Haematopoiesis in the context of "Hematopoietic stem cell"

Bone marrow is a semi-solid tissue found within the spongy (also known as cancellous) portions of bones. In birds and mammals, bone marrow is the primary site of new blood cell production (or haematopoiesis). It is composed of hematopoietic cells, marrow adipose tissue, and supportive stromal cells. In adult humans, bone marrow is primarily located in the ribs, vertebrae, sternum, and bones of the pelvis. Bone marrow comprises approximately 5% of total body mass in healthy adult humans, such that a person weighing 73 kg (161 lbs) will have around 3.7 kg (8 lbs) of bone marrow.

Human marrow produces approximately 500 billion blood cells per day, which join the systemic circulation via permeable vasculature sinusoids within the medullary cavity. All types of hematopoietic cells, including both myeloid and lymphoid lineages, are created in bone marrow; however, lymphoid cells must migrate to other lymphoid organs (e.g. thymus) in order to complete maturation.

A cell suspension or suspension culture is a type of cell culture in which single cells or small aggregates of cells are allowed to function and multiply in an agitated growth medium, thus forming a suspension. Suspension culture is one of the two classical types of cell culture, the other being adherent culture. The history of suspension cell culture closely aligns with the history of cell culture overall, but differs in maintenance methods and commercial applications. The cells themselves can either be derived from homogenized tissue or from heterogenous cell solutions. Suspension cell culture is commonly used to culture nonadhesive cell lines like hematopoietic cells, plant cells, and insect cells. While some cell lines are cultured in suspension, the majority of commercially available mammalian cell lines are adherent. Suspension cell cultures must be agitated to maintain cells in suspension, and may require specialized equipment (e.g. magnetic stir plate, orbital shakers, incubators) and flasks (e.g. culture flasks, spinner flasks, shaker flasks). These cultures need to be maintained with nutrient containing media and cultured in a specific cell density range to avoid cell death.

A mast cell (also known as a mastocyte or a labrocyte) is a resident cell of connective tissue that contains many granules rich in histamine and heparin. Specifically, it is a type of granulocyte derived from the myeloid stem cell that is a part of the immune and neuroimmune systems. Mast cells were discovered by Friedrich von Recklinghausen and later rediscovered by Paul Ehrlich in 1877. Although best known for their role in allergy and anaphylaxis, mast cells play an important protective role as well, being intimately involved in wound healing, angiogenesis, immune tolerance, defense against pathogens, and vascular permeability in brain tumors.

The mast cell is very similar in both appearance and function to the basophil, a type of white blood cell. Although mast cells were once thought to be tissue-resident basophils, it has been shown that the two cells develop from different hematopoietic lineages and thus cannot be the same cells.

Stromal cells, or mesenchymal stromal cells, are differentiating cells found in abundance within bone marrow but can also be seen all around the body. Stromal cells can become connective tissue cells of any organ, for example in the uterine mucosa (endometrium), prostate, bone marrow, lymph node and the ovary. They are cells that support the function of the parenchymal cells of that organ. The most common stromal cells include fibroblasts and pericytes. The term stromal comes from Latin stromat-, "bed covering", and Ancient Greek στρῶμα, strôma, "bed".

Stromal cells are an important part of the body's immune response and modulate inflammation through multiple pathways. They also aid in differentiation of hematopoietic cells and forming necessary blood elements. The interaction between stromal cells and tumor cells is known to play a major role in cancer growth and progression. In addition, by regulating local cytokine networks (e.g. M-CSF, LIF), bone marrow stromal cells have been described to be involved in human hematopoiesis and inflammatory processes.

Myeloid tissue, in the bone marrow sense of the word myeloid (myelo- + -oid), is tissue of bone marrow, of bone marrow cell lineage, or resembling bone marrow, and myelogenous tissue (myelo- + -genous) is any tissue of, or arising from, bone marrow; in these senses the terms are usually used synonymously, as for example with chronic myeloid/myelogenous leukemia.

In hematopoiesis, myeloid cells, or myelogenous cells are blood cells that arise from a progenitor cell for granulocytes, monocytes, erythrocytes, or platelets (the common myeloid progenitor, that is, CMP or CFU-GEMM), or in a narrower sense also often used, specifically from the lineage of the myeloblast (the myelocytes, monocytes, and their daughter types). Thus, although all blood cells, even lymphocytes, are normally born in the bone marrow in adults, myeloid cells in the narrowest sense of the term can be distinguished from lymphoid cells, that is, lymphocytes, which come from common lymphoid progenitor cells that give rise to B cells and T cells. Those cells' differentiation (that is, lymphopoiesis) is not complete until they migrate to lymphatic organs such as the spleen and thymus for programming by antigen challenge. Thus, among leukocytes, the term myeloid is associated with the innate immune system, in contrast to lymphoid, which is associated with the adaptive immune system. Similarly, myelogenous usually refers to nonlymphocytic white blood cells, and erythroid can often be used to distinguish "erythrocyte-related" from that sense of myeloid and from lymphoid.