Mesenchymal stem cells (MSCs) are multipotent cells with the ability to self-renew and differentiate into various cell types, making them promising candidates for cell and gene therapy. Despite their potential, the exact identity and mechanisms governing their behavior remain unclear. MSCs are primarily found in bone marrow, but they can also be isolated from other tissues such as adipose tissue, synovium, and skeletal muscle. Their existence is supported by their ability to form colonies in vitro, although their in vivo presence is still debated. MSCs have shown regenerative potential in various tissues, including bone, cartilage, and muscle, and can differentiate into multiple lineages. However, their differentiation capacity is heterogeneous, with some cells showing limited potential. The regulation of MSC differentiation involves complex molecular mechanisms, including signaling pathways such as Wnt, which play a role in osteogenesis. MSCs have been used in gene therapy through viral and non-viral methods, with the latter showing promise for efficient DNA delivery. Despite their potential, the limited number of MSCs and their limited self-renewal capacity pose challenges for clinical applications. Strategies to enhance their proliferation and maintain their multipotency are being explored, including the use of telomerase to extend their lifespan. Overall, further research is needed to fully understand the biology of MSCs and to develop optimal methods for their use in clinical settings.Mesenchymal stem cells (MSCs) are multipotent cells with the ability to self-renew and differentiate into various cell types, making them promising candidates for cell and gene therapy. Despite their potential, the exact identity and mechanisms governing their behavior remain unclear. MSCs are primarily found in bone marrow, but they can also be isolated from other tissues such as adipose tissue, synovium, and skeletal muscle. Their existence is supported by their ability to form colonies in vitro, although their in vivo presence is still debated. MSCs have shown regenerative potential in various tissues, including bone, cartilage, and muscle, and can differentiate into multiple lineages. However, their differentiation capacity is heterogeneous, with some cells showing limited potential. The regulation of MSC differentiation involves complex molecular mechanisms, including signaling pathways such as Wnt, which play a role in osteogenesis. MSCs have been used in gene therapy through viral and non-viral methods, with the latter showing promise for efficient DNA delivery. Despite their potential, the limited number of MSCs and their limited self-renewal capacity pose challenges for clinical applications. Strategies to enhance their proliferation and maintain their multipotency are being explored, including the use of telomerase to extend their lifespan. Overall, further research is needed to fully understand the biology of MSCs and to develop optimal methods for their use in clinical settings.