Capacity Of Bone Marrow-derived Cells Research Articles

Abstract 17998: Impairment of Vascular Bone Marrow Niche Predicts Death in Patients With Chronic Heart Failure

Background: The bone marrow vascular niche is essential for hematopoietic regeneration. Patients with chronic heart failure are characterized by myelosuppresion and anemia. Therefore, in order to investigate whether chronic heart failure is associated with an impairment in the vascular niche of the bone marrow, we measured in bone marrow plasma levels of the prototypical angiogenic factor PlGF (placental growth factor), as well as, its soluble inhibitor, sFlt-1 (Fms-like tyrosine kinase 1), which acts as a decoy receptor for PlGF, as a measure of the functional integrity of the vascular bone marrow niche. Methods and Results: Bone marrow plasma levels of sFlt-1 and PlGF were determined by ELISA in 187 patients (mean age: 62.2±11.3years) with chronic heart failure, who were enrolled in the Frankfurt Bone Marrow-Derived Mononuclear Cell Therapy Registry. Fifty-one patients died within the 5-year follow-up period. Patients with increased bone marrow-derived sFlt-1/PlGF ratio had a 1.35-fold increased risk for death (95%CI: 1.08 to 1.68, p=0.007). This association was robust after adjustment for age, gender, left ventricular ejection fraction (LVEF), eGFR and NT-proBNP serum levels (HR:1.3, 95%CI: 1.014 to 1.678, p=0.038) or the Seattle Heart Failure score (HR:1.38, 95%CI: 1.112 to 1.723, p=0.004). Importantly, this association remained significant even after adjustment for colony-forming unit capacity (HR:1.33, 95%CI: 1.051 to 1.675, p=0.018) and SDF-1-induced migratory capacity of bone marrow-derived cells (HR:1.35, 95%CI: 1.087 to 1.678, p=0.007). Conclusions: The present study for the first time discloses that an impairment of the angiogenic potential of the bone marrow microenvironment, defined as increased sFlt-1 to PlGF ratio in the bone marrow plasma, is independently associated with mortality in patients with chronic heart failure. These data further corroborate the importance of the bone marrow-heart axis to predict clinical outcome in patients with chronic heart failure.

Bone Marrow Therapies for Chronic Heart Disease.

Chronic heart failure is a leading cause of death. The demand for new therapies and the potential regenerative capacity of bone marrow-derived cells has led to numerous clinical trials. We critically discuss current knowledge of the biology and clinical application of bone marrow cells. It appears unlikely that bone marrow cells can develop into functional cardiomyocyte after infusion but may have favorable paracrine effects. Most, but not all, clinical trials report a modest short- but not long-term benefit of infusing bone marrow-derived cells. Effect size appears to correlate with stringency of study-design: the most stringent trials report the smallest effect-sizes. We conclude there may be short- but not substantial long-term benefit of infusing bone marrow-derived cells into persons with chronic heart failure and any benefit observed is unlikely to result from trans-differentiation of bone marrow-derived cells into functioning cardiomyocytes.

Different effects on bone strength and cell differentiation in pre pubertal caloric restriction versus hypothalamic suppression

Hypothalamic amenorrhea and energy restriction during puberty affect peak bone mass accrual. One hypothesis suggests energy restriction alters hypothalamic function resulting in suppressed estradiol levels leading to bone loss. However, both positive and negative results have been reported regarding energy restriction and bone strength. Therefore, the purpose of this study was to investigate energy restriction and hypothalamic suppression during pubertal onset on bone mechanical strength and the osteogenic capacity of bone marrow-derived cells in two models: female rats treated with gonadotropin releasing hormone antagonists (GnRH-a) or 30% energy restriction. At 23 days of age, female Sprague Dawley rats were assigned to three groups: control group (C, n=10), GnRH-a group (n=10), and Energy Restriction (ER, n=12) group. GnRH-a animals received daily injections for 27 days. The animals in the ER group received 70% of the control animals' intake. After sacrifice (50 days of age), body weight, uterine and muscle weights were measured. Bone marrow-derived stromal cells were cultured and assayed for proliferation and differentiation into osteoblasts. Outcome measures included bone strength, bone histomorphometry and architecture, serum IGF-1 and osteocalcin. GnRH-a suppressed uterine weight, decreased osteoblast proliferation, bone strength, trabecular bone volume and architecture compared to control. Elevated serum IGF-1 and osteocalcin levels and body weight were found. The ER model had an increase in osteoblast proliferation compared to the GnRH-a group, similar bone strength relative to body weight and increased trabecular bone volume in the lumbar spine compared to control. The ER animals were smaller but had developed bone strength sufficient for their size. In contrast, suppressed estradiol via hypothalamic suppression resulted in bone strength deficits and trabecular bone volume loss. In summary, our results support the hypothesis that during periods of nutritional stress the increased vertebral bone volume may be an adaptive mechanism to store mineral which differs from suppressed estradiol resulting from hypothalamic suppression.

Bone Marrow-Derived Cells Exhibiting Lung Epithelial Cell Characteristics Are Enriched In Vivo Using Methylguanine DNA Methyltransferase-Mediated Drug Resistance

Previous studies have suggested that donor bone marrow-derived cells can differentiate into lung epithelial cells at low frequency. We investigated whether we could enrich the number of donor-derived hematopoietic cells that have type II pneumocyte characteristics by overexpression of the drug resistance gene methylguanine DNA methyltransferase (MGMT). MGMT encodes O(6)-alkylguanine DNA alkyltransferase (AGT), a drug resistance protein for DNA damage induced by N,N'-bis(2-chloroethyl)-N-nitrosourea (BCNU), and the mutant P140K MGMT confers resistance to BCNU and the AGT inactivator O(6)-benzylguanine (BG). For this study, we used two MGMT selection models: one in which donor cells had a strong selection advantage because the recipient lung lacked MGMT expression, and another in which drug resistance was conferred by gene transfer of P140K MGMT. In both models, we saw an increase in the total number of donor-derived cells in the lung after BCNU treatment. Analysis of single-cell suspensions from 28 mice showed donor-derived cells with characteristics of type II pneumocytes, determined by surfactant protein C (SP-C) expression. Furthermore, an increase in the percentage of donor-derived SP-C cells was noted after BCNU or BG and BCNU treatment. This study demonstrates that bone marrow cells expressing MGMT can engraft in the lung and convert into cells expressing the type II pneumocyte protein SP-C. Furthermore, these cells can be enriched in response to alkylating agent-mediated lung injury. These results suggest that expression of MGMT could enhance the capacity of bone marrow-derived cells to repopulate lung epithelium, and when used in combination with a gene of interest, MGMT could have therapeutic applications.

Predominant fusion of bone marrow-derived cardiomyocytes

Here we address the capacity of bone marrow-derived cells (BMDCs) to trans-differentiate into mature myocytes under the physiological stimulus of exercise training. For this purpose, we have transplanted bone marrow from mice ubiquitously expressing enhanced green fluorescence protein (eGFP) into host mice that have been subjected to a prolonged program of exercise. In all successful bone marrow reconstitutions (greater than 80%), we observed rare but consistent events of bone marrow-derived cardiomyocytes, the frequency of which was unchanged upon exercise training. We have further determined whether these recruited myocytes are a product of trans-differentiation or fusion by the use of a genetic system that distinguishes cell fusion from trans-differentiation in a single-cell assay. We concluded that both in the unchallenged mouse and in the trained specimens, fusion is the most prominent mechanism by which bone marrow-derived cells are observed in the myocyte compartment.

Local Retention of Soluble Antigen by Potential Antigen-Presenting Cells in the Anterior Segment of the Eye

To determine the capacity of bone marrow-derived cells in the anterior segment of the eye to capture a fluorescence-labeled antigen (Ag) injected into the anterior chamber (AC). Uveal tract and corneoscleral tissues from Lewis rats were cultured in vitro, with or without FITC-dextran (4 microg/mL final concentration), for 48 hours and examined by confocal microscopy. To investigate antigen uptake in vivo 2 microL (20 microg) of Cascade Blue-labeled dextran (CB-Dx) was injected into the right AC of Lewis rats. The density of Ag-positive cells in the iris at 1, 3, 5, or 12 days after injection was examined by in vivo video fluorescence microscopy. The distribution and phenotype of Ag-positive cells in frozen and paraffin-embedded sections of ocular tissues and in iris wholemounts from animals killed at 24 hours and day 7 were analyzed by fluorescence and confocal microscopy. In organ culture conditions numerous cells in the iris, ciliary body, choroid, and corneal limbus were capable of capturing fluorescence-labeled Ag. In vivo observations and microscopic examination of experimental eyes at days 1 and 7 after AC injection revealed Ag-positive cells within the iris, iridocorneal angle, the suprachoroidal space and around limbal-episcleral vessels. Ag-bearing cells in the iris express combinations of macrophage markers but rarely expressed major histocompatibility complex (MHC) class II molecules. A reduced number of Ag-bearing cells were still present in the iris at day 12. Potential antigen-presenting cells (APCs) in the iris and ciliary body are capable of internalizing intracameral Ag. The characteristics of these cells in the iris are consistent with a predominantly macrophage phenotype. These observations also suggest that the Ag leaving the eye through both the conventional and nonconventional aqueous outflow pathways may be captured by potential APCs in the episcleral tissues.