In vivo osteogenic potential of human adipose-derived stem cells/poly lactide-co-glycolic acid constructs for bone regeneration in a rat critical-sized calvarial defect model

Recent studies suggest that human adipose tissue contains pluripotent stem cells, which are similar to bone marrow-derived stem cells. The objective of the present study was to assess the effect in bone regenerating capability of human adipose-derived stem cells (ADSCs) cultured in osteogenic media layered over poly lactide-co-glycolic acid (PLGA) and implanted in a critical nude rat calvarial defect. Twenty-seven nude rats were randomized into 3 groups (n = 9): 1) PLGA alone (control), 2) PLGA with undifferentiated ADSCs, and 3) PLGA with differentiated ADSCs. These 3 groups were divided into 9 subgroups (n = 3) according to in vitro pre-cultured periods (day 1 pre-culture (Group1), day 7 pre-culture (Group2), and day 14 pre-culture (Group3)) before implantation. An 8 mm critical-size circular calvarial defect was made in each nude rat. Specimens were harvested at 12 weeks post-implantation and evaluated radiographically and histologically. Radiodensitometric analysis revealed significantly higher bone growth in implants pre-cultured in osteogenic media for 14 days for Group 3. Histomorphometric analysis demonstrated that Groups 2 and 3 had bone formation filling 35% to 72% of the area of the defect after transplantation with cells that had been pre-cultured for 14 days. Constructs with differentiated ADSCs (Group 3) had noticeably more maximal and robust bone tissue regeneration than constructs with undifferentiated ADSCs (Group 2). These data provide evidence that constructs or implants made of PLGA and osteogenically differentiated ADSCs pre-cultured for 14 days before transplantation have better, more-robust bone regeneration capability in critical-sized skeletal defects than constructs with undifferentiated ADSCs. Human adipose derived stem cells can therefore be used as seed cells to construct tissue-engineered bone.     

Paper-based bioactive scaffolds for stem cell-mediated bone tissue engineering

Bioactive, functional scaffolds are required to improve the regenerative potential of stem cells for tissue reconstruction and functional recovery of damaged tissues. Here, we report a paper-based bioactive scaffold platform for stem cell culture and transplantation for bone reconstruction. The paper scaffolds are surface-engineered by an initiated chemical vapor deposition process for serial coating of a water-repellent and cell-adhesive polymer film, which ensures the long-term stability in cell culture medium and induces efficient cell attachment. The prepared paper scaffolds are compatible with general stem cell culture and manipulation techniques. An optimal paper type is found to provide structural, physical, and mechanical cues to enhance the osteogenic differentiation of human adipose-derived stem cells (hADSCs). A bioactive paper scaffold significantly enhances in vivo bone regeneration of hADSCs in a critical-sized calvarial bone defect. Stacking the paper scaffolds with osteogenically differentiated hADSCs and human endothelial cells resulted in vascularized bone formation in vivo. Our study suggests that paper possesses great potential as a bioactive, functional, and cost-effective scaffold platform for stem cell-mediated bone tissue engineering. To the best of our knowledge, this is the first study reporting the feasibility of a paper material for stem cell application to repair tissue defects.     

The nanoscale geometry of TiO2 nanotubes influences the osteogenic differentiation of human adipose-derived stem cells by modulating H3K4 trimethylation

Nanostructured materials can direct stem cell lineage commitment solely by their various, but controllable, geometric cues, which would be very important for their future application in bone tissue engineering and bone regeneration. However, the mechanisms by which nano-geometric cues dictate the osteogenic differentiation of stem cells remain unclear. Epigenetics is central to cellular differentiation, a process that regulates heritable and long-lasting alterations in gene expression without changing the DNA sequence. Here, we explored the varied osteogenic behaviors of human adipose-derived stem cells (hASCs) on titanium dioxide (TiO₂) nanotube arrays of different diameters. Both in vitro and in vivo studies demonstrated that the nanoscale geometry influenced cellular differentiation and TiO₂ nanotubes with a diameter of 70 nm was the optimal dimension for the osteogenic differentiation of hASCs. Moreover, we observed that TiO₂ nanotubes promoted the osteogenic differentiation of hASCs by upregulating methylation level of histone H3 at lysine 4 (H3K4) in the promoter regions of osteogenic genes Runx2 and osteocalcin, by inhibiting demethylase retinoblastoma binding protein 2 (RBP2). These results revealed, for the first time, the epigenetic mechanism by which nanotopography directs stem cell fate.     

Dental follicle cells combined with beta-tricalcium phosphate ceramic: A novel available therapeutic strategy to restore periodontal defects

Tissue-engineering strategies to restore the periodontal defects are being developed. It will result in the periodontal formation and growing new function tissue rather than new replacement of periodontium. Although a number of procedures have been investigated in an attempt to regenerate lost periodontal tissue, none has yet led to new cementum formation, remodeling of the periodontal ligament, and new bone formation in clinic. Dental follicle cells (DFCs), as a progenitor cell of periodontal ligament cell and stem cell, have more potential abilities than PDL-cell in formation of periodontal tissue. More researches focus on the inductive environments, such as bone morphogenetic protein-2 (BMP-2), dexamethasone, and transfer growth factor, and scaffold. We hypotheses that DFCs from Beagle’s dog are isolated, induced by BMP-2, basic-fibroblast growth factor and dexamethasone, and seeded by beta-tricalcium phosphate ceramic (beta-TCP), then the complex was auto-implanted into the periodontal defects in the same Beagle’s dog to observe the regeneration of periodontal tissue in vivo. The study will explore the feasibility and application of restore of periodontal defects by DFCs–beta-TCP complex. We believe it is especially helpful to future clinical study and application.     

Dental follicle cells combined with beta-tricalcium phosphate ceramic: A novel available therapeutic strategy to restore periodontal defects

Tissue-engineering strategies to restore the periodontal defects are being developed. It will result in the periodontal formation and growing new function tissue rather than new replacement of periodontium. Although a number of procedures have been investigated in an attempt to regenerate lost periodontal tissue, none has yet led to new cementum formation, remodeling of the periodontal ligament, and new bone formation in clinic. Dental follicle cells (DFCs), as a progenitor cell of periodontal ligament cell and stem cell, have more potential abilities than PDL-cell in formation of periodontal tissue. More researches focus on the inductive environments, such as bone morphogenetic protein-2 (BMP-2), dexamethasone, and transfer growth factor, and scaffold. We hypotheses that DFCs from Beagle’s dog are isolated, induced by BMP-2, basic-fibroblast growth factor and dexamethasone, and seeded by beta-tricalcium phosphate ceramic (beta-TCP), then the complex was auto-implanted into the periodontal defects in the same Beagle’s dog to observe the regeneration of periodontal tissue in vivo. The study will explore the feasibility and application of restore of periodontal defects by DFCs–beta-TCP complex. We believe it is especially helpful to future clinical study and application.     

成骨诱导脂肪基质细胞在骨组织工程体内成骨中的作用

背景：以往研究认为,经过成骨诱导后的脂肪基质细胞通过转化为成骨细胞分泌骨基质进而修复骨缺损,然而并没有明确结论证实。 目的：将经过体外成骨诱导的脂肪基质细胞复合支架材料分别植入骨缺损区和非骨区,根据是否成骨,验证经过成骨诱导后的脂肪基质细胞是否转化为成骨细胞。 方法：取12月龄犬背部皮下脂肪,经胶原酶消化法获得单个核细胞,将培养的第3代细胞与双相磷酸钙陶瓷形成复合物。在犬下颌骨两侧制备长20 mm、高10 mm的箱状缺损,拔除术区牙齿,将细胞支架复合物植入一侧术区,空白侧留作对照;另外在犬背部皮下肌肉区植入细胞支架复合物及骨诱导性磷酸钙陶瓷材料,术后6周及12周经组织学检测骨缺损修复情况。 结果与结论：脂肪基质细胞复合双相磷酸钙陶瓷在骨缺损区成骨,在肌肉区未形成新骨;骨诱导性磷酸钙陶瓷在肌肉区形成新骨。提示成骨诱导并不能将脂肪基质细胞转化为成骨细胞,其确切机制有待进一步研究。     

Periodontal tissue regeneration with adipose-derived stem cells

A number of surgical techniques have been developed to promote periodontal tissue regeneration. Bone marrow-derived stem cells have also been shown to promote periodontal tissue regeneration. In this study, we sought to determine whether adipose-derived stem cells (ASCs) can promote periodontal tissue regeneration as well. ASCs were isolated from a Wistar rat, passaged twice, mixed with platelet-rich plasma (PRP) obtained from inbred rats, and implanted into the periodontal tissue defect that had been generated in the test rats. Tissue specimens were harvested after 2, 4, and 8 weeks for histological analysis. Rats that received PRP only or were not implanted served as controls. A small amount of alveolar bone regeneration was observed 2 and 4 weeks after ASC/PRP implantation. Moreover, 8 weeks after implantation, a periodontal ligament-like structure was observed along with alveolar bone. These observations suggest that ASCs can promote periodontal tissue regeneration in vivo. Because large amounts of human lipoaspirates are readily available, and their procurement induces only low morbidity, ASCs may be useful in future clinical cell-based therapy for periodontal disease.     

Heterodimeric BMP-2/7 exhibits different osteoinductive effects in human and murine cells

As robust osteoinductive cytokines, bone morphogenetic proteins (BMPs) play a significant role in bone tissue engineering. Constituted of two different polypeptides, heterodimeric BMPs are more effective than the homodimers in bone formation. While most studies focused on the murine cell lines, such as murine preosteoblasts MC3T3-E1, the role of heterodimeric BMPs in the osteogenic differentiation of human cells remains uncertain, which hinders their application to practical treatment. In this study, we compared the osteoinductive effects of BMP-2/7 heterodimer in human adipose-derived stem cells (hASCs) with their homodimers BMP-2 and BMP-7, in which MC3T3-E1 cells were utilized as a positive control. The results indicated that BMP-2/7 was not a stronger inducer during the osteogenic differentiation of hASCs as that for MC3T3-E1, and extracellular-signal-regulated kinase signaling played a role in the different effects of BMP-2/7 between hASCs and MC3T3-E1. Our study demonstrates the osteoinductive effects of heterodimeric BMP-2/7 present in a cell-specific pattern and cautions should be taken when applying heterodimeric BMP-2/7 to clinical practice.     

Suppression of zinc finger protein 467 alleviates osteoporosis through promoting differentiation of adipose derived stem cells to osteoblasts

Osteoblast and adipocyte are derived from common mesenchymal progenitor cells. The bone loss of osteoporosis is associated with altered progenitor differentiation from an osteoblastic to an adipocytic lineage. In this study, a comparative analysis of gene expression profiling using cDNA microarray and realtime-PCR indicated that Zinc finger protein 467 (Zfp467) involved in adipocyte and osteoblast differentiation of cultured adipose derived stem cells (ADSCs). Our results showed that RNA interference for Zfp467 in ADSCs inhibited adipocyte formation and stimulated osteoblast commitment. The mRNA levels of osteogenic and adipogenic markers in ADSCs were regulated by si-Zfp467. Zfp467 RNAi in ADSCs could restore bone function and structure in an ovariectomized (OVX)-induced osteoporotic mouse model. Thus Zfp467 play an important role in ADSCs differentiation to adipocyte and osteoblast. This has relevance to therapeutic interventions in osteoporosis, including si-Zfp467-based therapies currently available, and may be of relevance for the use of adipose-derived stem cells for tissue engineering.     

A Novel Approach to Utilize Icariin as Icariin-Derived ECM on Small Intestinal Submucosa Scaffold for Bone Repair

Icariin (Ic) has been demonstrated as a potent osteoinductive compound for bone tissue engineering. However, toxic side effects of the drug and poor biocompatibility of drug delivery systems (DDSs) still limit its application for bone repair in the clinic. To overcome these disadvantages and utilize the osteoinductivity of Ic, we developed a novel method to utilize Ic as an Ic-derived osteoinductive extracellular matrix (ECM) on small intestinal submucosa (SIS) (Ic-ECM-SIS). The generated Ic-ECM-SIS scaffolds, as a natural construct, exhibited much better biocompatibility (including cell adhesion, cell survival and cell proliferation) than Ic-SIS scaffolds generated by traditional DDSs. Meanwhile, osteogenic differentiation was promoted by Ic-ECM-SIS with higher expression of alkaline phosphatase, bone sialoprotein and osteocalcin than ECM-SIS, which was same as Ic-SIS. BMP-4 expression was further increased in the cells on Ic-ECM-SIS compared to that on Ic-SIS. A mouse calvarial defect model was introduced to evaluate the function of Ic-ECM-SIS on bone regeneration in vivo. The bone regeneration was enhanced in the defects implanted with Ic-ECM-SIS, with a higher new bone formation ratio (BV/TV) than the defects implanted with ECM-SIS or Ic-SIS. Angiogenesis was also promoted by Ic-ECM-SIS implantation when compared with ECM-SIS or Ic-SIS. Thus, this work proposes a novel method for applying a drug as a drug-derived ECM-modified scaffold for bone tissue engineering.     

In vivo bone formation following transplantation of human adipose-derived stromal cells that are not differentiated osteogenically

A number of studies have shown in vivo bone regeneration by transplantation of osteogenic cells differentiated in vitro from adipose-derived stromal cells (ADSCs). However, the in vitro osteogenic differentiation process requires an additional culture period, and the dexamethasone that is generally used in the process may be cytotoxic. Here, we tested the hypothesis that ADSCs that are not differentiated osteogenically in vitro prior to transplantation would extensively regenerate bone in vivo when exogenous bone morphogenetic protein-2 (BMP-2) is delivered to the transplantation site. We fabricated a poly(dl-lactic-co-glycolic acid)/hydroxyapatite (PLGA/HA) composite scaffold with osteoactive HA that is highly exposed on the scaffold surface. This scaffold was able to release BMP-2 over a 4-week period in vitro. Human ADSCs cultured on BMP-2-loaded PLGA/HA scaffolds for 2 weeks differentiated toward osteogenic cells expressing alkaline phosphatase (ALP), osteopontin (OPN), and osteocalcin (OCN) mRNA, while cells on PLGA/HA scaffolds without BMP-2 expressed only ALP. To study in vivo bone formation, PLGA/HA scaffolds (group 1), BMP-2-loaded PLGA/HA scaffolds (group 2), undifferentiated ADSCs seeded on PLGA/HA scaffolds (group 3), and undifferentiated ADSCs seeded on BMP-2-loaded PLGA/HA scaffolds (group 4) were implanted into dorsal, subcutaneous spaces of athymic mice. Eight weeks after implantation, group 4 exhibited a 25-fold greater bone formation area and 5-fold higher calcium deposition than group 3. Bone regeneration by transplanted human ADSCs in group 4 was confirmed by expression of human-specific osteoblastic genes, ALP, collagen type I, OPN, OCN, and bone sialoprotein, while group 3 expressed much lower levels of collagen type I and OPN mRNA only. This study demonstrates the feasibility of extensive in vivo bone regeneration by transplantation of ADSCs without prior in vitro osteogenic differentiation, and that a PLGA/HA composite BMP-2 delivery system stimulates bone regeneration following transplantation of undifferentiated human ADSCs.     

Comparative study of osteogenic differentiation potential of mesenchymal stem cells derived from bone marrow and adipose tissue of osteoporotic female rats

Osteoporosis causes reduction of osteogenic differentiation of mesenchymal stem cells (MSCs) from bone marrow and adipose tissue. This study was designed to compare the osteogenic potential of bone marrow mesenchymal stem cells (BMMSCs) and adipose-derived stem cells (ADSCs) of ovariectomized (OVX) rats. MSC were harvested from bone marrow and inguinal fat pads of six OVX rats. The limitations of this report are that cells from different animals were pooled for the purpose of the experiments that were carried out in this study. At 7, 14 and 21?d of osteogenic differentiation, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) conversion, alkaline phosphatase activity and gene expression for collagen I, osteocalcin, bone sialoprotein, osteopontin and bone morphogenetic protein-2 bone morphogenetic protein-2 (BMP-2) were analyzed. At 21?d, percentage of cells per field and percentage of mineralized nodule were analyzed. The data were subjected to analysis of variance, and the means were compared by Student–Newman–Keuls test. The cells, regardless of group, showed phenotypic characteristics consistent with stem cells. MTT conversion, alkaline phosphatase activity, percentage of mineralized nodule and expression of collagen I, osteocalcin and BMP-2 of ADSCs from OVX rats were higher when compared to BMMSCs from OVX rats in at least one of the evaluated periods (p?p?相似文献   

Evaluation of the effect of adipose tissue-derived stem cells on the quality of bone healing around implants

Purpose/Aim: This study evaluates the efficacy of grafted adipose-derived stem cells (ADSCs) on blade-type implants in improving osseointegration in rat femurs using a low-densitybone model. Materials and Methods: After isolating and expanding ADSCs, twice-passaged cells were seeded on blade-type implants on culture plates. Osteogenic induction of grafted cells began after attaching cells to the prepared titanium surfaces and it continued for 4 days. The scaffolds were then implanted in the femurs of Wistar rats. Osteogenic differentiation of these cells was confirmed using polymerase chain reaction (PCR) and alizarin red staining ofthe mineralized extracellular matrix. After 8 weeks, histological and histomorphometric evaluations of undecalcified resin sections (bone–implant contact [BIC] % and bone mineral index [BMI]) were performed using light microscopy and scanning electron microscopy. Results: Alizarin red staining in conjunction with gene expression results confirmed osteogenic differentiation. Histomorphometric assessment using scanning electron microscopy demonstrated improved BIC% and BMI near the treated surface compared with the untreated surface. Conclusions: The complex of differentiated grafted ADSCs and extracellular matrix and the macrodesign and microdesign of the implant can improve osseointegration in low-density bone.     

Expansion and delivery of adipose-derived mesenchymal stem cells on three microcarriers for soft tissue regeneration

Cell/microcarrier combinations can be injected to repair tissue defects, but whether currently available microcarriers can be utilized to repair different tissue defects remains unknown. Here, we compared the suitability of fabricated micronized acellular dermal matrix (MADM), micronized small intestinal submucosa (MSIS), and gelatin microspheres as expansion and delivery scaffolds for adipose-derived mesenchymal stem cells (ADSCs). The results of MTS assay, scanning electron microscopy (SEM), and flow cytometry suggested that the three microcarriers all have good biocompatibility. Quantitative polymerase chain reaction revealed enhanced epidermal growth factor, vascular endothelial growth factor, basal fibroblast growth factor, and transforming growth factor-β expression levels after ADSCs had been cultured on MADM or MSIS for 5 days. After culturing ADSCs on microcarriers in osteogenic medium for 7 days, the expression levels of bone formation-related genes were enhanced. ADSC/microcarrier treatment accelerated wound closure. The ADSC/MADM and ADSC/MSIS combinations retained more of the original implant volume at 1 month postimplantation than ADSC/gelatin microspheres combination in soft-tissue augmentation studies. All implants displayed fibroblast and capillary vessel infiltrations; but ectopic bone formation did not occur, and the calvarial defect repair results were unfavorable. Our study demonstrates the potential utility of these microcarriers not only as a cell-culture substrate but also as a cell-transplantation vehicle for skin regeneration and soft-tissue reconstruction.     

高糖及糖基化终末产物对人脂肪干细胞成骨分化能力的影响

背景：因糖尿病条件下骨质代谢存在紊乱,对这类骨缺损的修复具有挑战性,研究糖尿病环境下脂肪干细胞的成骨特性将为其在特定环境下的应用提供理论基础。 目的：观察高糖、糖基化终末产物对人脂肪干细胞成骨分化能力的影响。 方法：选取27.5 mmol/L高糖、100 mg/L糖基化终末产物体外模拟糖尿病环境,干预人脂肪干细胞成骨分化;实验分为4组,每组设立6个样本。通过荧光染色检测脂肪干细胞诱导成骨21 d时的Ⅰ型胶原表达量,矿化结节染色观测各组中等量脂肪干细胞在14,21,28 d时矿化结节形成的数量。 结果与结论：21 d时,高糖联合糖基化终末产物组中Ⅰ型胶原荧光强度较正常组低2.76倍;5个视野下脂肪干细胞平均矿化结节数量与正常组、单纯高糖组、单纯糖基化终末产物组相比明显下降,差异有显著性意义(P < 0.01)。高糖及糖基化终末产物会抑制脂肪干细胞向成骨方向的同源分化,提示糖尿病环境下,高糖与糖基化终末产物的存在是导致脂肪干细胞成骨分化能力下降的不利因素。     

Uniformly-aligned gelatin/polycaprolactone fibers promote proliferation in adipose-derived stem cells and have distinct effects on cardiac cell differentiation

Cardiac tissue engineering is a promising technique to regenerate cardiac tissue and treat cardiovascular disease. Here we applied a modified method to generate ultrafine uniformly-aligned composite gelatin/polycaprolactone fibers that mimic functional heart tissue. We tested the physical properties of these fibers and analyzed how these composite fibrous scaffolds affected growth and cardiac lineage differentiation in rat adipose-derived stem cells (rADSCs). We found that uniformly aligned composite fiber scaffolds had an anisotropic arrangement, functional mechanical properties, and strong hydrophilicity. The anisotropic scaffolds improved cell attachment, viability, and proliferative capacity of ADSCs over randomly-aligned scaffolds. Furthermore, uniformly aligned composite fiber scaffolds increased the efficiency of cardiomyogenic differentiation, but might reduce the efficiency of cardiac conduction system cell differentiation in ADSCs compared to randomly-oriented scaffolds and tissue culture polystyrene. However, the randomly-oriented composite scaffolds showed no obviously facilitated effects over tissue culture polystyrene on the two cells’ differentiation process. The above results indicate that the scaffold fiber alignment has a greater effect on cell differentiation than the composition of the scaffold. Together, the uniformly-aligned composite fibers displayed excellent physical and biocompatible properties, promoted ADSC proliferation, and played distinct roles in the differentiation of cardiomyogenic cells and cardiac conduction system cells from ADSCs. These results provide new insight for the application of anisotropic fibrous scaffolds in cardiac tissue engineering for both in vitro and in vivo research.     

A comparative study of proliferation and osteogenic differentiation of adipose-derived stem cells on akermanite and beta-TCP ceramics

This study investigated the in vitro effects of akermanite, a new kind of Ca-, Mg-, Si-containing bioceramic, on the attachment, proliferation and osteogenic differentiation of human adipose-derived stem cells (hASCs). Parallel comparison of the cellular behaviors of hASCs on the akermanite was made with those on beta-tricalcium phosphate (beta-TCP). Scanning electron microscope (SEM) observation and fluorescent DiO labeling were carried out to reveal the attachment and growth of hASCs on the two ceramic surfaces, while the quantitative assay of cell proliferation with time was detected by DNA assay. Osteogenic differentiation of hASCs cultured on the akermanite and beta-TCP was assayed by ALP expression and osteocalcin (OCN) deposition, which was further confirmed by Real-time PCR analysis for markers of osteogenic differentiation. It was shown that hASCs attached and spread well on the akermanite as those on beta-TCP, and similar proliferation behaviors of hASCs were observed on the two ceramics. Both of them exhibited good compatibility to hASCs with only minor cytotoxicity as compared with the tissue culture plates. Interestingly, the osteogenic differentiation of hASCs could be enhanced on the akermanite compared with that on the beta-TCP when the culture time was extended to approximately 10 days. Thus, it can be ascertained that akermanite ceramics may serve as a potential scaffold for bone tissue engineering.     

Nitric oxide production during the osteogenic differentiation of human periodontal ligament mesenchymal stem cells

The critical tissues that require regeneration in the periodontium are of mesenchymal origin; therefore, the ability to identify, characterize and manipulate mesenchymal stem cells within the periodontium is of considerable clinical significance. In particular, recent findings suggest that periodontal ligament cells may possess many osteoblast-like properties. In the present study, periodontal ligament mesenchymal stem cells obtained from healthy volunteers were maintained in culture until confluence and then induced to osteogenic differentiation. Intracellular calcium ([Ca²⁺]_i) concentration and nitric oxide, important signalling molecules in the bone, were measured along with cell differentiation. Alkaline phosphatase activity was assayed and bone nodule-like structures were evaluated by means of morphological and histochemical analysis. Our results showed that the periodontal ligament mesenchymal stem cells underwent an in vitro osteogenic differentiation, resulting in the appearance of active osteoblast-like cells together with the formation of calcified deposits. Differentiating cells were also characterized by an increase of [Ca²⁺]_i and nitric oxide production. In conclusion, our data show a link between nitric oxide and the osteogenic differentiation of human periodontal ligament mesenchymal stem cells, thus suggesting that local reimplantation of expanded cells in conjugation with a nitric oxide donor could represent a promising method for treatment of periodontal defects.     

Locally applied vascular endothelial growth factor A increases the osteogenic healing capacity of human adipose-derived stem cells by promoting osteogenic and endothelial differentiation

Human adipose-derived stem cells (hASCs) are known for their capability to promote bone healing when applied to bone defects. For bone tissue regeneration, both sufficient angiogenesis and osteogenesis is desirable. Vascular endothelial growth factor A (VEGFA) has the potential to promote differentiation of common progenitor cells to both lineages. To test this hypothesis, the effects of VEGFA on hASCs during osteogenic differentiation were tested in vitro. In addition, hASCs were seeded in murine critical-sized calvarial defects locally treated with VEGFA. Our results suggest that VEGFA improves osteogenic differentiation in vitro as indicated by alkaline phosphatase activity, alizarin red staining, and quantitative real-time polymerase chain reaction analysis. Moreover, local application of VEGFA to hASCs significantly improved healing of critical-sized calvarial defects in vivo. This repair was accompanied by a striking enhancement of angiogenesis. Both paracrine and, to a lesser degree, cell-autonomous effects of VEGFA-treated hASCs were accountable for angiogenesis. These data were confirmed by using CD31(-) /CD45(-) mouse ASCs(GFP+) cells. In summary, we demonstrated that VEGFA increased osteogenic differentiation of hASCS in vitro and in vivo, which was accompanied by an enhancement of angiogenesis. Additionally, we showed that during bone regeneration, the increase in angiogenesis of hASCs on treatment with VEGFA was attributable to both paracrine and cell-autonomous effects. Thus, locally applied VEGFA might prove to be a valuable growth factor that can mediate both osteogenesis and angiogenesis of multipotent hASCs in the context of bone regeneration.