Bone Marrow-derived Multipotent Progenitor Cells Research Articles

Extracellular matrix-regulated neural differentiation of human multipotent marrow progenitor cells enhances functional recovery after spinal cord injury

Background contextRecent advanced studies have demonstrated that cytokines and extracellular matrix (ECM) could trigger various types of neural differentiation. However, the efficacy of differentiation and in vivo transplantation has not yet thoroughly been investigated. PurposeTo highlight the current understanding of the effects of ECM on neural differentiation of human bone marrow-derived multipotent progenitor cells (MPCs), regarding state-of-art cure for the animal with acute spinal cord injury (SCI), and explore future treatments aimed at neural repair. Study designA selective overview of the literature pertaining to the neural differentiation of the MSCs and experimental animals aimed at improved repair of SCI. MethodsExtracellular matrix proteins, tenascin-cytotactin (TN-C), tenascin-restrictin (TN-R), and chondroitin sulfate (CS), with the cytokines, nerve growth factor (NGF)/brain-derived neurotrophic factor (BDNF)/retinoic acid (RA) (NBR), were incorporated to induce transdifferentiation of human MPCs. Cells were treated with NBR for 7 days, and then TN-C, TN-R, or CS was added for 2 days. The medium was changed every 2 days. Twenty-four animals were randomly assigned to four groups with six animals in each group: one experimental and three controls. Animals received two (bilateral) injections of vehicle, MPCs, NBR-induced MPCs, or NBR/TN-C-induced MPCs into the lesion sites after SCI. Functional assessment was measured using the Basso, Beattie, and Bresnahan locomotor rating score. Data were analyzed using analysis of variance followed by Student-Newman-Keuls (SNK) post hoc tests. ResultsResults showed that MPCs with the transdifferentiation of human MPCs to neurons were associated with increased messenger-RNA (mRNA) expression of neuronal markers including nestin, microtubule-associated protein (MAP) 2, glial fibrillary acidic protein, βIII tubulin, and NGF. Greater amounts of neuronal morphology appeared in cultures incorporated with TN-C and TN-R than those with CS. The addition of TN-C enhanced mRNA expressions of MAP2, βIII tubulin, and NGF, whereas TN-R did not significantly change. Conversely, CS exposure decreased MAP2, βIII tubulin, and NGF expressions. The TN-C-treated MSCs significantly and functionally repaired SCI-induced rats at Day 42. Present results indicate that ECM components, such as tenascins and CS in addition to cytokines, may play functional roles in regulating neurogenesis by human MPCs. ConclusionsThese findings suggest that the combined use of TN-C, NBR, and human MPCs offers a new feasible method for nerve repair.

Mesenchymal stem cells as a novel vaccine platform

Vaccines are the most efficient and cost-effective means of preventing infectious disease. However, traditional vaccine approaches have thus far failed to provide protection against human immunodeficiency virus (HIV), tuberculosis, malaria, and many other diseases. New approaches to vaccine development are needed to address some of these intractable problems. In this report, we review the literature identifying stimulatory effects of mesenchymal stem cells (MSC) on immune responses and explore the potential for MSC as a novel, universal vaccination platform. MSC are unique bone marrow-derived multipotent progenitor cells that are presently being exploited as gene therapy vectors for a variety of conditions, including cancer and autoimmune diseases. Although MSC are predominantly known for anti-inflammatory properties during allogeneic MSC transplant, there is evidence that MSC can actually promote adaptive immunity under certain settings. MSC have also demonstrated some success in anti-cancer therapeutic vaccines and anti-microbial prophylactic vaccines, as we report, for the first time, the ability of modified MSC to express and secrete a viral antigen that stimulates antigen-specific antibody production in vivo. We hypothesize that the unique properties of modified MSC may enable MSC to serve as an unconventional but innovative, vaccine platform. Such a platform would be capable of expressing hundreds of proteins, thereby generating a broad array of epitopes with correct post-translational processing, mimicking natural infection. By stimulating immunity to a combination of epitopes, it may be possible to develop prophylactic and even therapeutic vaccines to tackle major health problems including those of non-microbial and microbial origin, including cancer, or an infectious disease like HIV, where traditional vaccination approaches have failed.

The ERK5 and ERK1/2 signaling pathways play opposing regulatory roles during chondrogenesis of adult human bone marrow‐derived multipotent progenitor cells

Adult human bone marrow-derived multipotent progenitor cells (MPCs) are able to differentiate into a variety of specialized cell types, including chondrocytes, and are considered a promising candidate cell source for use in cartilage tissue engineering. In this study, we examined the regulation of MPC chondrogenesis by mitogen-activated protein kinases in an attempt to better understand how to generate hyaline cartilage in the laboratory that more closely resembles native tissue. Specifically, we employed the high-density pellet culture model system to assess the roles of ERK5 and ERK1/2 pathway signaling in MPC chondrogenesis. Western blotting revealed that high levels of ERK5 phosphorylation correlate with low levels of MPC chondrogenesis and that as TGF-beta 3-enhanced MPC chondrogenesis proceeds, phospho-ERK5 levels steadily decline. Conversely, levels of phospho-ERK1/2 paralleled the progression of MPC chondrogenesis. siRNA-mediated knockdown of ERK5 pathway components MEK5 and ERK5 resulted in increased MPC pellet mRNA transcript levels of the cartilage-characteristic marker genes SOX9, COL2A1, AGC, L-SOX5, and SOX6, as well as enhanced accumulation of SOX9 protein, collagen type II protein, and Alcian blue-stainable proteoglycan. In contrast, knockdown of ERK1/2 pathway members MEK1 and ERK1 decreased expression of all chondrogenic markers tested. Finally, overexpression of MEK5 and ERK5 also depressed MPC chondrogenesis, as indicated by diminished activity of a co-transfected collagen II promoter-luciferase reporter construct. In conclusion, our results suggest a novel role for the ERK5 pathway as an important negative regulator of adult human MPC chondrogenesis and illustrate that the ERK5 and ERK1/2 kinase cascades play opposing roles regulating MPC cartilage formation.

Long-term functional improvement and gene expression changes after bone marrow-derived multipotent progenitor cell transplantation in myocardial infarction

The study examined the long-term outcome of cardiac stem cell transplantation in hearts with postinfarction left ventricular (LV) remodeling. Myocardial infarction (MI) was created by ligating the first and second diagonal branches of the left anterior descending coronary artery in miniature swine. Intramyocardial injections of 50 million LacZ-labeled bone marrow-derived multipotent progenitor cells (MPC) were performed in the periscar region (Cell, n = 7) immediately after MI, whereas, in control animals (Cont, n = 7), saline was injected. Functional outcome was assessed monthly for 4 mo with MRI and (31)P-magnetic resonance spectroscopy. Engraftment was studied on histology, and gene chip (Affymetrix) array analysis was used to study differential expression of genes in the two groups. MPC treatment resulted in improvement of ejection fraction as early as 10 days after MI (Cell, 43.4 +/- 5.1% vs. Cont, 32.2 +/- 5.5%; P < 0.05). This improvement was seen each month and persisted to 4 mo (Cell, 51.2 +/- 4.8% vs. Cont, 35.7 +/- 5.0%; P < 0.05). PCr-to-ATP ratio (PCr/ATP) improved with MPC transplantation, which was most pronounced at high cardiac work states (subendocardial PCr/ATP was 1.70 +/- 0.10 vs. 1.34 +/- 0.14, P < 0.05). There was no significant difference in scar size (scar/LV area * 100) at 10 days postinfarction. However, at 4 mo, there was a significant decrease in scar size in the Cell group (Cell, 4.6 +/- 1.0% vs. Cont, 8.6 +/- 2.4%; P < 0.05). No significant engraftment of MPC was observed. MPC transplantation was associated with a downregulation of mitochondrial oxidative enzymes and increased levels of myocyte enhancer factor 2a and zinc finger protein 91. In conclusion, MPC transplantation leads to long-term functional and bioenergetic improvement in a porcine model of postinfarction LV remodeling, despite no significant engraftment of stem cells in the heart. MPC transplantation reduces regional wall stresses and infarct size and mitigates the adverse effects of LV remodeling, as seen by a reduction in LV hypertrophy and LV dilatation, and is associated with differential expression of genes relating to metabolism and apoptosis.

Behavioral and Histological Characterization of Intrahippocampal Grafts of Human Bone Marrow-Derived Multipotent Progenitor Cells in Neonatal Rats with Hypoxic-Ischemic Injury

Children born with hypoxic-ischemic (HI) brain injury account for a significant number of live births wherein no clinical treatment is available. Limited clinical trials of stem cell therapy have been initiated in a number-of neurological disorders, but the preclinical evidence of a cell-based therapy for neonatal HI injury remains in its infancy. One major postulated mechanism underlying therapeutic benefits of stem cell therapy involves stimulation of endogenous neurogenesis via transplantation of exogenous stem cells. To this end, transplantation has targeted neurogenic sites, such as the hippocampus, for brain protection and repair. The hippocampus has been shown to secrete growth factors, especially during the postnatal period, suggesting that this brain region presents as highly conducive microenvironment for cell survival. Based on its neurogenic and neurotrophic factor-secreting features, the hippocampus stands as an appealing target for stem cell therapy. Here, we investigated the efficacy of intrahippocampal transplantation of multipotent progenitor cells (MPCs), which are pluripotent progenitor cells with the ability to differentiate into a neuronal lineage. Seven-day-old Sprague-Dawley rats were initially subjected to unilateral HI injury, which involved permanent ligation of the right common carotid artery and subsequent exposure to hypoxic environment. At day 7 after HI injury, animals received stereotaxic hippocampal injections of vehicle or cryopre-served MPCs (thawed just prior to transplantation) derived either from Sprague-Dawley rats (syngeneic) or Fisher rats (allogeneic). All animals were treated with daily immunosuppression throughout the survival period. Behavioral tests were conducted on posttransplantation days 7 and 14 using the elevated body swing test and the rotarod to reveal general and coordinated motor functions. MPC transplanted animals exhibited reduced motor asymmetry and longer time spent on the rotarod than those that received the vehicle infusion. Both syngeneic and allogeneic MPC transplanted injured animals did not significantly differ in their behavioral improvements at both test periods. Immunohistochemical evaluations of graft survival after behavioral testing at day 14 posttransplantation revealed that syngeneic and allogeneic transplanted MPCs survived in the hippocampal region. These results demonstrate for the first time that transplantation of MPCs ameliorated motor deficits associated with HI injury. In view of comparable behavioral recovery produced by syngeneic and allogeneic MPC grafts, allogeneic transplantation poses as a feasible and efficacious cell replacement strategy with direct clinical application. An equally major finding is the observation lending support to the hippocampus as an excellent target brain region for stem cell therapy in treating HI injury.