Generation of an osteoblast-based artificial niche that supports in vitro B lymphopoiesis

B lymphocytes are produced from hematopoietic stem cells (HSCs) through the highly ordered process of B lymphopoiesis, which is regulated by a complex network of cytokines, chemokines and cell adhesion molecules derived from the hematopoietic niche. Primary osteoblasts function as an osteoblastic niche (OBN) that supports in vitro B lymphopoiesis. However, there are significant limitations to the use of primary osteoblasts, including their relative scarcity and the consistency and efficiency of the limited purification and proliferation of these cells. Thus, development of a stable osteoblast cell line that can function as a biomimetic or artificial OBN is necessary. In this study, we developed a stable osteoblastic cell line, designated OBN4, which functions as an osteoblast-based artificial niche that supports in vitro B lymphopoiesis. We demonstrated that the production of a B220⁺ cell population from Lineage⁻ (Lin⁻) Sca-1⁺ c-Kit⁺ hematopoietic stem and progenitor cells (HSPCs) was increased ~1.7-fold by OBN4 cells relative to production by primary osteoblasts and OP9 cells in coculture experiments. Consistently, OBN4 cells exhibited the highest production of B220⁺ IgM⁺ cell populations (6.7±0.6–13.6±0.6%) in an IL-7- and stromal cell-derived factor 1-dependent manner, with higher production than primary osteoblasts (3.7±0.5–6.4±0.6%) and OP9 cells (1.8±0.6–3.9±0.5%). In addition, the production of B220⁺ IgM⁺ IgD⁺ cell populations was significantly enhanced by OBN4 cells (15.4±1.1–18.9±3.2%) relative to production by primary osteoblasts (9.5±0.6–14.6±1.6%) and OP9 cells (9.1±0.5–10.3±1.8%). We conclude that OBN4 cells support in vitro B lymphopoiesis of Lin⁻ Sca-1⁺ c-Kit⁺ HSPCs more efficiently than primary osteoblasts or OP9 stromal cells.

Inmunosenescencia: efectos de la edad sobre el sistema inmune / Immunosenescence: effects of aging process on immune system

El proceso de envejecimiento provoca cambios en el sistema inmune que afectan su funcionamiento y desarrollo. Estos cambios pueden manifestarse desde la linfopoyesis hasta la respuesta que orquesta el sistema inmune frente a determinada enfermedad o agente infeccioso. Ambas ramas de la inmunidad, innata y adaptativa, se afectan en este proceso, lo que genera un impacto negativo en la respuesta inmune de los ancianos y los predispone a padecer enfermedades infecciosas, cáncer, autoinmunidad y a desarrollar respuestas pobres tras la administración de vacunas...

The aging process produces functional and developmental changes in the immune system. Those changes may appear from lymphopoiesis up to the final response of the immune system facing a certain disease. Both branches of immunity, innate and adaptive, are affected by the aging process; hence these changes can have a negative impact on the immune response of elderly patients and increase their susceptibility to infectious diseases, cancer and decreased vaccine efficacy...

Roles of microRNAs in lymphocytopoiesis and lymphoid malignancies - review / 中国实验血液学杂志

microRNAs (miRNAs) are small molecular non-coding RNA with 21-25 nucleotides in a variety of eukaryotic systems, and regulate gene expression at the post-transcriptional level by degrading or translational repressing target messenger RNA (mRNA). Many studies have showed the roles of miRNAs in normal lymphocytopoiesis, giving an interpretative key to the aberrant expression observed in human lymphoid malignancies. The recent advances of understanding the roles of miRNAs in lymphoid malignancies show that miRNAs as tumoral biomarkers can effectively be used for diagnosis, prognosis, and prediction of response to therapy. This review focuses the roles of miRNA in development and differentiation of lymphocytes and the relation of miRNA to lymphoid malignancies.

Interpretation of maturing trilineage hematopoiesis

Normal adult bone marrow occupies the medullary spaces of large bones. The main function of bone marrow is the production of blood cells [hematopoiesis]. Bone marrow is composed of a matrix requisite for hematopoiesis as well as erythriod precursors, myeloid precursors with monocyte macropliage system, megakaryocytes, lymphocytes, plasma cells, blood vessels and stroma. Interpretation of bone marrow maturing trilineage hematopoiesis includes the assessment of the maturation seq uence and morphologic features for each lineage. This review presents detailed guidelines for interpretation of bone marrow maturing trilineage hematopoiesis according to the cell line and the pathologic condition

Linfopoese B associada ao granuloma hepático da esquistossomose: presença de precursores jovens e inibição da diferenciação / B lymphopoiesis associated with hepatic granulomas of schistosomiasis: youth presence of precursors and inhibition of differentiation

A reação inflamatória granulomatosa induzida, no fígado pelos ovos do Schistosoma mansoni é um sítio ativo de mielopoese extramedular potencialmente capaz de produzir todas as linhagens lielóides. O aumento da população de linfócitos B, ao longo da doença, associado à presença de precursores multipotentes, nos fez questionar se, em paralelo a mielopoese, haveria também linfopoese B. Foi demonstrado, por imunofenotipagem, a presença de células com característica de precursor B jovem (pro B) no granuloma. A expressão de RAG 1 e 5 foi demonstrada através da técnica de RT-PCR, confirmando a presença de precursosres B no granuloma. No entanto, colônias pré B não foram observadas, indicando um bloqueio na diferenciação de pro B para pre B. As células do estroma foram capazes de sustentar precursores B e a expressão de IL7 e SCF foi demonstrada. Porém, o meio condicionado de granuloma mostrou atividade inibidora da linfopoese B ao mesmo tempo que estimulava a mielopoese. Além disso, aproximadamente 50% dos precursores B do granuloma expressavam Mac 1. O estudo permitiu concluir que, há o desenvolvimento de um microambiente hematopoietico no granuloma, que permite a migração de progenitores e o multipotentes e o comprometimento para a linhagem B. No entanto, a produção extramedular de linfócitos B é bloqueada por fatores solúveis produzidos no granuloma