Novel Immortalized Human Bone Marrow–Derived Mesenchymal Stem Cells Overcome Primary Cell Limitations

Mesenchymal stem cells (MSCs) are adult stem cells that have the ability to differentiate into other types of cells. Additionally, MSCs can modulate the immune response and promote tissue repair. Due to their properties, primary MSCs have significant application potential in the treatment of various diseases. However, primary MSCs also have limitations such as limited life span, donor variability, source limitation, and heterogenicity, which hinders the utilization of primary MSCs in preclinical applications. These constraints could be overcome with cell immortalization. Cell immortalization technology enables the establishment of new cell models that retain normal physiology, demonstrate minimal cellular heterogeneity, and gain an indefinite lifespan. In this study, we generated a clonal cell line that was immortalized by stably expressing the human telomerase reverse transcriptase (hTERT) gene in normal human primary bone marrow–derived mesenchymal stem cells (BM-MSCs). This immortalized cell line has been cultured for over 200 days and has continued to proliferate over 120 population doublings. The immortalized BM-MSCs exhibited a normal karyotype and had a similar cell growth profile and cell doubling time as the parental primary cells. The immortalized BM-MSCs were positive for CD73, CD90, and CD105 and were negative for CD14, CD34, and CD45. In this study, we also investigated the adipogenic, osteogenic, and chondrogenic differentiation abilities of these immortalized BM-MSCs. In summary, the immortalized BM-MSCs present a novel cell model that avoids the limitations of primary cells and can be used as a valuable tool for cell and gene therapy.