BMP4 promotes vascularization of human adipose stromal cells and endothelial cells in vitro and in vivo

Protonation-mediated DNA tile self-assembly with nuclease resistance characteristic for signal-amplified detection of microRNAs

DNA nanotechnology, developing rapidly in recent years, has unprecedented superiorities in biological application-oriented research including high programmability, convenient functionalization, reconfigurable structure, and intrinsic biocompatibility. However, the susceptibility to nucleases in the physiological environment has been an obstacle to applying DNA nanostructures in biological science research. In this study, a new DNA self-assembly strategy, mediated by double-protonated small molecules instead of classical metal ions, is developed to enhance the nuclease resistance of DNA nanostructures while retaining their integrality and functionality, and the relative application has been launched in the detection of microRNAs (miRNAs). Faced with low-abundance miRNAs, we integrate hybrid chain reaction (HCR) with DNA self-assembly in the presence of double-protonated small molecules to construct a chemiluminescence detection platform with nuclease resistance, which utilizes the significant difference of molecular weight between DNA arrays and false-positive products to effectively separate of reaction products and remove the detection background. This strategy attaches importance to the nucleic acid stability during the assay process via improving nuclease resistance while rendering the detection results for miRNAs more authentic and reliable, opening our eyes to more possibilities for the multiple applications of customized DNA nanostructures in biology, including bioassay, bioimaging, drug delivery, and cell modulation.

Inhibition of BMP4 alleviates diabetic retinal vascular dysfunction via the VEGF and smad1/5 signalling

Objective:The aim of our study was to determine the molecular mechanism of BMP4 (bone morphogenetic protein 4) in DR (diabetic retinopathy).Methods: Human retinal endothelial cell (HRECs) induced by high glucose to simulate one of the pathogenesis in the diabetic retinopathy (DR) model. RT-qPCR and western blot were used to detect the mRNA and protein levels of BMP4 in the STZ/HG group. Flow cytometry and TUNEL staining were performed to detect the apoptosis. Angiogenesis was evaluated by tube formation assay. Transwell assay and wound healing assay were used to detect cell migration ability. H&E staining was used to evaluate the pathological changes.Results: BMP4 was significantly upregulated in the STZ/HG group. Sh-BMP4 significantly inhibited the migration and angiogenesis of RVECs induced by HG. In addition, both in vivo and in vitro experiments confirmed that sh-BMP4 could significantly promote RVECs apoptosis in the HG/STZ group. Western blot results showed that sh-BMP4 could down-regulate the expressions of p-smad1, p-smad5 and VEGF.Conclusions: Inhibition of BMP4 could alleviate the damage of diabetic retinopathy by regulating the p-smad1/5/VEGF signaling axis, inhibiting angiogenesis and promoting apoptosis.

The role of bone morphogenetic protein 4 in corneal injury repair

PURPOSE

Corneal injury may cause neovascularization and lymphangiogenesis in cornea which have a detrimental effect to vision and even lead to blindness. Bone morphogenetic protein 4 (BMP4) regulates a variety of biological processes, which is closely relevant to the regulation of corneal epithelium and angiogenesis. Herein, we aimed to evaluate the effect of BMP4 on corneal neovascularization (CNV), corneal lymphangiogenesis (CL), corneal epithelial repair, and the role of BMP4/Smad pathway in these processes.

METHODS

We used MTT assay to determine the optimal concentration of BMP4. The suture method was performed to induce rat CNV and CL. We used ink perfusion and HE staining to visualize the morphological change of CNV, and utilized RT-qPCR and ELISA to investigate the expression of angiogenic factors and lymphangiogenic factors. The effects of BMP4 and anti-VEGF antibody on migration, proliferation and adhesion of corneal epithelium were determined by scratch test, MTT assay and cell adhesion test.

RESULTS

BMP4 significantly inhibited CNV and possibly CL. Topical BMP4 resulted in increased expression of endogenous BMP4, and decreased expression of angiogenic factors and lymphangiogenic factors. Compared with anti-VEGF antibody, BMP4 enhanced corneal epithelium migration, proliferation and adhesion, which facilitated corneal epithelial injury repair. Simultaneously, these processes could be regulated by BMP4/Smad pathway.

CONCLUSIONS

Our results demonstrated unreported effects of BMP4 on CNV, CL, and corneal epithelial repair, suggesting that BMP4 may represent a potential therapeutic target in corneal injury repair.

Angiogenesis in a 3D model containing adipose tissue stem cells and endothelial cells is mediated by canonical Wnt signaling

Adipose-derived stromal cells (ASCs) have gained great attention in regenerative medicine. Progress in our understanding of adult neovascularization further suggests the potential of ASCs in promoting vascular regeneration, although the specific cues that stimulate their angiogenic behavior remain controversial. In this study, we established a three-dimensional (3D) angiogenesis model by co-culturing ASCs and endothelial cells (ECs) in collagen gel and found that ASC-EC-instructed angiogenesis was regulated by the canonical Wnt pathway. Furthermore, the angiogenesis that occurred in implants collected after injections of our collagen gel-based 3D angiogenesis model into nude mice was confirmed to be functional and also regulated by the canonical Wnt pathway. Wnt regulation of angiogenesis involving changes in vessel length, vessel density, vessel sprout, and connection numbers occurred in our system. Wnt signaling was then shown to regulate ASC-mediated paracrine signaling during angiogenesis through the nuclear translocation of β-catenin after its cytoplasmic accumulation in both ASCs and ECs. This translocation enhanced the expression of nuclear co-factor Lef-1 and cyclin D1 and activated the angiogenic transcription of vascular endothelial growth factor A (VEGFA), basic fibroblast growth factor (bFGF), and insulin-like growth factor 1 (IGF-1). The angiogenesis process in the 3D collagen model appeared to follow canonical Wnt signaling, and this model can help us understand the importance of the canonical Wnt pathway in the use of ASCs in vascular regeneration.

Enhancing engineered vascular networks in vitro and in vivo: The effects of IGF1 on vascular development and durability

OBJECTIVES

Creation of functional, durable vasculature remains an important goal within the field of regenerative medicine. Engineered biological vasculature has the potential to restore or improve human tissue function. We hypothesized that the pleotropic effects of insulin-like growth factor 1 (IGF1) would enhance the engineering of capillary-like vasculature.

MATERIALS AND METHODS

The impact of IGF1 upon vasculogenesis was examined in in vitro cultures for a period of up to 40 days and as subcutaneous implants within immunodeficient mice. Co-cultures of human umbilical vein endothelial cells and human bone marrow-derived mesenchymal stem cells in collagen-fibronectin hydrogels were supplemented with either recombinant IGF1 protein or genetically engineered cells to provide sustained IGF1. Morphometric analysis was performed on the vascular networks that formed in four concentrations of IGF1.

RESULTS

IGF1 supplementation significantly enhanced de novo vasculogenesis both in vitro and in vivo. Effects were long-term as they lasted the duration of the study period, and included network density, vessel length, and diameter. Bifurcation density was not affected. However, the highest concentrations of IGF1 tested were either ineffective or even deleterious. Sustained IGF1 delivery was required in vivo as the inclusion of recombinant IGF1 protein had minimal impact.

CONCLUSION

IGF1 supplementation can be used to produce neovasculature with significantly enhanced network density and durability. Its use is a promising methodology for engineering de novo vasculature to support regeneration of functional tissue.

Hypoxia enhances angiogenesis in an adipose-derived stromal cell/endothelial cell co-culture 3D gel model

OBJECTIVES

This study aimed to investigate the influence of hypoxia on angiogenesis in a 3D gel, with co-culturing adipose-derived stromal cells (ASCs) and endothelial cells (ECs).

MATERIALS AND METHODS

ASCs from green fluorescent protein-labeled mice and ECs from red fluorescent protein-labeled mice were co-cultured in 3D collagen gels at 1:1 ratio, in normal and hypoxic oxygen conditions, and morphology of angiogenesis was observed using confocal laser scanning microscopy. To discover changes in growth factors between monoculture ASCs and ECs, transwell co-cultures of ASCs and ECs were applied. Semi-quantitative PCR was performed to explore mRNA expression of growth factors.

RESULTS

Enhanced angiogenesis was observed in 3D gels implanted with 1:1 mixture of ASCs and ECs after 7 days hypoxia. Genes including VEGFA/B, EGF-1, HIF-1a, IGF-1, PDGF, TGF-β1 and BMP-2/4 in ECs, both monoculture and co-culture, were significantly enhanced after being cultured under hypoxia. In comparison, genes VEGFA/B, EGF-1, HIF-1a, TGF-β1 and BMP-2 in ASCs increased. In all, factors VEGFA/B, EGF-1, HIF-1a, TGF-β1 and BMP-2 increased in both ASCs and ECs after being cultured in hypoxia no matter whether as monoculture or co-culture.

CONCLUSIONS

Co-culture of ASCs and ECs at 1:1 ratio in a 3D gel under hypoxia promoted angiogenesis. Those growth factors which were increased in both ASCs and ECs, indicate that VEGFA/B, EGF-1, HIF-1a, TGF-β1 and BMP-2 might be responsible for enhancement in angiogenesis triggered by hypoxia.

Decellularized human amniotic membrane: how viable is it as a delivery system for human adipose tissue-derived stromal cells?

OBJECTIVES

Human amniotic membrane (HAM) has been widely used in soft tissue engineering both in its fresh form and decellularized; its efficiency to aid treatment of burn injuries is well known. On the other hand, it has been reported clinically by several studies that human adipose-derived stem cells (hADSC) are a promising cell source for cell therapy for burns. Recently, we have reported a new technique for decellularization of HAM. In this study, potential of prepared decellularized HAM (dHAM) as a viable support for proliferation and delivery of hADSC was investigated.

MATERIALS AND METHODS

Amniotic membranes were collected, decellularized and preserved according to the protocol described in our previously published study. hADSC were obtained from the patients undergoing elective liposuction surgery and cells were then seeded on the decellularized membrane for various times. Efficiency of the decellularized membrane as a delivery system for hADSC was investigated by MTT, LDH specific activity, DAPI staining and SEM.

RESULTS

The results showed that dHAM provided a supporting microenvironment for cell growth without producing any cytotoxic effects. In addition, the cells were spread out and actively attached to the dHAM scaffold.

CONCLUSION

These results strongly suggest that dHAMs have considerable potential as 3D cell-carrier scaffolds for delivery of hADSC, in tissue engineering and regenerative medicine applications.