Enhancement of angiogenic effect of co-transfection human NGF and VEGF genes in rat bone marrow mesenchymal stem cells

Bone marrow mesenchymal stem cells enhance autophagy and help protect cells under hypoxic and retinal detachment conditions

Our study aimed to evaluate the protective role and mechanisms of bone marrow mesenchymal stem cells (BMSCs) in hypoxic photoreceptors and experimental retinal detachment. The cellular morphology, viability, apoptosis and autophagy of hypoxic 661w cells and cells cocultured with BMSCs were analysed. In retinal detachment model, BMSCs were intraocularly transplanted, and then, the retinal morphology, outer nuclear layer (ONL) thickness and rhodopsin expression were studied as well as apoptosis and autophagy of the retinal cells. The hypoxia‐induced apoptosis of 661w cells obviously increased together with autophagy levels increasing and peaking at 8 hours after hypoxia. Upon coculturing with BMSCs, hypoxic 661w cells had a better morphology and fewer apoptosis. After autophagy was inhibited, the apoptotic 661w cells under the hypoxia increased, and the cell viability was reduced, even in the presence of transplanted BMSCs. In retina‐detached eyes transplanted with BMSCs, the retinal ONL thickness was closer to that of the normal retina. After transplantation, apoptosis decreased significantly and retinal autophagy was activated in the BMSC‐treated retinas. Increased autophagy in the early stage could facilitate the survival of 661w cells under hypoxic stress. Coculturing with BMSCs protects 661w cells from hypoxic damage, possibly due to autophagy activation. In retinal detachment models, BMSC transplantation can significantly reduce photoreceptor cell death and preserve retinal structure. The capacity of BMSCs to reduce retinal cell apoptosis and to initiate autophagy shortly after transplantation may facilitate the survival of retinal cells in the low‐oxygen and nutrition‐restricted milieu after retinal detachment.

Folate receptor mediated genetic modification of human mesenchymal stem cells via folic acid-polyethylenimine-grafted poly(N-3-hydroxypropyl)aspartamide

Mesenchymal stem cells (MSCs) are targeted as vehicles for cell mediated gene therapy. Here we report on a macromolecular carrier, which was designed aiming at successful targeted gene delivery into MSCs through the mediation of folate receptor and reduced cytotoxicity compared to established cationic polymer vector - polyethylenimine with a weight average molecular weight (Mw) of 25,000 Dalton (PEI25K). The carrier PHPA-PEI1800-FA was synthesized in a two-step procedure. PHPA-PEI1800 was prepared by grafting polyethylenimine with a Mw of 1800 Dalton (PEI1800) onto the α,β-poly(N-3-hydroxypropyl)-D,L-aspartamide (PHPA) backbone. PHPA-PEI1800-FA was obtained by chemically conjugating folic acid onto PHPA-PEI1800. The grafting degree of PEI1800 was 3.9±0.2% in relation to the CH groups of PHPA and the molar ratio of folic acid conjugated to PEI1800 (χFA) was 1.8±0.1 as calculated by NMR spectroscopy. The copolymers were biodegradable and exhibited lower cytotoxicity than PEI25K. Compared to PHPA-PEI1800, PHPA-PEI1800-FA led to a significantly higher transfection efficiency in human MSCs, which could be attributed to the mediation of folate receptor during the transfection process as confirmed by folic acid competition assay. Both marker gene (GFP) and therapeutic gene (VEGF) were delivered into human MSCs from multi-donors using PHPA-PEI1800-FA. The percentage of GFP+ MSCs showed an average value of 2.85±1.60% but a large variation for different samples. The VEGF expression level of the PHPA-PEI1800-FA transfected cells was significantly higher than that of either untransfected or naked DNA transfected cells. Conclusively, PHPA-PEI1800-FA is a suitable vector to deliver genes into human MSCs through the interaction with folate receptor.

Effect of Co-transfection of Anti-myostatin shRNA Constructs in Caprine Fetal Fibroblast Cells

Knockdown of myostatin gene (MSTN), transforming growth factor-β superfamily, and a negative regulator of the skeletal muscle growth, by RNA interference (RNAi), has been reported to increase muscle mass in mammals. The current study was aimed to cotransfect two anti-MSTN short hairpin RNA (shRNA) constructs in caprine fetal fibroblast cells for transient silencing of MSTN gene. In the present investigation, approximately 89% MSTN silencing was achieved in transiently transfected caprine fetal fibroblast cells by cotransfection of two best out of four anti-MSTN shRNA constructs. Simultaneously, we also monitored the induction of IFN responsive genes (IFN), pro-apoptotic gene (caspase3) and anti-apoptotic gene (MCL-1) due to cotransfection of different anti-MSTN shRNA constructs. We observed induction of 0.66-19.12, 1.04-4.14, 0.50-3.43, and 0.42-1.98 for folds IFN-β, OAS1, caspase3, and MCL-1 genes, respectively (p < 0.05). This RNAi based cotransfection method could provide an alternative strategy of gene knockout and develop stable caprine fetal fibroblast cells. Furthermore, these stable cells can be used as a cell donor for the development of transgenic cloned embryos by somatic cell nuclear transfer (SCNT) technique.

Vascular endothelial growth factor and biphasic calcium phosphate in the endosseous healing of femoral defects: An experimental rat study

Background/purpose

The presence of adequate bone volume is a critical factor in rehabilitative dentistry. Despite the use of many promising alloplasts, success in stimulating bone formation has been limited, mostly due to poor local biological response. Growth factors have been introduced to stimulate angiogenesis and new bone formation. This histologic and histomorphometric study aimed to evaluate the effect of vascular endothelial growth factor (VEGF) and a biphasic alloplastic graft material (BA) on the healing of endosseous defects in rats.

Materials and methods

Twenty male Wistar rats were used. Two critical-sized bone defects were created in both the right and left femurs of each rat. Each defect was randomly assigned to be treated with VEGF, BA, or VEGF + BA, or to be left empty as a control. Half of the animals were sacrificed after 1 week, and the remaining half were sacrificed after 2 weeks. Inflammation, necrosis, and new bone areas were evaluated by means of histologic and histomorphometric analyses.

Results

Compared to the control group, defects treated with VEGF alone or in combination with BA showed higher rates of bone formation (33.10–46.60%) on Day 7. Additionally, VEGF significantly reduced inflammation and necrosis (P < 0.001). However, the differences were no longer discernable on Day 14.

Conclusion

VEGF makes a significant contribution to angiogenesis and osteogenesis in the early stages of bone defect healing, and its combination with an osteoconductive grafting material (BA) may further enhance new bone formation.

Effects of nerve growth factor and basic fibroblast growth factor dual gene modification on rat bone marrow mesenchymal stem cell differentiation into neuron-like cells in vitro

Recent studies regarding regenerative medicine have focused on bone marrow mesenchymal stem cells (BMSCs), which have the potential to undergo neural differentiation, and may be transfected with specific genes. BMSCs can differentiate into neuron-like cells in certain neurotropic circumstances in vitro. Basic fibroblast growth factor (bFGF) and nerve growth factor (NGF) are often used to induce neural differentiation in BMSCs in vitro. However, previous studies regarding their combined actions are insufficient. The present study is the first, to the best of our knowledge, to thoroughly assess the enhancement of neural differentiation of BMSCs following transfection with bFGF and NGF. Sprague-Dawley (SD) rat BMSCs were separated through whole bone marrow adherence, and were then passaged to the third generation. The cells were subsequently divided into five groups: The control group, which consisted of untransfected BMSCs; the plv-blank-transfected BMSCs group; the plv-bFGF-trans-fected BMSCs group; the plv-NGF-transfected BMSCs group; and the plv-NGF-bFGF co-transfected BMSCs group. Cell neural differentiation was characterized in terms of stem cell molecular expression, and the neuronal morphology and expression of neural-like molecules was detected in each of the groups. A total of 72 h post-transfection, the expression levels of neuron-specific enolase, glial fibrillary acidic protein, and nestin protein, were higher in the co-transfected group, as compared with the other groups, the expression levels of β-tubulin III were also increased in the co-transfected cells, thus suggesting the maturation of differentiated neuron-like cells. Furthermore, higher neuronal proliferation was observed in the co-transfected group, as compared with the other groups at passages 2, 4, 6 and 8. Western blotting demonstrated that the transfected groups exhibited a simultaneous increase in phosphorylation of the AKT and extracellular signal-regulated kinases (ERK) signaling pathway. These results suggested that manipulation of the ERK and AKT signaling pathway may be associated with the differentiation of transfected BMSCs.

PDGF-BB does not accelerate healing in diabetic mice with splinted skin wounds

Topical application of platelet-derived growth factor-BB (PDGF-BB) is considered to accelerate tissue repair of impaired chronic wounds. However, the vast literature is plagued with conflicting reports of its efficacy in animal models and this is often influenced by a wide array of experimental variables making it difficult to compare the results across the studies. To mitigate the confounding variables that influence the efficacy of topically applied PDGF-BB, we used a controlled full thickness splinted excisional wound model in db/db mice (type 2 diabetic mouse model) for our investigations. A carefully-defined silicone-splinted wound model, with reduced wound contraction, controlled splint and bandage maintenance, allowing for healing primarily by reepithelialization was employed. Two splinted 8 mm dorsal full thickness wounds were made in db/db mice. Wounds were topically treated once daily with either 3 µg PDGF-BB in 30 µl of 5% PEG-PBS vehicle or an equal volume of vehicle for 10 days. Body weights, wound contraction, wound closure, reepithelialization, collagen content, and wound bed inflammation were evaluated clinically and histopathologically. The bioactivity of PDGF-BB was confirmed by in vitro proliferation assay. PDGF-BB, although bioactive in vitro, failed to accelerate wound healing in vivo in the db/db mice using the splinted wound model. Considering that the predominant mechanism of wound healing in humans is by re-epeithelialization, the most appropriate model for evaluating therapeutics is one that uses splints to prevent excessive wound contraction. Here, we report that PDGF-BB does not promote wound closure by re-epithelialization in a murine splinted wound model. Our results highlight that the effects of cytoactive factors reported in vivo ought to be carefully interpreted with critical consideration of the wound model used.

Injection of mesenchymal stromal cells into a mechanically stimulated in vitro model of cardiac fibrosis has paracrine effects on resident fibroblasts

BACKGROUND AIMS

Myocardial infarction results in the formation of scar tissue populated by myofibroblasts, a phenotype characterized by increased contractility and matrix deposition. Mesenchymal stromal cells (MSC) delivered to the myocardium can attenuate scar growth and restore cardiac function, though the mechanism is unclear.

METHODS

This study describes a simple yet robust three-dimensional (3D) in vitro co-culture model to examine the paracrine effects of implanted MSC on resident myofibroblasts in a controlled biochemical and mechanical environment. The fibrosis model consisted of fibroblasts embedded in a 3D collagen gel cultured under defined oxygen tensions and exposed to either cyclic strain or interstitial fluid flow. MSC were injected into this model, and the effect on fibroblast phenotype was evaluated 48 h after cell injection.

RESULTS

Analysis of gene and protein expression of the fibroblasts indicated that injection of MSC attenuated the myofibroblast transition in response to reduced oxygen and mechanical stress. Assessment of vascular endothelial growth factor and insulin-like growth factor-1 levels demonstrated that their release by fibroblasts was markedly upregulated in hypoxic conditions but attenuated by strain or fluid flow. In fibroblast-MSC co-cultures, vascular endothelial growth factor levels were increased by hypoxia but not affected by mechanical stimuli, whereas insulin-like growth factor-1 levels were generally low and not affected by experimental conditions.

CONCLUSIONS

This study demonstrates how a 3D in vitro model of the cardiac scar can be used to examine paracrine effects of MSC on the phenotype of resident fibroblasts and therefore illuminates the role of injected progenitor cells on the progression of cardiac fibrosis.

Reversal of ischemic cardiomyopathy with Sca-1+ stem cells modified with multiple growth factors

Background

We hypothesized that bone marrow derived Sca-1⁺ stem cells (BM Sca-1⁺) transduced with multiple therapeutic cytokines with diverse effects will induce faster angiomyogenic differentiation in the infarcted myocardium.

Methods and Results

BM Sca-1⁺ were purified from transgenic male mice expressing GFP. Plasmids encoding for select quartet of growth factors, i.e., human IGF-1, VEGF, SDF-1α and HGF were prepared and used for genetic modification of Sca-1⁺ cells (^GFSca-1⁺). Scramble transfected cells (^ScSca-1⁺) were used as a control. RT-PCR and western blotting showed significantly higher expression of the growth factors in ^GFSca-1⁺. Besides the quartet of the therapeutic growth factors, PCR based growth factor array showed upregulation of multiple angiogenic and prosurvival factors such as Ang-1, Ang-2, MMP9, Cx43, BMP2, BMP5, FGF2, and NGF in ^GFSca-1⁺ (p<0.01 vs^ScSca-1⁺). LDH and TUNEL assays showed enhanced survival of ^GFSca-1⁺ under lethal anoxia (p<0.01 vs ^ScSca-1⁺). MTS assay showed significant increased cell proliferation in ^GFSca-1⁺ (p<0.05 vs^ScSca-1⁺). For in vivo study, female mice were grouped to receive the intramyocardial injection of 15 μl DMEM without cells (group-1) or containing 2.5×10^5ScSca-1⁺ (group-2) or ^GFSca-1⁺ (group-3) immediately after coronary artery ligation. As indicated by Sry gene, a higher survival of ^GFSca-1⁺ in group-3 on day4 (2.3 fold higher vs group-2) was observed with massive mobilization of stem and progenitor cells (cKit⁺, Mdr1⁺, Cxcr4⁺ cells). Heart tissue sections immunostained for actinin and Cx43 at 4 weeks post engraftment showed extensive myofiber formation and expression of gap junctions. Immunostaining for vWF showed increased blood vessel density in both peri-infarct and infarct regions in group-3. Infarct size was attenuated and the global heart function was improved in group-3 as compared to group-2.

Conclusions

Administration of BM Sca-1⁺ transduced with multiple genes is a novel approach to treat infarcted heart for its regeneration.

Overexpression of β-NGF promotes differentiation of bone marrow mesenchymal stem cells into neurons through regulation of AKT and MAPK pathway

Bone marrow stromal stem cells (BMSCs) are fibroblastic in shape and capable of self-renewal and have the potential for multi-directional differentiation. Nerve growth factor (NGF), a homodimeric polypeptide, plays an important role in the nervous system by supporting the survival and growth of neural cells, regulating cell growth, promoting differentiation into neuron, and neuron migration. Adenoviral vectors are DNA viruses that contain 36 kb of double-stranded DNA allowing for transmission of the genes to the host nucleus but not inserting them into the host chromosome. The present study aimed to investigate the induction efficiency and differentiation of neural cells from BMSCs by β-NGF gene transfection with recombinant adenoviral vector (Ad-β-NGF) in vitro. The results of immunochemical assay confirmed the induced cells as neuron cells. Moreover, flow cytometric analysis, Annexin-V-FITC/PI, and BrdU assay revealed that chemical inducer β-mercaptoethanol (β-met) triggered apoptosis of BMSCs, as evidenced by inhibition of DNA fragmentation, nuclear condensation, translocation of phospholipid phosphatidylserine, and activation of caspase-3. Furthermore, the results of western blotting showed that β-met suppressed AKT signaling pathway and regulated the MAPKs during differentiation of BMSCs. In contrast, Ad-β-NGF effectively induced the differentiation of BMSCs without causing any cytopathic phenomenon and apoptotic cell death. Moreover, Ad-β-NGF recovered the expression level of phosphorylated AKT and MAPKs in cells exposed to chemical reagents. Taken together, these results suggest that β-NGF gene transfection promotes the differentiation of BMSCs into neurons through regulation of AKT and MAPKs signaling pathways.

VEGF induces sensory and motor peripheral plasticity, alters bladder function, and promotes visceral sensitivity

BACKGROUND

This work tests the hypothesis that bladder instillation with vascular endothelial growth factor (VEGF) modulates sensory and motor nerve plasticity, and, consequently, bladder function and visceral sensitivity.In addition to C57BL/6J, ChAT-cre mice were used for visualization of bladder cholinergic nerves. The direct effect of VEGF on the density of sensory nerves expressing the transient receptor potential vanilloid subfamily 1 (TRPV1) and cholinergic nerves (ChAT) was studied one week after one or two intravesical instillations of the growth factor.To study the effects of VEGF on bladder function, mice were intravesically instilled with VEGF and urodynamic evaluation was assessed. VEGF-induced alteration in bladder dorsal root ganglion (DRG) neurons was performed on retrogradly labeled urinary bladder afferents by patch-clamp recording of voltage gated Na+ currents. Determination of VEGF-induced changes in sensitivity to abdominal mechanostimulation was performed by application of von Frey filaments.

RESULTS

In addition to an overwhelming increase in TRPV1 immunoreactivity, VEGF instillation resulted in an increase in ChAT-directed expression of a fluorescent protein in several layers of the urinary bladder. Intravesical VEGF caused a profound change in the function of the urinary bladder: acute VEGF (1 week post VEGF treatment) reduced micturition pressure and longer treatment (2 weeks post-VEGF instillation) caused a substantial reduction in inter-micturition interval. In addition, intravesical VEGF resulted in an up-regulation of voltage gated Na(+) channels (VGSC) in bladder DRG neurons and enhanced abdominal sensitivity to mechanical stimulation.

CONCLUSIONS

For the first time, evidence is presented indicating that VEGF instillation into the mouse bladder promotes a significant increase in peripheral nerve density together with alterations in bladder function and visceral sensitivity. The VEGF pathway is being proposed as a key modulator of neural plasticity in the pelvis and enhanced VEGF content may be associated with visceral hyperalgesia, abdominal discomfort, and/or pelvic pain.