The therapeutic potential of mesenchymal stem cells in Alzheimer's disease:converging mechanisms

Mesenchymal stem cells （MSCS） are pluripotent stem cells isolated from various tissues, but mostly from bone marrow, adipose tissue, and umbilical cord blood. Well known for their mesenchymal lineages differentiation （e.g., bone, cartilage and fat tissues）, it was suggested that MSCs possess plasticity prop- erties enabling them to differentiate into non-mesenchymal lineages. Indeed, several protocols claimed for differentiating MSCs to neurons in vitro, but concern was raised for the ef- fectiveness and in vivo relevance of such differentiation. Thus, though their neurogenic differentiation properties are still in debate, they were nevertheless, suggested as candidates for treat- ing neurodegenerative disorders such as Parkinson＇s diseases, multiple sclerosis and Alzheimer＇s disease （AD）.

Glypican 4 down-regulation in pluripotent stem cells as a potential strategy to improve differentiation and to impair tumorigenicity of cell transplants

Recent advances in stem cell technologies have opened new avenues for the treatment of a number of diseases still lacking effective therapeutic options.Cell transplantation has emerged as among the most promising clinical intervention for disorders such as injuries,diabetes,liver diseases, neurodegeneration and heart failure （Lee et al., 2013; Forbes and Rosenthal, 2014; Tabar and Studer, 2014）.

Calcium channels and their role in regenerative medicine

Stem cells hold indefinite self-renewable capability that can be differentiated into all desired cell types.Based on their plasticity potential,they are divided into totipotent(morula stage cells),pluripotent(embryonic stem cells),multipotent(hematopoietic stem cells,multipotent adult progenitor stem cells,and mesenchymal stem cells[MSCs]),and unipotent(progenitor cells that differentiate into a single lineage)cells.Though bone marrow is the primary source of multipotent stem cells in adults,other tissues such as adipose tissues,placenta,amniotic fluid,umbilical cord blood,periodontal ligament,and dental pulp also harbor stem cells that can be used for regenerative therapy.In addition,induced pluripotent stem cells also exhibit fundamental properties of self-renewal and differentiation into specialized cells,and thus could be another source for regenerative medicine.Several diseases including neurodegenerative diseases,cardiovascular diseases,autoimmune diseases,virus infection(also coronavirus disease 2019)have limited success with conventional medicine,and stem cell transplantation is assumed to be the best therapy to treat these disorders.Importantly,MSCs,are by far the best for regenerative medicine due to their limited immune modulation and adequate tissue repair.Moreover,MSCs have the potential to migrate towards the damaged area,which is regulated by various factors and signaling processes.Recent studies have shown that extracellular calcium(Ca^(2+))promotes the proliferation of MSCs,and thus can assist in transplantation therapy.Ca^(2+)signaling is a highly adaptable intracellular signal that contains several components such as cell-surface receptors,Ca^(2+)channels/pumps/exchangers,Ca^(2+)buffers,and Ca^(2+)sensors,which together are essential for the appropriate functioning of stem cells and thus modulate their proliferative and regenerative capacity,which will be discussed in this review.