The sensitivity of human mesenchymal stem cells to ionizing radiation

Adipose mesenchymal stromal cells minimize and repair radiation-induced oral mucositis

“…Chk1 and Chk2 are main inhibitors of Cdc25A and Cdc25C resulting in Cdk/cyclin-mediated cell cycle arrest [71]. It has been suggested that DSB in MSCs are repaired by activation of both the homologous recombination (HR, during S and G2 phases) and the non-homologous end-joining (NHEJ, during all cell cycle phases) DNA repair pathways [95,104,106]. Our recent study showed the activation of HR and NHEJ repair pathways in irradiated aMSCs [159].…”

“…These mechanisms were also shown to be responsible for the IR resistance of cancer stem cells (CSC), also known as cancer initiating cells, which have been linked to cancer disease recurrence and aggression [100][101][102][103]. These mechanisms were tested in bmMSCs in earlier studies showing that these bmMSCs are relatively radio-resistant [95,96,[104][105][106]. Do MSCs from different tissue origins behave similarly?…”

“…The application of MSCs in radiation oncology regenerative medicine (RORM) was enhanced by their efficient radiation-induced DNA repair machinery and their relative radiation resistance [91,95,96,99,159]. Such radiation resistance was mediated by many mechanisms, e.g.…”

“…Such radiation resistance was mediated by many mechanisms, e.g. the ATM phosphorylation, activation of cell cycle check points (G2/M arrest), and activation of single and double stranded DNA repair by both homologous and non-homologous recombination mechanisms and other pathways [95,159] (Figure.3.4.1). DSB resulting from the direct and indirect radiation injury stimulate the phosphorylation of ATM which is the proximal step for cell cycle check point's activation (G2/M arrest).…”

“…In addition, the surface antigen CD105 presence is important for normal cellular DNA repair [94]. Different mechanisms have been reported explaining such radio-resistance such as, cell cycle (CC) arrest (G2/M arrest) and activation of double stranded DNA (dsDNA) damage repair; namely the homologous recombination repair (HRR) and non-homologous end joining repair (NHEJR) [95][96][97][98][99]. These mechanisms were also evidenced to be responsible for the IR resistance of cancer stem cells (CSC), also known as cancer initiating cells, which have been linked to cancer disease recurrence and aggression [100][101][102][103].…”