Stem cell niches exposed to tobacco smoke.

Stem cells (SC) were identified in both fetal and adult tissues. They appear a great potential for proliferation and differentiation. SC functions are affected by their local microenvironment, known as a SC niche, composed of extracellular matrix (ECM) and neighboring cells of other types. Both fetal and adult SC niches are potential targets for environmental pollutions. Environmental Tobacco Smoke (ETS) is one of the most dangerous sources of toxic and carcinogenic compounds. Adverse effect of tobacco smoke components on SC includes both direct influence on the cells and their regulatory mechanisms, as well as changes in SC microenvironment. Both mechanisms contribute to limitation of regenerative potential of the tissues. As targets for tobacco smoke during long-lasting active or passive smoking, SC can initiate malignant transformation. So called, cancer stem cells (CSC) exhibit some similarities as compared with SC, for example abilities of self-renewal and asymmetric divisions. Cancer treatment focused on CSC may contribute to increased efficiency of standard therapeutic methods. To sum up, effects of stem cells exposure to tobacco smoke may be particularly important in the context of tissue regeneration and carcinogenesis. Furthermore, SC exposure to tobacco smoke components may result in reduced number and quality of stem cells deposited in the tissue reservoirs. As a result the quality of SC derived from fetal (cord blood, amniotic fluid, placenta) and adult donors (i.e. bone marrow) for transplantations might be much reduced.

An experimental approach to the generation of human embryonic stem cells equivalents.

Recently, particular attention has been paid to the human embryonic stem cells (hESC) in the context of their potential application in regenerative medicine; however, ethical concerns prevent their clinical application. Induction of pluripotency in somatic cells seems to be a good alternative for hESC recruitment regarding its potential use in tissue regeneration, disease modeling, and drug screening. Since Yamanaka's team in 2006 restored pluripotent state of somatic cells for the first time, a significant progress has been made in the area of induced pluripotent stem cells (iPSC) generation. Here, we review the current state of knowledge in the issue of techniques applied to establish iPSC. Somatic cell nuclear transfer, cell fusion, cell extracts reprogramming, and techniques of direct reprogramming are described. Retroviral and lentiviral transduction are depicted as ways of cell reprogramming with the use of integrating vectors. Contrary to them, adenoviruses, plasmids, single multiprotein expression vectors, and PiggyBac transposition systems are examples of non-integrative vectors used in iPSC generation protocols. Furthermore, reprogramming with the delivery of specific proteins, miRNA or small chemical compounds are presented. Finally, the changes occurring during the reprogramming process are described. It is concluded that subject to some limitations iPSC could become equivalents for hESC in regenerative medicine.