Bone marrow-derived fibrocytes contribute to liver fibrosis

Chronic liver injury often leads to hepatic fibrosis, a condition associated with increased levels of circulating TGF-β1 and lipopolysaccharide, activation of myofibroblasts, and extensive deposition of extracellular matrix, mostly collagen Type I. Hepatic stellate cells are considered to be the major¹ but not the only source of myofibroblasts in the injured liver.² Hepatic myofibroblasts may also originate from portal fibroblasts, mesenchymal cells, and fibrocytes.³ Since the discovery of fibrocytes in 1994 by Dr. Bucala and colleagues, this bone marrow (BM)-derived collagen Type I-producing CD45⁺ cells remain the most fascinating cells of the hematopoietic system. Due to the ability to differentiate into collagen Type I producing cells/myofibroblasts, fibrocytes were implicated in the pathogenesis of liver, skin, lung, and kidney fibrosis. However, studies of different organs often contain controversial results on the number of fibrocytes recruited to the site of injury and their biological function. Furthermore, fibrocytes were implicated in the pathogenesis of sepsis and were shown to possess antimicrobial activity. Finally, in response to specific stimuli, fibrocytes can give rise to fully differentiated macrophages, suggesting that in concurrence with the high plasticity of hematopoietic cells, fibrocytes exhibit progenitor properties. Here, we summarize our current understanding of the role of CD45⁺Collagen Type I⁺ BM-derived cells in response to fibrogenic liver injury and septicemia and discuss the most recent evidence supporting the critical role of fibrocytes in the mediation of pro-fibrogenic and/or pro-inflammatory responses.     

Bone marrow interferon]

The nucleated cells of the bone marrow of mouse, rat, guinea pig, chick, cattle and humans proved to be capable of producing interferon in vitro following induction with the Newcastle disease virus. The production of interferon by these cells was characterized by high stability. The bone marrow interferon was not inferior in its activity to the corresponding interferon prepared with the blood leukocytes or splenic cells.     

Bone marrow to liver: the blood of Prometheus

The existence of hepatic stem or progenitor cells has been controversial for decades, though it was presumed that if such cells existed, they would lie within the liver. There is now consensus, however, that not only do facultative hepatic stem cells exist within the liver, but also that cells from extra-hepatic sites, in particular the bone marrow, can contribute to hepatocyte and cholangiocyte regeneration. Despite confidence that engraftment of marrow cells in the liver occurs, the mechanistic details of this process remain poorly understood. Moreover, the physiological importance and therapeutic utility of this phenomenon remains controversial.     

Bone marrow stroma cells are susceptible to prion infection

Abnormal protease-resistant prion protein (PrP-res) is the only surrogate biochemical marker for prion diseases, and a sensitive technique to detect PrP-res in blood or tissues is urgently needed. Primary cultured bone marrow stromal cells (MSCs) expressed PrP and were capable of supporting stable human prion infection. Using a mouse-adapted BSE strain, we demonstrated that PrP-res can be detected in expanded MSCs. We then analyzed the bone marrow cells collected at autopsy from two individuals with sporadic Creutzfeldt-Jakob disease (CJD), and, in both cases, cultured MSCs were positive for PrP-res. These data would suggest that ex vivo MSC expansion accompanied by PrP-res analysis could be a helpful tool in the definitive diagnosis of prion disease at an earlier stage in the disease process than is currently possible, and with considerably less distress to the patient.     

Bone marrow biopsy (BMB). II. Bone marrow biopsy in myeloproliferative disorders

The myeloproliferative disorders (MPD) are a domain in which the bone marrow biopsy (BMB) greatly proved its utility. We have studied the histology of the bone marrow (BM) in all the four entities of MPD: chronic myeloid leukemia (CML) with its subtype, chronic megakaryocytic granulocytic myelosis (CMGM), polycythemia vera (PV), hemorrhagic thrombocythemia (HT) and myeloid metaplasia with myelofibrosis (MMM). The work presents in short some of the clinical and hematologic characters of MPD with special stress upon the histologic modifications of BM, either specific or common to all MPD entities, underlying also the criteria for differential diagnosis.     

Bone marrow transplantation--an expanding approach to treatment of many diseases

Thus, we can conclude that marrow transplantation has already influenced medical practice greatly. It has offered a treatment which often cures patients of more than 20 otherwise lethal diseases. The treatment so horrendously difficult and dangerous at first has already been greatly improved, simplified, and made much safer. The availability of a suitable donor has been much extended and real progress has been made in prevention and perhaps even in treatment of graft-versus-host disease. This has made possible the option of marrow transplantation for every patient in whom we think the treatment may be beneficial. The problem underlying many cases of interstitial pneumonia has been identified and patients are already benefitting clinically from this progress. Progress has also been made which promises antiviral therapy which could reduce, prevent, and ultimately eliminate the intercurrent virus infections which limit the applicability of marrow transplantation, especially for children with severe immunodeficiencies. I do not know how far this line of investigation can be taken. However, just as we have learned stepwise to use marrow transplants from matched siblings to treat many diseases, to use fetal liver in place of bone marrow, to employ matched relative donors when a matched sibling is not available, and, finally, even to use parental donors to achieve correction of SCID, we now have good reason to believe that, ultimately, we can use marrow transplantation without fear of GVHD to address many additional genetically determined and acquired diseases; certainly, for those diseases that involve any of the cells that are derived from bone marrow cells, and perhaps for those attributable even to cells of other organs and tissues, the functions of which are, in whole or in part, a consequence of interactions of marrow-derived cells and cells of ectodermal or endodermal origin, marrow transplantation may be useful. To us, the future of marrow transplantation as a major modality of treatment or prevention of many diseases, including hemoglobinopathesis, immunodeficiencies, hematologic abnormalities, abnormalities of function of marrow-derived cells, and even inborn errors of function of cells of organs and tissues not of marrow origin, seems bright, indeed. Further, with the capacity to introduce resistance genes against viruses and malignancies, autoimmune diseases, and diseases dependent on anomalies of immune response genes, marrow transplantation for many other diseases seems a more remote possibility.(ABSTRACT TRUNCATED AT 400 WORDS)     

Bone marrow eythroid series cellular reaction to antigenic stimulation]

The authors describe changes in the cells of the erythroid series of the bone marrow against the background of immunization with diphtheria toxoid. Physiological saline was injected to control animals. Changes in the blood system were in one direction and were expressed in the erythroblastic reaction; this reaction was less pronounced in control than in the experimental animals.