An Optimized Human Erythroblast Differentiation System Reveals Cholesterol-Dependency of Robust Production of Cultured Red Blood Cells Ex Vivo.

The generation of cultured red blood cells (cRBCs) ex vivo represents a potentially unlimited source for RBC transfusion and other cell therapies. Human cRBCs can be generated from the terminal differentiation of proliferating erythroblasts derived from hematopoietic stem/progenitor cells or erythroid precursors in peripheral blood mononuclear cells. Efficient differentiation and maturation into cRBCs highly depend on replenishing human plasma, which exhibits variable potency across donors or batches and complicates the consistent cRBC production required for clinical translation. Hence, the role of human plasma in erythroblast terminal maturation is investigated and uncovered that 1) a newly developed cell culture basal medium mimicking the metabolic profile of human plasma enhances cell growth and increases cRBC yield upon erythroblast terminal differentiation and 2) LDL-carried cholesterol, as a substitute for human plasma, is sufficient to support erythroid survival and terminal differentiation ex vivo. Consequently, a chemically-defined optimized medium (COM) is developed, enabling robust generation of cRBCs from erythroblasts of multiple origins, with improved enucleation efficiency and higher reticulocyte yield, without the need for supplementing human plasma or serum. In addition, the results reveal the crucial role of lipid metabolism during human terminal erythropoiesis.

Engineered extracellular vesicles enable high-efficient delivery of intracellular therapeutic proteins.

Developing an intracellular delivery system is of key importance in the expansion of protein-based therapeutics acting on cytosolic or nuclear targets. Recently, extracellular vesicles (EVs) have been exploited as next-generation delivery modalities due to their natural role in intercellular communication and biocompatibility. However, fusion of protein of interest to a scaffold represents a widely-used strategy for cargo enrichment in EVs, which could compromise t the stability and functionality of cargo. Herein, we report intracellular delivery via EV-based approach (IDEA) that efficiently packages and delivers native proteins both in vitro and in vivo without the use of a scaffold. As a proof-of-concept, we applied the IDEA to deliver cyclic GMP-AMP synthase (cGAS), an innate immune sensor. The results showed that cGAS-carrying EVs activated interferon signaling and elicited enhanced antitumor immunity in multiple syngeneic tumor models. Combining cGAS EVs with immune checkpoint inhibition further synergistically boosted antitumor efficacy in vivo. Mechanistically, scRNA-seq demonstrated that cGAS EVs mediated significant remodelling of intratumoral microenvironment, revealing a pivotal role of infiltrating neutrophils in the antitumor immune milieu. Collectively, IDEA, as a universal and facile strategy, can be applied to expand and advance the development of protein-based therapeutics.

Wnt3a-Loaded Extracellular Vesicles Promote Alveolar Epithelial Regeneration after Lung Injury.

Compromised regeneration resulting from the deactivation of Wnt/ß-catenin signaling contributes to the progression of chronic obstructive pulmonary disease (COPD) with limited therapeutic options. Extracellular cytokine-induced Wnt-based signaling provides an alternative option for COPD treatment. However, the hydrophobic nature of Wnt proteins limits their purification and use. This study devises a strategy to deliver the membrane-bound wingless-type MMTV integration site family, member 3A (Wnt3a) over a long distance by anchoring it to the surface of extracellular vesicles (EVs). The newly engineered Wnt3aWG EVs are generated by co-expressing Wnt3a with two genes encoding the membrane protein, WLS, and an engineered glypican, GPC6ΔGPI -C1C2. The bioactivity of Wnt3aWG EVs is validated using a TOPFlash assay and a mesoderm differentiation model of human pluripotent stem cells. Wnt3aWG EVs activate Wnt signaling and promote cell growth following human alveolar epithelial cell injury. In an elastase-induced emphysema model, impaired pulmonary function and enlarged airspace are greatly restored by the intravenous delivery of Wnt3aWG EVs. Single-cell RNA sequencing-based analyses further highlight that Wnt3aWG EV-activated regenerative programs are responsible for its beneficial effects. These findings suggest that EV-based Wnt3a delivery represents a novel therapeutic strategy for lung repair and regeneration after injury.

Erythropoietic properties of human induced pluripotent stem cells-derived red blood cells in immunodeficient mice.

Transfusion of red blood cells (RBCs) is a life-saving intervention for anemic patients. Human induced pluripotent stem cells (iPSC) have the capability to expand and differentiate into RBCs (iPSC-RBCs). Here we developed a murine model to investigate the in vivo properties of human iPSC-RBCs. iPSC lines were produced from human peripheral blood mononuclear cells by transient expression of plasmids containing OCT4, SOX2, MYC, KLF4, and BCL-XL genes. Human iPSC-RBCs were generated in culture supplemented with human platelet lysate, and were CD34- CD235a+ CD233+ CD49dlow CD71low ; about 13% of iPSC-RBCs were enucleated before transfusion. Systemic administration of clodronate liposomes (CL) and cobra venom factor (CVF) to NOD scid gamma (NSG) mice markedly promoted the circulatory survival of human iPSC-RBCs following transfusion. While iPSC-RBCs progressively decreased with time, 90% of circulating iPSC-RBCs were enucleated 1 day after transfusion (CD235a+ CD233+ CD49d- CD71- ). Surprisingly, human iPSC-RBCs reappeared in the peripheral circulation at 3 weeks after transfusion at levels more than 8-fold higher than at 1 h after transfusion. Moreover, a substantial portion of the transfused nucleated iPSC-RBCs preferentially homed to the bone marrow, and were detectable at 24 days after transfusion. These results suggest that nucleated human iPSC-derived cells that homed to the bone marrow of NSG mice retained the capability to complete differentiation into enucleated erythrocytes and egress the bone marrow into peripheral blood. The results offer a new model using human peripheral blood-derived iPSC and CL/CVF-treated NSG mice to investigate the development and circulation of human erythroid cells in vivo.

Gene and protein expression in human megakaryocytes derived from induced pluripotent stem cells.

BACKGROUND: There is interest in deriving megakaryocytes (MKs) from pluripotent stem cells (iPSC) for biological studies. We previously found that genomic structural integrity and genotype concordance is maintained in iPSC-derived MKs. OBJECTIVE: To establish a comprehensive dataset of genes and proteins expressed in iPSC-derived MKs. METHODS: iPSCs were reprogrammed from peripheral blood mononuclear cells (MNCs) and MKs were derived from the iPSCs in 194 healthy European American and African American subjects. mRNA was isolated and gene expression measured by RNA sequencing. Protein expression was measured in 62 of the subjects using mass spectrometry. RESULTS AND CONCLUSIONS: MKs expressed genes and proteins known to be important in MK and platelet function and demonstrated good agreement with previous studies in human MKs derived from CD34+ progenitor cells. The percent of cells expressing the MK markers CD41 and CD42a was consistent in biological replicates, but variable across subjects, suggesting that unidentified subject-specific factors determine differentiation of MKs from iPSCs. Gene and protein sets important in platelet function were associated with increasing expression of CD41/42a, while those related to more basic cellular functions were associated with lower CD41/42a expression. There was differential gene expression by the sex and race (but not age) of the subject. Numerous genes and proteins were highly expressed in MKs but not known to play a role in MK or platelet function; these represent excellent candidates for future study of hematopoiesis, platelet formation, and/or platelet function.

BMI1 enables extensive expansion of functional erythroblasts from human peripheral blood mononuclear cells.

Transfusion of red blood cells (RBCs) from ABO-matched but genetically unrelated donors is commonly used for treating anemia and acute blood loss. Increasing demand and insufficient supply for donor RBCs, especially those of universal blood types or free of known and unknown pathogens, has called for ex vivo generation of functional RBCs by large-scale cell culture. However, generating physiological numbers of transfusable cultured RBCs (cRBCs) ex vivo remains challenging, due to our inability to either extensively expand primary RBC precursors (erythroblasts) or achieve efficient enucleation once erythroblasts have been expanded and induced to differentiation and maturation. Here, we report that ectopic expression of the human BMI1 gene confers extensive expansion of human erythroblasts, which can be derived readily from adult peripheral blood mononuclear cells of either healthy donors or sickle cell patients. These extensively expanded erythroblasts (E3s) are able to proliferate exponentially (>1 trillion-fold in 2 months) in a defined culture medium. Expanded E3 cells are karyotypically normal and capable of terminal maturation with approximately 50% enucleation. Additionally, E3-derived cRBCs can circulate in a mouse model following transfusion similar to primary human RBCs. Therefore, we provide a facile approach of generating physiological numbers of human functional erythroblasts ex vivo.

Highly efficient magnetic labelling allows MRI tracking of the homing of stem cell-derived extracellular vesicles following systemic delivery.

Human stem-cell-derived extracellular vesicles (EVs) are currently being investigated for cell-free therapy in regenerative medicine applications, but the lack of noninvasive imaging methods to track EV homing and uptake in injured tissues has limited the refinement and optimization of the approach. Here, we developed a new labelling strategy to prepare magnetic EVs (magneto-EVs) allowing sensitive yet specific MRI tracking of systemically injected therapeutic EVs. This new labelling strategy relies on the use of 'sticky' magnetic particles, namely superparamagnetic iron oxide (SPIO) nanoparticles coated with polyhistidine tags, to efficiently separate magneto-EVs from unencapsulated SPIO particles. Using this method, we prepared pluripotent stem cell (iPSC)-derived magneto-EVs and subsequently used MRI to track their homing in different animal models of kidney injury and myocardial ischemia. Our results showed that iPSC-derived EVs preferentially accumulated in the injury sites and conferred substantial protection. Our study paves a new pathway for preparing highly purified magnetic EVs and tracking them using MRI towards optimized, systemically administered EV-based cell-free therapies.

Generation and characterization of a novel human iPSC line from a resilient Alzheimer's disease patient.

Alzheimer's disease (AD) is a progressive neurodegenerative disease that is the major cause of dementia in older people. Here, we report the derivation of human induced pluripotent stem cells (iPSCs) from an AD patient at age of 80 who has the APOE ε4/ε4 genotype and is resilient to cognitive decline for 10 years. The iPSCs reprogrammed from the blood cells of this patient by transient expression of pluripotency genes maintain the ε4/ε4 genotype, are karyotypically normal and display typical iPSC characteristics. Upon differentiation, the iPSCs are able to differentiate into cells of the three germ layers, confirming their pluripotency.

Extracellular Matrix Protein Tenascin C Increases Phagocytosis Mediated by CD47 Loss of Function in Glioblastoma.

Glioblastomas (GBM) are highly infiltrated by myeloid-derived innate immune cells that contribute to the immunosuppressive nature of the brain tumor microenvironment (TME). CD47 has been shown to mediate immune evasion, as the CD47-SIRPα axis prevents phagocytosis of tumor cells by macrophages and other myeloid cells. In this study, we established CD47 homozygous deletion (CD47-/-) in human and mouse GBM cells and investigated the impact of eliminating the "don't eat me" signal on tumor growth and tumor-TME interactions. CD47 knockout (KO) did not significantly alter tumor cell proliferation in vitro but significantly increased phagocytosis of tumor cells by macrophages in cocultures. Compared with CD47 wild-type xenografts, orthotopic xenografts derived from CD47-/- tumor cells grew significantly slower with enhanced tumor cell phagocytosis and increased recruitment of M2-like tumor-associated microglia/macrophages (TAM). CD47 KO increased tumor-associated extracellular matrix protein tenascin C (TNC) in xenografts, which was further examined in vitro. CD47 loss of function upregulated TNC expression in tumor cells via a Notch pathway-mediated mechanism. Depletion of TNC in tumor cells enhanced the growth of CD47-/- xenografts in vivo and decreased the number of TAM. TNC knockdown also inhibited phagocytosis of CD47-/- tumor cells in cocultures. Furthermore, TNC stimulated release of proinflammatory factors including TNFα via a Toll-like receptor 4 and STAT3-dependent mechanism in human macrophage cells. These results reveal a vital role for TNC in immunomodulation in brain tumor biology and demonstrate the prominence of the TME extracellular matrix in affecting the antitumor function of brain innate immune cells. SIGNIFICANCE: These findings link TNC to CD47-driven phagocytosis and demonstrate that TNC affects the antitumor function of brain TAM, facilitating the development of novel innate immune system-based therapies for brain tumors.

Highly Purified Human Extracellular Vesicles Produced by Stem Cells Alleviate Aging Cellular Phenotypes of Senescent Human Cells.

Extracellular vesicles (EVs), including exosomes and microvesicles, mediate intercellular communications and exert various biological activities via delivering unique cargos of functional molecules such as RNAs and proteins to recipient cells. Previous studies showed that EVs produced and secreted by human mesenchymal stem cells (MSCs) can substitute intact MSCs for tissue repair and regeneration. In this study, we examined properties and functions of EVs from human induced pluripotent stem cells (iPSCs) that can be cultured infinitely under a chemically defined medium free of any exogenous EVs. We collected and purified EVs secreted by human iPSCs and MSCs. Purified EVs produced by both stem cell types have similar sizes (∼150 nm in diameter), but human iPSCs produced 16-fold more EVs than MSCs. When highly purified iPSC-EVs were applied in culture to senescent MSCs that have elevated reactive oxygen species (ROS), human iPSC-EVs reduced cellular ROS levels and alleviated aging phenotypes of senescent MSCs. Our discovery reveals that EVs from human stem cells can alleviate cellular aging in culture, at least in part by delivering intracellular peroxiredoxin antioxidant enzymes. Stem Cells 2019;37:779-790.

Heterozygous IDH1R132H/WT created by "single base editing" inhibits human astroglial cell growth by downregulating YAP.

Mutations in the isocitrate dehydrogenase 1 (IDH1) gene have been identified in a number of cancer types, including brain cancer. The Cancer Genome Atlas project has revealed that IDH1 mutations occur in 70-80% of grade II and grade III gliomas. Until recently, most of the functional studies of IDH1 mutations in cellular models have been conducted in overexpression systems with the IDH1 wild type background. In this study, we employed a modified CRISPR/Cas9 genome editing technique called "single base editing", and efficiently introduced heterozygous IDH1 R132H mutation (IDH1R132H/WT) in human astroglial cells. Global DNA methylation profiling revealed hypermethylation as well as hypomethylation induced by IDH1R132H/WT. Global gene expression analysis identified molecular targets and pathways altered by IDH1R132H/WT, including cell proliferation, extracellular matrix (ECM), and cell migration. Our phenotype analysis indicated that compared with IDH1 wild type cells, IDH1R132H/WT promoted cell migration by upregulating integrin ß4 (ITGB4); and significantly inhibited cell proliferation. Using our mutated IDH1 models generated by "single base editing", we identified novel molecular targets of IDH1R132H/WT, namely Yes-associated protein (YAP) and its downstream signaling pathway Notch, to mediate the cell growth-inhibiting effect of IDH1R132H/WT. In summary, the "single base editing" strategy has successfully created heterozygous IDH1 R132H mutation that recapitulates the naturally occurring IDH1 mutation. Our isogenic cellular systems that differ in a single nucleotide in one allele of the IDH1 gene provide a valuable model for novel discoveries of IDH1R132H/WT-driven biological events.

Conditional gene knockout and reconstitution in human iPSCs with an inducible Cas9 system.

Precise genome editing in human induced pluripotent stem cells (iPSCs) significantly enhances our capability to use human iPSCs for disease modeling, drug testing and screening as well as investigation of human cell biology. In this study, we seek to achieve conditional expression of the CD55 gene in order to interrogate its functions. We used two human iPSC lines that have unique genotypes, and constructed an inducible Cas9 gene expression system that is integrated at the AAVS1 safe harbor site in the human genome. Using paired guide RNAs, we observed efficient knock-out with an intended deletion in the coding region of several genes including CD55 and ETV6 genes. This paired guide RNA approach enabled us to efficiently identify homozygous iPSC clones with an intended deletion. Once an iPSC clone lacking CD55 expression was identified and characterized, we were able to use the same doxycycline system to induce expression of a CD55 transgene from a piggyBac vector, in both undifferentiated and differentiated iPSCs. This single cell line of gene knock-out complemented with an inducible transgene is sufficient to achieve conditional expression of the CD55 gene. The methodology described here is broadly applicable to other genes in order to interrogate their functions.

mTOR inhibition improves the immunomodulatory properties of human bone marrow mesenchymal stem cells by inducing COX-2 and PGE2.

BACKGROUND: Bone marrow mesenchymal stem cells (MSCs) are promising candidates for the treatment of various inflammatory disorders due to their profound immunomodulatory properties. However, the immunosuppressive capacity of MSCs needs activation by an inflammatory microenvironment, which may negatively impact the therapeutic effect because of increased immunogenicity. Here we explore the role of mammalian target of rapamycin (mTOR) signaling on the immunosuppressive capacity of MSCs, and its impact on immunogenicity in the inflammatory microenvironment. METHODS: Human bone marrow MSCs were cocultured with activated human peripheral blood mononuclear cells, CD4+ T cells, and mouse splenocytes to evaluate the immunosuppressive function. Immunosuppressive factors were assessed by quantitative real-time polymerase chain reaction (PCR), Western blot, and enzyme-linked immunosorbent assay (ELISA). The expression of major histocompatibility complex (MHC) was detected by flow cytometry. Short hairpin (sh)RNA was used to downregulate tuberous sclerosis complex (TSC)2, TSC1, and cyclooxygenase (COX)-2 in MSCs. RESULTS: Inhibition of mTOR signaling using rapamycin enhanced the immunosuppressive functions of MSCs, while prolonged exposure to rapamycin did not. The enhancement of the immunosuppressive function was independent of the inflammatory microenvironment, and occurred mainly through the upregulation of COX-2 and prostaglandin-E2 (PGE2) expression. Furthermore, mTOR inhibition did not impact the immunogenicity of MSCs. However, the upregulated expression of MHC class II molecules by interferon (IFN)-γ was attenuated by mTOR inhibition, whereas TSC2 knockdown had the opposite effect. CONCLUSIONS: These results reveal that the mTOR signaling pathway regulates MSC immunobiology, and short-term exposure to rapamycin could be a novel approach to improve the MSC-based therapeutic effect.

Generation of human iPSCs from an essential thrombocythemia patient carrying a V501L mutation in the MPL gene.

Activating point mutations in the MPL gene encoding the thrombopoietin receptor are found in 3%-10% of essential thrombocythemia (ET) and myelofibrosis patients. Here, we report the derivation of induced pluripotent stem cells (iPSCs) from an ET patient with a heterozygous MPL V501L mutation. Peripheral blood CD34+ progenitor cells were reprogrammed by transient plasmid expression of OCT4, SOX2, KLF4, c-MYC plus BCL2L1 (BCL-xL) genes. The derived line M494 carries a MPL V501L mutation, displays typical iPSC morphology and characteristics, are pluripotent and karyotypically normal. Upon differentiation, the iPSCs are able to differentiate into cells derived from three germ layers.

A synthetic three-dimensional niche system facilitates generation of functional hematopoietic cells from human-induced pluripotent stem cells.

BACKGROUND: The efficient generation of hematopoietic stem cells (HSCs) from human-induced pluripotent stem cells (iPSCs) holds great promise in personalized transplantation therapies. However, the derivation of functional and transplantable HSCs from iPSCs has had very limited success thus far. METHODS: We developed a synthetic 3D hematopoietic niche system comprising nanofibers seeded with bone marrow (BM)-derived stromal cells and growth factors to induce functional hematopoietic cells from human iPSCs in vitro. RESULTS: Approximately 70 % of human CD34+ hematopoietic cells accompanied with CD43+ progenitor cells could be derived from this 3D induction system. Colony-forming-unit (CFU) assay showed that iPSC-derived CD34+ cells formed all types of hematopoietic colonies including CFU-GEMM. TAL-1 and MIXL1, critical transcription factors associated with hematopoietic development, were expressed during the differentiation process. Furthermore, iPSC-derived hematopoietic cells gave rise to both lymphoid and myeloid lineages in the recipient NOD/SCID mice after transplantation. CONCLUSIONS: Our study underscores the importance of a synthetic 3D niche system for the derivation of transplantable hematopoietic cells from human iPSCs in vitro thereby establishing a foundation towards utilization of human iPSC-derived HSCs for transplantation therapies in the clinic.

Progress and challenges in generating functional hematopoietic stem/progenitor cells from human pluripotent stem cells.

The generation of hematopoietic stem cells (HSCs) from human pluripotent stem cells (hPSCs) in vitro holds great potential for providing alternative sources of donor cells for clinical HSC transplantation. However, the low efficiency of current protocols for generating blood lineages and the dysfunction identified in hPSC-derived hematopoietic cells limit their use for full hematopoietic reconstitution in clinics. This review outlines the current understanding of in vitro hematopoietic differentiation from hPSCs, emphasizes the intrinsic and extrinsic molecular mechanisms that are attributed to the aberrant phenotype and function in hPSC-derived hematopoietic cells, pinpoints the current challenges to develop the truly functional HSCs from hPSCs for clinical applications and explores their potential solutions.

[Research advances on directional induction and differentiation in vitro from human pluripotent stem cells into erythrocytes].

Red blood cell transfusion is an effective method to treat acute hemorrhage and severe anemia. However, blood source from donors is very limited, and transfusion-transmitted diseases occurred frequently, thus threatening human health. Therefore, the safe, abundant and functional blood source is needed. Generation of blood cells from human pluripotent stem cells(hPSC) will offer alternative approach. Lots of studies have been focused on erythroid cell differentiation in vitro, including how to enhance efficiency and improve their function. In this review, the research advances on differentiation methods and the regulatory mechanism are summarized. In addition, the progress in PSC differentiation into erythrocytes and the problems to be solved are discussed briefly.

Direct activation of human and mouse Oct4 genes using engineered TALE and Cas9 transcription factors.

The newly developed transcription activator-like effector protein (TALE) and clustered regularly interspaced short palindromic repeats/Cas9 transcription factors (TF) offered a powerful and precise approach for modulating gene expression. In this article, we systematically investigated the potential of these new tools in activating the stringently silenced pluripotency gene Oct4 (Pou5f1) in mouse and human somatic cells. First, with a number of TALEs and sgRNAs targeting various regions in the mouse and human Oct4 promoters, we found that the most efficient TALE-VP64s bound around -120 to -80 bp, while highly effective sgRNAs targeted from -147 to -89-bp upstream of the transcription start sites to induce high activity of luciferase reporters. In addition, we observed significant transcriptional synergy when multiple TFs were applied simultaneously. Although individual TFs exhibited marginal activity to up-regulate endogenous gene expression, optimized combinations of TALE-VP64s could enhance endogenous Oct4 transcription up to 30-fold in mouse NIH3T3 cells and 20-fold in human HEK293T cells. More importantly, the enhancement of OCT4 transcription ultimately generated OCT4 proteins. Furthermore, examination of different epigenetic modifiers showed that histone acetyltransferase p300 could enhance both TALE-VP64 and sgRNA/dCas9-VP64 induced transcription of endogenous OCT4. Taken together, our study suggested that engineered TALE-TF and dCas9-TF are useful tools for modulating gene expression in mammalian cells.

[Screening and identification of high-yield poly(ß-malic acid) bacterial strain].

OBJECTIVE: To isolate and identify the high-yield poly-malic acid (PMLA) bacterial strains from the nature. METHODS: Samples were collected and cultured. The high-yield PMLA bacterial strains were screened through morphological observation, qualitative PMLA tests by HPLC and ITS sequence analysis on the isolated bacterial strains. RESULTS: A high-yield PMLA strain II 04 was isolated, the yield of PMLA of the strain reached to 26.23g/L in the rotary shaker at 25 degree for 7d. From morphological observation and ITS sequences analysis, the strain belonged to Aureobasidium pullulans, and named as Aureobasidium pullulans ZUCC-41. CONCLUSION: A high-yield bacterial strain has been isolated from the nature and identified to be Aureobasidium pullulans.

Construction of a eukaryotic expression vector pEGFP-C1-BMP-2 and its effect on cell migration.

OBJECTIVE: Bone morphogenetic proteins (BMPs) are known to play an important role in bone and cartilage development. Recent research has shown that BMPs may induce tumorigenesis and promote tumor to spread, but the molecular mechanisms have not been elucidated. The aim of the present study was to investigate the regulatory function of BMP-2 in the migration of COS-7 cells and the underlying mechanisms. METHODS: Human BMP-2 genetic fragment was amplified and introduced into the pEGFP-C1 vector. After being confirmed by XhoI and BamHI digestion analyses and DNA sequencing, the recombinant pEGFP-C1-BMP-2 plasmid was transfected into COS-7 cells. The influence of BMP-2 on cell migration and cofilin activity was detected by cell scratch assay and Western blotting. RESULTS: The recombinant pEGFP-C1-BMP-2 was effectively expressed in COS-7 cells. An increased phosphorylation of both LIMK1 and cofilin and an enhancement of cell migration were observed in cells with overexpression of BMP-2. CONCLUSIONS: A recombinant pEGFP-C1-BMP-2 vector was successfully constructed and overexpression of BMP-2 regulated the activities of the downstream molecules of the Rho GTPase signaling pathway, which might contribute to the enhancement of cell migration.