Stem cells (SCs) play a crucial role in the generation and regulation of intercellular heterogeneity and ultimately physiological tissue homeostasis in higher eukaryotes. The body is always under attack from various kinds of stressors, mutagens, and carcinogens, which lead to genotoxic effects. Endogenous or exogenous sources of genetic lesions are harmful to SCs and are a potential source of threat for the function and survival of SCs.

Embryonic and adult SCs can combat the accretion of genetic lesions and repair them via various DNA repair mechanisms, thus avoiding their transmission to the daughter cells. After exposure to DNA damage, SCs undergo catastrophic consequences thus leading to the imbalance of homeostasis at tissue and organism level. Under oxidative stress and DNA damage, malignant SCs and normal cells initiate the mechanism of DNA damage response (DDR). Various pathways such as nucleotide excision repair (NER), base excision repair (BER), mismatch repair (MMR), homologous recombination (HR), and non-homologous end joining (NHEJ) of DNA repair are initiated under DDR. These DDR mechanisms are usually beneficial in healthy tissues by restoring normal SC function. However, these could be detrimental in malignant SCs as they could favor resistance and survival to cancer treatment. Moreover, DDR is also implicated in genetic reprogramming which leads to the generation of inducible pluripotent stem cells (iPSCs). These iPSCs have importance in clinical and practical applications.

The aim of this Special Issue is to attract original research and review articles focusing on how various mutagens and carcinogens can induce DNA damage, and how various pathways and mechanisms are initiated under DDR.

Potential topics include but are not limited to the following:

• Mutagen-induced oxidative stress in stem cells
• Mechanism of mutagen-induced oxidative stress in stem cells
• Mechanism of mutagen-induced genotoxicity in stem cells
• Cytogenetic effects of carcinogens in stem cells
• Epigenetic modifications in stem cells after DNA damage
• DDR in stem cells after carcinogen exposure
• Pathways in cancer stem cells after mutagen exposure
• Cross-talk between malignant stem cells and their exosomes after mutagen exposure
• DDR response and generation of inducible pluripotent stem cells (iPSCs)