hematopoietic stem cells vs mesenchymal stem cells

All of these changes explain the aging-related alterations seen in peripheral blood (PB) and tissues, including: (1) attenuated blood cell regeneration in response to radiation or chemical-induced BM damage (2) increased percentages of granulocytes and monocytes, which is always accompanied by a reduced percentage of T/B lymphocytes and impaired adaptive immunity (3) reduced anti-infective activity of neutrophils and (4) slightly reduced RBC and platelet numbers. Ĭhanges in elderly human, monkey, and mouse HSCs compared to younger adults include: (1) increased numbers (2) compromised HRC (3) skewed myeloid differentiation at the expense of T/B lymphocytes (4) expansion of functionally defective HSCs and (5) accumulation of clonal hematopoiesis, specifically, genetically mutant HSCs, due to the selective expansion of age-associated somatic mutant HSCs. Thus, a more in-depth elucidation of the molecular and cellular mechanisms by which HSC aging are inter-regulated will not only help in the development of medications for treating and preventing age-related hematopoietic and immune disorders, but also provide strategies to advance the quality of life of elderly populations by reducing the burden of dysfunctional hematopoiesis and immunity due to aging. In addition, this population may experience declining adaptive immunity, autoimmunity, vaccine failure, and experience increased innate immune-inflammation and susceptibility to infectious diseases. Consequently, elderly populations experience higher incidences of anemia, arterial thrombosis, and myeloid and lymphoid malignancies (such as age-related clonal hematopoiesis, myelodysplastic syndromes, acute myeloid leukemia, chronic lymphocytic leukemia, multiple myeloma and non-Hodgkin's lymphoma). The process of aging in HSCs is driven by both cell-intrinsic and extrinsic factors, which lead to a reduction in blood cell production and impairment of immune system function. Like most other tissue-specific stem cells, HSCs are vulnerable to aging-related stress and gradually lose their self-renewal and hematopoietic regenerative capacities (HRC). Normal homeostatic multi-lineage blood cell regeneration, including immune-related tissue, is primarily maintained through multipotent hematopoietic progenitors (MPPs), which become exhausted over time, whereas lifetime hematopoiesis and immunity are maintained by self-renewable hematopoietic stem cells (HSCs) that are localized within specialized BM microenvironments called HSC niches. To replenish the loss of blood cells, approximately the same numbers of blood cells must be produced from bone marrow (BM) hematopoietic progenitors daily. In the adult human, ~ 4–5 × 10 11 blood cells are lost every day due to cellular aging or damage. The primary functions of blood cells are transporting oxygen to tissues by red blood cells (RBCs), antagonizing infections caused by pathogenic agents (macrophages and neutrophils), maintaining coagulatory hemostasis (platelets), and confronting and responding adaptively to internal and external antigenic affronts (T and B lymphocyte-mediated immune defense).

Hematopoietic stem cells vs mesenchymal stem cells