bone marrow. This is a subject of intense research studies aim to provide new methods of treatments and perhaps the identification of new drug targets. This review also discusses the role of inflammation and the bimodal function of the transforming growth factor-β signaling pathway in the process of tumorigenesis. We bring attention to future prospects in breast cancer research, including the role of microRNAs in cancer quiescence in the bone marrow and the application of microRNAs to basic science discoveries in oncology. Finally, we discuss the cancer stem cell hypothesis, which is not a new idea, but has resurged with investigative questions.

Stem cell therapy has a place for future application in the treatment of degenerative diseases. Regardless of the origin of the stem cell, when placed within a milieu of inflammatory mediator, they will show varied functions. This review focuses on human mesenchymal stem cells (MSCs) and discusses neuronal replacement using multi- and inter-disciplinary approaches. We caution the enthusiasm of scientists since there is always the potential for tumor formation, even for adult stem cells. The review places RE-1 silencing transcription factor (REST) gene as central to the understanding of stem cell behavior in the microenvironment of tissue injury. REST is relevant in the development of dopaminergic and peptidergic neurons from MSCs. Premature downregulation of REST by the pro-inflammatory mediator, IL-1alpha, can prematurely lead to the expression of neurotransmitters, which in turn, could develop rapid crosstalk with immune cells. In-depth inter- and multi-disciplinary research will lead to rapid and safe translation of MSCs to patients. An understanding of the changes induced in MSCs by cytokines and other mediators will establish future application of MSCs and other stem cells for safe and effective treatments. This study also alludes to the potential of personalized medicine through engineering and mathematics.

Infl ammation encompasses diverse molecular pathways, and it is intertwined with a wide array of biological processes. Recently, there has been an upsurge of interest in the interactions between mediators of infl ammation and other cells such as stem cells and cancer cells. Since tissue injuries are associated with the release of infl ammatory mediators, it would be diffi cult to address this subject without considering the implications of their systemic effects. In this review, we discuss the effects of infl ammatory reactions on stem cells and extrapolate on information pertaining to cancer biology. The discussion focuses on integrins and cytokines, and identifi es the transcription factor, nuclear factor-kappa B (NFκB) as central to the infl ammatory response. Since stem cell therapy has been proposed for type II diabetes mellitus, metabolic syndrome, pulmonary edema, these disorders are used as examples to discuss the roles of infl ammatory mediators. We propose prospects for future research on targeting the NFκB signaling pathway. Finally, we explore the bridge between infl ammation and stem cells, including neural stem cells and adult stem cells from the bone marrow. The implications of mesenchymal stem cells in regenerative medicine as pertaining to infl ammation are vast based on their anti-infl ammatory and immunosuppressive effects. Such features of stem cells offer great potential for therapy in graft-versus-host disease, conditions with a signifi cant infl ammatory component, and tissue regeneration.