Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by memory loss and cognitive impairment. It is caused by synaptic failure and excessive accumulation of misfolded proteins. To date, almost all advanced clinical trials on specific AD-related pathways have failed mostly due to a large number of neurons lost in the brain of patients with AD. Also, currently available drug candidates intervene too late. Stem cells have improved characteristics of self-renewal, proliferation, differentiation, and recombination with the advent of stem cell technology and the transformation of these cells into different types of central nervous system neurons and glial cells. Stem cell treatment has been successful in AD animal models. Recent preclinical studies on stem cell therapy for AD have proved to be promising. Cell replacement therapies, such as human embryonic stem cells or induced pluripotent stem cell–derived neural cells, have the potential to treat patients with AD, and human clinical trials are ongoing in this regard. However, many steps still need to be taken before stem cell therapy becomes a clinically feasible treatment for human AD and related diseases. This paper reviews the pathophysiology of AD and the application prospects of related stem cells based on cell type.

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Hematopoiesis is finely regulated to enable timely production of the right number and type of mature immune cells to maintain tissue homeostasis. Dysregulated hematopoiesis may compromise antiviral immunity and/or exacerbate immunopathogenesis. Herein, we report an essential and new role of ubiquitin X domain containing gene 3B (UBXN3B) in balancing myelopoiesis and lymphopoiesis. Ubxn3b deficiency (Ubxn3b−/−) results in a remarkable increase in myeloid cells and neutrophil-to-lymphocyte ratio, along with a reduction in lymphocytes in steady-state mice. This dysregulation is exacerbated during viral infection and renders mice highly vulnerable to severe lung pathology induced by severe acute respiratory syndrome coronavirus 2 and arthritis by arthritogenic alphaviruses. Ubxn3b−/− mice present normal type I IFNs, higher viral loads and inflammatory mediators, lower virus-specific immunoglobulin G and slower resolution of disease, when compared to Ubxn3b+/+ littermates. Mechanistically, Ubxn3b−/− mice have fewer multipotent progenitors and common lymphoid progenitors, but more common myeloid progenitors. In particular, the precursor and immature B cell numbers are dramatically decreased in the bone marrow of Ubxn3b−/− mice. These data demonstrate that UBXN3B signaling is essential for restricting viral infection and immunopathogenesis by maintaining hematopoietic homeostasis.